Cutting dry carbon fiber

I’m getting my low rider machine tomorrow and will use it to build tooling for composite molds.

Does anyone have experience cutting dry fiberglass or carbon fiber with a CNC machine? I know that I would need to add a 4th axis which would turn where the router is normally placed. That’s what I need help with. There are rotary cutters on the market but I’d need to build a holder.

As far as holding the material, I have that covered as we use vacuum bagging techniques every day. Having the ability to cut Material would be a huge time saver and would take the quality of my parts up.

I need help adding the 4th axis.

Replacing an axis with a rotary axis has been done before. For example, letting it move in X and Z, but replacing Y with a rotational axis to allow engraving a pole like object. These posts are where I would start to get an idea on the mechanical set up. You’d basically need to drop the table, and build a stepper motor driven chuck. If you want to have it be gear or belt driven, you can accommodate the ratio in software.

The trouble with a 4th axis is the software. Marlin doesn’t support that 4th axis (unless you can abuse the extruder). But the CAM software also needs to know what to do. I remember seeing a fork of grbl that supported an A axis, but that was a long time ago. Something like LinuxCNC or Mach3/4 would probably be needed.

If you only need to carve from the cardinal orientations (like milling from top, rotate 90, then mill the top, etc… Then you can probably do that with some clever set up and a 3 axis machine.

Neat to know. What does Marlin do if it comes across G-code instructions it doesn’t recognize? If it simply ignores them, then two serial port readers could listen in parallel to one stream.

At that point, you could maybe set up a simple A-axis controller on the stepper motor and then the XYZ would be handled by the Marlin. Neither would be aware of the others existence.

It depends. If it is a complete code it doesn’t recognize, it will say so, and continue.

But that won’t matter, because moves would be compound moves. Imagine G01 X10 Y10 Z10 A10. It will read that in, look at the speeds and starting place before that move, and determine what accelerations and speeds of each axis are required to get there, and then step each axis in sync. If you had an outside controller for A, even if Marlin would just ignore the A axis, The external controller would not know what speeds Marlin was choosing for XYZ, or when it would start them. If Marlin was configured for moving the Z at a max speed of 1mm/s, then it might slow down that command, and A would need to slow down as well. It gets worse when Marlin uses max accelerations to reduce the speed further. And then even worse when it may pause right before moving, for any number of reasons.

It is pretty deterministic, and you could compute all of that, and reverse all the logic to repeat the sync on the controller, to a degree, but if you understood it that well, you could just add the A axis to Marlin.

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I’m not familiar with this technique since I basically never experimented with it, but I think the idea is very similar with what some people do with vinyl cutting.
So maybe you can try invoking one of the experts on this topic, I recall @dkj4linux did a lot work on this. Maybe he’ll have some interesting insight or suggestion regarding how to cut CF fabric.

Can it be laser cut? That would probably be easier if it was possible.

I don’t think that was me, Dui. I’ve never messed around with CF. Sorry… :sweat_smile:

Laser cutting isn’t an option… it does more damage than anything. Thanks for the feedback!