Can you suggest a better way to tighten belts? Hi, Some of the answers to the print quality questions I have posted suggested backlash or not enough tension on belts. Here is how my belt setup looks from top-down view: [attachment 92780 belt.jpg] As you can see, I have to make 2 loops (on the picture there is only 1 in place). The first loop doesn't really matter, as it is the anchoring point. But the second loop is the step that adjusts tightness, so it is crucial. What I do right now is to try to pull the belt manually as tight as I can, then make the loop and immedialtely attach 2 zipties to hold it in place. The interlocking belt teeth prevent any slipping if the zipties are firmly in place. However it seems that I am never able to get the required tension. To test the degree of tension that is achievable, I used a pliers to hold the loose end and rotated it a few turns to make the belt tight. What I can achieve this way is really perfect but there is no way to fix it in place because the end of the belt is now rolled and any attempt to remove pliers without loosing tension always fails. If I tighten it manually, I use belt tensioners but they never achieve the degree of tension acheivable by using the pliers. The spring belt tenisoners seem to introduce some artifacts as they are not rigid and tend to introduce some backlash themselves. Printed rigid tensioners are limited on what they can achieve, as you can never achieve the same amount tightness using pliers. I've looked at metal pieces to hold GT2 belts in place but they are not adjustable. So, what can I do to make these belts tight? Any method or device? Thanks https://reprap.org/forum/read.php?4,761116,761116#msg-761116 Wed, 11 Mar 2026 20:58:15 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,761116,765796#msg-765796 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,765796#msg-765796 simple belt tensioner.

This works well on my Delta, where there's a fair amount of belt that doesn't go through any pulleys. I've intentionally left the tensioner slightly weak, so that it breaks if undue tension is put on the belt (e.g. nozzle is driven into the bed or crashes against the side of the print) and hopefully reduces stress and damage to other parts of the printer. I always keep a couple of spare tensioners on hand.]]> frankvdh Reprappers Wed, 03 May 2017 16:29:58 -0400 https://reprap.org/forum/read.php?4,761116,765793#msg-765793 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,765793#msg-765793 AquaticsLive Reprappers Wed, 03 May 2017 16:14:11 -0400 https://reprap.org/forum/read.php?4,761116,765535#msg-765535 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,765535#msg-765535
Hope this helps.

Steve]]> sgomes Reprappers Tue, 02 May 2017 13:32:04 -0400 https://reprap.org/forum/read.php?4,761116,764926#msg-764926 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,764926#msg-764926 Srek your solution looks really great! how does it work?]]> affa Reprappers Sat, 29 Apr 2017 04:20:23 -0400 https://reprap.org/forum/read.php?4,761116,763813#msg-763813 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,763813#msg-763813
Play Bonny!

Soadyheid]]> Soadyheid Reprappers Sat, 22 Apr 2017 19:45:29 -0400 https://reprap.org/forum/read.php?4,761116,762997#msg-762997 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,762997#msg-762997
Quote
Ed would
I take you point but I think they are fine.

I only write from a position of personal experience.

The springs do stretch when pulled hard. I don't have anything to measure the force required to deflect per distance so I can't give you any numbers to calculate but I 'feel' that for an average reprap type setup of Nema17/ GT2/ low mass, the spring rate would be enough to overcome the forces applied to it.
I'd be interested if anyone has properly measured it. I'm happy to eat my words.

Ed
It is a matter of mass and acceleration. If you use a core x/y printer with a bowden hotend and normal acceleration chances are you wont see any problems. If you use a Bulldog extruder on a cartesian printer with high acceleration i would avoid a setup like this like the plague.]]> Srek Reprappers Tue, 18 Apr 2017 05:20:45 -0400 https://reprap.org/forum/read.php?4,761116,762994#msg-762994 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,762994#msg-762994
I only write from a position of personal experience.

The springs do stretch when pulled hard. I don't have anything to measure the force required to deflect per distance so I can't give you any numbers to calculate but I 'feel' that for an average reprap type setup of Nema17/ GT2/ low mass, the spring rate would be enough to overcome the forces applied to it.
I'd be interested if anyone has properly measured it. I'm happy to eat my words.

Ed]]> Ed would Reprappers Tue, 18 Apr 2017 04:57:47 -0400 https://reprap.org/forum/read.php?4,761116,762292#msg-762292 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,762292#msg-762292
I like to look around here to get some inspiration for a nice design: [www.thingiverse.com]]]> Evan Reprappers Fri, 14 Apr 2017 09:55:12 -0400 https://reprap.org/forum/read.php?4,761116,762055#msg-762055 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,762055#msg-762055
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Ed would
At the risk of under-complicating things. . .

