Southern Yosemite Climbing Discussions
Southern Yosemite Categories => General Discussion => Topic started by: daniel banquo merrick on June 25, 2013, 06:32:57 pm
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As some of you know, I have been experimenting with drill holders. I think the designs are ready to be tested outside my immediate circle so I am looking for testers. If anybody would like to try one out, I am letting the SDS holders go for $80 and the A-Taper ones for $50. If you don't want to keep it, I'll provide a full refund when you return it. Really not looking to make money here but don't want to give them away. Plan is to train my son to make them for pocket money if there is any interest and they don't fall apart or explode.
Production will be small and slow and each will be hand made in the garage right here at home. I suspect no two will be exactly the same.
There are three sizes of the SDS holders and the A-Taper one can be made pretty much any length.
More detail here:
http://danielmerrick.com/DrillHolder/
Low tech hardening of an A-Taper holder here:
https://www.youtube.com/watch?v=a-BqFXI4bNY
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Hi Dan,
I'd be really interested in trying them out. Admittedly, I probably won't do too much hand drilling until Pinnacles season starts back up.
Like the design. It looks like it leaves enough flute exposed to drill for either a Powers 2.25" or 3" bolt.
Will you be up at ShutEye July 4th weekend? If not, I'm in San Jose, are you up this way much?
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Nice, Dan. I like that these are made by child labor in your sweat shop with no safety devices or protection for miles. America was built on these values!
I really like your quick-change design for the SDS.
Dan, I believe you are familiar with the old 5.10 drills? I believe they are a copy of the old Rawl hex stock drills that look a lot like your A taper type. In your research, have you seen the old 5.10 type spade drills in A taper? Best bit for drilling 1/4", ever. They kinda look like a sharpened screwdriver tip. I don't know if that was something that 5.10 made or was/is commercially available. I have to make my own bits and therefore custom holders and is a pain, but would love to buy them if they are still around.
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Besides me, Bob, Clint and a couple others you don’t know have tried the holders. Everybody who has tried one wants one. Bob seems to want two sizes of the SDS holder and an A-Taper to boot but that’s how he is.
Munge-
I'm in Morgan Hill so stop by if you are coming through. Sadly, I am too easy to find using google. I try to stay away from San Jose but do have to go up there for work now and then. Since I am not teaching for the summer, I'm not up there as much as usual.
Plans for the 4th haven't really jelled yet. Bob wants to go to TM but part of me wants to stay home and hang out with my wife. What I do partly hinges on what I decide to do this weekend - my son wants to go climb a peak, perhaps Matterhorn or something similar.
John-
The kid is 21 and taller than me so it's hardly child labor. My ancient and unreliable lathe (old shaky) certainly lacks anything that might be considered a safety feature. I think a lathe is just about the most dangerous machine in a shop and therefore the most fun to use. Being bald is my main safety adaptation for the lathe.
I have seen 5.10 drill photos on supertopo. I have looked at the old Rawl and Star holders. I was looking at a pristine Star holder last weekend that a friend has. It has a steeper taper than an A-Taper which might be a good idea so the bits don't get stuck. I think the 5.10 drills have this steeper taper. There really aren't any standards for A or B tapers so I had to contact manufacturers to find out what the angle of the taper is: included angle is 2.75 degrees for an A-Taper.
I've tried but given up on HSS bits since I find they need to be sharpened often, jam and break easily. I bought some $10 diamond files on Amazon and use them to sharpen carbide bits. Sharpening a new carbide bit will cut the drilling time almost in half. Try filing a carbide tip to whatever shape you like.
I think the ideal rig would be a taper holder (no moving parts and solid connection) with a sharpened carbide tip bit. A steeper taper would be good but you couldn’t use off the shelf bits.
I have bought some carbide bits where the tip has shattered easily but I think that the carbide was the wrong grade or the tip of the drill shaft was too hard and brittle. After Bob and I had a several 3/8" drill bits from one batch shatter, I took some from the next batch and drilled hard granite with a 3-lb hammer. I couldn't break the tips.
I have thought about tapering HSS drill shanks with a grinding post on a lathe. I suppose one could anneal the HSS, taper it in a lathe and then harden again but it seems like it would be a lot of work. I have ground drill shanks to a taper on a belt sander but the results are a bit imprecise. I think it could be successfully done with a jig.
The other issue with HSS bits is getting the size right. Per ANSI standard ANSI B212.15, carbide bits are slightly oversize and anchors are designed for this slightly oversize hole. To meet Hilti or Powers specs, you need to get the hole the right size. ANSI B212.15 is easy to find using google.
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I measured an old A taper bit once and got one of those "inbetween" angles, like not near a round number or a half so I wasn't sure what to trust. If someone told you 2.75deg that would make more sense. Did you make a reamer?
The Rawl holders were notorious for inconsistent holes and sometimes the bits would go in so low into the drift pin recess that you couldn't ever get the bit out again.
No crap, lathes are so dangerous. I once saw a photo of a dead guy who got sucked into a big lathe when his flannel shirt got caught and will never forgive the guy who showed it to me. It will haunt me forever.
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I am broke but would give the a taper a whirl when I get some extra $$$.
Cool to watch the R+D over the weekends at 'the lot'
Hahhaah!
Cheers
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John-
I don't think I have the tools or know-how to make a decent reamer although I did search around to see if there was an off the shelf one I could buy. I set the compound on the lathe to 1.375 deg and use a tiny solid carbide boring bar. It takes some fussing around to get the compound just right but seems to work although it takes time to bore each one. My lathe is anything but accurate and it is easy to remove too much material letting the bit go in too deep. It would be much easier on a more precise lathe. A good CNC lathe could crank them out by the thousand. I doubt I will live long enough to sell them by the thousand though.
Don't search google images for lathe injury. especially if you have safe search turned off.
Yeti-
The price is basically a security deposit. Give me the money, go use it and when you give it back I give your money back. I might even loan a couple bits if I feel so inclined. I'd like people to try them out to see if they like them and if anything goes wrong. The money is so I either get them back or I get something for my effort.
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I was just checking out one of the A taper suppliers that you have in your PDF and they mention the A taper is a 1" in 20" taper. I don't know if that translates to 2.75deg included without doing math. Let me pull out my abacus....
I really want to try one of your A taper ones but we have like 5 hand drills right now. Two SDS and three homemade spade-drill/5.10-type holders that we resharpen.
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Yeah, I've seen the 1:20 which works out to 2.86 deg. It was Relton, one of the places I listed, that gave me the 2.75 deg. Since Relton is the biggest manufacturer, I went with that. The difference is 0.002" diameter in the length of the socket in the holder.
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I picked up some old Star drills and holder. My measurements indicate that the total taper (both sides) is about 1:12 and obviously steeper than an A-Taper. My gut feel is that a steeper taper might work better and bits would be less likely to get stuck. Of course if the taper is too steep, the bits will fall out. There doesn't seem to be much research into tapers and the types of tapers in use are probably the result of empirical investigation. Collet tapers are very steep (16.85 deg) so they don't stick at all and you need a drawbar to keep them in place. Morse tapers vary a bit with size but are roughly 1:20.
