1 Topic by Connor.Nation

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Topic: Grinding After Adjusting Y-Axis Belts...

Hi all,

Looking for some more help. I was having troubles with my SD3 printing correctly shaped circles, I was getting oblong circles with flat spots and sharp edges. I leveled the bed numerous times, and still ran into the same problem. I took the suggestion of adjusting the Y-Axis Belt, and found that my front right mount for the belt had broken. I fixed the piece and it holds exactly as it should now.

However, I am now getting a grinding noise. I unloosened my belts and found that it hasn't helped. When I move my motor in the -Y direction (towards me) I will get some skipping, or grinding from the machine. When I move it to +Y (home) there is no noise at all.

I undid my tension in the belts, and still the noise occurred, but less frequent, and now my circles are back to being oblong again. I can't seem to win.

Anyone have any suggestions on how I can remove this noise, and also get better looking circles?

2 Reply by wardjr

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Re: Grinding After Adjusting Y-Axis Belts...

So this is an alignment issue of the y belt.  Tighten them equally and fairly tight.  Then loosen the right rear drive pulleys set screw.  Now move (using both hands) the gantry back and forth several times stopping in the middle when you feel it is in a nice neutral position.  Then tighten the set screw without rotating the pulley.

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3 Reply by pirvan

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Re: Grinding After Adjusting Y-Axis Belts...

I had the same problems you had with oblongcircles, and while some people got rid of this problem by going the direct drive route, I did it a little different.

Check this link out, and see if it helps you.

http://www.soliforum.com/topic/8357/y-s … belt-slop/

To print or, 3D print, that is the question...
SD3 printer w/too many mods,  Printrbot Simple Maker Ed.,  FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.

4 Reply by knowack

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Re: Grinding After Adjusting Y-Axis Belts...

Can you localize the source of the grinding noise?  (motor, bearing, etc.)

I've got my SD4 pretty snug, with very good circles, and have not encountered grinding noises.  I'm sure we can figure it out.

-Kevin

5 Reply by jagowilson (edited by jagowilson 2016-06-08 16:06:39)

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Re: Grinding After Adjusting Y-Axis Belts...

pirvan wrote:

I had the same problems you had with oblongcircles, and while some people got rid of this problem by going the direct drive route, I did it a little different.

Check this link out, and see if it helps you.

http://www.soliforum.com/topic/8357/y-s … belt-slop/

On the circle issue... After about a year of not having this problem and doing a lot of research on belts, it makes sense to me why this works now.

The best solution, in my opinion, is two fold:
1. Replace all belts with GT-2
2. Drive the back rod directly with a well-aligned motor and coupler.

If you skip step 2, you should still get reliable Y axis behavior (no circle dents) with an equivalent closed-loop GT2 belt.

The fundamental issue is that MXL belts have a tooth profile that is not suited to precise linear motion. The tooth design inherently has quite a bit of slop, and the belts can also stretch under too much tension, deforming the tooth profile and causing more severe backlash. The stretchability of the belt also causes far more friction and noise than a belt like GT2. The MXL belts have these properties, though, because the belts were originally intended for rotational timing in one direction, so slop didn't matter.

The saving grace of MXL is that it's probably the cheapest timing belt out there. You can get massive rolls and massive closed-loop belts for next to nothing. In a rotational (non-linear) setting the backlash is knowable and can be accounted for easily. Now, I'm not sure what the load limit is on an MXL belt, but I think Solidoodle tried to get way more out of them than they're rated for.

6 Reply by pirvan

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Re: Grinding After Adjusting Y-Axis Belts...

I agree that the GT2 belts are sturdier and maybe they have less backlash than the MXL, but the tensioner mod was done when I still had the MXL belts, and it solved the flattened circle problem.

I have since replaced all my belts with GT2, but that didn't really improve the quality any further, it just made it easier to calculate the steps.  FWIW, I still have the tensioner mod on the Y drive , even with the new GT2 belts., and I still get nice circles.

One advantage to the mod I posted is that it can be done for only the cost of a 608ZZ bearing (about $2), a spring and some printed plastic parts.  In all about 10-15 minutes of work.  That's a lot less work compared to direct drive method.

To print or, 3D print, that is the question...
SD3 printer w/too many mods,  Printrbot Simple Maker Ed.,  FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.

7 Reply by jagowilson

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Re: Grinding After Adjusting Y-Axis Belts...

If I put any more effort into my SD4 aside from basic things like sealing the enclosure better, I plan to upgrade it to mdrVB6's CoreXY carriage system.

8 Reply by Connor.Nation (edited by Connor.Nation 2016-06-16 17:45:55)

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Re: Grinding After Adjusting Y-Axis Belts...

Thanks all for the help, sorry I've been absent.

I solved the grinding noises in my belts, it looks like it could have been an off-center issue when I was adjusting tension, or, something dealing with the tension.

However, I am now back to square 1, where I am getting oblong circles. Although now, I have narrowed them down to only happening in the top left and bottom right hand corners of the pieces (if you are looking directly down on the print bed). I've attached a photo to show, the S is also printed using Lakeview font, it should be curvy, but not that "wonky" looking. I can adjust the font, but the outer edge still shows a hiccup in those areas no matter what size I print at.
http://soliforum.com/i/?aCZbOrx.jpg

Thank you guys for being on here. I am learning a lot, I've already have many successful prints and can get a great print as long as it doesn't deal with any sort of circular shape on the base.

9 Reply by Connor.Nation

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Re: Grinding After Adjusting Y-Axis Belts...

I am currently going back to belt tensioning.... following forum here:
http://www.soliforum.com/topic/9064/cir … vincis-10/

Will update if I find the solution in mine, I had a cracked connection, I reprinted something to make it work though.