Getting A Decent Finish Cold Rolled Steel On Lathe

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umahunter

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Turning 1/2 cold rolled steel got my speed at 1200 trying to figure if I should have faster or slower auto feed to try and get past the lined looking finish any thoughts from those of more knowledge :) :)
 
a small radius on the tip of your tool will work wonders.
with a pointed tool you are in essence making very fine threads, if you were to look at the bar under magnification.
the rounded tool will leave less pronounced microthreads, and a finer finish.
the slower the carriage travel with respect to spindle speed will result in the finer of appearance.
in other words, set the autofeed to the slowest possible speeds for the best finish.
when roughing, appearance is not the goal, stock removal is!
a sharp tool is good for that, but for finishing a radius on the tool tip will leave a better finish
 
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I prefer the "Vertical Shear Bit" for finishing, see: http://www.gadgetbuilder.com/VerticalShearBit.html
It's limited to about 3 thou maximum cut so rough to size with another bit first. Depending on how rough the surface is it may take a couple passes to get the best finish with the vertical shear bit.

John

Edit: Video by Mr Pete:
 
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I'm with 'The Doctor' on this one.

CHuck the grumpy old guy
 
If you're talking about 1018 cold rolled then just about any tool other than a shear tool will leave lines.
 
1200 rpm is way to fast. Slow it down to 600 or less as see what happens. But cold roll is notorious for being hard to finish and the shear tool will do it.
 
I use a massive radius and very slow feed and of course shallow cuts. It's kind of an unconventional grind but pretty useful but will chatter very bad if I try to take very deep cuts. It looks more like a form tool than normal cutter. I also have great luck with the shear tool. But either way a very sharp edge is important. I am new and just do this as a hobby so there is no one there to make fun of my tool grind or tell me it's wrong so I try whatever I want and found one that works great for me. Sorry don't have any photos.
 
Actually,COLD ROLLED finishes a LOT BETTER than HOT ROLLED. The steel fibers are more compressed. Try some of the suggested cures.
 
I've had good luck with carbide and a decent nose radius.
 
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