Comments by "Paul Frederick" (@1pcfred) on "Is Used Motor Oil As Good As Cutting Oil for Drilling Metal?" video.

  1. Spit is better than nothing. Usually if I'm roughing it I'll have a shallow cup of water and dip the bit in it periodically to cool it. Most people just run too high RPM and then nothing helps. Drilling steel you need to keep the surface speed below 100 feet a minute. So a 7/32" diameter bit you need to run under 1,800 RPM. Which is about what a cordless drill typically turns. Any larger diameter bit you need to run even slower. But shallow hole drilling you can overdrive.
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  2.  @imadecoy.  WD-40 gives a great finish on aluminum and is certainly better than nothing at all. Plus the smell cannot be beat. WD-40 is the best male cologne on the market.
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  3.  jubjub247  if I am roughing it I'm lucky to find a cup. In my shop I use Rapid Tap. Straight water rusts my mill.
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  4. 3/8" diameter at 600 RPM = 58.9 peripheral Surface Feet Per Minute (SFPM= (PI X DIA X RPM) / 12). Which is a good speed for HSS cutting mild steel. Theoretically you can run up to 100 SFPM. But I like to keep it around 50 SFPM myself for drilling. Milling I run 100 SFPM. Harder materials you need to run slower. Harder tooling you can run faster. Like cobalt or carbide bits.
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