It is, but I mean: Many of us do just exactly that with 3D printers.
We get a new 3D-printing machine and install our own build of Marlin on it, or move it all over to Klipper. Sometimes that involves replacing the entirety of the brain-box controls and that's just par for the course.
At its root, it's only some stepper motors, fans (more motors), sensors, and heaters that are used in very particular ways.
That's pretty similar to a Cricut machine, isn't it?
Because closed source 3d printers grew out of an open source community, it's pretty easy to do this, and you get a pretty similar experience on most printers. Unfortunately, cricuts are not like that. There are a couple projects attempting this but afaik they offer a pretty rough experience.
Nice! I've had very good luck with most (not all!) of the Biqu boards I've used, at least in printing space. I've also had great (100%) luck with warranty claims.
If you're really launching into this thing, then: I came across a set of ifixit sorta-teardowns[1] on a Cricut machine earlier today. It showed what appeared to be relatively-small 4-wire motors (often with gear trains shown, which does matter), which strongly suggests that 2-pole steppers are being used. That's easy enough.
The TMC5160 on the Biqu Rodent seems like a strange choice for this job: The 5160 is a high-current dude that's meant more for grunt than precision. The availability of grunt doesn't necessarily outlaw the ability to be precise, but it may not necessarily represent an ideal set of tradeoffs.
Perhaps a board with smaller stepper drivers may be better-suited. After all, if the motors are small and they've got gear reduction on their outputs, then: They don't need much grunt to make the bits move move in predictable ways.
The photos also showed that some/many/all of these motors have optical encoder wheels. Perhaps they're optional in a build with a custom brainbox (we do usually get along fine without that kind of feedback in printing), but their presence is certainly interesting.
And: There were nowhere near enough connector pins shown on what was described as the motherboard for all of this stuff to happen. That's concerning.
It all combined to strongly suggest to me at that time that the ICs that drive the motors might be located elsewhere in the machine, and that there may also be some servo feedback that happens in stock form.
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That concludes my brain-dump on what I think I know about Cricut machines. Take it as you will. :)
And: The FluidNC Board Mapping Wizard is an amazing tool. I will save this for future use. Thanks!
Indeed, a retrofit would need something with hardware quadrature position tracking, and motor driver bridges. Servo control loops can get fussy, would likely take time to draft a custom PCB to handle the wiring harness, and some fiddling to prevent PID spin-up under dynamic load.
Avoiding pricey FPGA and mcu with special peripherals, a pico might be a good place to start for other reasons:
Replacing the entire Circut complexity might just reduce the overall materials cost. Might try a scalpel blade mounted to a spring-loaded spindle bearing on a 3D printer gantry over the weekend. A purely mechanical solution costing under $10 would be fun to bypass the entire ecosystem. =3
We get a new 3D-printing machine and install our own build of Marlin on it, or move it all over to Klipper. Sometimes that involves replacing the entirety of the brain-box controls and that's just par for the course.
At its root, it's only some stepper motors, fans (more motors), sensors, and heaters that are used in very particular ways.
That's pretty similar to a Cricut machine, isn't it?