At 01:23 PM 8/5/2005 +0100, you wrote:
>Hi,
>   Is anyone here using a Dremel (or similar tool) and tungsten-carbide bits
>to drill PCBs? If so, what speed do you run the bits at?

Optimum drill speed is determined by the surface speed at the drill
cutting edges, typically measured in SFM in North America. If we assume
400 SFM for a carbide tool in FR4*, we have:

RPM ~= 4*SFM/diameter

If the maximum RPM your Dremel can do is 30K, then you can run it flat out
up to diameter

dia= 1600/30,000 = 53 thou

So, above about 0.05" tool diameter, you should start cutting back the
drill RPM proportionally.

Hope this helps.

Best regards,

* http://www.taconic-stl.com/fr4%20processing_guide.pdf


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