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Thin material. Drilling thin material with conventional pointed bits can lead to snagging as the bit cuts the last few thou of material.
Curved surfaces - like maybe the side of a piece of pipe. The shape of the bottom of the hole drilled with this bit will leave a bit of material to support the bit when the points break through the high spots. Otherwise a conventional bit would drop into the interior of the pipe and snag as it turns...
Over lapping holes - as in chain drilling for the same reasons as curved surfaces.
A "drill" that leaves a similar bottom hole pattern is the super drill here... http://www.practool.com/super-drill.html makes a difference for snagging and overlapping holes...
My Wild A$$ed guess anyway.....
Design to 0.0001", measure to 1/32", cut with an axe, grind to fit
Paul, it's ground like a drill only with the cutting edges inside and more relief.
Well it's not for sheet metal, that was my first guess also, just tried it and it really cuts nice till it starts to break through then it shakes like all get out.
Tinkerer was that a guess or do you know that to be the use of these, their HSS.
Well, finally found a number to the manufacturer, he said they no longer produce them but it was for thin sheet metal ?????????? my little experiment sure didn't prove that, maybe it would work better if backed up with other solid material.
Need to find a spot weld I can try on the drill press
Tinkerer, that looks like it may be Cobalt which would be more suitable for spot welds, I would think, then HSS.
In a drill sharpening machine manual for a machine I had these were shown.
IIRC they were used in jigs, with the fishtail bit guided by a drilling bush.
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