A-Taper 2.75 deg or 1:20.8 (or perhaps 1:20)
Star taper 4.77 deg or 1:12
The A-Taper seems to be between a #0 (1:19.212) and a #1 (1:20.047) Morse taper in diameter. So, if you buy a Morse reamer, there is no size that will have the right diameter to match an A-Taper even if the angle of taper is close enough.
Over the weekend I chucked a broken A-Taper bit in the lathe and found that the steel was soft enough to turn. I might trim my A-Taper bits to match my A-Taper holders. I might also try a steeper taper and see how that works.
Not enough hand driller out there to be worth investing much into it though.
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You should see this bizarre bit Josh showed me this last weekend. It is a "Star" and has three straight flutes and a pointy end. The Star angle is very steep and the taper section is really short. I want to test it.
EDIT: Maybe all "Stars" are like that, three-fluted? I don't know.
Maybe you can grind or turn a drill blank to the right profile then grind it in 1/2 lengthwise, making a reamer.
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Two 3/8" (0.400" diam)
Three 5/16" (0.328" diam)
One 1/4" (0.263" diam)
All oversize just like modern carbide bits.
The better made ones say Star Hammer Twist on them. The rougher ones just have the size. The tips look pretty conventional but the shoulders are beveled back at a very shallow angle.
I've seen Rawl straight flute bits with two, three and four flutes.
(http://danielmerrick.com/SOYO_photos/StarDrills.JPG)
(http://danielmerrick.com/SOYO_photos/StarBits.JPG)
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I dug out a Rawl holder and drill. The shank of the Rawl has a straight part and a tapered part. The taper is very steep, about 1:7.5 as best I can measure it. The holder socket also has a straight part and a tapered part to match. The straight part is a very close fit. It seems that there were different holders for different drill sizes. The holder below says for 6-8-10-12 which must be the drill size. The drill shown is a 12 and measures 0.251" diameter. I have a 10 drill which measures 0.199" diameter. The sizing doesn't make sense to me. The 10 says made in England but the 12 doesn't identify a country. The holder is skinny 5/8" hex bar.
(http://danielmerrick.com/SOYO_photos/RawlDrill.JPG)
(http://danielmerrick.com/SOYO_photos/RawlBit.JPG)
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That is the same one that Josh had for sure. I must be confused about the "Star" label. Maybe I thought Star shaped bits were their thing and the suggestion screwed with my memory.
The numbers seem to be just numbers and don't really represent a measurement do they?
Josh lent me his Rawl holder just like the one you have with this giant handle with a hex hole in it. The handle is so thick you really could smash it with a sledge and probably not hurt your hand. Lost the friggin thing in the bushwhack down the left side of Big Sleep, right about where you guys just did some routes. We were doing the Tarzan-thing across the hillside and came out one drill lighter. Bummer.
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I have posted an offer for some of my prototype holders on SuperTopo. Feel free to ask for one. Sorry but I posted on ST for the mass exposure.
http://www.supertopo.com/climbers-forum/2180408/Free-drill-holders
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Well shoot, I'll test an A taper if you want.
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I was hoping you would. You'll need to send me your address.
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Just got my drill and am ready to wail on it! Thanks!
Dan, what does the "F" stamped on it mean?
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The F is just an identifier - a serial number. I've given that up and stamp them with a date code now.
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Ah, I see.
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John-
I am about to buy some bits, from ICS cutting tools 11.19 ea
NO minimum purchase.
Got any other ideas?
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ICS is probably fine. Are you getting the 1/4" or something else? I think I have one of your 17/64" in A taper in my gear somewhere. I was going to shape my own spade drills to work but want to try real A tapers too.
If you get 1/4, order me a few.....uh my wallet was right here...it must be in my car...uh...dresser...I would pay you right now but...I will pay ya back later..
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i am gonna get some sds 3/8 and 1/4.
I will trade you for shop time..
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Oh, you got one of the SDS drills? Could you order a few A tapers anyhow?
We should do a shop night for another hanger run. Maybe some 3/8" hangers also this time?
We should recruit more people who like to drink beer, make hangers and try not to lose fingers. Anyone? I think they grow back if you lose one, but I am not sure. I read that on the internet so I am pretty sure it is true.
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I watch eBay for drill bits. I see 25 1/4" SDS bits for $25 today. I bought some Relton A-Taper bits yesterday.
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John-
I have the A taper, and am looking for SDS and HSS bits.
I checked on ebay and not much 3/8ths or 1/4 for HSS or SDS.
So I may need to go with an order from a company.
What type of bits are you looking for? 1/4 HSS? What type of fluting?
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Are you aware that SDS will not work in an A taper? SDS is useless for 1/4" hand drilling anyhow.
You need one of these:
icscuttingtools.com/catalog/page_154.pdf (http://icscuttingtools.com/catalog/page_154.pdf)
They are cabide tipped like SDS.
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John-
I'm curious why you say the 1/4" SDS are useless. I have had them bend and once they start to bend, there is no saving them. I haven't drilled all that many 1/4" bolts so you certainly have more experience with them than I do.
A tip regarding the A-Taper holders. I always take the bit out when in storage and also try to take it out once a day or so when in use. My theory is that this helps prevent stuck bits. Steel about doubles in volume when it rusts so if even a little rust develops when the bit is pounded in tight, it will become hopelessly stuck.
I made a taper reamer as you suggested and although I was dubious, it seems to work really well. I turned it out of some 1/2" diameter O1 tool steel. It cuts much easier than I expected.
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Dan
Regarding SDS and 1/4" hand drilling, they simply don't progress fast enough and the hammer blows feel soft. I think they function better with the gazillions of tiny blows from a rotary hammer drill as compared to the perhaps only hundreds of really hard blows of hand drilling.
Sean and I did a route and tried a new 1/4" SDS and each hole took so friggin long we eventually switched to 3/8" shorties and got them in about the same time. To be clear, that is a 1/4"x 1-1/4" buttonhead in about 15 or more minutes and the 3/8" x 2-1/4" wedge anchors in about the same time.
I almost exclusively use my own homemade "spade"-type drill bits and homemade holder. The bits are modeled after the 5.10 bits and can get a bolt in granite clipped in about 3-5 minutes if I don't stop and rest. You can really feel that the hammer blows are more solid. They are nearly a solid shaft of hardened and tempered 1/4" HSS rod so they transmit blows as good as you can get. The bad side is that they need to be sharpened pretty often. I carry two drills when on a long FA, but they are so small and light, I am sure that two or maybe three of my drills weigh about as much as a single Hurricane drill.
As far as bits sticking, brush on some anti-seize compound on the taper and it should not get stuck. I think it is a powdered alloy of copper and some other goodies mixed into a paste and it forms a layer between the taper and bore that gives when drifted out. You can get it from any automotive supply store.
I am glad to hear your reamer worked. Too bad they aren't commercially available.
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Thanks for the correction John, I meant Carbide tipped A taper bit, the same that I saw in the Proto at the lot.
I drilled a rivet ladder, with a brand new 1/4 SDS bit, took me all day, and I am sure that sole experience ruined my drilling elbow.
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That sucks about your elbow.
Rivet ladder? Why don't you come back out for some vacation time from all that wall slavery? Your elbow will thank you.
I ordered an A taper bit from McMaster Carr and they are the same as an SDS but with an A taper base. I am sure it will not work as well as a solid bit like I have been using but I will try it anyhow. I am going to have to make a solid one for my special needs.
