Think so you damage the seal and scratch it. I only grease on the rail. That works on all printer well.
On the pictures are not a linear rail. They are only on top.
Or did I misunderstood your posting
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Greasing the rails won´t help, as written bevor.
The grease won´t get inside the Linear bearings if you just put it on top of the rods/rails.
You can read about it in my post above and in the post from Mechanikus.
In the image above, where I put the syringe inside the linear bearing, you can see a lot of grease on top of the sealings, because I tried to put it directly on the rods. It doesn´t work.
You have to be really carefully with the syringes, when you put in inside the bearings. There is a small gap between the sealing and the rod, where you can push the syringe through. You DON´T push the syringe tip through the sealing. On long terms you´re right, it will destroy the sealings with this technique I guess.
This thread is not about the linear rails for x and y.
My problems are with the Z-axis linear bearings.
I was able to record the clicking noise. Like mentioned bevor, the noise is only hearable when I move the z-axis down. But I can´t see or feel any resistance, when I move the z-axis by hand.
@RalosZk Great Howto!
Just one addition: You will need to regrease several times until the clicking will be gone because you will never get the grease into the inner ball guides of the bearings like that. This is not a big problem since it will get in there by the z motion over time, but you will need to fill up what was lost until there is enough grease in there.
If you take care to slide the tip of the syringe on the metal rod with the hole (and therefore any sharp edges) facing towards the rod, the seal will not be damaged.
Usually the linear bearings should be greased when they are pulled off the rod, but this is a way of “lazy relubricating” I have been using since years. Once you have managed to fill them with grease (you will bit of grease coming out then over some prints), the lubrication intervals will decrease drastically.
And once again for everyone who did not understand this yet: lubricating the rails only will not bring any significant amount of grease into these bearings, you only grease the seals by doing so.
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Hi All, I’m having same issues, in front of the bed the first layer is by far too high, at the back its too low. I investigated a bit further, also discussing the issue with Snapmaker support.
Z levelling works well, there is no software or process issue, the point is simply that the weight of the glass plate is missing and in my case difference at front side of the bed is 0,25mm with or without this add. weight of the glass. So this is clearly a mechn. issues. I have a made video to show this, but currently can’t upload it as a new member.
Then went a bit deeper checking the Z axis linear bearing, the are having a play about 0,04mm, which is a bit too much, Snapmaker will send news which I will try, lets see if this improves the situation. But I guess the mechn. design of the J1 is the issue, the 2pcs. 12mm rods are bit small and bending under load. So I think this problem with J1 can’t be solved entirely, only with a redesign.
I’m doing currently a trick, during Z calibration I’m putting a load to the middle of the heat bed ( similar to the weight of the glass plate) and it works perfectly.
First one with glass platte, you might see it in the backround.
Second one with glass, bed is going up by 0,25mm
@RalosZk were you able to fix your z-binding issues meanwhile. Was it suffice to lubricate the z- bearings?
I‘m currently fighting the same issue.
@Jade do you really believe lubricating the linear rails and z rods from the outside has any noticeable effect. Both have sealings to prevent dust entering and those seals block grease as well IMO.
Sorry guys, I was really busy in the past months, but I got a lot of help from the snapmaker Support.
I need to do some final test prints, which will show, if the problem is gone.
In short, I swaped the linear bearings with new ones, which I lubricated bevore assembly.
I will make a bigger post in the next 3 weeks, I´m really busy right now 
Snapmaker send you the new bearings? Did they send instructions how to replace them or had you fiddle that out on your own? Was it difficult?
Looking forward for the results of your test print.
Hi, sofar I haven’t received them, but I guess there will be no instructions included. Anyway I have no problems fiddling out how to do it, J1 is already disassembled. And yes this is only doable for experienced mechanics.
Hi there, also my 5 cents about lubrication:
First of all, answering your question, lubrication won’t have any noticebale effect, it will just reduce the noise and let it run more smoothly when going up or down fast.
I’m very experienced with this kind of linear bearings and it is very problematic if you put to much grease in it. Because then the rollers have problems to circulate and the behavoiur is more worse compared to running dry.
I would NOT recommend to do this grease injection, because you don’t know how much you really put in. I would recommend to put a thin grease layer at the entire rod and running up and down several times. The lip sealing from the bearing don’t really touches the rod, so there is small gap and grease can go in the bearings, and you will see that after the first try the bearings are running much smoother and more silent. But this won’t solve any Z leveling and binding issues.
