by MadReptillian

This table showing lathe cutting speeds in feet per minute. I use this table to calculate the speed of my lathe and my drills. Yes I am aware they are not as accurate when using them for drills, however they seem to work for me. The proper formula for calculating is as follows:

CS x 12 =   RPM

π x D

CS being 'Cutting Speed' which is locate in the table above and 'D' meaning diameter of stock

However you can shorten this down to make it easier, π (Pi) has a value of approximately 3.14 and divides into 12 just under 4 times.

So I use this shortened formula for working out my lathe speed.

CS x 4 =  RPM

D

Let say I have 3 inch ally stock and I'm using toolsteel to make the cut.  For roughing the formula would be as follows:

1000 x 4

3.000               =        1333.33 RPM

So 1300 RPM is the rough speed I should be cutting with 3 inch aluminium stock in a lathe.

Now lets say I now have 1.505" stainless steel and I want to do my finishing cut with toolsteel. The math is as follows:

46 x 4

1.505                   =     122.25 RPM

Easy isn't it? If your using metric and/or metres a minute for your cutting speed , you might want to convert the numbers above and create your own table.

Hope this helps,

'MadRep'
About the author

Hello there

I had a quick look up on google and i believe this is a high carbon steel (a common name for it is lead steel i think). I would use the speeds for Mild Steel and if it isnt cutting quite right try lowering your speed.

Good Luck