Circles not coming out Circles I recently printed the Simple Spool Hub from Thingiverse.com and noticed that my circles aren't coming out perfectly circular; they come out egg-shaped to some degree. It's probably hard to tell in the attached picture. Does anyone have any suggestions as to how to fix the non-circle circles? I'm printing with PLA and am using skeinforge. Thanks, Chad C https://reprap.org/forum/read.php?151,71788,71788#msg-71788 Wed, 16 Sep 2026 02:26:51 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?151,71788,172739#msg-172739 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,172739#msg-172739
>tightening belts: helpped a bit
>re-installing the hotend: had a decent effect
>raising the y belt to avoid friction: worked miracles]]> knarf2012 General Mendel Topics Sat, 22 Dec 2012 22:57:36 -0500 https://reprap.org/forum/read.php?151,71788,107937#msg-107937 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,107937#msg-107937 -------------------------------------------------------
> - Put small 'guides' on my washers so that the
> belt run's in the center of the bearings, so its
> not rubbing towards the borders.

Are your guides fixed or free to rotate? If they are fixed I would suggest the belt is dragging/rubbing enough to introduce lash. I couldn't print bearing guides like [www.thingiverse.com] and you probably won't be able to make accurate ones either, as you need to be able to print smooth, accurate, round circles, or it will introduce other problems. I did this: [forums.reprap.org] As suggested in that thread, you could also try using two bearings instead of one. Remember to make sure both Y- AND X-axis belts are not binding!]]> droftarts General Mendel Topics Sun, 27 Nov 2011 13:36:24 -0500 https://reprap.org/forum/read.php?151,71788,107585#msg-107585 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,107585#msg-107585 My eSteps where correctly configured (so i thought) but i saw that X has a value of 80.6something en Y had 79.8something... That is not possible because the belts are the same... the pulleys came from the same machine and there is (nearly) no backlash... So i set them to the same value...and presto! got circles again :)]]> Bramboterham General Mendel Topics Thu, 24 Nov 2011 14:09:40 -0500 https://reprap.org/forum/read.php?151,71788,107574#msg-107574 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,107574#msg-107574 korgon General Mendel Topics Thu, 24 Nov 2011 12:48:06 -0500 https://reprap.org/forum/read.php?151,71788,107412#msg-107412 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,107412#msg-107412
My circles are pretty good but there not circles, they kinda oval (lemon shaped) i have made a test piece to show it:



As you can see here, the 'ovals' are tilted slightly to the top left corner.

These things i have tried to fix my problem:
- Removed the backlash witth belt-tensioners ( like this: [i51.tinypic.com])
- Made sure that the motors had enough current (pololu drivers)
- Lubricated my axes.
- Put small 'guides' on my washers so that the belt run's in the center of the bearings, so its not rubbing towards the borders.
- Calibrated my firmware, on small sizes they are dead on (0.02 ish diverence) and on lager objects like .20 to .40mm
- Used commerical printed pulleys for my X, Y axes (and extruder) High infill and really nice quality.

Has anybody an idea what i'm doing wrong? Or what i should do to elaminate the 'lemon like circles' problem? ;)
]]> Bramboterham General Mendel Topics Wed, 23 Nov 2011 11:42:04 -0500 https://reprap.org/forum/read.php?151,71788,106979#msg-106979 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,106979#msg-106979 -------------------------------------------------------
> Ok, so long story short, my problem was indeed due
> to friction of the belt and the large penny
> washers meant to keep the belt in line. There was
> so much rubbing that the penny washers had been
> worn on those sections. In order to fix the
> problem I used longer bolts and placed another 624
> bearing under the first. I did this on all four
> of the x-axis belt guides and also on two of the
> y-axis belt guides on the non-motor side. Thank
> you nophead for your contribution to this project
> and your support on these forums!

