Need Help!- new at this

[azureskys]

I have a lathe and mill combo . how do i get a nice smooth finish on the lathe should i cut fast or slow and the same with the mill, I did some pratice today with the lathe and it came out rough and you could see where the bit was cutting the same with the mill, i was only cutting about 5 thousandths off not a lot and using HSS bits, what s going can anyone help ?

[packrat]

What feed rate are you using?

Cary

[CNCRim]

Originally Posted by azureskys I have a lathe and mill combo . how do i get a nice smooth finish on the lathe should i cut fast or slow and the same with the mill, I did some pratice today with the lathe and it came out rough and you could see where the bit was cutting the same with the mill, i was only cutting about 5 thousandths off not a lot and using HSS bits, what s going can anyone help ?

First, what kind of material you are cutting? second, what is the feedrate and sfm. The feedrate for lathe usually in FPR(feed per rev) and mill in FPM(feed per min). Post your program will help alot.

[azureskys]

Im not working with cnc im using a grizzly G0516 lathe mill combo and im cutting mild steel with HSS bits

[packrat]

Even a manual lathe has a feed rate/feed per revolution. It is usually listed with the thread per inch levers.

Your tool bit should have a slight radius stoned on the tip.

If you don't have anyone to help teach you, or even if you do, you owe it to your self to get some of these books; http://www.lindsaybks.com/bks/lathebk/index.html
The South Bend Lathe books are good for a beginner, even though you don't have a South Bend. The books are from a different era but the basics are still the same!

cary

[samu]

Cutting speed of mild steel is about 90 feet per minute. To caculate the rpm on a lathe : cutting speed *4/diameter of the work piece(inch).This formula is an aproximation assuming that PI=3. On a mill it is the same but you use the cutter diameter instead of the work piece diameter. For roughing, you can slow down the rpm and increase the feed and for finishing, increase the rpm and reduce the feed. But these are just a starting point, you have to try diferent setting to find the best.

[azureskys]

I changed the belts and put them on a lower speed and did a small cut came out real nice , there are some gears in there that can be changed i also sanded it with some 180 , probly with a finer grit emery cloth it would be even better . thanks for the book info i will get a couple of those and i guess trial and error does teach , thank you guys so much .