1 Topic by Retroplayer

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Topic: Y-Axis Timing belt replacements

Just had one of the belt break on me (at the adjustment screw - weak adjustment system if you ask me!) There was just enough slack to punch another hole and get some teeth into the nut with the screw.

So I am going to need to replace the belt as I am sure it will break again. I have searched around and cannot seem to find a clear answer. Can anyone tell me what the specs are on the belts? It appears to be 6mm wide, though 8mm would work within the pulleys. From what I gather, it is MXL, but all references are to the Y-Axis motor belt. There are no markings on this belt.

I need to know the type and pitch of the belts. Eventually I will go to GT2 with stronger belts, but that will require replacing all the pulleys (right?) So, for now, I would just like to put it back to stock to keep me printing.

Printer is an SD4 (purchased about a month ago so I assume whatever the latest configuration is.)

P.S. Yes, I am aware I can buy the replacements in the store. But I think a second source would be helpful!

2 Reply by grob

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Re: Y-Axis Timing belt replacements

MXL, 0.08" (2.032 mm) pitch, 1/4" (6mm) wide
Check on eBay and sdp-si.com, it's usually sold by the ft/m. If you're in the USA, mcmaster-carr will have it too.

Not sure on the length, but they can be cut to size anyway. I think about 600mm/belt is enough per belt (x or y's).

I've been working on a less stress-concentrating adjustment/tensioning/clamping mechanism built into the y carriages, in test at the moment, seems to work ok (but can't objectively compare it to the original really). V0.2 just printed, and a compatible carriage replacement for the x - but I'm a bit stuck on how to adapt my thing into the tight space in the x carriage, so it's on the old system for now.

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi

3 Reply by wardjr

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Re: Y-Axis Timing belt replacements

Go buy some 80 Lb test braided fish line (Spectra or Suffix brand).  Wrap around the drive pulley three times and just around the idler side.  Google how to tie a knot for that line and tighten.  Virtually no backlash and way stronger than belts.  Most affordable upgrade you can make. And yes it is an upgrade.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

4 Reply by Retroplayer (edited by Retroplayer 2014-07-28 03:32:34)

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Re: Y-Axis Timing belt replacements

wardjr wrote:

Go buy some 80 Lb test braided fish line (Spectra or Suffix brand).  Wrap around the drive pulley three times and just around the idler side.  Google how to tie a knot for that line and tighten.  Virtually no backlash and way stronger than belts.  Most affordable upgrade you can make. And yes it is an upgrade.

And just leave the timing pulleys as-is? There is no slipping? I'll check into it as I have read that quite a few times in here.


grob wrote:

I've been working on a less stress-concentrating adjustment/tensioning/clamping mechanism built into the y carriages, in test at the moment, seems to work ok (but can't objectively compare it to the original really). V0.2 just printed, and a compatible carriage replacement for the x - but I'm a bit stuck on how to adapt my thing into the tight space in the x carriage, so it's on the old system for now.

Interesting. I had been planning something similar myself using the Lawsy linear bearing carriage replacements before I do that upgrade. Something like a belt clamp with a screw pulling it in. Mine broke because for whatever reason, the right belt on the top is so lose it hangs, but on the bottom it is tight as... Well, when I tried to correct that, it ripped where the hole is punched for the screw. What a terrible idea! I knew it would break eventually. I do still need to figure why I can't get that one belt tight. I thought a clamp that let you adjust the belt from both sides might spread out the stress a little.

If Wardjr can confirm there isn't any slippage, I might go the sprectra line route and create a mount for that (crimp eyelets would probably work.) Any guess what the wire size equivalent that spectra line is?

5 Reply by Retroplayer (edited by Retroplayer 2014-07-28 20:19:30)

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Re: Y-Axis Timing belt replacements

A funny thing happened... when I was moving the carriages to get enough room to screw in my shortened belt, the left side kind of "popped". I think it was the bearing on the back rod sliding over. Now, it seems that my rods are more even than they have ever been. My circles are coming out perfect. Bonus.