Look at my post on the first page ;)...4th Post ;)]]> Vollnormal General Mendel Topics Sun, 20 Nov 2011 06:05:00 -0500 https://reprap.org/forum/read.php?151,71788,106241#msg-106241 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,106241#msg-106241 >
> [farm6.static.flickr.com]
> d29b09a.jpg
>
> I wish hardware developers can make a machine that
> people as us can assembly and don't have this
> problems, rendering useless the investment made.

I had a similar problem where the circles comes out flat on Y axis similar to your pic.

Solved the problem: the Y carriage was binding at both ends. It moves smoothly in the center area area but the binds near Y = 0 and Y=200. To confirm, I turned off the motors and move the bed with my fingers. And the bed will not zero; moves smoothly in center; will not move to the end.

I solved the issue by realigning the Y smooth rods so that they are parallel horizontally and vertically. Adjusted the bed spring as well so that the smooth rod remains parallel.]]> fteo88 General Mendel Topics Tue, 15 Nov 2011 01:49:30 -0500 https://reprap.org/forum/read.php?151,71788,104964#msg-104964 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104964#msg-104964 nophead General Mendel Topics Sun, 06 Nov 2011 15:43:55 -0500 https://reprap.org/forum/read.php?151,71788,104953#msg-104953 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104953#msg-104953 raldrich General Mendel Topics Sun, 06 Nov 2011 14:30:38 -0500 https://reprap.org/forum/read.php?151,71788,104859#msg-104859 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104859#msg-104859 korgon General Mendel Topics Sat, 05 Nov 2011 14:44:46 -0400 https://reprap.org/forum/read.php?151,71788,104731#msg-104731 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104731#msg-104731 -------------------------------------------------------
...
> I have been unable to find off the shelf pulleys
> with the correct tooth profile and 5mm bore. I can
> get 10 tooth T5 and 16 tooth T2.5 but they need
> drilling and reaming on a lathe and then tapping
> for the set screw.

This is how I wound up using GT2 belts and pulleys from SDP/SI. 5mm bore and a smaller pitch diameter than I can get with the usual belts (T5, etc.).]]> Dale Dunn General Mendel Topics Fri, 04 Nov 2011 09:07:06 -0400 https://reprap.org/forum/read.php?151,71788,104719#msg-104719 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104719#msg-104719 nophead General Mendel Topics Fri, 04 Nov 2011 08:15:53 -0400 https://reprap.org/forum/read.php?151,71788,104710#msg-104710 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104710#msg-104710 -------------------------------------------------------
> How did you generate that circular infill? Are
> they definitely supposed to be true circles?

Yes, I can see true round circles on SFACT!! Skeinforge have that option for infill since a few versions ago! did you missed it? :-)]]> casainho General Mendel Topics Fri, 04 Nov 2011 07:17:25 -0400 https://reprap.org/forum/read.php?151,71788,104709#msg-104709 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104709#msg-104709 nophead General Mendel Topics Fri, 04 Nov 2011 07:13:45 -0400 https://reprap.org/forum/read.php?151,71788,104707#msg-104707 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104707#msg-104707 -------------------------------------------------------
> I am using the first X motor bracket and yesterday
> my X axis belt just broke! the metal wires broke!
> Maybe it was due to me driving RepRap at 725mm/s
> for testing R2C2.
>
> No the first x bracket will break the belt after
> printing 4 Mendels ( ~ 200 hours) at moderate
> speeds. With the improved X bracket I have not had
> a belt snap.

For now I am back to the belt without metal wires. It will not break and at least the not round circles seems to not be related to that belt.


> If you have the metal pulleys from Hong Kong

I am sorry, I thought "pulleys" meaning the "bearing". I want to sat my bearings were from Ebay/China. Don't know if bearings have any role on this problem or not.

