[blaiseb]

Hi all! I have a Haas TM-1P and a plastic liner on the Y axis ball screw is giving me trouble for the second time in one year! I suspect it might have been installed backwards.


The plastic Liner has a flange and that flange gets pushed and gets stuck in the hole has seen on the picture. The load on the Y axis goes up and the machine needs servicing.


The plastic liner has a flange and on my machine, the flange is facing towards the back of the machine. If any one here has a TM-1P, could you take a look if it's the same on your machine? It would be greatly appreciated.


The plastic part is easily visible with a smart phone front facing camera or a mirror.


Thanks for the help!!


- Blaise

[morens]

I think it's right the way, that you show on the pictures. We have one tm1 and tm2p

Regards



Enviado desde mi Moto G (5) mediante Tapatalk

[Mecanix]

Must be made out of delrin with that CTE above 100ppm As soon as it heats up (or thermally expands) it jams up where the engineer forgot to grow tolerances by a factor of 100 (+30%).

Seriously, not familiar with TMs, what is this liner meant at doing exactly? Can't you just get this thing off the screw?

[blaiseb]

That liner is supposed to be a bumper!?! Bumper for what... No idea? I noticed that it was stock yesterday and a few hours later, the machine is unusable. The axis load goes up to 60% on a jog! The parts is making are all scrap. Last time it took three weeks for the tech to come fix it. This is a lot of down time for a plastic bumper!!!

[Mecanix]

I have absolutely no idea what those bumpers achieve, aren't those not supposed to be installed on vice jaws instead? Perhaps those tool builders thinks we are dumb enough to over travel their already under-sized envelop. Go figure...
Disassemble and bore (+30%) where it gets jammed up, should solve it. Although don't take my word for it; hard to see how the assembly is engineered from your pic (I'm not a TM owner, I only wish).

[Jim Dawson]

I checked again and my TM-2P does have that plastic liner. It doesn't look like my ball nut housing ever gets within 3 inches of it. Your ball nut must be running into yours. I would shorten up the soft limits a bit.

It looks like its purpose is to support the ball screw cover.

[blaiseb]

I normally have the same 3 inches clearance and since the first time it happened, I've been checking it periodically to make sure it wouldn't get stuck again.And I I have no idea why but it did it again. That thermal expansion idea might be it!? Could it be chips building up between the screw and the liner? At this point, I am clueless!

[Jim Dawson]

That thermal expansion idea might be it!? Could it be chips building up between the screw and the liner? At this point, I am clueless!

Maybe, I had a lot of plastic chips built up in that area, so much so that I couldn't even see it at first. I just cleaned it up.

Note to self: Remove the end mill from the spindle so you don't hit your head on it. :nono:

I guess I would pull the cover off and try to figure out what is going on. Doesn't look like too much of a job to replace it. Maybe the cover is a bit bent and putting pressure the liner?

[blaiseb]

I wanted to remove the cover but it looks like we have to remove the ball nut's pillow block or even the whole table. Clearly not an easy task! Sorry for your head bump!!

[Jim Dawson]

I took a closer look at mine, and I agree, it does look like a major job to get into that area. I stuck an inspection camera down in there and found that the cover seems to be all one piece. The ball nut is supported by a bridge that goes below the cover and is attached to the table on either side from the bottom. In order to actually remove the cover it looks like the saddle would have to come off.

If you have to go into that, make sure that you find the actual problem and get it corrected. My best guess is that there is something out of alignment.

[blaiseb]

Last time, to remove the plastic liner, the tech went from behind the machine. He removed the servo motor, freed the lead screw from the front bearing and shimmied the lead screw back enough to get to the liner. about a day worth of work!
This way tough, I don't think there is any danger of miss aligning anything when putting it all back together.

[Jim Dawson]

Last time, to remove the plastic liner, the tech went from behind the machine. He removed the servo motor, freed the lead screw from the front bearing and shimmied the lead screw back enough to get to the liner. about a day worth of work!
This way tough, I don't think there is any danger of miss aligning anything when putting it all back together.

Yeah, going in from the drive end would work also. My comment about alignment was really directed at the possibility that the cover bracket was not installed correctly from the factory. Maybe mount holes misaligned or something. As near as I can see, that might put pressure on the liner. But that is just a guess on my part based on very limited information, just what I can barely see in there.

[blaiseb]

Jim, can you confirm that the flange of the plastic liner is facing the back of the machine?

[Jim Dawson]

Jim, can you confirm that the flange of the plastic liner is facing the back of the machine?

Yes, that is correct.