Loose Y

[Tim Lucas]

Is this much play normal ??

https://www.dropbox.com/s/wnmxv4slig...59062.mp4?dl=0

https://www.dropbox.com/s/oev3g84pu0...19652.mp4?dl=0

I have not been getting a even cut in the X motion on a straight line, I thought it was linked to my Z being wore out and needing up graded, but today I was shaking it and noticed the Y movement does not seem normal -

I checked and tightened the pinion and the side I videoed is across from the drive but I want to know if it is normal

2004 PRT V4.17 running 3.6.24
with Gecko drives - Vextra Steppers A6497-9412 KTG

Thanks
Tim

[Brady Watson]

The pinion is loose on the shaft...

Pull the turnbuckle off (3.5 turns tight from loose when you put it back on...) and pull the motor pivot via 9/16" box wrench and deep socket + ratchet.

Pull grub screws, blue loctite them and put them back in - tight enough to tweak the 1/8" allen key. Use NO ball end keys. Square & fresh only. Make sure pinion is going to ride properly on rack gear before you commit to the gear position on the shaft.

-B

[willmorgan]

Brady is spot on again. I had this happen as well and that's exactly what i had to do to fix it. That guy is a wealth of information!

[Tim Lucas]

Brady,

Thanks for your reply, I did remove the stepper and the pinion, did not have blue loctite, but did have some red.

This is a rather long video of that process. https://www.dropbox.com/s/2jtikv4cb2...32863.mp4?dl=0

and here is a video of the cutting afterword https://www.dropbox.com/s/926bnhyt16...20cut.mp4?dl=0

That did take care of most of it, what I see now is where I have tabs and I think that is due to my Z rack is wore and sloppy,
not that I can move the router but I think when it rides up and down it is not smooth - I have adjusted the guide wheels with
all they have and it almost is not enough. I am worried if I file the Z rails it will be loose. Has anyone drilled new holes for the
wheels, or do they make a set with more adjustment? I checked with Shopbot and to replace the Z is the new upgrade, around $1500.00.
Would like to do that but am in the process of building a new shop so must choose my funds carefully.

Thanks
Tim

[Brady Watson]

Adjusting the T-rail to rollers is tricky because whatever you do to one side, you need to do to the other. You also need to keep an eye on Z rack to pinion lash because adjusting the v-rollers can pull it out of mesh, causing excessive backlash or premature t-rail wear if they are too tight.

Unfortunately the only option at this time is to spend the ducks and get the retroZ from SB. There is a lot of labor into fabricating a new one and properly grinding the edges.

If your Z doesn't have 8 v-rollers on it, you can add another 4 to spread the load. This makes the t-rail last a very long time. If it is too far gone, you would have to re-drill the holes, which is a precise operation, so plan accordingly.

On a side note, PRT tools need their rails dressed from time to time to eliminate roughness in the rails. When they get roll forged, they get bumpy. It's like having little rocks on the rail and that transfers to the cut. Hold a hand file on an angle, and remove the dross-like junk at the BOTTOM of the rail pyramid. You won't hurt anything if you have to knock down the PEAK of the pyramid. Then buff the rails with steel wool. NEVER ever use power tools to do this operation, no matter how good you think you might be.

-B