Hi, I would like to give an update about my try to replace the Z bearings. Like exepcted the, the new ones received from Snapmaker are the same and having no better functionality, then i bought from German supplier some high quality bearings and they are really better, the clearance/ play is reduced by half.
BUT it don’t really improve the situation, with the weight of the glass plate the bed is 0,3mm higher at front, so the automatic bed leveling will fail every time. Because when you add the glass the bed is too low at the front.
I can just repeat that this is really a mechanical design issues, the 12mm Z rod’s are too weak and they bending a tiny bit with the add. glass weight of 890gramm. So I don’t see any mechanical way to improve the printer.
I told Snapmaker that the design is really grab and I’m sure that they never tested this entirely, as long as you just print in the middle small parts like benchy everything is fine.
I also complained that the price is by far too high if the auto. leveling is not working.
I highly pleased them to bring quickly an update which allows an supported manual levelling.
Keep you informed about the answer from Snapmaker.
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ofcourse, this is waht I’m doing, but we all payed 1600€ for a printer with nice and unique features, which finally don’t work. And this problem leading to a manual bed levelling which is even not possible, because the software don’t support this. Yes, okay, you run the bed to level zero by using luban, but this is stone age not according the high price level, and for most of the unexperienced users highly stressfull.
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Interesting! You are the first apart from Snapmaker that tellls to grease the rods from the outside - not even any of the manufacturers we use (and additional ones that I checked) do recommend this, since as long as the sealing lips on the outside of the carriages are even remotely up to their task, you will not get any significant amount of grease into them where it needs to be.
May I ask where you got this information from?
Regarding greasing through the lubrication holes: in order to avoid stuck rollers, it is mandatory however to slowly move the carriages slowly several lengths back and forth to distribute the added grease and to expell any excess - that is something people ignore as often as they use wrong grease.
Sorry for the late reply, I´m still really busy.
In short, my problem is gone by now.
I disassembled the bearings, greased them with the proper grease and put everything back together.
I´m not 100% sure if the lacking grease was the problem to be honest.
Afterwards I think that problem were unparallel, or bend rods.
First of all I would check the two screws on the black Coupler on the threaded rod in the middle of the z-axis. They have to be tight enough, so there is no wobbling around when Z-Hop is enabled.
Second I would check if the Linear Z-rods are kind of parallel.
You can loose them, by loosening the nuts on top and at the bottom of the printer.
I´m not sure if my method is best one, but I first loosened both sides and moved the z-axis up and down in the menu (printer turned on). Then I tightened the left side, let the right side loose and moved the z-axis once again up and down. After that I tightened the nuts on right side and did the same thing on the left side.
Here is a guide from the snapmaker support (thanks Robicong) for swaping the bearings:
J1 Z axis disassemble.pdf (1.0 MB)
I finally got good looking layers.
Hope that helps.
It was a pain in the a** 
Snapmaker Support made a great job 
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@RalosZk thanks for that! It was so obvious that I did not think about it before I read your post - the exact same thing was what I needed to do years ago with my German RepRap. I expected that printer manufacturers would care about such things by now - seems I was wrong…
Just a side note: I found myself unable to tighten the nuts at the upper end of the z rods without moving them out of place well over a millimeter - the unevenness of the casted aluminium frame and the M8 nut with fixation teeth made an unlucky combination there. I replaced those nuts with a standard M8 nut and a fitting washer and everything worked as it should.
My procedure:
- after loosening all six nuts (there are four at the top!), move the z axis up and down several times to ensure the linear bearings running free again.
- pull out the black rubber from its holes in the bottom plate. You don’t want these to interfere if possible.
- move the bed down to the bottom.
- check if the bed is parallel to the printed lines or measure the distances from the printer housing. Try to even it out as far as the play of the axes in the holes allows.
- carefully tighten both nuts at the bottom. Use a “T” handle or a screwdriver, but not a ratchet or anything else that has a lever only at one side - the one-sided force increases the risk for you to shift the z rod out of place while securing it. If you feel or see the nut moving laterally, loosen it completely and tighten it again.
- move the bed all the way up to the top.
- turn the nuts beneath the upper frame by hand until they just touch the frame.
- if you want to be 100% correct, try to support the front of the bed just enough to lift its weight from the rods (difficult to achieve - if someone has a reliable working way of doing this, please share)
- Now tighten the upper nuts in the same way as you tightened the lower ones.
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… and did it make a difference in the quality of your prints? 