Bench Drill

[rusty69bus]

basically, bigger drill = slower speed/feed on steel

i.e. small pulley motor = large pulley drill shaft

best thing is to try it out,we all tend to think faster better at the start,then you lower the speed/feed and see the drills cut better/quicker than faster/red hot drill tip

 

[jugs]

Cheers Jugs / Rusty,

Has left me a little confused!

I assume the "ft/min" is refering to feed rates for milling / turning?

Thanks again,

Mick.

No it's the peripheral speed of the cutter (if you're milling/drilling) or work (if you're turning). However, you can ignore that.

Just look for the material you are working in at the top of the columns.
Then look for the size of drill or work you are using down the left hand side.
Then read off the stated RPM. These RPMs are for HSS tools. For carbide tools, take given RPM X 3. (see note at bottom of table).

EG 1. To drill a 3/8" (8mm) hole in mild steel (ie cutting speed 90ft/min), drill needs to run @ 916 rpm.

EG 2. In a lathe, to skim a 8" dia cast brake drum (ie 40 ft/min) using carbide tool, required speed =19 X3 = 57 rpm