I just recorded a video printing a part with infill made with circles. It's visible this problem: [blip.tv]]]> casainho General Mendel Topics Fri, 04 Nov 2011 07:02:57 -0400 https://reprap.org/forum/read.php?151,71788,104691#msg-104691 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104691#msg-104691
Quote

I am using the first X motor bracket and yesterday my X axis belt just broke! the metal wires broke! Maybe it was due to me driving RepRap at 725mm/s for testing R2C2.

No the first x bracket will break the belt after printing 4 Mendels ( ~ 200 hours) at moderate speeds. With the improved X bracket I have not had a belt snap.

If you have the metal pulleys from Hong Kong [www.ebay.co.uk] try holding the pulley in one hand and sliding the belt in the other. It moves a significant fraction of a millimetre because the teeth of the pulley are a lot thinner than the gaps in the belt. Also the holes are not well centred.

I found this type: [www.ebay.co.uk] from Bulgaria doesn't give backlash. The teeth are not the right profile, the valleys between them are semicircles, but the belt teeth wedge into them in a way that does not slip. Out of three though, two had badly centred holes.

I have been unable to find off the shelf pulleys with the correct tooth profile and 5mm bore. I can get 10 tooth T5 and 16 tooth T2.5 but they need drilling and reaming on a lathe and then tapping for the set screw.]]> nophead General Mendel Topics Fri, 04 Nov 2011 05:19:44 -0400 https://reprap.org/forum/read.php?151,71788,104647#msg-104647 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104647#msg-104647 -------------------------------------------------------
> My experience is:
> -alternative X motor bracket design don't give
> enouth attachment between belt and pulley
> -first X motor bracket design is said to brake the
> belt after some printing time

I am using the first X motor bracket and yesterday my X axis belt just broke! the metal wires broke! Maybe it was due to me driving RepRap at 725mm/s for testing R2C2.


> -if we often have the same belts, we don't often
> have the same pulleys, and there often is backlash
> between belt and pulley (various backlashs for all
> of us)

Until now I used 2 types of belts, one with metal wires and other without them. I am getting the not rounded circles with both. Hey, but my pulleys were cheap from Ebay/China!!! I hope to exchange the pulleys... thanks for the tip.]]> casainho General Mendel Topics Thu, 03 Nov 2011 19:22:19 -0400 https://reprap.org/forum/read.php?151,71788,104642#msg-104642 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104642#msg-104642 korgon General Mendel Topics Thu, 03 Nov 2011 18:27:38 -0400 https://reprap.org/forum/read.php?151,71788,104622#msg-104622 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104622#msg-104622 -alternative X motor bracket design don't give enouth attachment between belt and pulley
-first X motor bracket design is said to brake the belt after some printing time
-if we often have the same belts, we don't often have the same pulleys, and there often is backlash between belt and pulley (various backlashs for all of us)

So:
-I added 2 bearings to the alternative X motor bracket (photo into my August 09 post, those bearings are fixed with 2 of the motor's screws) to get a better belt/pulley attachment, without the too complex belt circulation of the first X motor bracket design
-and I modified firmware to get squares or circles correctly printed, for me (just for me! ;)):

#define X_STEPS_PER_MM 9.842
#define Y_STEPS_PER_MM 10.047]]> François Delègue General Mendel Topics Thu, 03 Nov 2011 16:16:43 -0400 https://reprap.org/forum/read.php?151,71788,104532#msg-104532 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104532#msg-104532 nophead General Mendel Topics Thu, 03 Nov 2011 05:51:19 -0400 https://reprap.org/forum/read.php?151,71788,104530#msg-104530 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104530#msg-104530
I had this problem on my Prusa and it was due to too much friction of the belt against the 608 pulleys. A 608 bearing is 7mm wide with a significant chamfer and M8 washers are 1.5mm thick so the belt rides over the side of the pulley and rubs against the penny washer.

