Upgrade bearings for x and y axis

ufodoctor3 · January 2019

Dear Forum
I received the better bearings by AliExpress
Do you know a tutorial for mounting these bearings?
Thank you for your advice
Greetings
Peter

Der_Muck · January 2019

There is a Video from Dahai on Youtube, you have to demount pritty much for that. I will do the same when the last bearing is here.

ufodoctor3 · February 2019

Dear Samuel
Thank you for your answer. 
Could you please tell me where I can find the Video from Dahai?
I have measured the friction of the AliExpress long lateral ball bearing on a polsihed Axis of 6 
+0/-0.02 mm, it is about 50 Gramm (0.5N) at start and about 25 Gramm (0.025 N) if already moving.
The step motor for the x-Axis generates a force of about 1.6 kg (16 N), at 17 N rattering!
Thus there is a safety factor of 32, looks ok!
But tomorrow I go to the SKF-Shop to ask, if Swiss bearings are better  with expected higher price
Kind regards
Peter

Samuel Pinches · February 2019

Hi Peter,

Der_Muck is not Samuel - I am Samuel

I just was saying thanks to @Der_Muck for the helpful comment - this is why he is a Super Member!

DaHai has his youtube channel here: https://www.youtube.com/channel/UCHsEE5cIC8gvoS5D4MkJUWQ/videos

I'm not sure of which video Der_Muck is referring to.

There is a button to say thank you to helpful posts here:

Image: https://jgmakerforum.com/uploads/editor/0g/5kzqg69tfxjb.png

Der_Muck · February 2019

Year me is me and Samuel is Samuel

The all about the Z axis should help with the X bearing demount.
The Y bearing is simple, just demount the 3 screws of each aluminium rail that holds the Y axis and loose the screws of the hot bed. Loose the connection to the hotbed and you should be able to get the bearings out.

I bought the fushi once and they seems to be very good in quality. SKF produce bearings also in china, so they where only good in the old times, they lost most of the old quality as i saw.

ufodoctor3 · February 2019

Hello Der_Muck
Thank you (I have still problems with the thank button is not not active!)
I shall try now the mouting of the China bearings. The x-bearing shows a friction of about 0.5 N, but compared with the maximal driving x-force of about 15 N it looks quite good.
I could not get better Swiss bearings, in stock there are only bearings with larger outer Diameter
Kind regards
Peter

Der_Muck · February 2019

I had a few problems with a contact problem of the E connection to the bord so i used that opening to get the new belt and the new bearings on Y.
It shows that the Y has a higher friction now but I think thats no problem. Maybe that helps with the gosting of the Y axes.
Fushi bearings from China are looking pritty good, I dont see the need of SKF expensive once, they are similar as I think.
X and Z bearings will be changed to, at X I dont understand why they used a long and a short bearing.
When I change, maybe its better to change the lower one to the long version. I simply dont understand why they mix long and short.
@ufodoctor3
Think about the passibility to change the belt to, I changed to the gates belt (brown look) and I must say yes its a better belt, less elastic than the standard one.

ufodoctor3 · April 2019

Dear Der_Muck

Thank you for your comment!

After systematic experiments I came out to the conclusion, that the replacement of the long lateral X-ball bearing make no sense: The same poor bearing quality!

Of course, after replacement at a well lubricated rod the new ball X-bearing works fine for some time.

But our dog is barking below the wrong tree: (in German: wir bellen unter dem falschen Baum)

The main problem is the contamination of the lubrication at the rod at height temperature (especially during ABS-Printing)

We need to find a solution for cleaning the rods during printing!

I got expensive NBS stripper washers “Schmutz-Abstreifer” by my SKF-expert, but NBS cannot withstand temperature above 100 Degree

Thus my next experiment will deal about home made Teflon strippers.

Nice would be an automatic lubrication, but the ambient temperature is too high for storing oil near the hot extruder for long time.

I could make a Mini-Refrigerators by Peltier elements (works fine realized for a former medical device), but this seems to be overkill!

Do you have better ideas,as a assume?

Kind regards
Peter

Der_Muck · April 2019

It depends what bearings you bought. So in my pack where 4 of those, that works a long time. One a year, makes 4 years live time by changing but only if there will be a massive problem.
Peletiers need to much power, I have a 40x40x10 fan on the cold end and will change it to a faster one next week to get even better cooling of the cold end. I have the 500°C hotend so I could burn the hell out of it every time

Sooo I dont see the need to change anything there, it is how the whole printer is, a compromise.
For my mods I am near the end of modding and beginn building a total own build printer. With enclosure and pi pa po

ufodoctor3 · April 2019

Dear Der_Muck

x-Bearing Check

The JGaurora 5 3D printer provides excellent printing results, if the nozzle and the x-rods are well cleaned before starting a new print.

In addition, the x-rods need to be lubricate periodically, if not the stepper motor will rattle and the upper printing layers will exhibit an x-offset of many millimeters!

Some forum colleagues think that the long upper bearing is of poor quality and replace it by an AliExpress JGaurora spare part. In fact, the new bearing works fine, but not for a long time!

