VCarve for CNC Rotary

bwatt · April 29, 2026, 1:03pm

With the help of Al Watson and a little AI-generated Python programming I was able to use VCarve to drive the CNC Rotary. Three tool paths: Rounding (via a gadget), Roughing and Finish and took about 90 minutes. Is it perfect, no, but it’s a good start. I’ll present what I did this Sunday, May 3rd at the CNC SIG.

Yet another Tiki - ha!

atwatsoniii · April 29, 2026, 5:03pm

This is great Brian! Vcarve will make this more accessible to everyone!

bwatt · April 29, 2026, 7:58pm

Some problems that the Python conversion program has to fix-up

Change file extension from .NC to .mmg.
Convert all Y-axis values to be A-axis values.
On the first G00 command set a default Y-axis value to Y0.000. If everything is switched to the A-axis then the Y-axis is undefined so define it as 0.000 which is good enough, that is, it is aligned with the axis of revolution.
Reorder output from [X] [Y] [Z][F] to [X] [Z] [A] [F].
Insert a halfway-point as a G00 or G01 GCode line between adjacent lines with A0 to A360, A360 to A0, A-180 to A180, and A180 to A-180 to create a full revolution for generating tabs. Reason: If the starting angle value and the ending angle value are the same then the CNC ignores the GCODE and doesn’t move. For example, it does not cut a circle of revolution when one line has A0 and the next line has A360 with everything else being the same. So I insert an matching G00 or G01 GCODE with an angle halfway around. In other words, it now works and moves from A0 to A180 to A360.

We need to have Python installed on all Asmbly computers especially the two CNC computers and the open-access ones outside of the MPR. OR The conversion program should be accessible as an upload/download webpage from our Asmbly website.

P.S. Added a bit more definition based upon the reply from Al Watson below.

atwatsoniii · April 29, 2026, 9:38pm

I think Vcarve post-processor changes could accomplish 1-4. Not sure I understand what 5 is doing.

It sounded like Vcarve will install a post-processor for us, we just have no way to test it in advance of it being installed. With your python script experiment, we have more confidence on what modifications are needed.

bwatt · April 29, 2026, 10:20pm

See write-up above - I added some more description.

bwatt · April 30, 2026, 4:58pm

Go to the following URL: Rotary CNC Converter | Asmbly Projects

And drag & drop your Laguna Turner .NC file and it will automatically convert it to an Asmbly Laguna Swift Rotary file (.mmg) and download it back to you.

ewei · April 30, 2026, 5:38pm

Brian, thanks for hosting this. Is there any guidance around setting up rotary toolpaths in Vcarve to get the initial .nc file?

I won’t be able to join the SIG but I’ll gladly watch the recording!

bwatt · April 30, 2026, 8:53pm

@ewei,

Here roughly how you install the “Laguna CNC Turner (mm) (*.NC)” post processor

In the post processing / output step

After the “Swift” machine, press the edit icon (box with pencil in it) to show the Machine Configuration Management panel

See last image below (but assume there is no “Laguna CNC Turner (mm) (*.NC)” post processor in the list)
Under its Associated Post-Processors, press the circle-plus icon to bring up the Post-Processor Management list.
In the list, select “Laguna CNC Turner (mm) (*.NC)” post processor and press Select button.

image757×1209 223 KB
Back on the Machine Configuration Management panel, press the Apply and OK buttons

image747×1266 111 KB
Now in the post processing / output step the “Laguna CNC Turner (mm) (*.NC)” post-processor should be in your list of post processors. Select it and write files to your disk. They should have a .NC file extension.

Remember if you reboot any Asmbly computer it’ll reset back to just the standard “Laguna Swift CNC (mm) (*.mmg)” and you will have to install / associate the “Laguna CNC Turner (mm) (*.NC)” post processor again.

atwatsoniii · May 1, 2026, 4:54am

Brian, did you put the rotary along the X axis?

bwatt · May 1, 2026, 12:46pm

Yes, the NEMA 23 motor & chuck was on the front left and the tail stock was on the front right of the Laguna Swift spoilboard.

bwatt · May 2, 2026, 3:00am

Latest “Rotary On Laguna Swift Workflow” attached as a PDF.

RotaryOnLagunaSwiftWorkflow.pdf (57.6 KB)

pconklin2000 · May 3, 2026, 6:04pm

Thanks for writing this up, Brian!