833tv flatness over x axis?

[LVLAaron]

Finally getting around to fully understanding my 833.

I have the center section of the X axis dead nuts across the 6 inches where my vise lives. If I extend to the left or right, the table starts to rise, obviously due to the weight now hanging off the opposite end. It's maybe a couple thou. I do not have exact measurements on hand. I'll pull the vise off when I'm done with what's in it and take some measurements.

What should I expect? Is it a matter of snugging up the gibs? The table does have slop in it... I extend out to one end, the bit under the spindle rises up, and I can lift the end that's "hanging out" and get things level again...

Just trying to temper my expectations for flatness ability on a machine like this

 

[T Bredehoft]

Gibs should take care of that... Is your 833 new? have you not established the proper 'drag' of the gibs? Yes, a bit should be expected, but not visually noticeable.

 

[LVLAaron]

Yep. Brand new. Haven't done any adjustment at all other than tramming the head to the vise.

 

[Janderso]

It seems to me the last time I adjusted the gibs in my beast of a mill, (10x50”) table,
The manual suggested .001-.002” of movement when lifting or pushing on the table with an indicator mounted.
Seems about right to me, I get decent accuracy and still have buttery smooth action.
Your manual may have suggested settings.

 

[cathead]

Balancing the table load with two vises may help to maintain a more level travel. Even a vise and a heavy chunk of iron would
work too of course.

 

[davidpbest]

Remove the gibs, deburr and stone them so they have no sharp or raised edges. Reinstall them and adjust so they present slight resistance to the lead screw turning. Then re-check the sag. Here are some videos of the process I used on my mill which can be adapted to a square column mill.

PM935 Knee Mill Gib Adjustment Verification

This is the empirical method to dial in gib adjustments. Based on specifications found in the Wells-Index manuals.

www.flickr.com

 

[LVLAaron]

I'll give it a shot!