Rostock Max servo chatter.

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Cobraphx
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Rostock Max servo chatter.

Post by Cobraphx »

I completed assembly of my Rostock Max yesterday. Worked through the little issues like installing the wrong servo on one axis. Updated the firmware to get the axis all moving in the correct direction on G28 home. Several times I've had chattering one one drive axis or another. Each time reseating pins in the connector for that servo, or powering everything on or off has cleared the issue.

I now have a constant chatter of the X axis motor. Just vibrates when a move is issued. My servo connectors are wired Red-Blue-Green-Black. I've loosened the cheapskate, has less friction now than Y and Z no change. There is no extension on my wires. I swapped X and Y servos, the chattering stayed with the X servo, so I think Rambo is fine. I varied the e drive value from 175 to 205 (195 was the default), doesn't seem to be current related. Not sure what else to check. I'll take the connector apart again and see if there is some issue with my crimps. Is it possible my X servo failed? Seems unlikely, but I seem to have the wires, the connector or the servo as the possible culprits.

Thanks,
-Matt

Cobraphx
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Re: Rostock Max servo chatter.

Post by Cobraphx »

As an update, I clipped the end off the X axis motor and put new pins on that motor. As soon as I homed again, X was great, and the problem moved to the Z axis. Now Z is chattering every time I home. I'm now thinking that my Rambo board must be the problem. Seems that one axis is going to chatter, but it has moved to a different axis at least 4 times since I started trying to calibrate my machine,

barnett
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Re: Rostock Max servo chatter.

Post by barnett »

You may have already done this, but I'd try adjusting the belt tension.
Barnett

Polygonhell
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Re: Rostock Max servo chatter.

Post by Polygonhell »

Chattering motors are usually a sign that the motor drivers are going into thermal shutdown.
If this is the case, you can change the digipot values in configuration_adv.h, the default is 195, just turn them down.
I'm not recommending this, but I usually set them by measuring the temperature of the drivers after they've been running for a few minutes.
FWIW although mine didn't chatter, they did go into thermal shutdown after running for 10 minutes or so.
I suspect who ever set the default value, was either very aggressive, or has heat sinks on the drivers, or had an earlier rev of the Rambo board, since it looks like the digipot range was changed at some point.

geneb
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Re: Rostock Max servo chatter.

Post by geneb »

That's really odd. I've run my machine for 2+ hours and haven't noticed any thermal shutdown issues.

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Polygonhell
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Re: Rostock Max servo chatter.

Post by Polygonhell »

Could just be variation in the digipots or stepper drivers, or stepper motors, or ambient temperature etc.
Mine would run for a while and then start doing this thing where it would pause 2 or 3 times on the long homing move. It's a single move, so it has to be the drivers. They were also excessively hot, though they get burn yourself hot long before the thermal cutoff.

Cobraphx
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Re: Rostock Max servo chatter.

Post by Cobraphx »

I tried as low as 175 on the digipot values... How low should I try? I'll also check temps on the drivers while its homing, if its heat related that would explain why the issue keeps moving. Maybe I can fix the issue by installing heat sinks and a fan if necessary. I'll also try reducing the belt tension... I have them pretty snug.

Polygonhell
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Re: Rostock Max servo chatter.

Post by Polygonhell »

Cobraphx wrote:I tried as low as 175 on the digipot values... How low should I try? I'll also check temps on the drivers while its homing, if its heat related that would explain why the issue keeps moving. Maybe I can fix the issue by installing heat sinks and a fan if necessary. I'll also try reducing the belt tension... I have them pretty snug.


I dropped them to 130 to start with, with the intention of increasing them as necessary.
The traditional pots are extremely finicky as much as 1/16 of a turn can make them not work.

Cobraphx
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Re: Rostock Max servo chatter.

Post by Cobraphx »

Finally got everything working. It seems it was the connectors all along. Took apart the connectors and re-crimped several of the pins. When I assembled them, I made sure that the pins locked in place. The connector for the X axis had a wire that was working it's way out. Now everything works great. going through the calibration process now.

cbuddha
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Re: Rostock Max servo chatter.

Post by cbuddha »

2nd on the connectors.

Belt tension too

In a haste to get the thing running I twisted my extensions and did pin swaps. Each time I had chatter it was wiring. All extensions are soldered now. This even happened on the extruder, which I thought was jammed.

Of note: If you remove the belt (achieved by loosening the tension all the way and removing the belt off the pinon gear. Watching the motor - you will see it oscillate. One step to one direction then the reverse direction back and forth, back and forth

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