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Squeaking and or Circles aren't round? Check this! 56k warn!
#1
I've referenced the white pulley in the past for its clearance issue and contribution to circles that are not round.. It's worse than I thought. This printer has approximately 300 hours on it.

There have been many reports of a squeaking noise as the extruder moves left/right. It is especially prone to happen once the belts are adjusted.

Once I pulled the pulley, I could hear the exact same squeak when I rotated it within the housing. There appears to be no lube. I am of the opinion it should be lubricated, and I intend to do so. I am using "Super Lube Synthetic Grease with PTFE" as it has proven to be plastic safe in the past for me. Your results may vary, do this at your own risk. I can not promise that any of this will not void your warranty.

Having said that, I recommend inspecting your pulley.

Here is the problem:
https://www.youtube.com/watch?v=lz7thzPYftQ

Here is after my fix:
https://www.youtube.com/watch?v=tiav8bvDLZo




Here is whats going on. Look at the excessive tolerance between the axle and the housing.
(Keep reading, I'm going to show you how to fix it without parts!)



Here you can see there are the grooves actually worn into the plastic housing.









Look at the wear. It appears there is NO LUBE from the factory!

So what to do? Easy. We are going to fix this by using a technique which reduces tolerance through intentional controlled wear. You must be careful doing this - go to far and you will need a new part, so proceed at your own risk.

You will need a set of micro files. These are only a few bucks at most tool shops, and they come in very handy for finishing plastic parts. In this case I have a small round and a small flat.






Using the thinnest edge of the flat file, file a very small groove dead in the center of where the axle rides, closest to the extruder side. Remember, you can always file more, but you cant add back. (OK, you could fill with JB Weld and start over, but I digress.) Work only one side at a time. Just 5 or 6 strokes using only the first portion of the file. Then repeat for the other side with the same number of strokes and pressure. You must keep the grooves as even and consistent as possible.





***TO BE CONTINUED***[Image: 7.jpg][Image: 1.jpg][Image: 2.jpg][Image: 3.jpg][Image: 4.jpg][Image: 5.jpg]
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#2
The purpose of that groove was to force the round file to the center of where the axle wants to naturally ride. Now we expand the groove to *partially* fit the axle. We DO NOT want the entire axle to sit into a rounded hole. The reason is the axle is going to wear more, and we want to save as much plastic as possible.In addition, with this modification the wear *should* work to better fit the axle - in other words the tolerance very well could improve instead of getting worse. This happens because we have created a small "well" for the axle to wear into, as opposed to just letting it float wherever as the factory did.
Here is how to expand the groove. I used the small round file, again 5-6 short strokes with medium pressure on each side.



Test fit the pully/axle into the houing. Wrap the belt on it so you can apply some tension and see if the mod is effective. If so, lube it and reassyble. If not, repeat as needed. Again, be careful not to file to much plastic away. If you cant tension the belt tight enough you can probably move the stepper motor a little bit to compensate.

Once satisfied with the fit I lube the contact areas for the axle and sides of the pulley. Just a little on a cotton swab goes a long way







I also lubed the slides. It was only two more screws to release the rods and gentle removal of the belt to take the entire carriage out. No benefit to removal, just showing it apart "in case."





Hope this helps - if you have any questions please feel free to ask. Smile



Enjoy!
Kieth[Image: 6.jpg][Image: 8.jpg][Image: 9.jpg][Image: 10.jpg][Image: 11.jpg][Image: 12.jpg]
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#3
Excellent write up Kieth.

I've too, identified this X axis wheel design to be a problem. My printer doesn't have nearly as many hours as yours so the wheel carriage on mine does not have any wear groves, I simply took it apart because I was annoyed by the squeaky wheel.

The squeakiness does go away after lubing the shaft (I used silicone dielectric grease) but comes back after a while after all the lube gets pushed away from the shaft. This part should have been pre-lubed from the factory and should be regularly lubed as a preventive maintenance to reduce wear.

I got pretty tired of taking it apart to lube after the 3rd or 4th time, so I turned a replacement ball bearing wheel on my lathe. Smile[Image: 2014-05-1519.47.23.jpg]
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#4
Thanks for the heads up.
I decided to get ahead of the problem and lubed mine with a paste of graphite and Super Lube grease. I wanted to use moly powder, but I ran out of that. I figure the graphite/moly will embed in the plastic and stop the wear before it starts.
Of course the best idea is the ball bearing, but it might be overkill if the graphite does its job.
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#5
Next go round, if it need be, I will steal the bearing idea. It seems the best for long term. Frankly its so cheap to implement I'm kind of surprised they didn't do so from the factory.

Kieth
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#6
chilicoke, i was thinking about doing your ball bearing idea as well, but not sure which size or where to get the exact one that would fit, in live in the US.

I'm getting my da vinci this saturday delivered which will be my 1st 3d printer. I can't wait.
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#7
Just saw this nice mod. Too bad I don't have lathe to make one. Did some measurement. The idler shaft is 3mm diameter. OD around 10.5 mm W around 10mm.
I think two F623zz bearing might do the job. Direct replace the idler and using the current shaft. I might get some and test it.
[img]
Here are some basic data
Bore Dia (d) 3.0000mm
Outer Dia (D) 10.0000mm
Flange Dia (Df) 11.5000mm
Width ( B ) 4.0000mm
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#8
Finally found the possible replacement parts for the idler. Not the best.. it is made for 4mm belt should fit 5mm okay, 6mm one is 1mm too wide for Da Vinci. Didn't get the price and shipping cost. Anyone want to try?
Here is the part number datasheet link is here
[img]
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#9
I try several designs try to add bearing to X axis idler. I end up using 683ZZ 3x7x3 bearings and reprint the idler holder.
Here is my current V4 design. Looks the printed parts hold up well.. Let me know what you think.

