sharpening help

[Cody Cantrell]

Can someone help me find some info on sharpening center bits? I have seen a post on how to do it but cant seem to find it now. I recently acquired some and need to get them going. Thanks for any help.
Cody

[Joe Bailey]

Center bits?

[Mark Dorman]

http://www.fullchisel.com/blog/?p=123 try here for info.
He has a I drawing with the sharpening order.

[Cody Cantrell]

Thanks Mark for the link. Next question is how do you keep the geometry right when you adjust the outside spur, the top of the bevel, and the center point?

Joe a center bit is the one on the left in Marks post.

[Joe Bailey]

OK - thanks for that - don't know why I didn't recognize the reference in the first place.
Here's another option: http://www.youtube.com/watch?v=MSbN5bhKVAw
center bits start at about 2:16

[Jim Koepke]

Thanks Mark for the link. Next question is how do you keep the geometry right when you adjust the outside spur, the top of the bevel, and the center point?

My understanding is the outside of the spur should not be adjusted as it changes the outside diameter of the bit.

jtk

[Jim Neeley]

Cody,

A couple of recommendations:

* All of your sharpening should be done inside the perimeter of the bit; do not take a file to any outside edges.

* You want point 5 to be the point of first contact with the wood, followed by 1 and 3 last. I know this is a no-brainer but because of the limited metal on 1 and 5 and the larger surface on 3, it's easy to shorten them quicker than 3 so the mission is to remove the absolute minimum necessary metal from 1 and 5. This occurs because if 1 becomes shorter than 3 your cut quality suffers dramatically and if 1 gets too short the bit is useless. This has occurred over the years on many of the old brace-style forstners out there. When that happens the bit pretty-much becomes an ornament.

[Mark Dorman]

I agree with not filing the outside; of any bit actually.

[Mark Dorman]

Good video Joe; thanks for sharing that.

[Cody Cantrell]

Thanks for the video Joe.

Jim's that is about what I was thinking thanks for confirming it.

Cody