On Sat, 24 Apr 2010 06:51:38 -0700, "Jon Danniken"
wrote:

Gunner Asch wrote:

Frankly Jon..you would be better served if you made up templates to
mark your holes, center punch them..and then use a 1/2" drill motor.

Heya Gunner, good to see ya, mate! Hope everything is well in Gunnerville.
Thanks for the suggestion, but I just don't have the precision with a hand
motor to get anywhere near straight. I have seen the little holders for
hand motors, but I don't know how precise I could be with one of those.

While you could perhaps(not likely) drill them with a 1/4hp drill
press..you will have to work very slowly, and probably increasingly
bigger holes first.

Okay, now that brings up a question I have. If you had an adequately rated
drill press, and needed to drill a number of one inch diameter holes in 1/8"
mild steel, would you use a hole saw or a twist bit? What would you
consider to be the minimum horsepower for either type of bit?

Also, would you consider a S/D bit suitable for a one inch hole if your
chuck was only 1/2"?

Thanks Gunner,

Jon

A hole saw with plenty of cutting fluid will be the lowest-torque
approach. Next would be a step bit, last choice would be a 1" dia
twist drill. The twist drill would be better for production rate in
heavier material with suitable machinery driving it, but hole saws and
step drills (unibit) work much better when the dia of the hole is
considerably larger than the thickness of the material.

1/4 hp at 620 RPM is 25.4 in-lbf of torque. That might drive a good
holesaw if nothing binds up due to deflection. It would help a lot if
you could change pulleys to get the speed down. That would increase
your torque and decrease heating.

At 620 RPM a 1" hole saw will have a tooth speed of 162 SFPM, which is
on the high side of the range for bimetal cutting mild steel but not
absurdly out of the ball park. The range generally goes from 80 to
200 SFPM. Use lots of juice. Slower would be better.