There is the files, include OpenSCAD and DXF drawing file

I print mine in ABS with support. I use Kissicer with 0.25mm layer height , 0.4mm extruding with 50% infill.

Here is the original idler add 683ZZ bearings on both side.

Make sure you have enough grease and put the the idler back to work
[Image: ScreenShot2014-06-15at8.33.49PM.png] https://forum.voltivo.com/images/X_Idler_holder_v04.zip[Image: printing.jpg][Image: Add_683zz_Bearing.jpg][Image: Installed.jpg]
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#10
Got the price for AHTFW20-S2M040-3 today. Cost $26.79+shipping for 1 unit. $15.61/each for Qty=10.
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#11
What are the exact dimensions on the wheel (if anyone has theirs out, or measured while it was out)?
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#12
Use the figure for flanged idler , Let us know if you can find anything we can use as replacement.
L: 9mm
d: 3mm
F:16mm
D:10.67mm
W: [Edited]~8.0mm ,I don't have measurement for this , (The belt width is 5mm, s2m type )
[img]
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#13
Thanks, could you verify this? I made the 8.5 section 8.0 because only .25mm wall per side seemed small. I don't have a belt in front of me to measure actual belt thickness. Additionally--are there teeth in the plastic one? I'm not at home to verify.

AND, one more thing--how do we disassemble that section? My printer's running production so I'm not wanting to disassemble it currently, but I'd like to work on a solution if I can. I work in manufacturing, so even if I can't find something off the shelf, I might be able to modify a handful of replacements.

My problem is, how is that belt tensioned? I haven't looked, but we're limited to size changes based on how much adjustment that belt has from the factory. If there's a bit of room to move in, going with a slightly larger diameter off the shelf bearing would work, but you would need washers on each side to eliminate digging into the plastic. Same for adjustment to tighten--we could go with a slightly smaller diameter bearing.

[URL=http://s133.photobucket.com/user/Ovrclck350/media/Idler_zps62597e3e.jpg.html"/>[/URL]
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#14
The belt type is s2m 5mm width. The printer has spring on the back of the idler holder for tension the belt.
For the idler I was looking for S2M/GT2 20T idler pulley for 5mm belt with right width ( max width to put in the holder is 10.5mm ). But no luck for it
The current solution I can think about is get GT2 20T pully (size close enough) with 8mm bore and mill it down to right width then add 2 3x8x4 bearing.

GT2 Pulley 20 Teeth 8mm Bore
[img]
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#15
Forgot to mention the Idler is smooth idler, no teeth on it.
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#16
Better yet, make a new pin, 5mm diameter, with 3mm ears to fit into the holder--or reprint the holder to take a 5mm pin.
USE this bearing: http://www.astbearings.com/product.html?product=HK0608
with a washer on each side of it. I'd have to look up the washer to use, or make my own, but to me, that's the solution.

As far as width, you want the extra width to compensate for slight misalignment and torquing.



-OR-
Use this bearing with current pin, and 3d print the rest of the idler to go around it/mill out current idler to 6mm:
http://www.astbearings.com/product.html?...t=HK0306TN



I didn't see the specs for your toothed idler above in the 6mm belt version--what is the overall width and what diameter does the belt ride on? If it's 10mm diameter and anything less than 9mm overall width it should work fine. The extra belt width isn't going to hurt you, but the narrower one will.
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#17
These are the S2M Idler. The sad part is they don't offer 5mm belt width one and the 6mm belt parts is 0.5 mm wider ( W=11mm) then the holder's max width(10.5mm). 4mm is too narrow for it. If we can find the source for those plastic idler inside Da Vinci with 8mm ID or GT2 20T idler that should work too.
I did try 3d print the idler from Da Vinci then add 3x8x4 bearings .... The parts is usable after add bearing but I will not recommend it as accuracy is not good enough to meet my requirement.
Here are S2m Idler Dimensions for 4mm/6mm width belt.

[Image: s2m_idler.png][Image: s2m_20t_dimension.png]
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#18
I'm more inclined to go with my first option then. I know that won't be feasible for some, but I run a shop with multiple Swiss Screw machines (Citizen L20's). Making a pin 3mm-5mm-3mm would take me less than 30 seconds (and roughly 2-3 minutes entering the code).
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#19
Finally got my pulley to implement the bearing idler idea form chilicoke.
This is the parts I have
(1) GT2 20T pulley 8mm bore ( right parts should be S2M 20T pulley 8mm bore)
(2) 2x 693zz bearing , 3x8x4 mm
This is what I got now. GT2 20T pulley 8mm bore. The correct parts should be S2M 20T pulley 8mm bore. unfortunately I can't find one.
Right now I just stay with GT2 for testing.

After mill the pulley width down to 9.5mm and I am ready to add 693zz bearing.
Bearing size is 3x8x4 mm.You need to add 1.5~2mm spacer between bearings.

Bearing in the pulley

On holder

The all parts goes together as I wished but need to do more prints to see how well the GT2 pulley idler go with S2M belt on the long run.[Image: GT2_20T_pulley_8mm.jpg][Image: GT2_20T_pulley_693zz_bearing.jpg][Image: GT2_20T_pulley_693zz_bearing_installed.jpg][Image: pulley_on_holder.jpg]
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#20
Chenglung - Terrific looking work. Thanks for sharing. Since you are not altering the required number of steps to move the extruder a given position, regardless of idler pulley size, it should not effect the print quality. This of course assumes you have eliminated excess tolerances with your modification.

Kieth
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