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I have a plan to do some drill tests in the garage to compare how fast various drills drill. My enthusiasm is low since I really don't want to spend the time pounding. I keep picturing a homemade trip hammer. I'll get to it someday.
I'm probably repeating myself (I'm old so it's allowed) but do try sharpening your carbide bits. My impression is that drilling time is cut almost in half compared to the factory points. A cheap diamond file will do the trick. I got a set of little flat diamond files for less than $10.
Something like this:
http://www.ebay.com/itm/6pc-DIAMOND-FLAT-FILE-Set-ceramics-tile-glass-/390088222449#vi-content
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I have a plan to do some drill tests in the garage to compare how fast various drills drill. My enthusiasm is low since I really don't want to spend the time pounding. I keep picturing a homemade trip hammer.
I like the automated hammer idea. I picture a Rube Goldberg machine.
I agree with the sharpening being a key factor.
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So the wife is working late so I went down to the garage and got out two brand new SDS bits and two brand new drill holders. I sharpened both bits to a similar shape. The 1/4" bit is a DeWalt made in Germany. The 3/8" bit is a Makita made in Japan. I whacked the 3/8" drill 40 times then hit the 1/4" drill 40 times, repeat, repeat, etc. After every 80 whacks I cleaned the holes. I used a heavier hammer than my usual Yosemite hammer.
After I got some depth, I started measuring the depth to the deepest part of the hole.
Turns out the 3/8" bit went 118% as fast as the 1/4" bit. I think a 1/4" hole is only faster because you don't have to drill so deep.
3/8" bit went 0.00321 inches per whack
1/4" bit went 0.00271 inches per whack
A 2.5" x 3/8" hole takes 623 whacks
A 1.25" x 1/4" hole takes 461 whacks
(http://danielmerrick.com/SOYO_photos/25v375drillrates245.jpg)
(http://danielmerrick.com/SOYO_photos/25v375drillrates246.jpg)
(http://danielmerrick.com/SOYO_photos/25v375drillrates247.jpg)
(http://danielmerrick.com/SOYO_photos/25v375drillrates248.jpg)
(http://danielmerrick.com/SOYO_photos/25v375drillrates249.jpg)
(http://danielmerrick.com/SOYO_photos/25v375drillrates.jpg)
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Huh. I wouldn't have had a guess for a winner on that one.
I would bet a 1/4" 5.10-type drill would beat the 1/4" SDS drill. I think the former would be the best contender for its class and the 3/8 SDS for its own.
Why am I envious of your granite block? I think I need one!
Another interesting experiment Dan. Thanks for sharing it.
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I drilled two holes using the same, resharpened, 3/8" SDS bit and a sharpened 3/8" A-Taper bit. The procedure was the same as for the earlier test. The SDS bit drilled at basically the same rate (0.00324 inches/blow) while the A-Taper bit drilled faster (0.00386 inches/blow).
So we have:
1/4" SDS 0.00271 "/blow (100%)
3/8" SDS 0.00322 "/blow (119%)
3/8" A-Taper 0.00386 "/blow (142%)
The A-Taper bit is shorter, has shallower flutes, is held more rigidly in the holder and the holder is lighter. Any or all of these may increase the drilling rate.
(http://danielmerrick.com/SOYO_photos/SDSvA-Taper250.jpg)
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That is really interesting. They could each be made of different materials too.
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I've been cross posting this to StupidTalko, hope that's OK.
There has been some relevant research into the efficiency of drill bits. This paper is a very good source:
https://etd.lib.metu.edu.tr/upload/12608282/index.pdf
Chapter 3 beginning on page 62 is the good part.
I've been going over the thesis paper and have a few observations.
The blow to the end of the drill produces a stress wave or impulse that travels down the length of the drill bit. The efficiency of transmitting the impulse to the tip of the drill is key to understanding what is happening in my experiment. For hard rock like granite it is most efficient if this impulse is short. For softer rock, a longer impulse is more efficient. Short or long impulse can be envisioned as either time or length. Hitting the end of the drill causes a compression impulse traveling at a fixed speed. This compression wave has a length in both time and distance. The speed is a material property and is constant for steel. The speed or velocity is c=(E/p)^.5 where E is the modulus of elasticity and p is the density. For steel this is about 5000 meters/second or 16,000 ft/sec.
Small diameter drills have a longer impulse so are more efficient in soft rock. Fat drills have a shorter impulse so are more efficient in hard rock.
Any changes in the cross section of the drill cause a portion of the impulse to reflect back. The 3/8" SDS MAX drills have nearly constant cross section so very little of the impulse is reflected. The 1/4" bits neck down quite a bit so a lot of the impulse is reflected back towards the hammer where it reflects again and them reflects yet again at the neck down delivering a series of decreasing impacts to the tip. In soft rock these successive impacts can advance the drill but they do not in hard rock.
In hard rock, the length of the drill has very little effect for a straight shank drill. If a drill has a change in diameter, shorter drills will be more efficient.
The shape of the hammer influences the duration and shape of the pulse.
The drill holder certainly influences the pulse.
For most efficient drilling in hard granite, we would want a short, sharp impulse. Any changes in the drill section (Diameter, flutes, slots) will tend to dull and/or reflect the impulse.
It would be good to do tests comparing different drill holders.
Using my granite block (~100 lbs) probably effectively makes the rock somewhat softer. The difference might actually be more than the 18% I got when drilling in a large mass of rock.
We should test some straight shank 1/4" drills. I think the 1/4" drills that John makes are straight shanked.
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Wow, I was surprised to see such a long paper on the subject.
This seems to support how the flutes, since they are not really necessary for most hand drilling, would be better if shallower and therefore more material could transfer the energy to the rock.
I can send you one of my drill holders with bit if you want to test a straight-shank bit. Give me your address to ship it to.
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Google Daniel Merrick to get my address or:
www.danielmerrick.com
I'm frighteningly public.
I also want to grind down the shoulder on a 1/4" SDS bit to see if I can reduce the reflection of the hammer pulse and thereby improve efficiency.
I am also trying to figure out the interaction between the holder and the drill bit. The reduction from the holder to the bit is also subject to impulse reflection.
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Got the address, I will get you a drill soon.
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I tried grinding a 1/4" SDS bit down so there is a tapered transition from the SDS part to the drill part. I simply mounted the bit backwards in an electric drill and spun it while I worked it on the bench grinder. It didn't take long and came out pretty good. Its pretty hard steel and the lathe won't cut it.
(http://danielmerrick.com/SOYO_photos/0.25SDS-a.jpg)
1/4" SDS bits. The left one is ground down to create a smooth transition in diameter.
I took somebody's advice and got a grinding wheel. I ended up with green Silicon Carbide. It works well and I am sure I got the bits sharper than before.
Using the newly extra sharp drills and a Black Diamond hammer instead of the Omega Pacific hammer I found that the ground down 1.4" SDS bit drilled 21% faster than the bit with the shoulder. I really find this hard to believe and think I need to find a volunteer to do a blind test.
Looking back to the first test, the plot I made used a trend line with the intercept set to zero which isn't right since the drilling rate isn't linear when starting a hole. So I recalculated everything and here are the three tests so far:
Test 1, Hand sharpened bits, OP hammer
1/4" SDS 0.00279 "/blow
3/8" SDS 0.00326 "/blow (117%)
Theory: The shoulder in the 1/4" bit reduces impulse efficiency and smaller drills are not as efficient at the stone face.
