# Turning Stainless Steel  On G0602 Any Tips



## umahunter (Mar 11, 2016)

I have some  cups I need to turn and bore to except bearings never turned stainless just steel and aluminum I have sclr holders and boring bars with seco ccmt tp2500 32.51 inserts wondering if these will do or if I should get a different insert any tips and opinions welcome


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## Bob Korves (Mar 11, 2016)

What stainless alloy is it?


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## umahunter (Mar 12, 2016)

My local shop probably has 304 or 316 I suppose I could order online if a different grade turns way better it's going to be a bearing cup for a mud motor


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## Tony Wells (Mar 12, 2016)

Mud motor as in downhole tool, or mud motor as in flat bottom pusher?


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## umahunter (Mar 12, 2016)

Boat motor


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## Ulma Doctor (Mar 12, 2016)

if you can get away with 304 you'll have a much easier time doing what you want, 
316 will work harden if you even look at it for too long .
whichever grade you use, take moderate cuts at a heavy feed rate- 
light cuts will only frustrate you- don't ask how i know that....


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## mikey (Mar 12, 2016)

Given the marine environment, 304 would probably be your best bet. It sucks to machine but it has good corrosion resistance.

I know you mentioned carbide inserts but I much prefer a sharp cobalt HSS tool for turning stainless with 12-15 degrees of side and end relief and 25+ degrees of side rake and a 1/64" nose radius. This tool cuts much better and much cooler than a CCMT insert does on the lathe and the increased side rake helps to get the heat out of the cut fast. Stainless has low heat conductivity so heat builds in the area of the cut; a lot of cutting fluid, sharp tools and a consistent feed rate will help deal with this.

Also remember that 304 likes to come off in very, very sharp strings that will cut you up rather well so be careful.

Edit: forgot to add that holding tight tolerances in a blind hole/cup in 304 can be somewhat of a challenge, at least for me. I've tried cobalt, solid carbide and inserted tip carbide bars in 304 and what works best for me is a positive lead bar with flat-topped inserts with a 0.007-0.008" nose radius. The reason is pretty simple. A flat topped insert, as opposed to a chip breaker insert, can take lighter cuts and still work properly. This allows a reasonable depth of cut with a feed rate that moves along fast enough so the work doesn't harden. This, in turn, allows for finer finishing passes that allow you to come in on size with a consistent ID all the way down the bore.

You'll be fine. 304 isn't that hard to work with. Use sharp tools, lots of cutting fluid, maintain a consistent feed rate and it will go well.


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