Drilling small holes

[Gordon]

How do you get a really small drill started? I had to drill the burner jet for a Cracker Loco I am building. (see other thread) The hole was to be .2 MM or .008" in brass. I bought some drill bits and tried drilling in my Grizzly CNC mill. 2500 RPM is max. I peck drilled .005 and set feed at 25% of recommended. The biggest problem is getting started. As soon as the drill bit touches the material it starts to walk. The smallest spotting drill I have is 1/8" which leaves a large flat spot so is of no use. I tried drilling the first one and the bit broke as soon as it touched the piece. The next one made it most of the way and broke off inside the piece. The next one I drilled a few thousands deep with a .5 MM drill and then finished drilling with a .013 drill since the .008 drills were gone. This went all the way trough but I touched the drill with my finger while taking the piece out of the vise and it also broke. Either my equipment is not accurate enough for the job or I am doing something wrong.

Any words of wisdom?

Gordon

 

[Sshire]

Gordon
I've made a few small spotting drills that have been a big help with tiny drilling.
.0625 and .0312 oil hardening drill rod. I had them extended just enough for the point in the 5C collet on the lathe and turned a tapered point. Hardened and tempered. Since I only use them for aluminum and brass they should last forever. I suspect they would work well in 12L14 as well.

WD40 when drilling tiny holes in aluminum and brass works well for me. The tiny drills have so much flex that chucking them up as short as possible, combined with VERY light (1 finger) pressure and numerous pecks, is my formula. Also, withdraw very slowly. If I were doing this very frequently, I'd probably look at getting one of the very precise small drilling machine kits and build one.

When I started making small engines, I thought that one drill bit was as good as another. I started replacing the broken bits with good bits and realized that a great deal of the problem was poorly (cheaply) made bits. I've had good results with Hertel bits.

My 2 cents.

 

[Gordon]

Stan I also believe that getting a starting spot is the answer. When you say you made a spotting drill did you make it with just a point and no flutes? I did not think that it would cut at all and just wear the point off. Trying to make flutes in a 1/16 dia rod is beyond my ability. I did think about trying to make a "D" bit but that gets pretty touchy too.

 

[aonemarine]

I have used a thumb tack to make a small spot to keep the bit centered, but im also a bit spoiled with my dumore micro drill press when it comes to the actual drilling..

 

[aonemarine]

So there was this Chineese guy at a machinist convention bragging to a guy from Texas that he made drill bits so small he could drill a hole thru a human hair. The Texan did not seem to be impressed so the Chineese guy offered to send him some drill bits to show off his work. the Texan recieved the drill bits and mailed them back to the Chineese man with a hole drilled thru them. Not sure what the moral of the story is, but its kinda funny....

 

[Sshire]

Gordon
I did forget that part. Before hardening, I used a very small Jewelers triangular file to cut a "flute." Certainly not the correct geometry, but they do work.
I thought about the flutes after I had filed them. A 0.01 or 0.02 slitting saw would have probably been better.

 

[Woodster]

So there was this Chineese guy at a machinist convention bragging to a guy from Texas that he made drill bits so small he could drill a hole thru a human hair. The Texan did not seem to be impressed so the Chineese guy offered to send him some drill bits to show off his work. the Texan recieved the drill bits and mailed them back to the Chineese man with a hole drilled thru them. Not sure what the moral of the story is, but its kinda funny....

Almost correct!. It was actually a Japanese tooling manufacturer and Rolls Royce Aero Engines.