I would use the slow speed. 10000 rpm would be ok for plastic maybe brass if you ar carefull. Use slow speed and DO NOT FORCE the bit.
It's part nickel, zinc and copper. I would think copper and brass would be considered on the soft side. Do you really have a drill that turns at 10,000 rpm or even 3000 rpm?
Henry
COB Potomac & Northern
Shenandoah Valley
I'm experimenting with drilling holes in rail to attach invisible feeders. The instructions with the drill bit says to run at 3,000 RPM for hard materials and 10,000 RPM for soft material. In this case would nickel silver rail be considered hard or soft?
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