I ordered the Spectra line, for a possible future upgrade. I'll probably customize the linear bearing carriages to use the line first.

Edit: Correction, I think it was the glue on the X axis rods. Hmm, maybe they were tweaked a little and that was why I couldn't seem to get the left side tight. I did notice when I was trying to do the adjustment for those rear pulleys, that right around mid-way, they would want to be in a different place and could never get them quite right.

6 Reply by wardjr

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Re: Y-Axis Timing belt replacements

I use Suffix brand as the spectra line seems to fray a bit.  There is absolutely no slippage just use the pulleys that are on there.  Three loops around the drive and none on the idler side.  I used Spectra with fine results but I do feel that the Suffix brand is better.  I only switched because I was changing a bunch of other stuff and Suffix was all I could find locally.  My point is don't get to hung up on brand.  Just find a good digital braid 80  Lb line.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

7 Reply by Retroplayer

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Re: Y-Axis Timing belt replacements

wardjr wrote:

I use Suffix brand as the spectra line seems to fray a bit.  There is absolutely no slippage just use the pulleys that are on there.  Three loops around the drive and none on the idler side.  I used Spectra with fine results but I do feel that the Suffix brand is better.  I only switched because I was changing a bunch of other stuff and Suffix was all I could find locally.  My point is don't get to hung up on brand.  Just find a good digital braid 80  Lb line.


I ordered some 100lb Spectra line (was cheaper than the 80lb.) But fraying has me slightly concerned. I wonder if rubber on the pulleys would help...

8 Reply by wardjr

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Re: Y-Axis Timing belt replacements

I wouldn't worry about it.  The stuff I had was yellow and mostly was dirty from greasy hands and stuff.  Fray was probably too strong of a word more dingy than anything.  I am hammering the extra mass of a Bulldog XL at speeds most people only dream of.   Try it and you'll like it I promise.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

9 Reply by Tomek

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Re: Y-Axis Timing belt replacements

Rubber would maybe not be good (squishy, changing diameter. Probably consistent, possibly not.)

Fraying for me only happened BC I forgot to grease some pulleys (it had been a long time) and they would get stuck.

10 Reply by michaudtime

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Re: Y-Axis Timing belt replacements

I just pulled my printer apart to polish the rods and get everything oiled up... looks like ill give this a shot too!!! :-)

Solidoodle 3, Bulldog XL Direct Drive, Well Nut for Z axis, borosilicate glass, E3D V6 Hot end, Custom Encloser, Lawsy Carriages with Linear Bearings and Polished 8mm Chrome rods.

11 Reply by wardjr

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Re: Y-Axis Timing belt replacements

I suppose you want a new duct designed to fit your v6?

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

12 Reply by michaudtime

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Re: Y-Axis Timing belt replacements

Lol, I wouldn't complain if I found one :-P I trimed down your V5 one and it takes away some of the angle so it's not really blowing towards the tip any more so I'm not sure how well it will work

Solidoodle 3, Bulldog XL Direct Drive, Well Nut for Z axis, borosilicate glass, E3D V6 Hot end, Custom Encloser, Lawsy Carriages with Linear Bearings and Polished 8mm Chrome rods.

13 Reply by Retroplayer

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Re: Y-Axis Timing belt replacements

grob wrote:

I've been working on a less stress-concentrating adjustment/tensioning/clamping mechanism built into the y carriages, in test at the moment, seems to work ok (but can't objectively compare it to the original really). V0.2 just printed, and a compatible carriage replacement for the x - but I'm a bit stuck on how to adapt my thing into the tight space in the x carriage, so it's on the old system for now.

Do you have a post here elaborating on this, Grob?

14 Reply by grob

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Re: Y-Axis Timing belt replacements

Not yet... Getting to it! smile

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi