turning table legs

[seawolf217]

Hey all,

This is my first post. I am a newbie at machining. I have a customer who wanted to turn 4 steel table legs. Each leg is 25.75" long. They start at .75" on one side and end at 2" at the other side. Its angled from one side to the other - no steps. I programmed this on my lathe but I was having trouble getting a good finish. I was using 1018 steel with a carbide insert taking a finish cut of .05" a sfm of 450 and a feed rate of .009 ipr. I ended up having to polish each leg after this machining. What was I doing wrong?

Thanks in advance

[Donkey Hotey]

Others will be along to share their wisdom (and I'm waiting to read it) but...

...1018 steel doesn't mill or turn very well, in my experience. The surface tears instead of cuts and it creates a nasty finish.

I'd bet there isn't much you could have done to improve it without carefully choosing the inserts and even then, I doubt it would have improved much.

By comparison, I've turned some grades of leaded steel and stainless steel that were absolutely gorgeous with the same inserts and speeds/feeds.

[warfreak]

i would try experimenting by lowering the ipr to maybe about .006 and increase your rpm a bit.
also make sure coolant is getting to the cutting edge and that the chips are breaking off instead of making long strings that might be wrapping around your tool

[01_nasty]

Yeah I agree with warfreak. Generally to improve surface finish, lower the feed rate, increase the RPM and make sure your cutting insert is in tip top condition. Also ensure that the coolant is being directed to the cutting tip, and not just the part. I would also try to reduce the depth of your finishing cut, 0.05" or (1.2mm for us metric freaks) seems a bit much, carbide tools can be very prone to chipping.

Hope this gets ya sorted!!