Re: The Culprit
Response To:
The Culprit *PIC* ()

Keith L Newton
Hey Mark, I think if I were doing this, rather than just cutting the screw off, I would go ahead and cut it on down to where the spiral flute starts, otherwise your going to have negative hook angle due to that little negative flute that creates that side edge which you don't need. Also rather than just cutting it square, I would angle it down a little going toward the right side of the image. It looks like this is a single flute bit, so that should make it easier. Also once its cut off down there, you should grind a little bit of top back angle from the cutting edge maybe 5ยบ. Too flat on top will limit the chip size, and too far down might make it try to bite too much. Then if it is a single flute rather than double, the flute depth might be almost over to the center, so you won't be looking at a split point type grind, so it should be easier to just carry the cutting edge over to the middle.

It appears from the photograph that the end is a bit larger than the flute on down to give some clearance, and there is plenty length of the larger end to still keep that. IF once you start to use it, and it dulls to quickly, being all endgrain cutting, you can widen the sharpness angle by flattening the front of the edge established by the flute. You can get there easily enough. The only hard part that I see is carrying the edge right to the middle, but that may not be too hard if you just remember that taking more off the top moves the edge forward toward the center, and taking more off the front moves it back. It may be hard to see the center without it spinning, and at that length it would likely be wobbling, but if you can drill through a block then hold it near the edge while spinning backwards you might could touch it with a sharpie.

I hope this makes sense, if not send me your email and I'll try to draw it out for you. Good luck.

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