Test 2, Hand sharpened bits, OP hammer
3/8" SDS 0.00324 "/blow
3/8" A-Taper 0.00386 "/blow (119%)
Theory: The A-Taper bit is shorter and held more rigidly.
Test 3, Wheel Sharpened bits, BD hammer
1/4" SDS 0.00323 "/blow
1/4" SDS ground down shoulder 0.00390 "/blow (121%)
Theory: The in the standard 1/4" SDS bit the shoulder reflects the hammer impulse reducing efficiency.
Test 3 doesn't seem consistent with Test 1 so I want to repeat #3 and have somebody else do the drilling and not let them know which bit is which. However, I am pretty confident that it is good data. I hit one 20 then the other 20 and kept cycling so my hits should have been pretty consistent. I think the difference between 1 & 3 is sharper bits and the way I hold the two hammers. I find I naturally choke up more on the OP hammer. Also, the paper we have been looking at has a section where the author discusses the shape of the hammer and how it affects the impulse and efficiency.
(http://danielmerrick.com/SOYO_photos/0.25SDS-b.jpg)
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That is quite a find. I have to admit, I don't really understand why the shoulder would help or hinder performance but it is an interesting feature to focus on.
One thing to remember about your new grinder to never let hardened metal get too hot for too long or you can unintentionally ruin the hardening. Grind/dip/grind/dip works. Use machining coolant in the dipping water so you don't rust everything around you too.
I am going to buzz out some holders and bits soon and get one off to you to be tested in the lab. Looking forward to seeing the results. I should have given you one when we saw you last weekend. Duh.
I do think the bits look cooler with the smooth lines which is very important.
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Cross post from StupidTalko
Got done with my work early today so I repeated the 1/4" SDS comparison above. I mounted the two drills in identical holders and positioned the foam grips so that I couldn't tell which was which. I mixed them up (I can hide my own Easter eggs) until I really didn't know which was which and then drilled two holes. 20 blows to one then 20 to the other and repeat until I got to 480 blows. When I was done I pulled the bits to see which was which. The bit ground to a taper was once again faster.
This time it was 27% faster.
The tapered drill went 271 blows/inch or .0037 inches/blow. This was with the BD hammer.
I'm still pretty amazed.
(http://danielmerrick.com/SOYO_photos/BlindDrill.jpg)
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I think your drills look good with their new accessory belts on. They have a flattering slimming effect.
27% is significant. Wow.
I got a chance to try the A taper 1/4" rig and the bit bent! I don't know what to think about it yet.
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The belts on the drill holders are very slimming and stylish but they keep the foam from sliding and also lock down the springs so you can't pull out the drill bit.
I've had a 1/4" bit bend before and it's super frustrating. there is no way to straighten one. I can't recall for sure if it was A-Taper or SDS but I think A-Taper.
I measured the force required to press fit the striking surface in my drill holders and got as much as 10,000 lbs. The striking pins can be knocked in with a hammer so I think we can generate a force that large when drilling. In a 1/4" bit with flutes that probably equates to something on the order of 300 ksi. This would mean you need a Rockwell C of something more than 60. Delicate balance between getting the steel strong enough and not too brittle.
What brand was it? I'd call them and send it back. I'd be curious to hear what they say. I've been contacting drill manufacturers about making a batch of short 3/8" SDS bits. The only conclusion I've come to is that all US manufacturers of percussion carbide bits are complete idiots. Like I say, I'd be curious to hear what they say about bent bits but keep your expectations low.
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I ran a very simple impact FEM model to show how the impulse bounces back from the shoulder of the bit. In the animated GIF, compression is blue and tension is red. An impulse is applied to the left end and the right end is fixed. In the model, the cross section area of the small part is 1/2 the large part. The difference is larger in 1/4" SDS pits so the effect will be more pronounced.
http://engr.sjsu.edu/dmerrick/misc/hammer.gif
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Nice model!
So it looks like a taper on the bit end of the holder would be beneficial too, correct?
I got like 20 hits out of the bent bit, so you bet your ass I am sending it back. I am disappointed though, I got it from McMaster Carr which I order from almost daily so I would have liked to order the bits from them again. Almost everything they have is really great quality with a few clunkers once in a very rare while. They only have one type in A taper and it sucked so that is a dead end for me.
I want to make my own bits for the A taper holder. The carbide tipped types are slightly oversized so splitshafts go in way too easily for my comfort. The ones I make are truly .250". I am thinking a John taper to A taper adapter will work fine.
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So it looks like a taper on the bit end of the holder would be beneficial too, correct?
I think so. I really don't know what happens at the taper interface. If the taper fit is good, it may nearly act as continuous steel. If the fit is less than perfect, who knows what happens. The drift pin hole is also a problem but I haven't run any tests to see how much of problem.
The 3/8" A-Taper drilled faster than the 3/8" SDS but the drills were not the same length so I can't say A-Taper is better than SDS yet. The next test I plan to do is to compare 1/4" SDS and A-Taper with bits that are roughly the same length.
Bob wants to try a one off A-Taper holder without a drift pin hole and with a tapered snout. This is pretty easy to do because I wouldn't brother to heat treat the steel. Even if the taper fits well, there will be a gap at the end of the bit so it won't be perfect.
The perfect bit would have no change in diameter, no flutes and no holder.
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Dan-
BTW, on the drill I have, the bit sunk too deep into the drift pin hole and i had to heat up the drill to get the bent bit out. The tapered hole needs to be shallower or perhaps the hex stock thicker.
All
We are having a shop night on Thursday at my shop in Concord if anyone is interested in coming out and making drills and bits and hangers and drinking beer. Contact me if interested.
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I just purchased 2 ea of 3/8 1/4" a taper Carbide tipped from ICS.
Dan, I am going to try an mod 1 ea of these the way you did.
Maybe get some better rock crunching going on.
The 1/4" has a DD of 1.75" or something, just like the rawl's.
"The perfect bit would have no change in diameter, no flutes and no holder"
Hard to beat the chisel tips we used in the rawl system, 2 out of 3 aint bad.
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After having a sandwich for lunch, I went down to the garage and tried some 1/4" bits. Comparison is a 1/4" SDS (DeWalt, Germany) with a 1/4" A-Taper (Relton, USA). First I sharpened both and I used the BD hammer for pounding.
(http://danielmerrick.com/SOYO_photos/Compare0.25_a.jpg)
They drilled at the same rate so I can't say one drills better than the other.Somewhere around 100 hits, the A-Taper bit started to bend. The bent bit actually still drilled as fast (The impulse followed the bend?) but after awhile it started to spall the top of the hole.
After the test, I hit the A-Taper a number of times about as hard as I could to see if it would bottom out. It didn't and it came out easy enough. I think the holder I sent to John was a prototype that had the taper cut with a boring bar and it was hard to get it just right. The new ones where I cut the taper with a reamer may be more accurate. I should send a replacement.
My SDS holder seems to work well. Perhaps because the striking surface is very close to the end of the bit which may keep things focused.
(http://danielmerrick.com/SOYO_photos/Compare0.25_b.jpg)
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What version did I get?
I will just stick with 3/8ths if this will be an issue with the drill you sent me? If not, I want to try the 1/4"
Thanks for the cool write-ups, and I will get back to you soon on this Dan.
