Small drill
I am using small Hobby drill (cheap dremmel tool) t make holes in PCB. Recently I broke several high speed steel drills. I decided to explore, why the drills are broken. After some investigation, I discovered that drill is moving a bit to side. The problem is in the drill grip. Sometimes, one element of the grip is “delayed" and the drill is not centered. When I use flexible steel drills, the drill is flexible enough to compensate the movements. But when I used high speed carbon steel for PCB, the brittle drill is damaged very fast.
I disassembled the drill. Here the image of the parts…
The drill is very simple: Chinese made electric motor, brass axle, one ball bearing and drill grip.
March 20th, 2008 at 6:20 pm
that looks like a pretty good brand of drills, i guess it works like a charm eh?
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March 22nd, 2008 at 9:22 pm
Good job of tracking down the problem. I may not understand exactly what your problem is so forgive me if I give you information that may not help. I've messed with a few motors before including hand held drills and VCR capstain (speed regulator) motors. Most of the cheap ones (including expensive VCR motors) don't use steel ball bearings to center the rotor shaft, but use a thick brass washer. Sometimes the brass wears out and the shaft can wobble. I've temporarily (sometimes permanently) fixed the wobble by coating the inside of the brass bearing with silver solder. I then reassemble the motor after drilling the center out, or else if the solder was thin enough simply force the shaft back in and manually wiggle the shaft a little to loosen it up.