HF 8x12 Lathe - Upgraded Replacement Motor

I have done .04" doc on my 8x14 before, but never at that diameter.

Whats you are doing is asking the machine for more power than it has. If you have a machinist handbook, you can calculate how much power you need for a given cut if you know the material, doc, feed, and rpm.
 
Those charts are interesting, BUT they seemed backward. I would think that Carbide is a lesser to HSS, so HSS should be capable of cutting at a higher speed. Please explain ?

It depends what you are trying to accomplish. HSS is sharper (takes a finer edge when ground properly), and thus requires less force to make a given cut. however it's much more susceptible to heat damage (loss of temper), and thus needs to be run slower. Carbide is blunter and thus requires more power to make a given cut, but it can sustain very high cutting temperatures and can thus be run significantly faster. basically everything is a trade off that comes back to the power & rigidity of the machine.

Check out this video i made a while back of my 8x14
https://www.youtube.com/watch?v=P1xbg4KKbeU


hot rolled 4140
360fpm
0.005 in/rev
0.02 doc
1000 rpm
 
I watched that video - that is a carbide insert correct ? and that chuck was really spinning (I usually run at 125 rpm) and that was a deep cut and there was no lubricant and no smoke ?
 
I watched that video - that is a carbide insert correct ? and that chuck was really spinning (I usually run at 125 rpm) and that was a deep cut and there was no lubricant and no smoke ?


Yea, it's a carbide insert. the cut was 20 thousands of an inch, and no lubricants. I could push 45 thousands or so at that diameter but the machine will really start to complain.
 
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