Dynomotion

Group: DynoMotion Message: 12891 From: semperfikurt Date: 2/27/2016
Subject: Slaved Y Axis Missing steps/all screwed up

This problem was part of another thread on this group, but since parts of the original problem are solved I moved it here for the sake of clarity once it had been a bit better isolated.  


The problem I am having is that the slaved y axis steppers are missing steps and not working consistently.  I can jog all day and type in gcode commands and everything works perfectly, but when I run a program, the Y starts going crazy.  Sometimes it works, sometimes only one stepper works, sometimes they fight and rotate in opposing directions, sometimes it skips etc... It is a bit all over the place.  


At first this problem manifested after an hour or so of hard back-and-forth tool paths and I figured it might be that I was torture testing my motors so to speak and they were just at their stress/heat limits.  But after resolving that, they still skip, even minutes into starting a program, and far worse now than I have ever experienced with them.  


Attached is an image of my motion planner settings, step response configs, and the most recent program I tried running that made my machine lose it's mind!  

   @@attachment@@
Group: DynoMotion Message: 12892 From: Tom Kerekes Date: 2/27/2016
Subject: Re: Slaved Y Axis Missing steps/all screwed up [4 Attachments]
Hi Kurt,

I understand Axis 1 is your Y axis Master Axis. It doesn't have a Master so its Master Axis setting should be set to -1. You have it slaved to itself which may well be the problem. 

HTH
Regards
TK

On Feb 27, 2016, at 6:14 PM, semperfikurt@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

 

This problem was part of another thread on this group, but since parts of the original problem are solved I moved it here for the sake of clarity once it had been a bit better isolated.  


The problem I am having is that the slaved y axis steppers are missing steps and not working consistently.  I can jog all day and type in gcode commands and everything works perfectly, but when I run a program, the Y starts going crazy.  Sometimes it works, sometimes only one stepper works, sometimes they fight and rotate in opposing directions, sometimes it skips etc... It is a bit all over the place.  


At first this problem manifested after an hour or so of hard back-and-forth tool paths and I figured it might be that I was torture testing my motors so to speak and they were just at their stress/heat limits.  But after resolving that, they still skip, even minutes into starting a program, and far worse now than I have ever experienced with them.  


Attached is an image of my motion planner settings, step response configs, and the most recent program I tried running that made my machine lose it's mind!  
Group: DynoMotion Message: 12893 From: kurt huizenga Date: 2/27/2016
Subject: Re: Slaved Y Axis Missing steps/all screwed up [4 Attachments]
Ahh I totally didn't see that, that little fix made everything much smoother!  AWESOME! 

Something Else that I have been messing around with that I haven't been able to figure out is that all my non-orthogonal movements not being straight, they are wavy.  If I move in X or Y by themselves, the motion is straight as an arrow however, if I move diagonal or curved in any way, the line is wiggly.  That or the line is straight, but with a little bend at the end of it.  The images attached show it really well.  Ortho lines super straight and nice, anything else is wavy or with the bent end.  

I have tried the same drawing on multiple locations of the bed so I don't think it is a mechanical issue, also I looked at the steppers and can see them moving through the wiggly curves, no skipping or belt slippage.  

I also tried rotating the line geometry in RhinoCAM 180 degrees and regenerating the toolpath and that changed the location of the wiggly artifacts, but did not get rid of them.  I think motion direction has some kind of effect on it but I haven't sorted that entirely.

The the instances I have checked, the gcode does not show a curved line, but a straight motion from one point to the next.  Is there something within my configuration that might be causing this? 

Thanks! 


   @@attachment@@
Group: DynoMotion Message: 12895 From: Tom Kerekes Date: 2/28/2016
Subject: Re: Slaved Y Axis Missing steps/all screwed up [5 Attachments]
Hi Kurt,

Its hard to comment without knowing the scale of the images.  Or the Speed and directions of the paths.  Or anything about the rigidity of your system.

Can you measure the approximate peak-to-peak "waviness" in the paths?