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NO QUARTERS FOR YOU YETI!!!
Man up
LOL
Sincerely,
QuarterLength Munge
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Yeti-
If I recall, you got an SDS holder not an A-Taper holder. A-Taper bits won't work in it if so. If you bought A-Tapers and need SDS, I'd be happy to trade you some. I'd like to try a different brand of 1/4" A-Taper bit.
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Hey Dan-
You sent me the A taper, and it seems that the bits only go in 1/2 way, so maybe it is different depth than johns?
I just received my 1/4" and 3/8" in the mail, and on the way to SHOP NIGHT WOOOHOOOO!!!
Machines and brews, fingers will be lost..
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I'd love to stop by this evening but Concord is soooo far away and I have a job in Half Moon Bay tomorrow early.
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Too bad you can't make it. Hopefully we will end up with something we will want to share here later, other than missing fingers.
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planning on shop, but it's a long way. Don't drink all of them.
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Fun at shop night... and no finger loss!
(http://i1099.photobucket.com/albums/g388/jhgodar/fingies_zps28d2d982.jpg) (http://s1099.photobucket.com/user/jhgodar/media/fingies_zps28d2d982.jpg.html)
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You guys need to get a real rock.
How did the ICS drill work?
John still hasn't said what brand drill he got from McMaster.
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That rock fell off of the decorative wall on the outside of my building! It is my testing rock and I think it is limestone, but I don't know for sure. Don't tell the landlord.
We had every type of hand drill on the planet represented last night, even Warren Hardings personal Rawl drill.
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A like the 1/4" I used last night, 1.75" DD made it a nice compact unit.
I buzzed it out later on the grinder, so it should be carving on the next route.
Pretty happy with your drill so far Dan, and am looking forward to putting both options 3/8-1/4" to use.
Set munge up with a UBER light backcountry drill kit and Titanium pins. Pretty much the lightest set up out there.
That Harding->Bosque->Yeti->Munge drill has a mean slugging record, dating from the mid 70's. It is 2.75" long!
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Dan, McMaster-Carr replied that they do not have the brand information for the drill bit. Though they did offer to credit the bit and send a replacement without asking for anything in return.
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Dan, But John pointed out that we have the packaging for the bit. It's B & A Mfg. out of Riviera Beach, FL.
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That Harding->Bosque->Yeti->Munge drill has a mean slugging record, dating from the mid 70's. It is 2.75" long!
Stoked to use on it something backcountry and big! (or not bolt at all if we don't need to)
light is right
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I am bending 1/4" Relton bits and John is bending 1/4" B&A bits. So, we'll have to see how the ICS bits work. If they don't, we may need to start buying Chinese ones. It might be that 1/4" is just too small for carbide insert bits that get hit as hard as we hit them. It may be impossible to keep the temper hard enough when brazing the insert in.
I contacted Relton and B&A about making a run of short 3/8" SDS bits. Neither managed to provide me with a price although B&A offered to cut down a single bit and braze in a new tip for $68. I actually had to convince the Relton guy that the bits I wanted weren't in their catalog.
10 Chinese manufacturers gave me prices for short 3/8" bits in one day. $0.35 to $0.70 each (depending on "quality") will get you any length you want but you have to buy 500 and the shipping is high. Still, a dollar each will get you whatever you want. The main risk is forking out $500 for a bunch of bits that might be junk.
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I can do the logistix :)
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I just can't quit about the drills and drill holders.
ANSI standard for 10mm drills is 10.2 to 10.45 mm (0.402" to0.411"). ANSI standard for 3/8" is 0.390" to 0.398" which is very close. 10mm drills are available in 110mm (4.33") length. Drilling depth is about 2.25". Perfect for my holders. If you want a spec 3/8" drill, just grind down the sides a few thousandths.
(http://danielmerrick.com/SOYO_photos/P1060611.JPG)
(http://danielmerrick.com/SOYO_photos/P1060612.JPG)
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Also, off topic, trip report from last weekend here;
http://www.supertopo.com/tr/Return-to-Watchtower-Peak-FA-Northeast-Ridge/t12108n.html (http://www.supertopo.com/tr/Return-to-Watchtower-Peak-FA-Northeast-Ridge/t12108n.html)
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Nice job and great TR. Some of those shots in the smoke are eerie.
I remember that older trip report too.
I haven't forgotten I need to get you one of my drills but I am doing a short run of the bits when I get spare time in the shop which has been rare and the machine setups keep me from getting you one early. Soon though.
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Thanks for the link to the TR Dan, and those are some otherworldly shots with the smoke.
Way to get out there!
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I really enjoyed your TR and photos! This is inspiring, and though I don't like reading the part about the fall climbing over worsening rock.... I'm really glad you include it and of course were just fine... It's nice to see you made it up another way for sure. Way to go!
Also, I may not "get" everything about the drills.... but all your posts on this are really great.
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Susan - watch the mail.
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USPS or email?
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USPS Priority
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ok. no mail today. maybe tomorrow.
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Sorry Susan, I just dropped it off at the PO yesterday morning.
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Got the drills and they look awesome.
One thing I need to mention is that whatever method you are using to swage the cables doesn't stay swaged. Are you using a butt connector crimper?
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Yeah, I need to improve that. I've been trying bicycle cables since they are run through a die or something and have a smoother surface which allows them to slide in the slot easily. Smooth also probably makes them harder to get a good swage. I think the ones you got were simply a piece of copper tubing crimped in place. Copper tubing is probably too soft for the purpose. Oh well, I'm sure you can come up with an excellent repair.
I also need to know what works and what doesn't so please do continue to let me know.
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If you are headed out through Morgan Hill this evening, you can stop by and we can try to fix any busted cables even though it will be embarrassing to let you see the crappy tools I have in my shop. Just let me know. I'm home alone this weekend. My wife and son are in Indiana and my daughter is in Berlin.
This evening I want to test a 3/8" SDS that I have ground down so it has a square tip. There is a small chance a square tip is more efficient. I've been reading an old research paper concerning how the tip penetrates and pulverizes the rock. I now know why sharper tips and tips with a smaller angle work better. Small angle or narrow tips are more efficient but dull faster and shatter more easily.
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All alone on a three day weekend? Too bad or perhaps a good opportunity to get some me time? Thanks for the invite, but we will have to see your laboratory some other time since we have family events to attend this weekend.
I am sure your tools aren't crappy since you have been making such cool stuff with them. Don't worry about the cables, I have a Nicopress so I can re-cable the drills.
Looking forward to hearing about your next discoveries from Merrick Labs.
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I'd be interested in knowing how that tip will work on an SDS drill so please post it. I make a chisel bit out of high speed drills for hand drilling and for comparison I can hand drill a hole in "average" granite in 5-7 minutes with that set up and it takes about 15-20 minutes with an SDS.
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Had a 3/8ths wedge bolt pull out on me a few days ago, it was a spinner. Same SDS bit I have used on most thunderstud anchors. Blow tube and brushed, it just failed.
Good news is The notion that you cant remove a wedge is false.
Bwahahhaha!
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Yeti -
I've never had that happen. I wonder what the cause was.
