Custom XYZ-B CNC problem with GRBL PP output

[020144]

Hi Everyone

Long time first time. 

I have made myself a CNC with a B 4th axis.

TLDR: Simulation looks perfect but g-code. 1. 100mm of movment in the X when there should be none. 2. 100mm in the Z when there should be only about 40mm.

I have created the machine in the "Machine Builder" and am using the default Grbl post processor
The Simulation with the Machine is working fine.

In the Simulation you can clearly see that the X axis is not moving at all, the B axis is spinning, the Y axis is moving down after each 360 on the B and the Z axis is moving in an out by no more then about 60mm. 

Then I post and the nc file and. 
The A axis and the Y axis doing the correct thing but...
The X axis going from "X50.249" to "X-50.249" a around about each rotation of the B
And also the Z axis is moving way to much "Z39.175" to "Z-55.172".
see "NoChanges to PP.nc" attached. 

so then I start playing with the PP file and change from.

to 
Save and update the Machine .

Now I can't run the Simulation with the Machine.
error "Machine tool simulation disabled: Machine configuration is overridden by the post script"

And if I post it gives me different gcode but still with the same 100mm change in both the X axis and the Z.

See "With Changes to PP.nc"

Does anyone know what I am doing wrong?

[AchimN]

Hello,

The reason why Fusion does error when you try to run machine simulation is that you enabled the machine  configuration inside of the postprocessor.
Once that is done, the postprocessor will overwrite the configuration you made inside Fusion.

For the coordinate issue you have, that sounds like TCP is set incorrectly within the configuration. Could you please share your sample part + machine file? I´ll have a look.

[020144]

Thank you Achim for answering.
I have attached what I thing are the sample part + machine file. cnc XYZB v11.f3d = machine. CncFirstTest v13.f3z = test part. 

With the postprocessor the configuration is that the "Updating post processors for machine configuration support" part of this page? 

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Configuring-a-post...

Thanks Again


Andrew

[AchimN]

Thanks,

without knowing on how you build your machine, i assume that the machines coordinate system looks like shown below. If thats the case, you need to adjust the orientations and the origin of the machine you created in Fusion, since in your file Z is pointing into the opposite direction of the spindle and the origin is located outside of the center of the table.

Also make sure that the WCS in your setup is set correctly as well to match the new orientations.
From the postprocessor side i dont see a problem with the output once the setup is adjusted.

[020144]

Ok I have recreated the machine and turned it 180 and moved the origin to be in the center of the table.  

I also re did the WCS making sure it lined up with the machine origin.

Same thing happens. Simulation works fine. gcode has crazy x and z.

I don't think this should make much of a difference but I will try setting up the machine as if it is a normal A axis. So on the side. If that works I can just change g-code manually.  

[AchimN]

Hmm should work just fine. Please have a look into the attached files, I´ve adjusted your configuration to what i think it should look like. The output with this machine setup looks correct to me.

[020144 · Accepted solution]

I think that may have worked. I will test it out. the g code looks better for sure. 

At first I couldn't get your machine it to simulator.
After recreating to machine for the 4th time without the rot axis. simulation worked.
Then I added to rot axis in and simulation worked. And the G code looks better. I did call the Rot A and just have it running on the Y but I can't see that making a difference as I have tried that before.  

I will test it and see. 

Can you tell me what you did? and I will try recreate it. 

Thank you Achim.

Andrew

[020144 · Accepted solution]

So for anyone that has this problem.

It's the rotary toolpath

It would seem that you can't have a WCS point that does not align with the center of your rot axis if you are doing a rotary tool path.