Drilling Large Holes

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Bob McCarty

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I always have a problem with chattering even with starter holes that I've enlarged several times. Did a search to try and learn a new trick. Most suggestions involved using a mag drill, stepped bits or a technique that I don't have the tools to do. The one post that caught my attention said to place a folded piece of emery cloth (smooth sides out) between the drill bit and starter hole. It said the bit would self center and cut cleanly. As soon as a shoulder has been cut to contain the bit, you can remove the emery cloth. I tried it this morning on a piece of 5/8" steel. Enlarged a 1/2" hole to 13/16" without any chatter at all, and ended up with a nice clean edge. Anyone have other tricks?

Bob
 
Bigdog, Have you ever seen a picture posted by me. :oops: I just laid the folded emery cloth flat on top of the pilot hole, then turned on the drill press and lowered down the bit. The bit had already been centered before I put the emery cloth there. I have no explanation why it worked, but it sure did.

Bob
 
I'll have to try that. I've spent a lot of time trying to get the cutting edge ground the same on both sides.
 
Bob Do I understand this correctly? By smooth side out you mean the drill bit works against the smooth side and the emery cuts against the object you are drilling into? The emery wears a champher into the work piece. Once you get it as wide as the drill bit you remove the emery and drill from there.
You are not running the drill bit against the emery to even the cutting edges if I understand correctly
 
Bill take a small strip of emery cloth and fold it in half so the smooth side is out. Place the folded piece on what you are cutting, then lower the drill bit. There is a smooth side against the drill bit, and a smooth side against the piece being cut. Again, don't ask me how it works, but it sure does.

Bob
 
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