X-motors loosening up

[bill_lumley]

I have a PRS Alpha and previously a Standard and notice the same thing on both. It seems one has to regularly(every few days) check that the motors on the X have not loosened up to cause wiggle on that access when you try to move it by hand when powered up . Is this just something we have to live with or are there extra steps besides tightening the Cap screws very tight people have discovered to go longer between motors tightening ..

Thanks Bill

[Gary Campbell]

Bill...
My X motor on the -Y end of the gantry does the same thing. I need to adjust it about every 30 sheets. Somethimes this is every other day. Dont know why the other one never seems to loosen. That motor also seems to wear pinions a little faster too. Unless someone has some magic, I think we have to live with it.

[gundog]

I thought I had that problem at one time but it ended up being a bad control board. When you find the motor loose shut off the machine control box let it sit for a few minutes and power it back up and see if it is still loose. I pulled my hair out for almost a year until i found the real problem and like you I thought the motor was slipping each time I powered down and readjusted it seem to fix it for a while what I did not know was it was the powering down that actually fixed it.

Mike

[myxpykalix]

couldn't you use a bit of locktite?

[ken_rychlik]

Mine does it too. I wish it didn't. A spring loaded automatic tensioner would be nice.

Jack, the motor is just held on with 4 small scres that ride in slots. I don't think the screws are comming loose, but the motor is slipping down in the slots. We may need to figure out a way to stop it.

Maybe a bolt under the motor with a cabient shim tapped in ??

Kenneth

[coach]

same issue here, mine was opposite side as Gary's.
I put star washers on the bolts. I have no problems with moving for over a year now.
I also checked all my pinions 2 days ago and all are perfect after 2 1/2 years of almost daily use. PRS Alpha 5 x 10.
This machine is getting posted on the for sale section. I won't respond on this link.

[Gary Campbell]

In my opinion the problem is in the design. The only thing that keeps the gantry on the rails is the motor. Any force when traveling in the X direction is being counteracted only by the pinions engagement on the rail. This may or may not contribute to pinion wear. As you increase the cuts speeds, the amount that the motors will move is also increased.

[ken_rychlik]

I agree that it is a weak point in the design, but what to do about it is the question.

I'm going to give the star washers a try, but mine is one of the early versions that they used washers to shim the motor away from the gantry. I think this could be a large part of the issue on mine.

Who else has shimming washers between the motor plates and frame?

Kenneth

[bill_lumley]

Thanks guys for confirming I am not alone ... again :) Always nice to know you are not doing something stupid.

Yes it is the same side for me Gary . I will try the star washer route but the design does seem weak in this area ....

Bill

[Gary Campbell]

Kenneth...
I would check with SB on that one. You bought a used machine, maybe the previous owner did that for some reason, or misunderstood the assembly instructions. I dont believe I have seen any of the lit that says to do that.

[coach]

to be clear........I am not shimming anything.
I placed a star washer only on the hex bolt. My issue was the bolt dug into the motor bracket and I had a "memory" issue where the bolt needed to be about 1/16" from original location and it kept slipping into the mark from the bolt head. Maybe I should have put a flat washer when I first assembled the machine?

[ken_rychlik]

I may have to take mine apart and do some grinding :mad:
I asked Frank at SB and he said they had to do it on some of the early ones because there was not enough clearance. I think this may be enhancing the slipping down on mine.

Kenneth

[Gary Campbell]

Kenneth...
That makes sense now. Instead of a shim, McMaster has internal and external tooth lock washers. That may slow down the movement. We will see what "nuances" the new machine will bring.

[bill_lumley]

Dave , I tried the star washers but they seemed to have no impact . I replaced the flat washer and split washer combo with a start washer and split washer combo . I found the motors loosened up after 1 sheet in both cases after tightening the cap screws as tight as I could with an allen key . I did this with the motors powered up . Should I do with the motors
powered down ??

I would like to solve this one so I don't need to adjust every day :(

Thanks Bill

[ken_rychlik]

Bill,

I did mine with the power off and after making some mods to the motors to get the shim washers out of there, it is holding well after about 20 sheets.

If you got it adjusted with no slack with the motors on, it really should stay adjusted though.

If I have any more trouble I am going to get some grade 8 bolts instead of the allen screws.

Did you use a clamp to put "mild" pressure on the rack before tightening the bolts?
(to tight is not good either)

Kenneth