Drilling large holes

Sun Feb 13, 2011 3:41 pm

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
Last edited by Bob McCarty on Wed Aug 31, 2011 3:30 pm, edited 1 time in total.

Re: Drilling large holes

Sun Feb 13, 2011 4:14 pm

Bob - are you saying to "tent" the drillbit with the emery? I'm not grasping the idea. Maybe a picture??

Re: Drilling large holes

Sun Feb 13, 2011 6:48 pm

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

Re: Drilling large holes

Sun Feb 13, 2011 7:38 pm

OK - emery folded to the inside then just drill down through the cloth. Got it!

Re: Drilling large holes

Sun Feb 13, 2011 10:32 pm

Bob:

Cool trick. Must remember that one. :!:

Re: Drilling large holes

Mon Feb 14, 2011 11:35 am

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.

Re: Drilling large holes

Wed Aug 31, 2011 12:11 pm

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

Re: Drilling large holes

Wed Aug 31, 2011 3:32 pm

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

Re: Drilling large holes

Fri Oct 21, 2011 11:16 am

Bob, now that you have received your certificate in photo posting, can we expect some pictures soon? :mrgreen: :D

Re: Drilling large holes

Fri Oct 21, 2011 11:19 am

Raymond, NO, but there is a nice picture of a restored Silver King in the Photohost now. :D

lBob