Hi all, I am having an issue where I cannot get the y-axis belt to not drift left and right (RepRapPro Mendel). I've lined up the bearings as precisely as I can, made sure everything is nice and square, but it still continues to drift several mm and hits the ends as I move the frog back and forth. I can reposition the front bearing and somewhat improve it, but then the back one starts to drift, and then if I adjust the back one, the front one drifts. Any tips? Thanks! Thanos https://reprap.org/forum/read.php?4,180949,180949#msg-180949 Mon, 14 Sep 2026 16:25:16 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,180949,186746#msg-186746 https://reprap.org/forum/read.php?4,180949,186746#msg-186746 That improved the situation a lot as my whole metal structure is now perfectly square/parallel (even though the plastic feet do no seem aligned, but this is not important if the metal is ok, as it is what support the whole stuff)
I have also bought 2 more LM8UU bearings to enlarge the area where the belts goes and allow more variance while avoiding it to touch any border.
I bought GT2 belts and associated GT2 alluminium pulleys as well from there (France):
[www.reprap-france.com]
[www.reprap-france.com]
Now my Y axis is just fine. Let's start the X axis corrections now :)
See some pictures on the result of this part in this message.]]> rs7k Reprappers Fri, 22 Feb 2013 06:44:09 -0500 https://reprap.org/forum/read.php?4,180949,186361#msg-186361 https://reprap.org/forum/read.php?4,180949,186361#msg-186361
Well at least thats what i did to my Z-axis, i am using XL belts over a distance and to prevent sagging, it has to be really tight, and aligning everything into straight and perpendiculars really takes some time, and i have to use flanged idlers to keep gravity from pulling them off rollers on the long run.

i also try to pull the belt in weird ways to see what will happen if there are any way the mechanisms will allow it to move into weird corners. poke, pull, roll it manually etc. imagine a belt it is not like a flat string, but the left edge is 1 rubber string and the right is another, both MUST have equal setting else they will just twirl all over.

the pic is the Z-axis frame i am fiddling with, and how 1 stepper will drive 2 threaded rods. its not very good btw lol my steppers are WEAK ! lol]]> redreprap Reprappers Wed, 20 Feb 2013 23:01:53 -0500 https://reprap.org/forum/read.php?4,180949,186359#msg-186359 https://reprap.org/forum/read.php?4,180949,186359#msg-186359 this picture, note the darker dots between the teeth that go laterally from one side to the other - on my belt they don't go all the way to one side as do from the other - in other words, it's not simmetrical. So I tried to reverse the belt and I got some improvement - now, different from before, my belt drifts more one the side of the motor, and stays somewhat ok on the other bearing. Then I rotated the pulley, so that it's wider part is away from the motor. This way it can constraints more gently the belt to stay straight. The belt still drifts on the motor-side bearing a good 2 mm, but after much frustration I decided to consider this a modest success.]]> DRepBRo Reprappers Wed, 20 Feb 2013 22:46:21 -0500 https://reprap.org/forum/read.php?4,180949,186352#msg-186352 https://reprap.org/forum/read.php?4,180949,186352#msg-186352 DRepBRo Reprappers Wed, 20 Feb 2013 20:52:46 -0500 https://reprap.org/forum/read.php?4,180949,185347#msg-185347 https://reprap.org/forum/read.php?4,180949,185347#msg-185347 self-centering crowned pulley as well.
It needs to be printed with precision to get the crown even, and if you have a serious underlying problem it might not help that much.

I've tried it on my X-axis, and even though my print wasn't perfect, the belt has yet to slip off with no washers (fingers crossed).

/Andreas]]> anwe79 Reprappers Sun, 17 Feb 2013 08:03:20 -0500 https://reprap.org/forum/read.php?4,180949,185304#msg-185304 https://reprap.org/forum/read.php?4,180949,185304#msg-185304 smartroad Reprappers Sun, 17 Feb 2013 04:06:38 -0500 https://reprap.org/forum/read.php?4,180949,184299#msg-184299 https://reprap.org/forum/read.php?4,180949,184299#msg-184299
For the X axis, the small adjusters that bear against the end of the smooth rods can be used to adjust the bracket so the bearing is at the correct angle.

