Drilling question

D

Dave Hub

Joined
Dec 10, 2014
Messages
57
So every time I drill a hole through my pre-heat treated knife blank, the bit binds and stops drilling just as it breaks through the other side. the quill continues to spin but the bit doesn't move and it's a pain to get it broken loose from the blade. I have tightened the Sh*t out of the chuck too. If the blade isn't clamped down, it will ride up on the bit and spin around. Did it only once and I was lucky to avoid getting cut.

Am I drilling too fast? It does it on new and old bits. I am using 440C and ATS34. Both 5/32" thick.
 
Not sure what is happening but you try putting a backing on it to let the bit go into something else may help.
 
I will try both options. Should I use a metal backing or would a piece of scrap wood suffice?

Kdog- what brand of carbide bits would you suggest?
 
If you are not going to clamp the blank at least put a clamp or something else on the table for it "dog" against.
When you feel the bit about to break through ease up on the down force to let the bit clean the hole out.
 
It's hard to see but the cutting edge of a drill bit is a lot like the threads on the end of a scew. What's happening is that as the metal thins out at the bottom of your hole and the chisel point breaks through, there is no more axial resistance and the cutting edge of the drill gets under the small bit of metal remaining, and it tries to thread up the bit.

The resolution to this is to put another piece under your work piece, and not wood, because that keeps axial resistance on the drill bit. The other solution is to clamp your work down and just before you break through, take pressure off of the quill handle and slow your feed down until the entire face of the drill is through.
 
I get carbide bits from usaknifemaker. Ordered them when I had to order other stuff. Check Amazon, you can get them cheaper I believe.
 
Clamping the work (which you should always do) and putting a metal backing plate under the work piece should solve the problem. Good quality steel bits should do fine, as long as the blades have not been hardened. Carbide bits are only necessary for hardened steel. They are expensive and brittle, so they break easily. There are a couple of previous threads on here that go into drilling steel in more detail which you should read.
 
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