Excessive play in x-axis linear module bracket

The mounting bracket on the linear module on the x-axis on my A350 is loose. The toolhead is tight to the bracket but the bracket itself now rocks up and down a millimeter or two.
I couldn’t tell if there is a way to tighten up something inside. I tried opening the end like they suggest to look for the silicone pad, but they warn about messing up the limit switches so I didn’t want to go any further.
I put in a support ticket, but would love to solve it myself. I could probably just swap out for one of the other axis for now. The play is only vertical.

Anyone else have this problem? Thought I remembered somebody mentioning it but couldn’t seem to find it.



Videos showing play:

The rollers are loose and/or have come loose on the inside carriage. Contact support before attempting to repair it yourself so you you don’t void your warranty.

There are four steel rollers that ride on 5mm steel rods. The rollers are adjusted by turning the eccentric nuts securing two of the rollers. Get them too tight and you will have premature wear on the rods. They may have been too tight from the factory and are now worn out early because of it.

Is there a known torque value the cam nuts should be tightened to? I have play in my Y axis that I plan on seeing to this weekend but am afraid of over tightening!

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Same exact problem (one of a long list, by now, unfortunately), shot a video that is pretty similar…

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This was response from support:

You need to adjust the slider on the X-axis but it is difficult.

So how do I actually do this? I’m sure I can figure it out, but it would be nice to have some instructions (I asked). On the support article about how to check for the silicone pad it warns about messing up the limit switch if you pull it out too far.


Here’s a video that might help you: https://www.youtube.com/watch?v=2gg3Fd4_8RM As far as I understand it’s not “official”.


That’s perfect!
Definitely helped with a couple things it would’ve taken me a while to figure out.

Finally got a chance to pull it apart. (I swapped one of the Y’s with the X to get by).

Arnold’s video was helpful, but incomplete and also a couple things wrong.
I didn’t have time to make a video but I took a couple pictures.
Here’s the procedure (note that this is how I did it and not official. Since all I got from support was “Need to adjust the sliders” and “it’s difficult” I’m considering that as sufficient instructions that I can proceed without voiding my warranty. Proceed at your own risk)

Find a clean place to work. While there was some sawdust already since I’ve been mostly doing cnc work (the strips do a pretty good job but they aren’t dust proof), you want to keep as much dirt and debris out as possible.
You need a 3mm hex bit besides the bits that come with the SM supplied screwdriver.
You can follow most of this through Arnold’s video.

  1. Slide the bracket away from the cable end.

  2. Remove the 4 screws that hold the strips on. There are two little rectangular pieces that are used to keep the strips tight. (do not lose these!) The strips will be loose so be careful that you don’t bend or damage them. They’re pretty sturdy, but still.

  3. Remove the 8 screws (4 on each end) that hold the end caps on.

  4. Carefully pull out the end with the cable. There will be two wires (B&W) that plug into the circuit board assembly. In the video he uses pliers, I prefer to use a spudger or just grab with two fingers and carefully wiggle and pull. (I’ve had more problems deforming soft plastic connectors than pulling out a wire accidentally. Also, It’s keyed so you don’t have to worry about remembering which way it goes in.)

  5. Continue to pull out the stepper motor assembly and screw until you have enough of the screw revealed that you can grab it with your fingers (In the video he kept turning the whole stepper assembly, but I think he said it had seized.) Make sure your hands are clean or wear gloves. Turn the screw CCW until it releases from the bracket and you can remove it from the housing. Set it aside where it won’t get damaged or dirty.

  6. Pull off the other end cap

  7. Slide out the bracket assembly along with the strip (I didn’t remove the strip. I don’t know how hard it is to get back in, you don’t need to, but again be careful)

  8. Now you’ve got the part you need to work on:

  9. Loosen the 2 small set screws that hold the eccentric nuts tight. (One on each side)

  10. This part I’m not positive I was doing in quite the right order or best way, but it worked for me. The way the eccentric screws is different than ones I’ve dealt with before. (The allen screws don’t just change the orientation of the nut but also need to be tight.) I loosened the allen screws (red arrows) with a 3mm hex bit. This turned the eccentric nuts (green arrows) which raise or lower the rollers. The rollers have markings to show how much they’re turning, but I just watched what it did from above and guessed. (You could probably use calipers and measure) I adjusted to my best guess of what was necessary and then tightened the set screws. Then I tightened the allen screws. (Note: I did this on two linear modules, and on 3 of 4 allen screws when they turned the eccentric nuts turned accordingly. On one I had to use a small screwdriver on the markings on the eccentric nut to turn it)

