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Mazak SQT10MS rear sub-spindle alignment and gib adjustment

mkalavitz

Aluminum
Joined
Sep 7, 2006
Location
Grand Rapids, MI
Hello,

I have a grandma SQT10MS.

Several years ago, I had the rear spindle rebuilt. My machine repair guy re-installed it, adjusted the gibs, etc.

Currently, I have been running the same production part for several months now. It is really a non-critical part, so have
ignored what I believe is a sub-spindle alignment / gib issue. That is until today....The part has been running well overall until now.

Upon pulling the last two parts off from the machine, the machining of the OD and OD threading coming off the sub spindle is way off. That is, on a 3/8"-24 thread, I can physically feel that the part feels like it has flats on it. It almost a triangular feel to it.

In addition, I have notice for the past several months of machining, that when machining on the sub, I can visible see the spindle 'lift' very slightly when putting pressure on the part during machining. I knew it was doing this, but never caused a problem with the quality of the male threaded part being made. I have been more worried about getting parts off from the machine.

In addition, I believe part of the same overall problem, I have had to reduce the transfer speed of the sub spindle to the front spindle for a transfer down to a slow 20% transfer speed. If I transfer any faster to the front, I can see the sub-spindle chatter on the rails. Literally, it looks like it has a slight bounce to it.

Given the transfer speed, chatter issue on the transfer, and now the problem with machining in the back, I have not choice but to address the issue(s). It needs a serious alignment of the sub spindle / gib adjustment.

So far, in order to check alignment, I turned a short bar in the front spindle. Then, I moved sub-spindle forward toward the front spindle. Attached a gauge to the sub and swing it around the machined bar in the front spindle. The guage swings +/_ .040" on a full revolution! WOW! It appears that this .040" on the swing is in the vertical 'X' direction.

I then skin cut a bar in the rear spindle, approximately 8" long in order to check for taper. After doing this, it seems there is approximately .005" taper over the 8" length.

So, the questions are:

1. Am I evaluating this correctly?
2. What is the proper procedure for adjusting the gibs, not to tight, not too lose on this machine in the rear?
3. What is the proper method for checking and adjustment of the alignment of the sub spindle to the front spindle?

I am attaching some pics to this post. Are these two blocks somehow used for the adjustment? If so, how? Under the wiper cover, there is the adjustment for the gibs. Does anyone have proper detail on how to adjust the gibs on this machine?

Thanks in advance for any advice or comments!

thx
Mike
 

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the check you did is proper for head to head
it should work both directions
gibs in general are tighten to snug back it off 1/4 turn
that machine is real close to one i froze a gib on the sub (sqt15ms) so i'd work up to tight slowly
if you can find the load meters in the control they can be a good tool for gib adjustment 30 or 40% would be my limit for a 10 thou pulse wheel movement until i had a better handle on where i was at.
im not sure where the height adjustment would be. not to be a ball buster be it may be shims under the sub head casting
 








 
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