My rigorous investigation came to the result, that the long x bearing is effective of sub-optimal quality, but adequate for the our printing job. On a well cleaned rod lubricated by a thin oil or Teflon spray the friction is about 50 gram (0.5 N), and the maximum stepper force is about 1500 gram (15 N)

I have written a PDF documentation about the disassembly of the x-system with 32 photos for x-friction check

If you want to look it at send me a comment, but the disassembly is really a hard, time consuming work!

BUT: within the bearings circulate dozen's of tiny spheres in a U-channel. Thus, small dirt particles (from the printing before) will block these spheres, provoke heavy friction.

Thus, replacement of the bearing after operation time < 100 hours make no sense!

The effective problem is the accumulated dirt by the heat contaminated oil on the axis.

I propose a friction monitoring system with acoustical warning. with short interval beeps if the friction is at 50 % of the maximum torque of the stepper motor an a constant beep for 75 %

This monitor could be an external device, powered by the internal USB connector (with an USB-extender Box) an a hall sensor at one of the three supply wire of the x-stepper motor.

Please comment this proposal if it makes sense for you!

Regards

Peter

Samuel Pinches · April 2019

Hi Peter, sounds like you’ve prepared a lot of hard work to document the bearing upgrade process! Let me know if you want any help to share it - we could put it all on the wiki if you would like.

ufodoctor3 · April 2019

Dear Samuel
Thank you for your kind comment!

First:
Please tell me how the “Thank Button” works! I see only the”unthank” field without reaction if I push on it!

Second: 
The documentation about the dissembling of the x-axis was really a hard work and with the 32 Fotos. I hope that I can assembly the x-axis for proper operation again! If the assembly works fine, I will write an extended report for your publication in the forum. 

Third: All this work was useful for testing the original x-bearing. The original x-bearing was still perfect, not worse than the ordered spare parts!

Forth: 
I think that an external box for “x-axis cleaning alert” without galvanic contact to the JGaurora PCB would be fine. It needs only a sensor cable with a Hall sensor to one of the driving cables of the x-Stepper motor. The power can be provided by the existing USB-terminal and an USB-Extender.

Best regards
Peter

Der_Muck · April 2019

@ufodoctor3
To change the original bearings with spare bearings from JG makes no sense, they are the same and same shitty

Why dont you change to a other company?
Isnt a toiletpaper roll and some oil enough before every print?

For me its not a problem to do a service when the bearing are in a inprintable condition, when you are fast, you can change the bearings in 30min.
Try to use PTFE high temp oil, I use it on my fine plasma cutting machine and on my JG, I add it in the bearings before I assambled them.

ufodoctor3 · April 2019

Dear Der_Munk
I agree with you: the original x-bearing and the spare parts from JG are suboptimal! (politicly correct expressed)

But I could not find a company for this bearing with the same dimensions

If I clean the rod by Isopropanol with a fine tissue and lubricate by PTFE oil every time before printing all is OK. 

But sometimes I forget the cleaning by not following my checklist! So I trust on my new idea about an acoustic friction alert system. 

Not clear for me is how you can change the x-bearings within 30 minutes! 
There are dozens of screws and following my near coming out tutorial this is a 2 hour job.

Greetings

Peter

Samuel Pinches · April 2019

Hi Peter, I have listed many spare parts on the wiki. One item I organised on there is a full set of premium bearings:

Https://sampin.ch/A5-bearings

Der_Muck · April 2019

Its easy, unplug the Z motors, lose the motor clunch, pull the motors off.
Secure the X axes with panzer tape. Unscrew the Z threads. (not the nuts!)
Pull the Z rods off, the X axes is now free.
You dont have to lose the upper attachments for the rods.
In total 4 screws to unscrew, dont unscrew the other attachments because you have to recalibrate the positions by driveing the X axes up and down with Z. Otherwise you will have wobble on Z or the Z rods will give preasure on the X axes.
Dahai has a good video how to change the Z axes on youtube.

P.S. Ofcause the bearing will withstand 1000h or something

1 Print I did was alone over 45h, nothing changed there.

ufodoctor3 · April 2019

Dear Sam and Der_Muck
Below you will see my first tutorial on x-bearing check and replacement for the JGaurora 5 3D-Printer

Please look it at give me your comments. You may use this docu for a wiki-input, if you like it!

My next project will be a small box for x-friction detection and alert, connected to the USB port (for supply) and a cable bridge to the x-motor (for x-current sensing), without any further contacts to the JGaurora PCB.

Greetings
Peter

ufodoctor3 · April 2019

Hello Sam and Der-Muck
It seems that I have a problem with upload a 30 kB PDF document for the forum? Can you read it now?
Regards
Peter

Samuel Pinches · April 2019

@ufodoctor3
Thank you for sharing that document, I can see it has been a lot of effort to replace the x bearings. I wonder if there is any shortcuts that could be taken.

Der_Muck · April 2019

@ufodoctor3
Good documentation for a total disassambling!
But only to change or check the bearings you dont have to disassamble anything, its much easyer.
I had everything disassambled but I realy didnt even one of your steps, its much easyer, just watch dahais video about it, its no problem in 30min and most of the parts stay as they are. Thers no need to unscrew the extruder or the upper rod holder, no need to unscrew the whole frame, thats simply not nessesary.

