Mini lathe speed

Yes Work material, diameter, cutter material and type of cut will all affect the speed.

This table should help, look up the FPM for your material then enter that and the diameter in the boxes and it will give a guide speed for hobby size machines. Use that as a starting point and adjust as needed

You might find it worthwhile taking out a digital subscription to Model Engineers' Workshop. That will give you access to all the backnumbers on this site and you can look at Neil's series, "Lathework for Beginners".

Russell

The approximation 10000 / diameter in mm is a good start. It works directly for HSS on steel, so a 25mm diameter steel rod would be spun at about 400rpm, and 5mm at 2500rpm. It assumes a single point tool in good order.

For other materials, halve the calculated rpm for cast-iron and stainless. Add 25 to 50% for Brass, and double it for Aluminium.

If using carbide rather than HSS, multiply the HSS result by 4 to 6. (If your machine can deliver the necessary power and speed!)

Be prepared to experiment. Much depends on what you're doing and the limitations of your set up. With the rpm in the right area, adjust depth of cut and feed rate for best results. If you get problems like chatter, poor finish, or overheating, play with rpm as well. Don't expect a hobby lathe to work at industrial production rates! I liked to run my mini-lathe so it sounded loaded without being unduly stressed, prioritising finish over metal removal rate.

Dave

For high speed steel tool bits, when turning steel, RPM = 400 divided by the job's diameter in inches.

So for 1" diameter steel, rpm = 400rpm. Half inch diameter = 800rpm. 2" diameter = 200rpm.

For carbide tooling you can double (or more) the rpm. When turning aluminium or brass, double the rpm.

When in doubt, go slow. Going too fast will burn the cutting edge off the tool. Going too slow will work OK, just take a bit longer to get the job done.

Edited By Hopper on 07/09/2018 13:48:08