I believe you have the Trajectory Planner Corner Tolerance set to 30 mils.  That might add significant rounding at corners but shouldn't cause waviness.  You might reduce this.

The obvious thing would be mechanical stiffness issues in your mechanical structure, drive train, or gantry.   For example if after a shock (due to acceleration) your gantry rocks back and forth (in Y ?) then as long as you are doing a horizontal line there won't be any noticeable issue (only feed rate variations along a straight line), but a diagonal line will show waves.

Regards
TK

On 2/27/2016 10:35 PM, kurt huizenga semperfikurt@... [DynoMotion] wrote:
 
Ahh I totally didn't see that, that little fix made everything much smoother!  AWESOME! 

Something Else that I have been messing around with that I haven't been able to figure out is that all my non-orthogonal movements not being straight, they are wavy.  If I move in X or Y by themselves, the motion is straight as an arrow however, if I move diagonal or curved in any way, the line is wiggly.  That or the line is straight, but with a little bend at the end of it.  The images attached show it really well.  Ortho lines super straight and nice, anything else is wavy or with the bent end.  

I have tried the same drawing on multiple locations of the bed so I don't think it is a mechanical issue, also I looked at the steppers and can see them moving through the wiggly curves, no skipping or belt slippage.  

I also tried rotating the line geometry in RhinoCAM 180 degrees and regenerating the toolpath and that changed the location of the wiggly artifacts, but did not get rid of them.  I think motion direction has some kind of effect on it but I haven't sorted that entirely.

The the instances I have checked, the gcode does not show a curved line, but a straight motion from one point to the next.  Is there something within my configuration that might be causing this? 

Thanks! 
Group: DynoMotion Message: 12897 From: kurt huizenga Date: 2/28/2016
Subject: Re: Slaved Y Axis Missing steps/all screwed up
Hey Tom,
I did a whole phalanx of tests today and finally figured out what the issue was.  My belt clamps wore the belts and they came loose.  Stupid problem really, I should have thought of that sooner!   Anyway thanks again for all the terrific support!


On Sunday, February 28, 2016 3:39 PM, "Tom Kerekes tk@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:


 
Hi Kurt,

Its hard to comment without knowing the scale of the images.  Or the Speed and directions of the paths.  Or anything about the rigidity of your system.

Can you measure the approximate peak-to-peak "waviness" in the paths?

I believe you have the Trajectory Planner Corner Tolerance set to 30 mils.  That might add significant rounding at corners but shouldn't cause waviness.  You might reduce this.

The obvious thing would be mechanical stiffness issues in your mechanical structure, drive train, or gantry.   For example if after a shock (due to acceleration) your gantry rocks back and forth (in Y ?) then as long as you are doing a horizontal line there won't be any noticeable issue (only feed rate variations along a straight line), but a diagonal line will show waves.

Regards
TK

On 2/27/2016 10:35 PM, kurt huizenga semperfikurt@... [DynoMotion] wrote:
 
Ahh I totally didn't see that, that little fix made everything much smoother!  AWESOME! 

Something Else that I have been messing around with that I haven't been able to figure out is that all my non-orthogonal movements not being straight, they are wavy.  If I move in X or Y by themselves, the motion is straight as an arrow however, if I move diagonal or curved in any way, the line is wiggly.  That or the line is straight, but with a little bend at the end of it.  The images attached show it really well.  Ortho lines super straight and nice, anything else is wavy or with the bent end.  

I have tried the same drawing on multiple locations of the bed so I don't think it is a mechanical issue, also I looked at the steppers and can see them moving through the wiggly curves, no skipping or belt slippage.  

I also tried rotating the line geometry in RhinoCAM 180 degrees and regenerating the toolpath and that changed the location of the wiggly artifacts, but did not get rid of them.  I think motion direction has some kind of effect on it but I haven't sorted that entirely.

The the instances I have checked, the gcode does not show a curved line, but a straight motion from one point to the next.  Is there something within my configuration that might be causing this? 

Thanks!