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.