Its a good video but only at min 5:00 you dont have to disassamble the upper rod holder, its ok when they stay as they are.
https://www.youtube.com/watch?v=NTJ7fz0F7Ks
Do that on both sides and the X axes is free.

ufodoctor3 · April 2019


Thank you very much for your input!

However, the video https://www.youtube.com/watch?v=NTJ7fz0F7Ks seems to me like a presentation of a bikini, with nice details displayed, but the essential details are still hidden How do you disassemble the long x-bearing for testing or replacement?

Still wondering
Peter

Der_Muck · April 2019

When you disassamble the 2 Z rods, X is free and hanging, you just have to get the PTFE tube out, unscrew the 2 screws which hold the print head together and lose the belt (unscrew the belt screw and pull it out). Now you have the X axes in out hand and just pull the rods out of one side.

ufodoctor3 · April 2019

X-Bearing Friction
Dear Forum Members
The attachment shows our investigation on the x-bearing problem!
There is some hope!
Kind Regards
Peter

ufodoctor3 · April 2019

Hello Forum!

For Der_Muck and Samuel

Dear Der_Muck
I still not understood how to get the x-system out of the tower without dismounting at least one 
of the U-sheets at the bottom of the tower.
Dismounting the z-rods you need to re-adjust the left and right spindle for perfect horizontal
positioning afterwards?

Dear Samuel: the proposed better bearings do not fit to the JGaurora extruder, sorry!

But now to my experiments with reduced x-stepper torque:

With the two serial 68 Ohm resistors inserted temporarily in the A/B stepper motor power line,
the zone of the friction of the x-bearing on the rods can be located easily. 


In my case I found out, that the two x-rods are not perfectly parallel.
Squeezing the rods together by about 1 N the friction becomes less!

As proposed by Der_Muck it make sense to construct a 3D-Printer at your own,
but with thicker x/z rods (better stability) and professional larger (Swiss?) bearings


But now the low-cost re-assembled JGaurora 5 works fine for the moment!
Regards
Peter

Samuel Pinches · April 2019

Sorry! That was the wrong link, here is the correct one: A5-bearing-set

ufodoctor3 · April 2019

Hello Samuel
Thank you for the correct link. I got these bearings already by AliExpress, however they are of the same suboptimal quality as the originals installed in my JGaurora 5.

Here a new idea:
Your previous link https://sampin.ch/A5-bearings show linear bearings of 12 mm inner and 21 mm outer diameter. I could buy these bearing and test it on a precise INOX D12 rod.
If the friction is less that 0.25N it would make senses, to adapt the JGaurora 5 Printer for 12 mm rods.
Of course, The alu printer head must be reconstructed and manufactured, but I have a well equipped tool shop!

What do you think about this proposal?
Kind regards
Peter

Samuel Pinches · April 2019

Hi Peter,

This seller is the highest rated bearing seller I could find on Aliexpress. These bearings (at the correct link) did improve the performance for me. If they are not working for you, please contact the seller for a replacement, because you should receive a good product.

I don't recommend investing time upgrading the A5 mechanical structure. I think that time is better spent on building a new printer, correctly, from the start.

Best regards,

Sam

ufodoctor3 · April 2019

Hi Sam,
It could be, that you got an improvement of the performance by 
changing the long x-bearing, because your old bearing was worn out! 

In my case the original long x-bearing was still ok, thus a replacement made 
no sense.
Both, old and new bearing showed a friction of about 0.5N, so far 
not optimal, but acceptable.

I think that the very small spheres in the u-channels of the long upper 
8mmm x-bearing are the main source of the friction problem, if the rod 
is not perfectly lubricated.

In addition, we have an upper and a lower rod, not perfectly parallel 
aligned, giving additional friction.

The 4 AliExpress replacement bearings for the y-axis (10 mm rod diameter)
shows much less friction!

I think I should make a mechanical test-setup with upper and lower 
10 mm x-rods equipped with 2 bearings at the top, separated by about 50 mm, 
and one on the lower rod in the middle.

What do you think about this experimental approach?

If it works fine, we could design a new printer, using base and tower 
from JGaurora 5

Best Regards
Peter

cs2000 · April 2019

Just a thought, has anyone tried Drylin bearings? I had these on my old machine and they were amazingly reliable

Samuel Pinches · April 2019

For me, I installed my bearings on the A5S y-axis when it was new. The factory bearings were beyond terrible. The A5 bearings were not great, but not terrible, so I have not tried to change them.

I look forward to hear how your testing goes.

I also tried some drylin bearings, but I found they were very sloppy. They need to be properly preloaded, and I didn't manage to do that successfully.

ufodoctor3 · April 2019

Hello Forum
Here a better insight to the x-bearing vibration problem.
It was a hard work to find out that the x-bearing needs to be cleaned after every use!
Please look at the attached PDF Doku.
Best regards
Peter

Upgrade bearings for x and y axis

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