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Beltrouting is causing VFA ?  

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Ckobar
(@ckobar)
Estimable Member
Beltrouting is causing VFA ?

Hi there,  since the core one is my first core-xy-printer.....

  Looking at the meanics of the belt-routing i wonder, if this might cause some inaccuracies.

For exsample: When the belt puls the linear-rail back, the "force" of the y-belt is applied to the pulley on the left side of the linear-rail , if it moves forward  the "pulling -force" is applied on the other side of the linear-rail .

Since its has been discussed elsewere, that the linear-holdes are quite flexible. I wonder if this flex is transfered to the linear rail during printig. ?

 

But maybe i`m wrong ?  Thanks for your input 🙂

Posted : 14/05/2025 10:12 am
Jürgen
(@jurgen-7)
Prominent Member
RE:

Belt ripple is observed while the print head moves linearly, at constant speed -- i.e. in the absence of direction changes or accelerations. So I don't think deformations of the drive train due to dynamic load changes play a big role with belt ripple.

The general assumption is that it is linked to the belt teeth, although it is unclear what the exact mechanism is. It might have to do with teeth rubbing on the flanges of the idlers; or with the toothed side of the belt running over smooth idler wheels (in two locations); or the different elasticity/hardness of the teeth vs. the gap regions of the belt. Motion that is uneven on a microscopic scale, due to imperfect micro-stepping of the motors, might also have an effect.

Users have tried various fixes, in the Core One and other printers before it. The only consistent observation seems to be that there are always some printer units where a particular fix has helped, and others where it has no effect at all. 

Posted : 14/05/2025 11:01 am
1 people liked
ticric
(@ticric)
Active Member
RE:

Hi everyone, I’m about to build my core one in the next week and was thinking at replacing the 2 smooth idler where the tooth of the belt is rubbing with 2 toothed idler,I don’t know if it’s a good idea.I have made that on my mk4s on the bed axis and saw an improvement.I want to know if  anyone have try this on his core one? Thanks!

Posted : 18/05/2025 12:31 pm
Jürgen
(@jurgen-7)
Prominent Member
RE: Beltrouting is causing VFA ?
Posted by: @ticric

Hi everyone, I’m about to build my core one in the next week and was thinking at replacing the 2 smooth idler where the tooth of the belt is rubbing with 2 toothed idler,I don’t know if it’s a good idea.I have made that on my mk4s on the bed axis and saw an improvement.I want to know if  anyone have try this on his core one? Thanks!

@altaic and @brian-12 have looked into this here, but I am not sure whether one of them has already tried the modification. Seems that no direct drop-in replacement part was found, but that the mounting blocks for the idlers need some adaptation to make things fit.

Posted : 19/05/2025 9:28 am
2 people liked
ticric
(@ticric)
Active Member
RE: Beltrouting is causing VFA ?

Thanks I will follow that!!

Posted : 19/05/2025 11:07 am
Brian
(@brian-12)
Prominent Member
RE: Beltrouting is causing VFA ?

I am still planning on installing them on my Core One anyways because I bought them at the same time as I bought them for my XL.  I have already altered the cad for the gantry pieces and will just need install then whenever I get the printer.  I'm sure they won't change anything but I'll do it anyways as I know it won't hurt and it can eliminate the question for others. 

Posted : 19/05/2025 11:42 pm
5 people liked
Krzysztof Papuga
(@krzysztof-papuga)
Member
RE: Beltrouting is causing VFA ?

Here it is shown that someone has already done it and writes that it has been fixed by VFA

https://www.facebook.com/share/p/16Qs7ncy5R/

Posted : 06/06/2025 5:18 am
iftibashir
(@iftibashir)
Noble Member
RE: Beltrouting is causing VFA ?

What did they say - its a private group so cannot see the post.....

Posted by: @krzysztof-papuga

Here it is shown that someone has already done it and writes that it has been fixed by VFA

https://www.facebook.com/share/p/16Qs7ncy5R/

 

Click here for VIDEO BUILD GUIDES + 3D Printing Tips!

--> Core One - MK4 - MK4S - MINI+ - MMU3 - Accelerometer Guide <--

Posted : 06/06/2025 9:21 am
2 people liked
rinkel
(@rinkel)
Estimable Member
RE: Beltrouting is causing VFA ?

 

Posted by: @krzysztof-papuga

Here it is shown that someone has already done it and writes that it has been fixed by VFA

https://www.facebook.com/share/p/16Qs7ncy5R/

I have done this modification, toothed idlers. I can tell you: no changes at all, nothing.

Posted : 08/06/2025 2:52 pm
4 people liked
Chocki
(@chocki)
Noble Member
RE: Beltrouting is causing VFA ?