The trouble must be with the wedge on the end of the bolt or the collar that the wedge expands. If the bolt was spinning inside the collar, that is one problem. If the collar was spinning inside the hole, that is another problem altogether. Did you try another bolt in the same hole? Did you have to pound the bolt in or did it slip in easier than usual?
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I tried the square verses V carbide tip drills. I used two brand new matching drills but ground the tip of one so it was square. I sharpened both. The included angle of the two tips may have not matched just right. A small included angle should drill faster but be more susceptible to dulling and chipping.
First, I bought a new hammer. Seems to be military surplus. Finish is rough but seems to be very well made. It looks like a copy of the BD hammer but the handle has a round wedge instead of the flat one BD uses. Also, the handle and side plates are set in what appears to be epoxy. I think the $50 I paid was good but sadly, there are no more to be had.
(http://danielmerrick.com/SOYO_photos/IMAG0274.jpg)
The two tips before drilling:
(http://danielmerrick.com/SOYO_photos/IMAG0275.jpg)
(http://danielmerrick.com/SOYO_photos/IMAG0276.jpg)
The square one wanted to drill a triangular "Wankel hole" to start but the hole got round as it got deeper.
(http://danielmerrick.com/SOYO_photos/IMAG0277.jpg)
The square one drilled slower than the V-tip until the square one blew a tip and then it went very much slower.
(http://danielmerrick.com/SOYO_photos/IMAG0281.jpg)
I think the square tip is a bad idea for carbide since carbide is so brittle. The square corner is probably too prone to chipping off. I'll be sticking with the standard V-tips for carbide.
I don't know if a square HSS bit drills faster than a standard carbide. Somebody will have to come by Merrick Laboratories with their HSS drills to run some tests someday.
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Wankel hole. I actually get it!
That hammer looks heavier than the BD?
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Dan,
Seriously? No more hammers? For $50, that would be a stellar deal.
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John - The hammer looks bigger than a BD even when compared side by side but weighs exactly the same on my postal scale.
Munge - I like hammers, the most fundamental and oldest of tools. Oddly, we know very little about using them. As a member of the Human Factors and Ergonomics Society I have access to all manner of studies about how people interact with various tools and such but there is nothing about the ergonomics of hammers.
To be completely honest, there is one study concerning the curved hatchet type handles you see on carpenter's hammers. They had college students pound nails to come up with the optimum curvature. WTF do college students know about swinging hammers? I think it's a stupid study but it sure changed the hammer handle market. Talk to an old carpenter or blacksmith about swinging a hammer and you will think he is some kind of zen mystic. Today carpenters use nail guns and hammering nails may be a lost art.
So, as I pound away with my hammers I try to get that optimum swing which produces the hardest hit with the least effort while not ruining my elbow. I worked with an old carpenter one summer. He spent quite a bit of time trying to teach me how to use a hammer but I think I was a disappointment to him. He said "let the hammer do the work" and kept trying to get me to use my wrist more and arm less - or was it more shoulder and less wrist. Something about throwing the hammer.
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You trained under the Hammer Yoda? Cool.
"Hammer you will".
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No doubt. Hammer-Zen is what getting a 3/8" bolt on stance in is all about!!
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I am once again cross posting from Supertopo. I am linking to the photos on Supertopo this time to see if they will let me do that.
I managed to get a copy of an old paper that is the only one that I can get my hands on that discusses how a percussion drill does its job. "Basic Studies of Percussion Drilling" was published in January 1959 in Mining Engineering on page 68-75. In the introduction the author states that although materials and equipment have improved, rock drill bits have undergone no major modification since they were first used in the 1860's for drilling blast holes in mines. Looking at his discussion, I would say that other than developing carbide tips, not much has changed since 1959 either.
The main area of interest to me is the investigation of how the drill tip penetrates the rock and breaks it up. They figured this out with high speed photography. As the tip impacts the rock, the rock below the tip crushes into a fine powder. The tip penetrates the fine powder and the powder expands outward in its space causing chips to flake off on each side. For a given volume of rock, it takes more energy to pulverize the fine powder than a corresponding volume of chips. This means we want to minimize the powder and maximize the chips. You can minimize the powder by having a sharp drill and by having a drill tip with a small included angle. If the tip is too sharp, it dulls easily and if the included angle is too small the bit will chip. The optimum angle is probably a function of the rock and the bit material. Carbide is very brittle so it probably needs a larger angle than HSS. On the other hand, carbide is very hard so it can be kept sharper. The paper states that the angle must be 90 degrees or less to result in any chips at all. Carbide bits are very close to 90 degrees so not very efficient.
(http://www.supertopo.com/photos/19/81/319598_15234_XL.jpg)
The tests were done on a flat surface rather than in a hole so they could photograph the process. In actual use, the bit is in a hole and the chipping might be limited by the space available at the base of the hole.
(http://www.supertopo.com/photos/19/81/319599_1025_XL.jpg)
In Fig. 4 I think they used 1.5 inch drills which must be the standard for drilling blasting holes in mines.
The width and depth (or volume) of the crater is a function of the included angle of the tip, the sharpness of the bit, the blow energy and the rock. The rock factors might be the crushing strength, the shear strength and the grain size.
My conclusion is that part of the reason a 3/8 drill is faster than a 1/4 inch drill is because the larger hole size allows more chipping and less pulverization. This could be checked by collecting the crushed rock from a 3/8 inch hole and from a 1/4 inch hole then analyze the samples for particle size. Very boring work but I did this particle size analysis in soils lab as a student.
Indexing is what the author uses to describe the amount of rotation between each blow. He states that indexing can be too small and reduce drilling efficiency but cannot be to large. Maximum indexing is one half the angle between the cutting edges of the bit which is 90 degrees for the flat tip bits we use. If you use a cross tip, it would be 45 degrees. I really don't know what the minimum rotation is but for the single cutter bits we use but it must be 90 degrees or less. I generally rotate at least 15 degrees per blow. 30 degrees might be better but my wrist will only twist so much.
It may be that a 1/2 inch drill is faster than a 3/8 inch drill. Need to check that.
Unfortunately, the paper I have is only a summary of research. I'd like to see that original paper which was published by Drilling Research, Inc in "Collected Reports" vols 1-6 1949-1954. There is a copy of this at Stanford but I don't believe it can be checked out.
The 1954 vol 6 pp 9-18 seem to be what I want. If anybody is at Stanford, perhaps they could get me a photocopy or scan. Also 1953 2nd qtr pp 14-18.
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Dan
I ended up hand shaping a special drill and bit for you since I am not getting anywhere with making several. Sue will send it out to Merrick Labs today.
The drill handle is from a bit-locking design that didn't work out but it is otherwise the same as the rest of my drill handles but I used a spring pin instead of a solid pin as usual. I mentioned to you how my bits would shatter if I mounted them too rigidly with a solid pin. My fix was to undersize a narrower "waist" in the solid pin which provided a slightly loose fit and that has worked well for a long time. The spring pin should have a little spring left in it and may provide enough cushioning to keep the bit from shattering. If you break it I have more to send and I can give you a "waisted pin".
The bit is solid .250" HSS and the angle is whatever it is from grinding by hand. I finished it on the diamond wheel so it is smoother than normal but i can't imagine it making any difference in performance. As far as resharpening, I usually quickly sharpen the tips on my bench grinder in my garage when we are packing to go climbing and don't pay much attention to the angle, but I am looking for something around 90deg.
