What are these used for?

dbb-the-bruce

Dave
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They look like really large engraving bits to me. "Single flute" in the sense that there is only one cutting edge - like a D-Bit. Pointy like an engraver, my first thought was that they had the tips broken off, but they both are "broken" the same way - so probably not broken. The one thing I can't explain is the screwdriver slots in the top end of the bits, why? If they are held stationary when used then maybe that allows you to adjust the angle of the cutting edge relative to the workpiece.

Tried to look them up based on the markings "Tarpley" chesterland o "1/16 B"
Found a mention of Tarpley in Chesterland OH - but not much else.

So why the screwdriver slot in the back end of the bit?

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Dave
 
I ended up with a few tools just like this, in the remnants of the shop of a pretty inspirational tool-and-die maker in Milford. He could make a tool out of anything, it seems - ejector pins, dowel pins, nails, needle files, broken taps. Everything but the usual screwdriver, so those he must have seen as worth repairing. So, in regards to the slots, they may be a feature of what the cutters were made from ( a headless shoulder bolt? who knows).

Many of the the similar cutters I had were labeled with angle measurements, so I think they were countersinks.

I have not tried them out in the mill, and maybe I ought to. I have used them on the lathe, when I needed a cutter that would get into a tight spot.
 
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So, in regards to the flats, they may be a feature of what the cutters were made from ( a headless shoulder bolt? who knows).

That's an interesting thought. The shape of both bits is identical, the markings look like what you'd see on a mass produced tool bit, not hand engraved or anything. So I wouldn't expect them to be made out of bolts, but who knows. The bit shape is a taper profile with single cutting edge like you would have on a D Bit. Half the taper is removed and the trailing side relieved.

I'm thinking that the screw driver slot helped in setting the bit up either for cutting or sharpening.
 
the screw driver slot helped in setting the bit up either for cutting or sharpening.

That occurred to me as well, but I couldn't think of a mechanism that would use a slot. Maybe a shop-built grinding fixture. So perhaps the original steel was a milling cutter or drill bit?

Those sound quite similar to what I've got. On some, there is an edge and relief, on others there isn't (probably in a bunch made as blanks for future use). My money is still on shop-made countersink, but I am curious what some of the more worldly gentlemen think.
 
I have a number of virtually identical cutting tools that I made to cut custom tapers on small plastic parts that we made., They are easy to make and remove the restriction of having to use stock tapers in a design.
 
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