Bruce wrote:

I use my drill press mostly to drill metal...very little wood, yet my
press, which I was given, was intended to drill wood, so it really
runs too fast. I have it set at its slowest ratio setting, but still
I think it is too fast. I am planning on switching out the belt
pulleys to achieve the speeds I should be running for metal. Thus
the questions.....what is a good speed range to target for and what is
the formula for pully size? I would like to stay with a set of three
step pulleys and have a nice range of metal speed cutting. Most of my
drilling is 1/2 inch thickness or less. Too slow is better than too
fast....I would guess...right??


That is exactly correct. Going very slow will naturally increase your
machining time but unless you a drilling a lot of holes you will
typically spend much more time in handling then cutting. If you go too
fast then you have to make sure you are feeding quick enough to produce
a chip. As soon as you fail to feed quick enough to produce a chip the
drill bit will begin to abrade instead of cut and your cutting tool
life will be drastically reduced. Besides this you have to contend with
keeping the drill bit from overheating. The only real downside of going
too slow for someone not on the clock is that your surface finishes will
typically suffer from the higher feed rates. This is usually offset by
the fact that your cutting tools will be sharper and potentially last a
long time. One word of caution- low speeds usually mean high torque and
when you are using a drill press you frequently hold the parts by hand,
so be careful, especially when the drill breaks through and wants to
thread up on the helix of the bit. If you frequently drill thin parts I
would highly recommend the varibit drills.



Thanks