Thanks @Riskey for the update! I do have to admit though I am a little disappointed - the only obvious changes I could find so far are to wipe away old grease and to use lithium grease of unspecified consistency. The basic wrong way to grease these rails remains unchanged.
You see, the video i3sven embedded above (Snapmaker J1 linear lager X-Achse - YouTube) shows your linear guide slides have sealing lips on both sides - which is great during normal use since these lips keep any grease inside the linear guide and dirt outside.
But this also makes your whole greasing specification useless, since these sealing lips will stop any grease appiled onto the guide rail to get to where it is needed, i.e. into the inside of the slider.
Therefore, all the greasing suggested in the manual is about as fruitful as trying to feed a baby that keeps its lips pressed shut. The only thing you manage with this process is to smear grease onto places where it does not help.
Please take a look here: Search | Bosch Rexroth Germany
This link points you to the guide rail manuals from Bosch. They are available in several languages, even in Chinese. And then open the chapter “lubrication” (page 220 in the english version). Do not get confused about the length of the chapter - the Bosch manual is extremely detailed.
Apart from the general information there, please take a look at the pictures on where to lubricate (page 228 in the english version).
While most linear guide slides do not have that many greasing holes to select from, most have the greasing holes in the centre of each side of the slide. If you take a close look at time 1:54 of i3sven’s video, this also seems to apply to the slides used in the J1.
Therefore, for me it is quite clear on how to grease these rails correctly (taken from the Bosch catalogue and from the “General explanation → Lubrication” information from the IKO Nippon linear guide catalogue under IKO Technical Service Site :
- use lithium soap base grease specified for linear guides only. Take care to use grease that is suitable for temperatures of at least 100°C (max. temperature of the bed - I do not know how warm the linear guides will get, but I do not expect them to get hotter than that. Snapmaker might want to confirm this by measuring the worst case temperature). Lubricant specified for higher temperatures should survive longer. Do not use lubricants with solid particles such as graphite or MoS2.
The consistency class of the grease to be used is unclear as of now - Snapmaker should definitely test and include this in the manual. - using a syringe with a suitable adapter, insert grease into the lubrication opening of the linear rail slide until old grease is discharged. A shortened blunt syringe needle of about ∅1mm might do the trick (the larger the syringe, the easier the grease will come out). As noted above, lubricating the guide rail outside of the slide does not make sense.
Snapmaker should point out the position of the lubrication openings of the slide in the manual.
(Remark: I am using the simple-but-dirty greasing procedure suggested by IKO Nippon here since I suspect your rail manufacturer does not provide detailed greasing instructions.) - the slide will not run as smooth as it should since there is too much grease in there. To get rid of that, run in the slide by slowly moving it about 10…20 times back and forth until the slide runs smooth again. Excess grease will be expelled from the slide in this process.
- Remove any grease that has come out of the slide and resume normal operation.
(edit: clarified, corrected typos and changed video time where greasing hole is seen)