Heavy 10 Saddle question

E

EarlH

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Been turning a bunch of 6061 al lately and the last few parts had a noticeable "pattern" to the finish. Today, I was making a part out of some 416 stainless. The finish that I got with my tangental tool what horrible. Looked like sandpaper. Tried a tool with a brand new warner hss insert and it looked as if I was threading it. Turned off the power feed and fed it by hand. Quite a bit better. Pulled up hard on the clutch lever and it cut a groove in the part about .007" Got out the dial indicator and found that I could rock the saddle over .010" by pulling up on the hand wheel or clutch lever. I know that there is a gib on the back side of the saddle but it appears that the only thing holding the saddle down on the operator's side is the apron. I'm not sure what to do about this. All suggestions are welcome.
Earl
 
There maybe a clamp plate on the underside of the carriage behind the apron? Could that be loose or in need of reshimming to take out the clearance?
 
There is nothing but the apron attached to the front side of the saddle. As far as I can make out, only the lead screw and gravity keeps the saddle down in the front. I tightened up the 3 nuts on the rear gib and then the carriage wouldn't move! loosened them up until the carriage would just move. The finish improved immensely. The bolts were just finger tight. Must have been loosening up over the last two years that I have had the lathe! I guess I will have to shim that gib so I can tighten up the bolts and keep this from happening again. That is going to be a bear. I have the lathe up to within about 8 inches of a wall. It is a real pain to move. After the last time I moved it (put the VFD in), it took about three weeks to settle down. Leveled it about twice a week for three weeks.
 
Doing a bit more research. (parts manual) it appears that the carriage rack also holds the the saddle down. Perhaps some shims between the rack and the underside of the ways may be in order. hmmmmmm. need to think on that a bit.
 
I think that the back gib is all that there is to worry about. the cutting forces should push the operator's side of the saddle down against the ways.
 
Forces from cutting is all there is holding the front down. There shouldn't be a ton of slop, except for running clearance, though. This should only be a problem if you're running a tool upside down. That's one reason I don't care for that, as a general rule. I'll do it if there is no other way.

It could be an issue with your way lube, Earl.

Another check is to put an indicator on and see if you can "spin" the carriage on a vertical axis. This will tell you of there is excessive front to back clearance. Put the indicator on the front of the carriage and try to pull pr push a long bar in a tool holder, in line with the bed. If there is clearance front to back, you'll see it spin. Try this on the left and right sides. It's not quite the same as testing linear clearance by shoving and tugging in the center, where the wheel is. I've seen most clearance on the trailing side, since cutting forces tend to push away, the entire carriage will try to move ccw as viewed from above.
 
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