I posted this elsewhere but if you need to get by with those lead screws that far out of whack for awhile here is a good method to try so you can even climb cut with them bad... I always cut this way because control triples at least!!
((((Not sure if this will help at all or not but if you'd like to climb cut and bury the cutter on a manual mill, lock the gibbs down pretty snug and put a 3/4" box wrench on the nut at the handle... This will give you incredible leverage to override the gibbs being snug and you can climb cut, not to mention get a sick finish compared to conventional milling. The point being your cutter can't jerk the work into your cutter and snap it... I like to think of it as 'poor mans ballscrews'... I've done it on a manual lathe too and it knocked down chatter considerably when coupled with a small stick rubbing on the part~
I agree with Ken though, waaaay to many variables, I go by feel normally, or if I get a good cut on my cnc's write down what works for a ball park reference next time and adjust in 10% increments...
ps
lock your gibbs in both X & Y or you'll regret it, chances are you'll break some cutters learning this method, so don't try it on something important...))))
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