Dear SamuelThank 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
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?
JGaurora 5 3D printer provides excellent printing results, if the
nozzle and the x-rods are well cleaned before starting a new print.
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!
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!
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)
have written a PDF documentation about the disassembly of the
x-system with 32 photos for x-friction check
you want to look it at send me a comment, but the disassembly is
really a hard, time consuming work!
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.
replacement of the bearing after operation time < 100 hours make
effective problem is the accumulated dirt by the heat contaminated
oil on the axis.
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 %
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.
comment this proposal if it makes sense for you!
Thank you for your kind comment!
Please tell me how the “Thank Button” works! I see only the”unthank” field without reaction if I push on it!
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!
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.
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.
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.
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?
Dear Forum Members
The attachment shows our investigation on the x-bearing problem!
There is some hope!
For Der_Muck and Samuel
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
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!
Hello SamuelThank 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?
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
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
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.