We look forward to the results.
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Dan, I will try to get it in the mail today by flat rate small box.
John, It is 6.85 oz. The other drills are even smaller and lighter, though. I would like another of those.
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The other drills are even smaller and lighter, though. I would like another of those.
Susan - I don't know what drills you are talking about.
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Sorry Dan, I meant that last comment for John.
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She is referring to my "lollipop" drills. Picture a small marshmallow stuck on a half of a pencil but metal. They weigh about the same as a large stopper but are a little stressful hitting such a small target with a hammer without any hand protection. I carry two or even three for a long route.
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Got the drill holder. Thanks. It's too pretty to use but I might try a speed test compared to my tapered 1/4" SDS.
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Bob and I used one of my medium size holders with a sharpened 110x10 mm bit this past weekend. It drills really fast. I think it drills fast because the holder and the bit are short (research shows shorter bits are faster) also because it was really sharp and the drill shank is fat with small flutes. The bits are just long enough to drill a 2-1/4" deep hole.
Bob drilled quite a few holes and I drilled one. I managed to screw mine up and the bolt wouldn't tighten up (we'll yank and replace it one day). I think this is because I drilled at awkward maximum reach and probably wobbled the drill also because it is a slightly oversize 10mm bit. Bob noted that the bolts he placed had quite a bit of thread showing by the time they got tight so he started tightening before installing the hanger so he could pound the bolt in farther. I don't think the extra exposed threads weakened the bolt because I believe the collar on the wedge is at the same depth as always, the wedge just had to pull farther to get tight.
Anyway, from now on I will be grinding down the sides of the 10 mm bits so the holes are smaller. MY 10 mm bits measure about 0.411" and my 3/8" bits measure about 0.395". Spec for 3/8" drills is 0.390 to 0.398".
(http://danielmerrick.com/SOYO_photos/841.jpg)
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Having placed literally thousands of bolts between the ASCA and my own routes here are some observations. With a 3/8" bit if the hole is to true the bolt will be very tight and possibly damaged when pounding it in. This holds true for both 5 piece and Red Head type bolts.
When hand drilling there will always be some wobble if the hammer blows are hard enough to drill a hole quickly so I always use a 3/8 bit. My bits are the titanium coated bits sharpened to a chisel tip. I haven't broken one in years and typically can drill a hole in granite in less than 10 minutes and they last 3-5 holes depending on rock hardness. The angle the bit is sharpened at will also determine how fast you can drill and how long the bit will stay sharp.
For power drilling the hole is almost always fairly true and a 10mm SDS bit is fine as the bolt ideally goes in with medium blows rather than pounding. However, Greg Barnes recommends 3/8 bits for everything. Personally I can't afford new SDS bits after 15 or so holes so as they wear I introduce a little wobble when power drilling as I haven't found 10mm SDS bits in Fresno and certainly not in Oakhurst.
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Some of these designs worked, others...........not so much.
(http://i1099.photobucket.com/albums/g388/jhgodar/Public%20Pics/P1080003_zpsd6ebf1ad.jpg)
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I have a box of various holders I have made but have started getting rid of them. The prototypes that worked are given away and the ones that didn't are scrapped.
Did you ever try the little holder with side springs I sent for you to try?
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I did try the drill holder you sent me and it worked fine. I haven't had many opportunities lately but will probably have more when we start climbing again in the Valley this winter.
What I do have to say is the springs are so strong it is difficult to remove the bit by hand, so maybe only one is needed? I pulled off the foam handle and regretted it since the shock of the hammering hurts like hell. I don't have that issue with my small drills so didn't think it would be an issue on yours.
I assume you are using an electrical butt connector crimper for your swaging? If you need anything swaged let me know and I can use my Nicopress swager or you can come on down to shop night and really go bonkers. I just repaired the wires on about 4 of our Aliens with it. Man, the blue Aliens are a major pain in the booty to rewire.
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I think the leash loop on the holder I sent to you was a poorly considered experiment as far as the leash loop goes. It was a piece of copper tubing crimped with an electrical crimper. Trying to go cheap doesn't work. I cut all of those off the holders I have off and redid them with Nicopress. I have three Nicopress swagers of various sizes and a 4th Chinese knockoff. The jaws don't exactly line up on the Chinese one but the swages it does test just as strong.
I never use a leash when drilling anyway and only once in awhile hang them on a biner. When Bob uses my holder, he always hits the leash loop with a hammer and it eventually falls off anyway. I have been trying to come up with the perfect leash system but no luck so far. I suspect a soft leash like the Petzl Rocpec might be best but it needs a wider groove and has to be sewn. Seems like it would be out of the way of the hammer if it was on the bit end but I would have to make the holder longer to do that.
I've tried them without the foam and also found it very painful.
I have made different spring stiffnesses by varying length or thickness. It is a compromise between getting the bit out and keeping it in. When bits get stuck redrilling a 1/4" hole it can be very frustrating if you can't pull on it. The little cinch strap is good for helping keep the bit in when you have to yank on it.
If I have trouble pulling a bit out of the holder, I just stick the bit through the hole in a box wrench or the bolt hole in a hanger and pull it out with that. The short 10mm bits are hard to grip with your hand but a bolt hanger locks onto the twist grooves in the bit shank easily.
I don't recall which foam you got but I have found some denser, tougher, thinner foam than I was using.
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I think the sling on the Rocpec is riveted instead of sewn. Maybe try rivets?
I still have the foam handles, I just need to put one back on.
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Saw one of your drills in action last weekend Dan. The leash was a swage, that frayed immediately. I like how it is shorter.
my rocpec is on its last legs. Got any left?
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Sure Munge, I have some holders. Who did you see using one?
Besides the ones I been using I have:
4 medium bayonet type
4 short bayonet type
2 A-Taper type
2 A325 bolt type
I still have trouble with leashes. It seems like if I get them sturdy enough, they won't rotate. I have replaced all the crappy swages that John commented on with copper Nicopress ones. They seem to work pretty well but I don't know for sure since I never use a leash when drilling. I only use them to hang on a carabiner.
The 2 A325 holders are turned from 7/8" A325 bolts. A325 bolts are what they use to bolt steel buildings together. The steel is tough, fairly ductile and high strength. They have a deep socket shown in the photo below with the usual 6-1/4" x 3/8" SDS drills. The drill is held in place with two set screws similar to the old Pika drill. The set screws are set with thread lock which I have found keeps them from working loose while still allowing them to be removed. The larger head makes a good leash easier to do and the cord leash works very well. Pretty bomb proof but heavier. 14.4 ounces with the bit installed.
People are giving me $80 for the bayonet type, $50 for the A-Taper and I'd take $40 for the A325 with leash. Send me a message if you want one.
(http://danielmerrick.com/SOYO_photos/Drillholders.jpg)
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Those bolt-type drills look badass. Nice work.
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Man those are sweet!
I may however hang up my hand drilling days, as i destroyed my wrist using a Mcdevitt hammer and a hurricane drill combo.
I will proudly serve as sub-man on any further forays into pro-less leads.
FML
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Man those are sweet!
I may however hang up my hand drilling days, as i destroyed my wrist using a Mcdevitt hammer and a hurricane drill combo.
I will proudly serve as sub-man on any further forays into pro-less leads.