For the Y axis you must first accurately line the bearings up with the clamp (which should sort the front bearing) and then the motor bracket can be adjusted by moving one side along the same axis as the belt to make it perpendicular to the belt.

Tension in the belts should be moderate - they should twang a bit when plucked but at a fairly low frequency (double bass rather than violin).

The weakness of this design is the need to align lots of parts but if you take your time and get everything as square as possible it will work well.]]> MarkMarsh Reprappers Wed, 13 Feb 2013 06:06:55 -0500 https://reprap.org/forum/read.php?4,180949,184204#msg-184204 https://reprap.org/forum/read.php?4,180949,184204#msg-184204
It is important that you bear in mind that once set up correctly the belt will run true, it can be done.

My X-Axis worked fine .. I conclude that i was lucky.

My Y-Axis has been bad, then great then bad again. My approach was to move the stepper motor mount backwards and forwards by a minute amount in order to get it running true and then make adjustments on the other side very carefully until ir runs within the limits set by the big washers.

In the end I just started printing a 80mm x 80mm bracelet and adjusted as I went along. This messed up the print but I was able to move the non motor side until it started to run true.]]> Splashy Reprappers Tue, 12 Feb 2013 18:36:56 -0500 https://reprap.org/forum/read.php?4,180949,183920#msg-183920 https://reprap.org/forum/read.php?4,180949,183920#msg-183920 sbliven Reprappers Mon, 11 Feb 2013 16:56:57 -0500 https://reprap.org/forum/read.php?4,180949,183840#msg-183840 https://reprap.org/forum/read.php?4,180949,183840#msg-183840 www.thingiverse.com]]]> NumberSix Reprappers Mon, 11 Feb 2013 10:26:47 -0500 https://reprap.org/forum/read.php?4,180949,183830#msg-183830 https://reprap.org/forum/read.php?4,180949,183830#msg-183830 thanos Reprappers Mon, 11 Feb 2013 09:41:50 -0500 https://reprap.org/forum/read.php?4,180949,183695#msg-183695 https://reprap.org/forum/read.php?4,180949,183695#msg-183695
The motor bracket can sometimes have the motor axle out of parallel to the threaded rod and cause the belt to ride left or right. You might have to move the lower clamping point of the motor mount to change the angle of the motor axle.]]> NumberSix Reprappers Sun, 10 Feb 2013 18:32:09 -0500 https://reprap.org/forum/read.php?4,180949,183690#msg-183690 https://reprap.org/forum/read.php?4,180949,183690#msg-183690 thanos Reprappers Sun, 10 Feb 2013 17:58:06 -0500 https://reprap.org/forum/read.php?4,180949,183689#msg-183689 https://reprap.org/forum/read.php?4,180949,183689#msg-183689 Do you have large washers (fender washers) on the outside of you idler bearings? Is your problem that the belt is drifting too much and rubbing against your washers, or is it just running off the bearing because there's no washers?

I would advise against the printed Idler unless you have extremely good print quality, as a printed idler will just introduce print quality issues. There is another post here from someone that was having print quality issues due to printed idlers. You might take a read through that.

Regards,
NumberSix]]> NumberSix Reprappers Sun, 10 Feb 2013 17:56:14 -0500 https://reprap.org/forum/read.php?4,180949,182237#msg-182237 https://reprap.org/forum/read.php?4,180949,182237#msg-182237
I think my plan is to tune it as best I can, and then print me one of these (http://www.thingiverse.com/thing:38753) as suggested by an earlier poster...

