I don’t know if this helps because the colors aren’t in the photos but…
I have the two older replaced Y rails ‘for parts’ will undo one of them and look, lol.
@Artezio that picture and that guide don’t mention which way to insert them - they assume one was looking lol. In fact that guide assume a crap ton as a) it doesn’t show the correct way to unhook the metal strip or how to re-insert that too, nor does it talk about being super careful not to break the endstops when putting the slider back in (luckily i saw that on a random you tube video).
Oh and one slider is borked - unclear if it came that way or was because I overtightened the grub screw.
And its freaking almost impossible to adjust as they say and get that measurement, managed to on one slider after an hour of tinkering. Also the instructions to say tighten the bearing bolt - but if one does that after tightening the grub screw (as it says) it adjusts the bearing again…
@Artezio oh most definitely 
they have all the details and are, i think, going to inspect two rails and then send them to me as known good to stop me claiming the rails are no good 
in the mean-time i am going to put the one rail back together with the good slider and raid one of the old rails for another slider (i hope that doesn’t reintroduce the slope)
It’s not unreasonable to assume that the presence of the instructions on their public website condones following their procedure.
There haven’t been any issues I’ve heard of resulting in people opening their rails on their own. And if you don’t break anything they would be unable to tell.
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@brent113 to use a horrible phrase ‘i don’t disagree’ but I have just learnt from other support interactions with other companies don’t open something until told to; then there is no risk of ‘you broke it, you pay for it’ - to be clear, I am super happy and impressed with snapmaker support. Nicole has been awesome.
Also having done this ‘procedure / instructions’ is very generous description of that page - seems more like ‘random facts’ and a ‘whole lot missing’ and possibly ‘some wrong’ (like i am not sure one is supposed to re-tighten the bearing screw as stated in step 5 as a)it will grind the cuff the grub screw has been tightend into and b)the screw isn’t something to be tightened its on some sort of weird mounting that makes it move in left / right and just goes round and round on 3 of the 4 screws. i give a good chance that step 5 is what caused this (but cant rule out it shipped like this as i wasn’t looking that closely until i got the second slider out and noticed the difference):
@brent113 true. I just saw people saying a while back that their warranty got denied because they opened a component without Snapmaker saying to. But it didn’t always cause them to deny a warranty, it was hit or miss and I think the mentality became “better safe than sorry” on its own lol. As for me… I still have 6 months on my warranty, need to get using the machine again.
Of course that’s the most conservative thing to do.
I have just noticed an increase in the quantity of posts and also fervor of variations of “do not open without support’s blessing or they will void your warranty, remotely disable your machine, and drive to your house and kick your dog”
Just mentioning I don’t agree with the blanket ban against opening up your machine without support’s blessing #righttorepair
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What’s worse is it’s from the official distributor service manual. Not to mention the rusty part in their official photo…
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Oh, thought you grabbed it from here, same photos: What should I do when the slider of the Linear Module comes loose? – Snapmaker
And yea, the instructions are bad in my opinion, it should be a functional spec. Calling out 34.29mm is hilarious as there’s no way the rails are manufactured to 0.01mm tolerance
Also, Discourse, back off
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@brent113 the fact that it’s a constant issue guarantees it’s not within a .01 tolerance, it’s a fool’s errand to adjust it to that exact spec, it would come out of that spec so fast it’s not even funny.
And wtf discourse, they actually track/respond to that?
Found my previous blurb:
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i wonder if there is some other mechanical approach they should take on future rails?
for example instead of fixed bearing witn grub screw etc - have the bearing exert pressure outwards towards the guide rail so that it is always snug / self adjusts. Unless that would create too much friction on the rails inside the rail?
If we’re going back to the drawing board, so to speak, the first major flaw is the bearings are so close they have very little restraint against rotational forces, the ones allowing your bed to tilt forward and backward.
Also those appear to be cheap bearings that are non-standard over here, the internal balls have worn out for a few people and I don’t think I’ve seen anyone successfully locate replacement u groove rollers for this application. I’ve tried…
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Easy.
First, they should use an actual linear bearings. There are lots of resources on the internet about them. It’s very easy to notice that none of them are designed like the bearings in the linear modules. That’s because the bearings in the linear module are a bad design.
Second, they should understand that anything that needs to be fixed in linear motion needs two bearing positions on the rail, separated as widely as possible. One of the main design defects of the SM is that there’s only a single bearing assembly per rail. If there are “two points”, they’re separated by a couple cm, not 10 - 20 cm like they need to be. If they even considered it, they discarded it because it would mean making the linear modules longer for the same length of travel, and that would mean they would cost more.
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getting these rail units back together is hard too.
managed to destroy one of the micro end stop switches and can’t work out how to get that out so not evening going to try.
(and yes i was super careful to make sure that the end stop switch was depressed when i inserted the slider - that isn’t what broke it.)
at this point i am giving up and waiting for new rails
(apologies for only now finally putting this on the right thread, not trying to spam).
So i have managed to get one of the two rails I took apart (to adjust bearings) back together.
some thoughts on assembly / disassembly for posterity:
- this video is great - though note they thread the metal strip through the black clips incorrectly (refer to the official video on support site for this).
- if you pulled the black/white cable out more than about 2mm when extracting the motor end be VERY careful during reassembly as the wire excess gets pulled from the switch end to the motor end and has a tendency to curl as you push the motor unit back in, this risks the wire bending and touching the linear screw rod (which will quickly lead to unit failure). To pull the wire back down you will need to remove the end stop switch and pull, unless you can hook fish the wire - i tried that and found i couldn’t reliably snag it without pulling it out of the switch.
- removing the end stop switch was massive PITA - the front screw bolt is fine, the rear one is super hard - only attempt using a L shaped allen wrench/key and hold the nut with good pliers. This will take a while to get loose enough to slide the switch out, do not remove the nut if you don’t have to.
For now i am going to use the one checked unit snapmaker sent me with this unit i adjusted and re-assembled. If this doesn’t improve matters i will cycle back through the original 2 linear units (the ones with the slope, on an assumption that one of those may be good). I am not going to manually adjust the bearings again new units should be adjusted correctly from the factory.
ok an actual update.
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I fitted the used/tested/calibrated y rail from snapmaker to the left of my machine
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I fitted the old right y rail shown in this video on the right after I adjusted the bearing (remember the previous 2 rails was maybe 5 hours old from factory to replace my sloping rails).
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now after adjustment and the adventure that was re-assembly it looks like this which i think is a positive result - but incredible that two linear units fresh from retail supply were mis-calibrated.
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I also repeated the manual jog test where i jog the bed to a set XY co-ordinate and then jog the bed back wards and forwards in multiples of 10mm steps - the pressure on the white card never varied, it was consistent at the same XY co-ordinate every time now (i did find another weird result, will share that later… as i am not sure it has any bearing on this thread… )
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I did my single square test in the problem area (this is a saved file so its the same every time)
This is the result (shown with a monitor as a rear light box)
While not perfect i think folks can see how much better it is compared to what i was getting:
i am now repeating the 25 square version across the whole bed… will report back when i am able
closing this thread with the solution being disassemble both Y linear units and adjust the gap between bearings to spec
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Much improved. The wobble while minor was making significant difference. Wobble check should, imho, be one of the standard checks folks do after basic calibration.
Still many questions on layer height differences. I have one observation to share later. But for now here is the much improved 1st layer. Any remaining issues are not mechanical wobble.
