PM833T Table Adjustment?

[Jason812]

When I run the table all the way to Xpos, where the X power feed is hanging as far away from the machine as possible, the table is dropping off. It is almost .002" all the way out. Also, the gear makes more noise and the handle is a little harder to turn as if the table is in a bind. When you stop the table, you can see the needle bouncing on the indicator. All the way Xneg (power feed closest to spindle), I only get a .0002" rise.

I chucked the indicator mounting rod in a collet and ran it back and forth several times and got the same results.

Is there any adjustment to take care of this or am I expecting too much on a machine of this size?


About center of the table - 0 on indicator


X=-4.0000; 0 on indicator


X=-8.8; .0002" on indicator


X=+4.0000; .0003" on indicator


X=+6.0000; .0007" on indicator


X=+7.0000; .0009" on indicator


X=+8.0000; .0012" on indicator


X=+8.8; .0018" on indicator

 

[davidpbest]

I would start be removing the X-axis gib, lightly stoning it to remove any burrs, reinstall and adjust the gib so that you feel some resistance when hand cranking the positioning handle, then repeat the check. You might also hang your indicator out close to where the saddle ends and check droop there as well as directly over the spindle - that will tell you if the gib has too much taper at one end and thus is not conforming to the two dovetail surfaces at each end. I had an RF45 with a pretty crudely fitting gib, ended up doing some bluing and testing to determine what was going on and discovered the gib taper was slightly off which allowed the table to droop at one end but not the other.

 

[Jason812]

David, Thanks for the help. I pulled the X-axis gib out and checked for burrs. There was a slight one so I took care of that. Put it back in, no real change. Then I noticed the Y-axis gib was under the side that was lifting up. When I went to remove the screw closest to the handle, it didn't seem very tight. I checked it for burrs, it had an ever so slight of one. Took care of that, put the gib in a little farther than it was originally installed. Checked the table, it was better. Adjusted the screws to push the gib in farther and ended up with .0005" rise at the end that was .0018" and less than .0002" on the other side. I must have checked it a dozen times.

 

[mksj]

Gibs wear and can also bind if not properly adjusted or loose. You can also feel some binding of the table at both extremes of the extension, as there is uneven wear between the center and toward the extension extremes. I would say with the adjustment noted above, that is about as good as it gets.

 

[Jason812]

Mark, I briefly thought about chasing that half a thou... but only briefly.

 

[davidpbest]

Sounds to me like your table is now dialed in about as good as you might expect unless you're prepared to blueprint the gib/dovetail interface and do some scraping.