Author Topic: Backlash?  (Read 1153 times)

jhferguson

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Re: Backlash?
« Reply #15 on: December 08, 2018, 04:44:43 AM »
Well, I have tried, rebuilt, and replaced just about everything that I can think of and I still canít get it to look better with Bi-directional turned on.

I have tightened and loosened wheels, loosedned and tightened the belt just millimeters at a time, and ordered a bunch of extras off of thingiverse to straighten this out and I canít get it to look any better so I guess I will just burn one direction at a time lol.

If you all have any ideas I would love to hear them.
« Last Edit: December 08, 2018, 10:58:13 AM by jhferguson »

ggallant571

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Re: Backlash?
« Reply #16 on: December 08, 2018, 11:10:13 AM »
Do you have a local "Maker Space" where you might find people with similar equipment?
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Zax

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Re: Backlash?
« Reply #17 on: December 08, 2018, 01:38:05 PM »
It sounds like you have covered all the normal causes so let's consider what else it could be.

If your motor current is too high that may be a factor, or it could be some play in the motor itself.

Here's a crazy idea, load my 1.1e Axis Swap firmware from the custom menu. It's exactly the same as the default but the X and Y axis are swapped, so you would have to rotate your machine 90 degrees. The reason this isn't the norm is you have more mass to move so can actually get worse backlash (inertia is higher) but it's worth a try.

If it works, maybe you could swap one of the Y motors with the X and see if that helps or if you have a volt meter check the X driver is 0.3~0.4V.

jhferguson

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Re: Backlash?
« Reply #18 on: December 08, 2018, 01:41:28 PM »
Unfortunately no. When I tell folks that I have a laser in my garage, albeit a small diode laser, they act like I am crazy lol.

jhferguson

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Re: Backlash?
« Reply #19 on: December 08, 2018, 01:43:51 PM »
It sounds like you have covered all the normal causes so let's consider what else it could be.

If your motor current is too high that may be a factor, or it could be some play in the motor itself.

Here's a crazy idea, load my 1.1e Axis Swap firmware from the custom menu. It's exactly the same as the default but the X and Y axis are swapped, so you would have to rotate your machine 90 degrees. The reason this isn't the norm is you have more mass to move so can actually get worse backlash (inertia is higher) but it's worth a try.

If it works, maybe you could swap one of the Y motors with the X and see if that helps or if you have a volt meter check the X driver is 0.3~0.4V.

I actually have extra motors. Should I just replace it? Also, I have noticed some black dust from the belt on the pinion gear if that indicated anything in particular.

ggallant571

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Re: Backlash?
« Reply #20 on: December 08, 2018, 01:49:13 PM »
Just plug in a spare motor. Nothing else.
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jhferguson

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Re: Backlash?
« Reply #21 on: December 09, 2018, 04:40:04 PM »
Connecting a new motor didn't help and neither did swapping the axis with the firmware. Also, I currently have the motors sitting between 0.3 and 0.4v (0.32 and 0.36 to be exact) and it acts like that is not enough power to move the motors. It stutters and gets out of line and mostly just burns...lol

Any other ideas? Also, what firmware do I need to put it back on?

Zax

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Re: Backlash?
« Reply #22 on: December 10, 2018, 04:24:51 AM »
Only the X-axis should be 0.3~0.4VDC, the Y-axis would be ~0.6VDC.

If this is what you had and the motors were stuttering then there's a friction issue, which would also explain the backlash. With the belts disconnected you should be able to lift the side of the machine 2~3" and have the carriage slide over to the opposite side. It should be extremely free and not bind at any point. The same is true for the gantry front to back, in fact the extra mass usually means this moves with very little elevation.

Generally if the motors don't have enough torque (due to friction or poor current adjustment) you'll lose steps rather than see backlash, but it sounds like you are compensating with higher current which could lead to overheating of the drivers.

See if you can loosen the wheels without causing any slop, but get things moving freely. Then go back to the default firmware but after loading enable reduced acceleration and see if that helps (keep bi-directional enabled).

jhferguson

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Re: Backlash?
« Reply #23 on: December 10, 2018, 05:03:44 AM »
Is the default 1.1e? Listed as 1.1e(DEFAULT) in the menu lol dumb question I know but I was thinking folks were on 1.1f for some reason.

jhferguson

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Re: Backlash?
« Reply #24 on: December 10, 2018, 05:05:24 AM »
Only the X-axis should be 0.3~0.4VDC, the Y-axis would be ~0.6VDC.

Not sure what they were originally but both were higher than 0.3 - 0.4. I just set them to lower based on what I read here but mistakenly set the Y axis as well. I will change that this evening.

Zax

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Re: Backlash?
« Reply #25 on: December 10, 2018, 11:14:35 AM »
Yes, use the 1.1e Default that's in the Machine menu (not in the custom firmware menu).

jhferguson

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Re: Backlash?
« Reply #26 on: December 10, 2018, 04:25:05 PM »
Some of the nylon spacers are squished a little bit. Any recommendations on where I can buy some new ones? Or if someone can print some from Thingiverse I would gladly pay you for them. Figured I would check here before trying to order online and possibly getting the wrong size.

ggallant571

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Re: Backlash?
« Reply #27 on: December 10, 2018, 05:22:26 PM »
My A5 came with 2 different length nylon spacers. I did not pay attention and ended up with with a mismatch. Caused lots of problems on a Y-carriage wheel assembly.

About a year ago there was a discussion about replacing nylon with metal. Perhaps the author can comment.

My axles are slightly less than 5mm in diameter and the spacers appear to be standard US sizes. I bought some at the local hardware store.
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jhferguson

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Re: Backlash?
« Reply #28 on: December 10, 2018, 06:21:33 PM »
So I took everything apart. I oiled up the wheel bearings and did exactly as you said, at about 2-3 inches without the belt, each axis will slid easily to the other side. Everything seems well assembled, the voltages are 3.5 and 6.2. The stepper motor drivers donít feel hot anymore so thanks for that. With Bi-directional on and with reduced accelleration it looks like it loses steps as seen in the picture below.

With reduced accelleration off and everything else normal, it still looks pixelated. And I adjusted all belts millimeters at a time for hours. Iím done for the night.

ggallant571

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Re: Backlash?
« Reply #29 on: December 10, 2018, 07:44:05 PM »
Did you mean 0.35 & 0.62 volts measured at the pot? I have X,Y acceleration set at 5000.

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