Haas TM2 Y-Axis Ballscrew

RMS Machine · Apr 16, 2020

Has anyone replaced the Y-axis ball screw on their TM Mill (1,2 or 3 should be about the same) This would be on a mid 2000's model before the enclosed models.

I have about 0.0018-.0020 play in the Y-Axis and it is affecting my surface finish during certain operations.

Any tips or tricks to this work, anything I should watch out for? I was planning to take it out and send it to a rebuild company.

Any good recommendations on ball screw rebuilders?

magno_grail · Apr 16, 2020

I do not have a TM but my '91 VF-1 had backlash in the Y axis from the thrust needle bearing disintegrating. I replaced it with the later double angular contact ball bearing.
If your backlash is everywhere I would check the thrust bearings. A ball screw problem would be more local.

RMS Machine · Apr 16, 2020

I was planning on replacing the thrust at the same time.

I can put an indicator on base of the machine with the indicator on the table I get the play that I mentioned above (admittedly I only checked the table in the middle, not the extreme ends of travel)

If I put the indicator on the base with the indicator on the red hand wheel at the front of the machine I cannot get any movement on the indicator.

This is what is leading me to the ball screw.

Is this a good test or should I check in a different way?

magno_grail · Apr 17, 2020

I would put the indicator in the spindle then place a block on the table and measure the backlash with the jog wheel. Move the block to a few locations and measure again.

ripperj · Apr 17, 2020

magno_grail said:
I would put the indicator in the spindle then place a block on the table and measure the backlash with the jog wheel. Move the block to a few locations and measure again.

This will give the total backlash, but it sounds like the OP has measured the amount.
The total backlash is the total of slop in the thrust bearings, the ballscrew and the ballnut and the balls themselves. This assumes the motor to screw coupling is has no slop and the encoder has no slop.
Most people replace the entire screw/nut/balls as a unit, but some attempt to re-ball the screw.

If the end of the ballscrew is accessible , you can put an indicator on the end of the screw and see if the screw moves axially. If the hand wheel that the OP refers to is directly mounted on the end of the screw, this should be the same thing.

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RMS Machine · Apr 17, 2020

I just did some testing at the ends and middle of travel for the y-axis. Tested pushing in and out on the table.

Far "+" travel - 0.0025"
Far "-" travel - 0.0035"
Middle of travel - 0.0045"

Quite a bit worse that what I thought I had measured previously.

When I put the indicator on the handwheel (end of the ball screw) I can barely get the needle to wiggle.

Right now with this info I am assuming the ball screw needs to be replace and while in there I will do the thrust also.

Should I have the ball screw reground/rebuilt or buy a new replacement? Near as I can tell it is about $1000 difference between the two options.

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