I'm wondering if it's the actual belts themselves, the stretch on mine in just a few weeks of light use makes me think these are not Gates belts, rather a cheap no name brand from Ali

Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.

Posted : 09/06/2025 11:58 am
Jürgen
(@jurgen-7)
Prominent Member
RE: Beltrouting is causing VFA ?
Posted by: @chocki

I'm wondering if it's the actual belts themselves, the stretch on mine in just a few weeks of light use makes me think these are not Gates belts, rather a cheap no name brand from Ali

Hmm -- they don't have any print on the back, which I think the original Gates belts have? 

Seeing that Prusa have moved to cheaper motors and Y bearings, and make their own idler wheels (which can apparently be improved upon by buying brand-name replacements), it would not come as a surprise that they try to save money on the belts as well. They must be in a tough position: Prusa's use of brand-name parts used to be one of their differentiators over the cheap Chinese competition. But with the competitors having caught up in terms of innvovation, performance and print quality, apparently the price pressure is so high that Prusa now switch to no-name parts as well. 

The THK-made X rail is the only branded component I have found in my Core One kit, electronics parts aside.

Posted : 09/06/2025 12:44 pm
Ckobar
(@ckobar)
Estimable Member
Topic starter answered:
RE:

Just checked on my Mk4.  It’s an Gates belt. If the core one belts not gates ones, it would be interesting if replacing them does make a difference?

does anybody know what length the xy bets of the core are?

Posted : 09/06/2025 1:33 pm
Ckobar
(@ckobar)
Estimable Member
Topic starter answered:
RE: Beltrouting is causing VFA ?

Btw. How to distinguish between cheap and „good“ idlers ?

Posted : 09/06/2025 2:15 pm
Jürgen
(@jurgen-7)
Prominent Member
RE: Beltrouting is causing VFA ?
Posted by: @ckobar

Btw. How to distinguish between cheap and „good“ idlers ?

I misspoke when I mentioned idlers, sorry -- I meant the pulleys (toothed drive gears on the X/Y motors). Switching to branded ones has been found to reduce belt ripple significantly. 

I don't think the parts themselves are marked, but it is "known" that Prusa make their own. I once stumbled upon a Prusa drawing for what they called a "Prulley" -- pun alert -- but can't find that anymore.

Posted : 09/06/2025 2:28 pm
1 people liked
gb160
(@gb160)
Estimable Member
RE: Beltrouting is causing VFA ?

Its weird, I could've sworn my Core One had Gates belts...Ive definitely seen Gates somewhere in the last few days, after reading your post I was so sure I went to double check before replying...lo and behold no Gates writing on my belts. 

Posted : 09/06/2025 4:27 pm
1 people liked
Chris Hill
(@chris-hill)
Reputable Member
RE: Beltrouting is causing VFA ?

My CORE One kit has Gates belts.  Batch 1, dispatched April 9th.

Posted : 09/06/2025 4:37 pm
3 people liked
Jürgen
(@jurgen-7)
Prominent Member
RE: Beltrouting is causing VFA ?
Posted by: @chris-hill

My CORE One kit has Gates belts.  Batch 1, dispatched April 9th.

How do you recognize them? Mine is a kit from batch 1 too, dispatched a bit earlier, and I do not see any markings on the back of the belts.

Posted : 09/06/2025 4:53 pm
Jürgen
(@jurgen-7)
Prominent Member
RE:

Hang on, it does say Gates(R) Powergrip! On the upper belt directly to the left of the Nextruder, i.e. in a section where the back has never touched an idler. Does the print wear off quickly when the belt runs over the idlers maybe?

Posted : 09/06/2025 5:00 pm
gb160
(@gb160)
Estimable Member
RE: Beltrouting is causing VFA ?

 

Posted by: @jurgen-7

Hang on, it does say Gates(R) Powergrip! On the upper belt directly to the left of the Nextruder, i.e. in a section where the back has never touched an idler. Does the print wear off quickly when the belt runs over the idlers maybe?

Yeah that makes sense...thats where I saw it.

Posted : 09/06/2025 5:04 pm
Chris Hill
(@chris-hill)
Reputable Member
RE: Beltrouting is causing VFA ?
Posted by: @jurgen-7

Hang on, it does say Gates(R) Powergrip! On the upper belt directly to the left of the Nextruder, i.e. in a section where the back has never touched an idler. Does the print wear off quickly when the belt runs over the idlers maybe?

I don't think that's it - on mine the printing is visible on the two belts at the back between the motors.  I'm pretty sure those bits regularly run over the idlers.

Posted : 09/06/2025 5:11 pm
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