Hi everyone, So the situation is I need to make some wooden spindles.

Hi everyone,

So the situation is I need to make some wooden spindles. I’ve got a cnc with a fouth axis. My plan was to simply use the gcode generated by fusion 360 turning option, but fusion is saying that the “Turning toolpath is not supported by post processor”.

Does that mean that the tinyg/chilipeppr won’t support a turning toolpath?

Or am I going about this the wrong way?

Am i restricted to indexed fourth axis tool paths?

Any suggestions for how best to use the fouth axis to turn spindles would be most welcome?

thanks, Jody

Here is a screen shot of the failed gcode
missing/deleted image from Google+

What post processor are you using? I would use the TinyG processor. Am I misunderstanding you?

That’s a good question, I wasn’t clear. I’m using the one on the fusion 360 post processor list, its called:

tinyg.cps - Generic TinyG

Is that the one you mean?

Turning toolpaths are for lathes, not for fourth-axis machines. I don’t know off-hand what Fusion 360 toolpath to use for your case.

thanks for your reply, interesting tinyg doesn’t accept the fourth axis as a equivalent to a lathe.

I think my only other option within fusion 360 is to do indexed tool paths with the 4th axis.

Oh another thought: is it possible to use another post processor which does accept turning toolpaths and then adapt the gcode for tinyg… if so can anyone recommend one?

I would like to use my 4th axis soon as well via Fusion360 / TinyG / ChiliPeppr, but I have not done this yet either so would love to know if you figure this out. The most important thing really is to get the rotational axis to spit out as the A axis in the Gcode. ChiliPeppr doesn’t know how to show the A axis in the 3D viewer once you get that part figured out, but it does still send that to TinyG so it will work fine from CP.

TinyG does support rotational axis. I have used the a axis on TinyG to create patterns in dowels but I used aspire to generate the tool paths.


Yeah I think the puzzle is how to set up turning capabilities in the tinyg post processor for fusion 360. There’s a really helpful video (see below) of how to do it in fusion for Linux cnc. This guy just went into the post processor configuration drop down menu opened the file and where it says:


he simply added


so it looked like this


Now this would solve the problem really easily. However, for some reason I don’t have the post configuration drop down menu option… possibly because they’ve changed it since the video was recorded or because I’m on a mac.

here is a link to video incase you’re interested

I think that contacting support for 360 might be a good thing to check? I do not know much about 360 can u post the TinyG preprocessor?

Progress report:

So it turns out that part of the problem was that the mac wasn’t letting me do post process configuration easily within fusion. If you’re on windows this is much more straightforward.

For anyone on a mac here is how to edit the post processor for tinyg for fusion and add turning capability

  1. Go here and download the post processor file for tinyg


  1. Follow this path and drag the download into here

Users/accountname/autodesk/fusion cam 360/posts

  1. Now you can open this file in brackets

  2. create a new line on line 23 and write this (on one line)


There are still a bunch of issues to resolve but now at least fusion gives us some gcode to work with.

John you’re right, the main puzzle is the getting the Gcode for the A axis.

The other puzzle is getting it to automatically swap the Z and the X (or Y depending on how your 4th axis is orientated)


So I can get my Axis to rotate by putting in g0 A10 at the beginning of the gcode, but it never moves beyond that command.

Is there a command which allows the A axis to rotate continuously while allowing the subsequent commands to be executed?

Oh I see what you are trying to do. Short answer is no. TinyG does coordinated motion control. You are not using the a axis as a 4th axis but like a lathe which is not what the hardware is.

This is what I am talking about. This is a TinyG v2 code running on shopbots handibot. https://m.youtube.com/watch?v=yaDRiY6mmZA

Thanks Riley, I definitely want to do 4th axis wrapping like the video you shared. From what your saying it sounds like it might be my only option, and a good option it is. I’ll look into how to do that in fusion.

@Jody_Koomen ​ np let’s see it when you get it working. :wink:

So I was looking at that video you posted Riley. At one point it shows the software turning the round candle holder into to a flat profile. It occurred to me that I could do the same for my spindles. I made the profile for the spindle and instead of rotating it, I extruded it 100mm. I then got fusion to make parallel tool paths accross this extrusion. Then in chillipeppr I set it so that my fourth axis was my Y axis and that one rotation was a 100mm. Worked a treat for milling spindles on the fourth axis.

Apparently fusion are just about to release an update which will enable continuous 4th axis toolpaths, I think some people call it wrapping (not sure what it’s called officially). So hopefully that will make more complex 4th axis stuff easier.

Well if you are just turning it down to a certain size you could always just do something like.
say you want to make it rotate like 50 x times (Ie 18000 degrees)
z-1 (mm)
a18000 x500 (if your spindle was 500mm long)

Then it would continue to rotate 5x times while moving to 500mm at a z depth of -1

I’m using TinyG and Chilipeppr on a homemade CNC (mostly Openbuilds parts) exclusively for 4th axis work (I build woodwind instruments). I haven’t tried Fusion yet, but I’m using CNCwrapper to generate my initial rounding toolpaths, and then I’m doing everything else in Vcarve (although its gcode is pretty inefficient, especially with the laser I just added). I’ve found that most of the TinyG postprocessors out there don’t support 4th axis Y to A conversion, but the ones for Mach3 do and seem to work just fine with the TinyG.