Countersink Question

A

Arkham Drifter

Joined
Sep 29, 1999
Messages
195
I am clueless when it comes to countersinks (and other shop tools but I'll spare everyone and limit this thread to countersinks. ;-D).
According to the book "How To Make A Knife" I would be using a countersink to relieve the holes drilled into the tang to prevent stress cracks that could otherwise form during the heat treat. I have no practical experience with this process and have never used a countersink before.
When I looked them up in the DeWitt catalog I found about six pages of various countersinks avaible with different numbers of fluting and different angles (i.e. 30 and 60, 45 and 90, etc). What should I be looking for in a countersink?
Thanks guys.
 
If all you are doing just a fixed blade and want to break the edge of the hole, it doesn't really matter what angle it is. A knifemaker told me that you can even use a larger drill bit to break the edge. If you are countersinking to put flathead screws in though, that is a slightly different story.

Just don't get a countersink for countersinking mostly wood. I got a countersink from Vermont American, single flute, black oxide coated. It has dents in it at the 1/8" and 3/8" diameter diameter areas because the steel of the knife was just as hard as the countersink. Make sure its a countersink that is made for metal.
 
Chang,
Thanks for the info. As a novice knifemaker I am only concerned with fixed blades with pinned scales at this point so its good to hear that I don't have to be too technical with regard to my c'sink needs. I was looking at Cobalt countersinks for metal work in hopes that it will last a long time.
Thanks again.
 
After slightly beveling the pin holes be sure to run the pin size drill bit through again. Sometimes a countersink will put a burr in the pin hole making it smaller and when hardened the pin wont fit again. Trying to redrill the pin holes after heat-treat will ruin your drill bit.
 
drill your holes oversize even. then break the edge will a carbide drill bit. i have had drilled holes shrink when cryo- treated. having to be redrilled to fit thr 8-32nds loveless bolts i like to use. :p
 
Bruce Bump & RHINO,
Thanks alot for the additional tips! Had you both not explained this process then I would have had to learn them the hard way which is no fun. Besides I have a feeling that my learning curve is going to be plenty steep as it is!;)
Thanks again.
 
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