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usnfc
08-29-2014, 10:47 AM
Hey everyone,

I have this mystery tool, and I'm hoping someone can identify it. I got a ton of them in a bulk tool buy recently. I'm not a seasoned machinist, but I have never seen one before. It appears to be some sort of chamfering or countersinking bit, but I can't find it on the web.

Thanks for any help!http://i466.photobucket.com/albums/rr24/syburstang/photobit.jpg

Royldean
08-29-2014, 11:10 AM
Looks like the tip of an old-skool medical trocar.... but I'm pretty sure that's NOT what it is...

usnfc
08-29-2014, 11:12 AM
They are made by Horton, and have different degree's marked on each one. The tip is sharpened for cutting....

TGTool
08-29-2014, 11:53 AM
It looks like a straightforward spade drill grind. I'm not familiar with Horton, but they might have been for different countersink angles. You might also compare them with "die drills". They have the same geometry but in carbide and are designed to drill holes in hardened steel. They work really well from the little use I've made. McMaster Carr lists them at http://www.mcmaster.com/#die-drill-bits/=thpqmp

usnfc
08-29-2014, 12:31 PM
I think you got it TGTool! I googled spade drill and it popped up in images. Here's one on Amazon http://www.amazonsupply.com/chicago-latrobe-high-speed-uncoated-conventional/dp/B006O2S4XI

What would this be used for? It's not carbide.

38_Cal
08-29-2014, 05:41 PM
I've used small (#31 and #28) spade drills in gunsmithing projects for scope and sight mounting. Chips usually break up rather than get long & stringy. You do have to clear them frequently. If nothing else, you've got a good supply of what is probably some variant of drill rod!

David

garyhlucas
08-29-2014, 05:58 PM
So is that what a drill bit looked like before they figured out how to make twist drill?

Toolguy
08-29-2014, 06:32 PM
Yes. Watchmakers still use that kind. I use a lot of solid carbide spade drills like the one in post #5. They are the toughest geometry because they don't have flutes. One of the best uses for those is drilling out a broken tap. They come in a lot of sizes from 1/16 to 1/2".
They are also relatively cheap to buy and easy to make from a broken end mill.

usnfc
08-29-2014, 09:50 PM
Yeah, I was thinking maybe someone had these made out of drill blanks or something. All of the ones I have found online are carbide. They must have been professionally done because they have different angles for the tip and they are etched with the degree of the angle. I'm sure I can find a use!

browne92
08-30-2014, 09:29 AM
The fact that each is ground to a specific angle makes me think they were special purpose countersinks of some sort. But yea, I'm sure you can find a use. Besides just straight up drilling, they would be useful for overdrilling pre-existing holes and drilling acrylic, as they would not have the tendency to dig in as a twist drill would.

usnfc
08-30-2014, 10:30 AM
I do countersunk screws on micarta knife handles...they should work good for that. Thanks everyone for the help!