Turning Hr Steel

AGCB97

AGCB97

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Is it possible to get a reasonable finish when turning hot rolled stock? I've just been using it to practice turning but the finish comes out terrible, like its torn off. What type and shape of tool would be best? As I say, it's just for practice cause I have it and it's cheap.
Thanks
Aaron
 
Using inserted carbide tooling keep the SFM as high as possible for the diameter being turned and as high a depth of cut as the machine will handle whilst holding dimensions. Do not be shy on the feed rate either and if finish is a priority use flood coolant.

Can't help you if you are using HSS tooling as I haven't run a turning job with it in 30 years.

Last week I ran 300 parts from 1 3/8" 1018 hex stock, 1500 RPM's, .050 DOC and .010 IPR feed for roughing and .008 DOC at .005 feed for finishing and the finish was excellent using an 80 Deg. negative insert with a .015 nose radius designed for interrupted cuts from Sandvik.
hexpart_zpshw5ap3li.jpg
 
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Wreck is 100% correct if you're making a paycheck or have the budget to invest into modern tooling and machinery. But us H-M must look at things a lot different.
Take your piece of HSS and do some sharpening on it. You want a nose radius of 1/32 to 1/16, depending on the size of your lathe. Next, put a healthy back rake or top rake on the tool to give it a shear action when cutting. Last hone the edges until they are near razor sharp! Including the nose radius. As Wreck said use the coarsest feed as you can for roughing on hot rolled mild steel (A-36, 1018-1026 grades and others). Coat the surface of the part that you are turning with a good cutting oil. This should remove the "dragging" or "build up" as you see on the surface currently. Back off on your feed rate to around .005-.010" on your last two or three final passes. Keep applying cutting oil to the surface on the last cuts.
 
Wreck™Wreck said:
I do not discourage home shop machinists, I try to encourage them with the little wisdom that I have gained over the years, anything that I post has worked for me.
Doing this for a living gives one a different perspective.
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Doing it for a living, definitely makes a difference in one's approach, and generally means stouter, and higher quality machines to do the work. On my 12" Craftsman I have also made good use of a file and emery cloth to get a good finish. I'm looking forward to eliminating some of those steps with the new to me TOS I've yet use. The great thing about this forum, Is that you get so many different, and valid approaches to to the same issue. Mike
 
savarin said:
I use a shearing bit with very slow auto feed to finish off my hot rolled steel.
It leaves a finish that only needs a tiny bit of emery cloth to polish.
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Their dead handy for steel that just seems to be very very gummy and for an amazing finish with very shalow doc.

I use hss tools almost exclusivly but i use feed's and doc along the lines of what wreek wreek sujests, (less rpm though my lathe dosn't go that fast :) ) also I find a very slight nose radius works well for me, I generaly stick to my favrit knife edge tool for the hot roled where I can.

Stuart
 
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