Thanos]]> thanos Reprappers Tue, 05 Feb 2013 12:57:36 -0500 https://reprap.org/forum/read.php?4,180949,182207#msg-182207 https://reprap.org/forum/read.php?4,180949,182207#msg-182207
I'm in the process of buiding my ReprapPro Mendel too, and I face the very same issue.
Thanks for the advices, I'll try some of them further and let you know.
Thanos, if you find the trick I'd be very interested to know it :)

Thanks.]]> rs7k Reprappers Tue, 05 Feb 2013 11:13:51 -0500 https://reprap.org/forum/read.php?4,180949,181214#msg-181214 https://reprap.org/forum/read.php?4,180949,181214#msg-181214 xclusive585 Reprappers Fri, 01 Feb 2013 14:16:06 -0500 https://reprap.org/forum/read.php?4,180949,181191#msg-181191 https://reprap.org/forum/read.php?4,180949,181191#msg-181191 thanos Reprappers Fri, 01 Feb 2013 12:45:41 -0500 https://reprap.org/forum/read.php?4,180949,181188#msg-181188 https://reprap.org/forum/read.php?4,180949,181188#msg-181188 PeteD Reprappers Fri, 01 Feb 2013 12:39:58 -0500 https://reprap.org/forum/read.php?4,180949,181185#msg-181185 https://reprap.org/forum/read.php?4,180949,181185#msg-181185 thanos Reprappers Fri, 01 Feb 2013 12:16:12 -0500 https://reprap.org/forum/read.php?4,180949,181184#msg-181184 https://reprap.org/forum/read.php?4,180949,181184#msg-181184 PeteD Reprappers Fri, 01 Feb 2013 12:14:56 -0500 https://reprap.org/forum/read.php?4,180949,181182#msg-181182 https://reprap.org/forum/read.php?4,180949,181182#msg-181182 thanos Reprappers Fri, 01 Feb 2013 12:08:55 -0500 https://reprap.org/forum/read.php?4,180949,181181#msg-181181 https://reprap.org/forum/read.php?4,180949,181181#msg-181181 PeteD Reprappers Fri, 01 Feb 2013 12:06:43 -0500 https://reprap.org/forum/read.php?4,180949,181123#msg-181123 https://reprap.org/forum/read.php?4,180949,181123#msg-181123 -------------------------------------------------------
> That's kind of what I was wondering, since I have
> lined up everything very carefully to within less
> than mm tolerances, and I cannot even get this to
> be remotely stable on the bearings. Hmmm....

I've not even started to commission my machine yet and I'm already worried about it LOL]]> KevinBennett126 Reprappers Fri, 01 Feb 2013 09:17:05 -0500 https://reprap.org/forum/read.php?4,180949,181122#msg-181122 https://reprap.org/forum/read.php?4,180949,181122#msg-181122 thanos Reprappers Fri, 01 Feb 2013 09:14:48 -0500 https://reprap.org/forum/read.php?4,180949,181121#msg-181121 https://reprap.org/forum/read.php?4,180949,181121#msg-181121 Most designs I've seen have the same type of bearings ... surely they don't all have a problem?

Kevin.]]> KevinBennett126 Reprappers Fri, 01 Feb 2013 09:12:26 -0500 https://reprap.org/forum/read.php?4,180949,181012#msg-181012 https://reprap.org/forum/read.php?4,180949,181012#msg-181012
[www.thingiverse.com]

[www.thingiverse.com]]]> waitaki Reprappers Fri, 01 Feb 2013 01:33:54 -0500 https://reprap.org/forum/read.php?4,180949,181000#msg-181000 https://reprap.org/forum/read.php?4,180949,181000#msg-181000 redreprap Reprappers Fri, 01 Feb 2013 00:12:25 -0500 https://reprap.org/forum/read.php?4,180949,180949#msg-180949 https://reprap.org/forum/read.php?4,180949,180949#msg-180949
I am having an issue where I cannot get the y-axis belt to not drift left and right (RepRapPro Mendel). I've lined up the bearings as precisely as I can, made sure everything is nice and square, but it still continues to drift several mm and hits the ends as I move the frog back and forth.

I can reposition the front bearing and somewhat improve it, but then the back one starts to drift, and then if I adjust the back one, the front one drifts.

Any tips?

Thanks!

Thanos]]> thanos Reprappers Thu, 31 Jan 2013 18:13:46 -0500