Issues with 3-axis interpolation

[X-Pam]

Hello everyone,
I have a software parameters issue when I work with 3-axis interpolation, I guess it's a problem with fine tuning of Constant Velocity Mode (that is the way I set the software right now).
Actually it is set to factory parameters, when the machine works there is a constant change of speed of the axes and the movement it's abosolutely not fluid, I'm using the same Gcode I used for years with Mach3 without any issue.

I uploaded a short videoclip of the machine and the issue:
http://www.alusonic.com/varie/cnc.mp4

Can someone help me please?
Thank you!

[dezsoe]

Does it really change or is it only a display problem? I couldn't hear any change in the speed. Could you make a similar video but with the spindle turned off and cuttong only the air, so we could hear the axis motors? And also, my always first question: which version of UCCNC with wich controller do you use?

[X-Pam]

Yes it change, it is possible to listen a wave sound and also to see the set speed changing from 2.000 to 800, then 2.000 to 1.000 etc randomly.
I have the latest version of the software with AXBB-E ethernet just purchased, closed loop.
I've noticed of this issue on 3D drawing with interpolation, not problems on simple cut X-Y.
I really don't know why, with Mach3 the same Gcode it works perfectly.
Is there something I can change in the software setup?

[dezsoe]

OK, I try again. The set speed display is a display which may be faulty and there was a problem with it if I can recall. But that is only a display, the speed did not change. I listened to your video a couple of times, but could not hear the speed change, however the spindle is very loud, so I could hardly hear the axes. I still don't know the exact software version: at the moment the "latest" can be 1.2111 or 1.2114, depending on where did you download it. (1.2111 is the latest stable and 1.2114 is the latest development version now.) Also, there may be an issue with the factory settings of CV if you mixed metric with imperial. Which do you use and how are the CV parameters set?

[X-Pam]

Thanks for you support mate!
If you can please try yourself the code and tell me what happens on your machine, it's a code that involve the 3 axis on whole programm:
http://www.alusonic.com/varie/gcode.rar (clic on and save link with name)

Never used imperial, we are in Italy and we only use metric.
I use ArtCam and the post processor is Mach3_4-Arcs(MM)(*.TAP) I don't know if it is the best choice, anyway with other 2D code it works perfectly, only with 3-axis interpolation I have troubles.

Here how UCCNC is set, there's something wrong maybe:

[X-Pam]

This is a new video without spindle.
http://www.alusonic.com/varie/cnc2.mp4

I changed something on CV parameters adding more tolerance etc. but the result it's always the same.
Absolutely not smoth, bad sound, it seems it slows down feed rate at each interpolation (and there are a lot of code lines) it's very frustrating.
In Mach3 there is only CV or Exact Stop option, not other parameters and the code run perfectly with CV.
Now it seems to run on Exact Stop while actually I set CV, the software version is 1.2111

[cncdrive]

Try to set the linear unify and linear addition length to a long distance value.

[cncdrive]

And what do you mean by Mach3 that it runs "perfectly"?
What perfect means?
That it does not slowdown in the motions?
If you ment that then the reason for this is that it optimises the path in an unknown way, it erases details of the path as it thinks it is OK for smooth running, in my opinion this is not perfect at all. It might be acceptable for your type of work though if it is not very detailed 3D path or if reducing the details does not matter.
With the UCCNC you have full control over the CV optimisation process.
Please read the users manual to understand how they work, so you can adjust for your works as nessessary.

[X-Pam]

And what do you mean by Mach3 that it runs "perfectly"?
What perfect means?
That it does not slowdown in the motions?
If you ment that then the reason for this is that it optimises the path in an unknown way, it erases details of the path as it thinks it is OK for smooth running, in my opinion this is not perfect at all. It might be acceptable for your type of work though if it is not very detailed 3D path or if reducing the details does not matter.
With the UCCNC you have full control over the CV optimisation process.
Please read the users manual to understand how they work, so you can adjust for your works as nessessary.

First all thanks for the reply.
Probably it's like you say, something in Mach3 makes the path fluid and smoth ignoring parts of the path, it's works good for my type of works.
Now, I read the manual about CV and maybe I have to set Linear addition length and Linear Unify length, am I right?
There is not an example about values, by default there are set to 1 and 2, what does it mean?
Can you please share an example of values to obtain a linear and smoth motion?

[X-Pam]

This is the way to obtain a smoth movements on this Gcode that is not so complex and strange (is the back of a guitar neck) generated by ArtCam:
http://www.alusonic.com/varie/gcode.rar (clic on and save link with name)

LINEAR ERROR MAX: 0.5
LINEAR ADDITION LENGHT MAX: 200
LINEAR UNIFY LENGHT MAX: 200
CORNER ERROR MAX: 0.1
ARC RADIUS TOLERANCE: 0.1

They seem a bit extreme as parameters, I have to try on the wood, when the linear unify and linear addition length are set so hight is the 3D path clear and roundend on the corners or it flattens the 3D?