[attachment 92951 bspring.JPG]

The simple tensioner spring does a very good job of taking up slack and keeps a positive 'sprung' tension on the belt without needing a mechanically set position of motor/ pulley
While that solution is very common, it introduces elasticity where you usually do not want it. The belts have steel or fibre wires to prevent stretching and to minimize elasticity along the length. Adding such a spring counteracts this intention.]]> Srek Reprappers Thu, 13 Apr 2017 07:50:40 -0400 https://reprap.org/forum/read.php?4,761116,762035#msg-762035 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,762035#msg-762035
[attachment 92951 bspring.JPG]

The simple tensioner spring does a very good job of taking up slack and keeps a positive 'sprung' tension on the belt without needing a mechanically set position of motor/ pulley]]> Ed would Reprappers Thu, 13 Apr 2017 06:52:52 -0400 https://reprap.org/forum/read.php?4,761116,761983#msg-761983 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761983#msg-761983
]]> Srek Reprappers Thu, 13 Apr 2017 03:16:45 -0400 https://reprap.org/forum/read.php?4,761116,761965#msg-761965 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761965#msg-761965
Another popular trick is to remove all but one screw from the motor so that that the motor can rotate in the mount, attach your belt ends at the right length, pivot the motor back into place, and replace motor screws.

Also, here's how Prusa3d does it:
Tighten Y Axis
Tighten X Axis]]> tray Reprappers Wed, 12 Apr 2017 20:18:12 -0400 https://reprap.org/forum/read.php?4,761116,761248#msg-761248 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761248#msg-761248
Quote
the_digital_dentist
Quote
drmaestro
Hi,

Some of the answers to the print quality questions I have posted suggested backlash or not enough tension on belts. Here is how my belt setup looks from top-down view:

[attachment 92780 belt.jpg]

s

You've gone to a lot of trouble and some expense to use linear guides to get high precision, but you have a fundamental error, visible in your photo. The right side attachment where you have locked the belt with zip ties is too high. The belt segments that attach to the carriage have to be parallel to the guide rail at all positions along the rail or the belt tension will vary with the position of the carriage and the prints will be distorted.

The same is true in the Y axis. The belts must be kept parallel to the guide rails or you will have problems.

Thanks for mentioning that. I'll try to correct it. It is probably due to the diameter of the idler, which is 16 mm. I have another one which measures 12 mm, maybe it will help with the alignement.]]> drmaestro Reprappers Sat, 08 Apr 2017 15:44:10 -0400 https://reprap.org/forum/read.php?4,761116,761166#msg-761166 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761166#msg-761166
Quote
drmaestro
Hi,

Some of the answers to the print quality questions I have posted suggested backlash or not enough tension on belts. Here is how my belt setup looks from top-down view:

[attachment 92780 belt.jpg]

s

You've gone to a lot of trouble and some expense to use linear guides to get high precision, but you have a fundamental error, visible in your photo. The right side attachment where you have locked the belt with zip ties is too high. The belt segments that attach to the carriage have to be parallel to the guide rail at all positions along the rail or the belt tension will vary with the position of the carriage and the prints will be distorted.

The same is true in the Y axis. The belts must be kept parallel to the guide rails or you will have problems.]]> the_digital_dentist Reprappers Sat, 08 Apr 2017 08:49:42 -0400 https://reprap.org/forum/read.php?4,761116,761137#msg-761137 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761137#msg-761137 anvoice Reprappers Sat, 08 Apr 2017 05:50:37 -0400 https://reprap.org/forum/read.php?4,761116,761121#msg-761121 Re: Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761121#msg-761121
Ie keep one end of the belt around the plastic, the other looped around nothing just zip tied on itself, use larger 6mm zip tie just around the plastic and the last 6mm zip tie to join the loped belt and the zip tie around the plastic. tension by pulling the zip tie

eg like this



You just have to make sure the extra zip tie doesn’t hit or interfere with anything.
]]> Dust Reprappers Sat, 08 Apr 2017 04:06:58 -0400 https://reprap.org/forum/read.php?4,761116,761116#msg-761116 Can you suggest a better way to tighten belts? https://reprap.org/forum/read.php?4,761116,761116#msg-761116
Some of the answers to the print quality questions I have posted suggested backlash or not enough tension on belts. Here is how my belt setup looks from top-down view:

[attachment 92780 belt.jpg]

As you can see, I have to make 2 loops (on the picture there is only 1 in place). The first loop doesn't really matter, as it is the anchoring point. But the second loop is the step that adjusts tightness, so it is crucial. What I do right now is to try to pull the belt manually as tight as I can, then make the loop and immedialtely attach 2 zipties to hold it in place. The interlocking belt teeth prevent any slipping if the zipties are firmly in place. However it seems that I am never able to get the required tension. To test the degree of tension that is achievable, I used a pliers to hold the loose end and rotated it a few turns to make the belt tight. What I can achieve this way is really perfect but there is no way to fix it in place because the end of the belt is now rolled and any attempt to remove pliers without loosing tension always fails.

If I tighten it manually, I use belt tensioners but they never achieve the degree of tension acheivable by using the pliers. The spring belt tenisoners seem to introduce some artifacts as they are not rigid and tend to introduce some backlash themselves. Printed rigid tensioners are limited on what they can achieve, as you can never achieve the same amount tightness using pliers.

I've looked at metal pieces to hold GT2 belts in place but they are not adjustable.

So, what can I do to make these belts tight? Any method or device?

Thanks]]> drmaestro Reprappers Sat, 08 Apr 2017 03:44:29 -0400