  11. Carefully take the assembly and fit it back into the housing. You’re just trying to insert and check the first set of wheels. They should fit snugly between the two rails (blue arrows). (Watch out for the limit switch (yellow arrow) Use a small screwdriver to hold it out of the way. There are several points where it will catch)

    Don’t force it! It should be tight but not excessively. If it doesn’t fit, you need to readjust the wheels. If it does fit check if there is play. If it seems loose, pull it out and re-adjust. If the first two wheels seem right, then proceed with the 2nd set.
    Again watch out for the limit switch. Again, don’t force it.
    If it fits, go ahead and try sliding it. It should move smoothly without much force necessary. (You don’t want it to have play, but you don’t want to burn out the stepper motor by making it work too hard.) If it wobbles front to back (up and down) you need to adjust both screws tighter. If it rotates, the 2nd wheel is too loose and needs adjusting.

  12. If everything feels good and tight but still moving well, you’re ready to reassemble. Pretty much the reverse of disassembly except I put end cap back on just before re-fastening strips. Be careful when inserting the motor end that you don’t snag the wires when you’re sliding it in.

  13. Use the strip tension tool that came with your SM to tighten the strips. (Tighten each screw a little at a time to keep the rectangular pieces from rotating).

  14. Reinstall on your machine and check that everything moves and sounds right.

That should cover it. Let me know if there’s anything I missed or confusing or think I did wrong.

I didn’t do any lubrication. There was still plenty on leadscrew and everywhere that seemed like it was supposed to. I did blow out some sawdust and wiped away a little from one of the rails with a q-tip.
Some people have oiled the dust strips to get rid of squeaking. I think this isn’t necessary if everything is adjusted properly. It will only cause dust to collect and build up and cause problems down the road. (There may be a way to adjust tension on strip while doing this procedure. I didn’t need to so didn’t investigate)
While you’ve got it apart, check to be sure that the silicone pad that has been missing and causing early failure is present and properly placed:


FYI, There is now an official repair guide:



High performance, zero backlash rust

I will add that I think adjusting to 34.29mm is a fool’s errand. I had success test fitting until there was a slight ‘pop’ when you insert each pair of bearings - a slight resistance to insert, but once inserted rolls smoothly.

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Agreed. That’s what I did. Hopefully that was communicated in my guide.
When I have a chance I need to take a closer look and see how my instructions compare.
Just wanted to make sure the official instructions were up here.

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interesting that this is an ‘official guide’… wonder if Snapmaker have given up with QC and are just expecting end users to perform this sort of adjustment

Estimate for the torque rating for the tiny screw in step 4?

Even if there qc is perfect it will still need adjusting over time. Mine was from pushing step-down a little too hard when it hits some knots in some oak and was vibrating the hell out of it. I learned that doing conventional milling (as opposed to climb) in fusion helps a lot.

Oh man I didnt know we had these instructions available I’d love to take apart this old loose module :smiley:

The new official instructions are actually missing some steps.
It doesn’t mention anything about the dust strips and from the illustrations they’ve removed the bracket assembly from the strip. I would suggest keeping the dust strips and bracket assembly together. Just be careful not to bend the dust strip.

They also make no mention of the limit switch. You need to be very careful not to damage this and it’s very easy to do so.

One nice difference from my instructions is that it turns out that you only need to remove the non-driven end cap.

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I’ve had 2 modules with rust on the bearings now and 6 failed bearings with excessive play or grinding races (Both Y modules and X module). I’ve replaced these off my own back as i wasnt getting anywhere with support. It completely changed the quality of prints. The reason I think the bearings have failed is due to the carriage being far to tight between the rails from factory.

You installed new bearings in your rails and it had an impact on your print quality?

That sounds very interesting to me.

My experience with support and a loose bracket was a sent replacement, im surprised that didnt happen for you.

Any other tips with working with oak using Fusion 360? I’ve just loosened my bracket the exact same way as you (hitting knots in oak).

It’s mostly about work speed and step down. Start at 400mm/m. I generally find that to be a good work speed. I can sometimes push to 600 depending on the particular piece of wood. For step down I tend to just keep it at .5mm. I can get away with 1mm on rough clearing passes with a quarter inch bit but not usually worth pushing it.
Lastly I find that adaptive clearing can sometimes be too aggressive. So I tend to use pocket.It may be slower but have less problems with it.