Well, tomorrow I tackle my first ever Gib adjustment on my 770.
I was running some parts today, and noticed a little 'wobble' in my spot drill when it contacted the part.
I thought I was seeing things. NOPE!!
I put an indicator on the spindle nose and moved it back & forth about .003 by hand. YIKES!
I also checked X and Y for slop.
.0005 in X, .003 in Y.
Oh Boy.....
I had previously been endmilling pretty heavy-handed, Lots of chatter and vibration... OOPS!
so...
Any advise, tips or tricks to adjusting the Z and Y gibs?
There's a tightening screw and a locking screw. I forget which is which, but the tormach manual will tell you. Since you're already close to where they should be, I'd skip the dead reckoning step and just start to tight them by:
-loosen the locking screw
-tighten the other screw 1/2 or 1/4 turn
-retighten the locking screw
-test backlash at center of table of that axis
You want to stop tightening when your backlash begins to climb due to the gib being too tight. You'll have to back off the tightness some when you notice this is happening. I aim for around .0005-.0007 backlash on the X and Y. That's assuming your ballscrews are properly preloaded, of course. That's another can of worms.
I found that some of the Tormach manuals appear to have some incorrect information about gib adjustment. The manual I had in the shop was different than the one I downloaded two days ago. So, just note the changes you make and use an indicator to see the results.
I have an 1100 Series 2, not a 770, but... For example, my _0415A manual shows on page 156 in the gib adjustment procedure for the Y axis under the "Tighten" column show "Left screw counterclockwise/right screw counterclockwise". Of course, the gib screws for the Y axis are not right and left. For the Z axis it shows "Front screw clockwise/back screw counterclockwise".
So, I was not sure which was correct or right, so I downloaded the _0916A manual. It shows the Y axis as "front screw clockwise/rear screw counterclockwise".
That seemed confusing to say the least. So, I used the words in the latest manual and started with an indicator to see what happened.
I got the gib adjusted, but for instance with the Y axis, I turned the rear screw clockwise (as looking at it from the back, screwdriver side) to tighten the gib after turning the front screw CCW to loosen it to give it room to move. I used the indicator and slowly adjusted it to about .0007". In addition, I measured go both ways and in different table positions although that is probably not necessary. When it was where I wanted it, I turned the front screw CW until it was tight and checked the back screw and all was tight. I checked the adjustment once more and it was right where it was so I called it good. That is what worked for me yesterday, but I need to look at the part schematic to see how it works mechanically and plan to jot down my notes for future reference. Maybe the Tormach manual can be updated in the future to make it clear and easy. I assumed the reference point for the turn directions was from the screwdriver end, but maybe that is not correct.
It looks like you were going to do this a day or two ago. How did it go?
I got it tightened.
I used 2 indicators.
For Z, I had one against the spindle nose to check 'Wiggle" as I pushed the head back & forth, and a second indicator under the spindle to check backlash.
After tightening, I got the "wiggle" to within .001, and the backlash set at .0005". Good enough for me.
Then in X, it was real sloppy.
I got the X table "wiggle" to within .001 (It was moving about .005, by hand! OOPS..) And I got the backlash to about .0007".
I was afraid of over-tightening the gibs, so these settings are good enough for me.
I'll see how she runs in the coming weeks.
Advise or tips for Gib adjusting?
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