FML
That's not exactly an admission that you will start using a bosch, now is it? :)
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I've searched the academic journals and there is surprisingly little about hammer ergonomics. There are few few papers about handle shape and these found a curved handle very helpful. This is what you see on most framing hammers these days and what we used to call a hatchet handle. Basically they say you can swing the hammer with your wrist in a more natural position. I've read the paper and the main problem i have with the study is that they used some students and faculty to evaluate the hammers. I guess they couldn't find any carpenters or blacksmiths on campus that day.
From Human Factors: The Journal of the Human Factors and Ergonomics Society:
The theoretical justification for putting a bend in a tool handle is reduction of stress on the flexor tendons and median nerve as they pass through the wrist. Our three experiments used brief «5 min) trials of people without wrist problems. The overall conclusion is that people like a bend in the hammer handle (although not as much as 19 deg) and that there are no performance differences. Note that driving a nail straight with a bent handled hammer is not a problem
Applying the established ergonomic principle of bending the tool and not the wrist to the hammer could produce less biomechanical stress on the wrist while maintaining the performance of a straight hammer. For novices, bending the hammer handle to 20 or 40 degrees significantly reduces ulnar deviation and might decrease the incidence of CTDs caused by the hammer.
cumulative trauma disorders (CTDs).
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Bingo Dan.
Sloppy technique caused this from a bad drilling stance.
Lotta holes on my wrists, bound to happen sooner or later.,
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Are you getting Bosch-Curious YETI?
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May have to start free climbing now.
I tried the machine once, maybe again the next morning? On some anchor bolts. I had been drinking and was peer pressured into it by my closest friends.
It was low moment, and I had to find a local group to meet with, eat doughnuts, and talk about my problem for months afterward.
I may slip again, and need everybody to keep an eye on me, don't want any little boschlets on the rack just yet.
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I pulled out the drill holder that we have been using this past year to see how it is holding up. Bob is a pretty good tester since he likes to hit (too) hard. I let him use my holder and some stubby bits both of which are more efficient at transferring the impact to the bit. He hits just as hard so all he does is blow out carbide tips every bolt or two. I may have to buy him a girlie hammer.
The swaged leash is holding up well although I think it has only been used to hang the holder on a carabiner. The striking surface looks as good as new. The set screws that keep the bit from rotating are in good shape still. The four screws holding the springs are still good. The thread lock that holds the springs and spring screws in place is working well.
The end of one spring has broken off and the spring on the other side has a crack. Where the spring is broken off I can see a slight bulge where the ball bearing has been pounding against the steel. The broken spring doesn't seem to affect function at all.
If any of you have a holder with broken parts, I'd be happy to fix it for you if you can get it to me.
(http://danielmerrick.com/SOYO_photos/Wear1.JPG)
(http://danielmerrick.com/SOYO_photos/Wear2.JPG)
(http://danielmerrick.com/SOYO_photos/Wear3.JPG)
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That sure doesn't look like a drill with a year of use.
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When I first started making drill holder I considered putting the leash loop at the bit end of the holder where it wouldn't get hit by the hammer. Bob convinced me not to saying it would be in the way there. It still seems like it might be a reasonable place to put it. Even if the holder is short and your hand wraps the leash it would work because your hand would simply turn the leash as you turn the bit. This would require making the holder a bit longer.
Another idea would be to make the groove wider and use a piece of tied cord rather than cable. This might require making the holder a little bit longer because I don't like removing too much of the material wrapping the striker insert. Although this has never happened, I have always been concerned that the dowel pin insert would become loose and the pin fall out.
I have bought some slippery plastic coated cable that is more flexible and slides in the groove better but I still think that if you hit the swage with the hammer, the loop is a goner.
Any thoughts?
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You have to strip the coating of that type of cable or the swages are really weak.
I was considering a similar design placing the loop lower down to be clipped as backup for if you slipped. Less leverage down lower. It would work like how many hand drillers clip the bit with a daisy while drilling so the bit may catch a fall. If the hole is deep enough, they can and do hold you and have saved quite a few folks from the big ride.
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The leashes I've made in the past have not been very good so I decided to come up with something better. I made the holder a little longer which gave me space for a cord leash. I was concerned about not leaving enough material to hold the dowel pin (striking surface) securely so I used a longer pin and drilled a deeper hole for it. I was supposed to end up with 1/8" of the 1" pin exposed but when I hammered the pins in, they wouldn't go in all the way. I know hammer blows can generate about 10,000 pounds on a solid surface. I decided to try and press the pin in and put it in my test frame with a 20 ton cylinder. I got to almost 30,000 pounds when the holder crumpled. Darn pin didn't go anywhere. Either the fit is way too tight or I didn't drill the hole deep enough.
I made two of the new design and the leashes seem to work really well. They rotate easily and don't bind up. I still have one left and was wondering if anybody wanted it. Since the pin didn't seat right and I tapped one of the screw holes a bit crooked, anybody who wants it can have it for $40. Maybe Munge will want it.
Test frame:
(http://danielmerrick.com/SOYO_photos/Holder-Leash-a.jpg)
Crushed holder:
(http://danielmerrick.com/SOYO_photos/Holder-Leash-b.jpg)
Remaining holder:
(http://danielmerrick.com/SOYO_photos/Holder-Leash-c.jpg)
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must... not... reply...
save... elbows... save... wrist...
cool... design...
CRUXING!!!
:)
ok.
I'm such a push over.
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Nice leashes. Nice frame of fun destruction too.
I mentioned before that you can't press something into a blind hole without giving the air a place to go. Air pockets will resist pressing to the point of crushing/bending metal. A flat ground lengthwise on the pin would be enough to relieve the air. You should grind it apart to find out what happened.
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Munge,
Since I have given away prototypes in the past, I'll send you this one for free if you promise to use it, or get somebody to use it, and let me know how the leash works.
If Munge doesn't want it or simply wants to preserve his elbow, I'm sure somebody will.
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Took the grinder to it. The dowel pin was seated. Turns out the pins are 1-1/4" long. Why I didn't notice that is beyond me. I will attribute it to senility.
(http://danielmerrick.com/SOYO_photos/DowelPina.jpg)
(http://danielmerrick.com/SOYO_photos/DowelPinb.jpg)
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Well there ya go.
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Hello All,
I guess news travels. That was my drill with the fraying swage. That being said I really like the Merrick Bayonett. I took Munge's advice, cut the cable off and replaced with a piece of 3mm cord. Works great now! You do not get the pinching like the rockpec and they seem to be more aggressive at making holes. Highly recommended! Thanks again Daniel!
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Hi Aaron, Nice to see you post! Hope you are getting out there these days.
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Somebody asked me for a drill holder a couple days ago and after a long search through the garage and all my climbing gear, I cannot find a single bayonet type holder. I did find one of the holders made from a bolt.
I don't think I will make any of the bayonet type again although I have the materials and tools to do so. The hammers are more satisfying to make.
I had a couple of the bayonet holders that I was using but I loaned them to Eric Sloan to try out. Eric says he is collecting gear for people to use replacing bolts and he later asked me to donate them for that purpose. He also kept the DAMMERR I had been using. He said he used them to replace bolts on the dawn wall for TC and KJ and I asked him to take photos of that but he didn't. I always keep the defective stuff for myself so he got used seconds.
Anyway, no more bayonet holders unless somebody wants to make them.