Myford Super 7

I have recently bought a Myford Super 7; it is in great condition. I
have stripped and reassembled it. My problem is that when I can a cut
in mild steel I end up with ridges in the metal. I have tried varying
the speed of cut, depth, cutter type, height etc to no avail. I have
machined a piece of brass but without the same problem. I have adjusted
the saddle and the cross slide so that they move more freely. The is no
placy in the saddle or the headstock bearing.
Anyone any ideas.
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Get some free cutting mild steel.
Use a tool with a slight radius on the tip instead of a point.
Ensure a sharp tool and appropriate geometry of same.
Use HSS tools, keep them sharp.
If the problem went away when machining brass, dropkick the steel bar into the weeds in the alley behind the house, and refer to the first line. Life is too short to dick around trying to get a good finish on scrap metal.
Some mild steel is just plain miserable to get a decent finish on. It tears,and raises a rough finish, until you crank the speed WAY up and plow into it with a decent carbide insert. Tough on a small machine like a Myford.
Cheers Trevor Jones
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Trevor Jones
Dear Humph, I suspect you may have a loose spindle. Excessive end float. If you have the Myford S7 manual, go thru the spindle adjustment procedure. It's a little confusing, but when done correctly, the tendency to cause chatter and such will be much reduced. The spindle thrust bearing package is moved to the left to adjust the tapered bush clearance to a minimum without causing undue heating. End thrust is carried by the thrust bearings, not the bronze bush. Be sure to use the correct oil as well. The S7 is a solid lathe and can take goodly cuts with ease and then turn to 10ths without problems. RichD, Atlanta
humph wrote:
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I go along with both replies but I would also suggest that Humph checks the saddle yet again. Older models work on the narrow guide or inner shear principle and more than me have found the inner guide to be curved. Again, and other readers must be sick of me saying it, there can be wear on both the top of the bed and the front shear which is 6" or so from the chuck.
Again, the cut should only be attempted when ALL but one of the sliding parts are locked.
Finally, the leadscrew and or the feed nuts might cause problems from wear.
All of the foregoing will help narrow down the problem
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