Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

How much runout does it have?  And, how much runout is too much.?

I ask this because while I was in the process of building a inverted drill (to drill PCBs from the bottom up) at one point I had a runout of at least .01 inches. This is probably much more than your average Dremel. Despite this I was able to drill holes down to .0225 (#74 drill) using carbide drills without breaking any bits. Admittedly I was using 45X magnification to align the board and was watching as the drill broke through, therefore I did not plunge the drills to half or more of their length.

I seriously doubt that the problem people are having with drill breakage using Dremels is due simply to runout. I also don't doubt that they are having better results with other tools such as Proxxon rotary tools.

The reason I mention this is that it would be difficult for the average person to improve the runout of tools such as the Dremel but if another cause for drill breakage was found perhaps that could be easily corrected.

Craig