Re: Sensitive Drill Feed, and drills

Denny Anspach <danspach@...>

Larry Jackman writes-

600 rpm for a drill of the size
you talk about is TO SLOW should be at least 10,000 RPM and if you do
it right you will not break you drill.
A quick review of my post on this subject substantiates that I was relating the 600 rpm **only to the drilling of styrene** (that is- plastic), not metal.
10,000 rpm through styrene would be universally fatal for the model at hand (at least in my hands).

That said, modeler-machinist-builder (and violin teacher) Bragdon in the extensive documentation that was included with his precision drill press argues that such high speed is not necessary for tiny drills through metal; and he makes a strong argument for using much lower speeds for the drills that his press can handle c.#50-80-?. I am in no position to either judge or argue either side of this issue, but here is at least one contrary opinion from someone who was in the business.

In real time, I believe that for given drill quality and sharpness, the majority of fine drills broken in modeling come from the stresses introduced either by lack of concentricity of the spindle or chuck, or effective manual lateral or angular movement of the spindle/chuck assembly , whether hand held or in a press.

Denny S. Anspach, MD

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