Author Topic: Backlash?  (Read 1152 times)

jhferguson

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Backlash?
« on: December 04, 2018, 03:16:54 PM »
I posted on here a while back and found that I was experiencing backlash. While I didn't resolve the issue I was able to get the image to look better and less pixelated by tightening my X axis and replacing my belt tensioners with these.

https://www.thingiverse.com/thing:2799028

But as you can see in this picture I am still getting a pixelated looking image.

nottingham82

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Re: Backlash?
« Reply #1 on: December 04, 2018, 03:19:55 PM »
I posted on here a while back and found that I was experiencing backlash. While I didn't resolve the issue I was able to get the image to look better and less pixelated by tightening my X axis and replacing my belt tensioners with these.

https://www.thingiverse.com/thing:2799028

But as you can see in this picture I am still getting a pixelated looking image.
Most likely it is the resolution of image. If you post the original file I might be able to help.

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Laser: 2500mw A5 eleks maker
OS: Windows 10 all in one pc
Software: T2
http://www.gearbest.com/3d-printers-3d-printer-kits/pp_290386.html Paid $160 in 2016

jhferguson

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Re: Backlash?
« Reply #2 on: December 04, 2018, 03:21:01 PM »
This is what I get with Bi-Directional turned off. And honestly the picture doesn't even do it justice. I would like to get this quality every time but turning off Bi-directional doubles my time and this small 75mm image takes 20 minutes already.

Also, I have this on order https://www.thingiverse.com/thing:2767575 but is there something that I am doing wrong? I feel like my laser should be able to put out quality like this without all of the extras. Is that just wishful thinking?
« Last Edit: December 04, 2018, 03:22:24 PM by jhferguson »

jhferguson

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Re: Backlash?
« Reply #3 on: December 04, 2018, 03:24:44 PM »
Most likely it is the resolution of image. If you post the original file I might be able to help.

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Definitely not the resolution as both images that I uploaded were burn from the same image only Bi-directional being turned off in-between.

nottingham82

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Re: Backlash?
« Reply #4 on: December 04, 2018, 03:28:06 PM »
Definitely not the resolution as both images that I uploaded were burn from the same image only Bi-directional being turned off in-between.
Yeah my next suggestion was the x axis tension adjuster. If it only happens with bi directional on then Its an x axis issue


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Laser: 2500mw A5 eleks maker
OS: Windows 10 all in one pc
Software: T2
http://www.gearbest.com/3d-printers-3d-printer-kits/pp_290386.html Paid $160 in 2016

jhferguson

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Re: Backlash?
« Reply #5 on: December 04, 2018, 03:46:14 PM »
Man it just doesn't seem like I can get the belt any tighter but it is on the way. Thank you for the confirmation.

nottingham82

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Re: Backlash?
« Reply #6 on: December 04, 2018, 03:54:55 PM »
Man it just doesn't seem like I can get the belt any tighter but it is on the way. Thank you for the confirmation.
The x axis tension adjuster isn't to fix belt tightness its about wheel tightness. The wheel holes can be too close together which causes the wheels to deform and adding extra resistance in certain spots. The 3d print allows you to adjust wheel tension. Also while you wait for the 3d print you can check the stepper motor voltage

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Laser: 2500mw A5 eleks maker
OS: Windows 10 all in one pc
Software: T2
http://www.gearbest.com/3d-printers-3d-printer-kits/pp_290386.html Paid $160 in 2016

jhferguson

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Re: Backlash?
« Reply #7 on: December 04, 2018, 04:05:18 PM »
What should the stepper motor voltage sit at?

Zax

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Re: Backlash?
« Reply #8 on: December 04, 2018, 04:43:10 PM »
Since disabling bi-directional solves the problem it isn't a motor issue (or a controller or driver for that matter). Backlash is purely a mechanical issue.

It can be caused by slop in the gears, a loose belt or belt stretching. Since the belts are tight, maybe check the other options.

Is the pinion gear tight on the motor shaft?

Have you tested using reduced acceleration with bi-directional enabled? (this reduces belt stretch, which should be an issue but perhaps you got a bad batch)

Don't give up, you're really close - that 2nd picture looks amazing so that tells me the machine is otherwise well adjusted.

jhferguson

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Re: Backlash?
« Reply #9 on: December 05, 2018, 04:39:24 AM »
Zax,

I checked the pinion gear and made sure it was snug and tried reduced acceleration with bi-directional enabled and the output was similar to the first picture. As for the belt, I was thinking something similar so when I replaced the belt tensioners I went ahead and replaced the belt as well. Do you have any other suggestions that I can try?

ggallant571

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Re: Backlash?
« Reply #10 on: December 05, 2018, 05:11:12 AM »
I think you need to work with simple patterns to verify the operating behavior. For backlash and bidirectional functions simple lines or nested shapes with known (2 pixel) line widths work best for me. See attached image. 0.2 mm lines with 0.8mm gap
« Last Edit: December 05, 2018, 06:21:05 AM by ggallant571 »
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ggallant571

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Re: Backlash?
« Reply #11 on: December 05, 2018, 06:22:27 AM »
There is an extra pixel in the image.
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jhferguson

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Re: Backlash?
« Reply #12 on: December 05, 2018, 06:11:22 PM »
Worked on it for a while tonight but just could get any better quality than when I turn off bi-directional. Itís not even worth posting more pics lol. Try again tomorrow.

Zax

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Re: Backlash?
« Reply #13 on: December 06, 2018, 04:38:22 AM »
Do you feel any play (loose movement) in the carriage, if you gently try to move the laser will it do anything without moving the belt / motor?

jhferguson

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Re: Backlash?
« Reply #14 on: December 06, 2018, 06:59:39 AM »
It seems pretty secure. I even removed the belt to make sure it wasnít wobbly. I did notice though before I went to bed that the bolts that hold the wheels are not level. I am probaly going to take the x axis apart when I get home today and rebuild it now that I know what to look out for. I may wait for the tensioner to arrive tomorrow.