I find the Mendel idler pulleys with the smaller bearings and washers work much better but the instructions are for 5mm belts made with the belt splitter. If you have 6mm you need an extra washer. Also you need to put the penny washers the right way up. They generally have a chamfer on one side and a burr on the other due to being pressed. The smooth side must be towards the belt. Similarly the smaller washers should have the smooth side towards the bearing.]]> nophead General Mendel Topics Thu, 03 Nov 2011 05:33:53 -0400 https://reprap.org/forum/read.php?151,71788,104515#msg-104515 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104515#msg-104515 -------------------------------------------------------
> I have been trying to fix this problem on my
> mendel. I've tried so many things... Still
> cannot seem to find the problem. I just replaced
> the pulleys with better quality ones, I have
> tightened, loosened, changed steps per mm, and
> printed one to many test parts. I also am using
> ultimachine belts, alternate x-axis and ramps 1.2
> w/marlin.
>
> This is driving me crazy. Anyone have any insight
> into this?

I am being printing a lot and changing my Mendel also, now I have much better firmware, changed the belts, better pulleys but still nothing!]]> casainho General Mendel Topics Thu, 03 Nov 2011 04:02:41 -0400 https://reprap.org/forum/read.php?151,71788,104504#msg-104504 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,104504#msg-104504
This is driving me crazy. Anyone have any insight into this?]]> korgon General Mendel Topics Wed, 02 Nov 2011 23:58:51 -0400 https://reprap.org/forum/read.php?151,71788,97116#msg-97116 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,97116#msg-97116
So I suppose now that the problem was coming from the size of the teeth of the pulley, which are only 1.7mm width: it is not very much, and it's not a problem if the belt turns enouth around the pulley.]]> François Delègue General Mendel Topics Thu, 08 Sep 2011 08:42:36 -0400 https://reprap.org/forum/read.php?151,71788,93524#msg-93524 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,93524#msg-93524
Belt from Ultimachine and pulleys profi-printed from Mendel-parts.com.

Reading all your posts: perhaps the problem was coming from a too little belt/pulley hanging into the alternative x-bracket,, not from the side of the belt. Perhaps adding 2 bearings, fixed with 2 of the motor screws, would fix that (see attachment). I'll mount int one day and tell you the result!]]> François Delègue General Mendel Topics Tue, 09 Aug 2011 08:02:15 -0400 https://reprap.org/forum/read.php?151,71788,93010#msg-93010 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,93010#msg-93010 Replaced the pulley with a new XL pulley and no more problems.

ST]]> stefanst General Mendel Topics Thu, 04 Aug 2011 10:29:20 -0400 https://reprap.org/forum/read.php?151,71788,92577#msg-92577 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,92577#msg-92577 brupje General Mendel Topics Mon, 01 Aug 2011 05:57:36 -0400 https://reprap.org/forum/read.php?151,71788,92521#msg-92521 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,92521#msg-92521
I think it must either be due to belt tension, or perhaps the type of belt. Perhaps the teeth are more rigid on some, while others deform. I trust you have a proper timing belt with steel or kevlar wires in it and not simply a toothed rubber belt?]]> nophead General Mendel Topics Sun, 31 Jul 2011 12:41:41 -0400 https://reprap.org/forum/read.php?151,71788,92451#msg-92451 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,92451#msg-92451
Of course I prefer a working reprap with a belt to change sometimes than a non-working one…

If someone else can solve the same problem with the same solution, shall we say it's a strong solution!

PS: the belt on the Y axe also runs around a bearing, but with a 180° angle (something like 3/4 of the bearing circumference) so the "full and empty" belt effect is less, or not, sensitive.]]> François Delègue General Mendel Topics Sat, 30 Jul 2011 13:53:11 -0400 https://reprap.org/forum/read.php?151,71788,92442#msg-92442 Re: Circles not coming out Circles https://reprap.org/forum/read.php?151,71788,92442#msg-92442
I use that bracket and my holes come out round. With the old bracket the belt snaps after 200 hours of use.]]> nophead General Mendel Topics Sat, 30 Jul 2011 11:47:19 -0400