Need input on mcu selection

General Discussion
1

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Printer Model:Custom
MCU / Printerboard:
Host / SBC
klippy.log

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Describe your issue:

Hi! My first post here. Question is not directly klipper related but hoping that someone with more experience got some good advices.

I have been looking into a printer build for some time and started looking for control system. My intention is to build a large format pellet printer with a screw extruder. The issue i ran into is that i have quite a few I/O’s and stepper motors. To be more precise 9 stepper motors that i would like to control separately.

The “biggest” card i could find was the Manta M8P but even that card does not have enough drivers and io. Having one card also means alot of wiring between the junctionbox and toolhead.

So i am looking into having a separate mcu mounted at the toolhead and another one to control the movement, bed heating and ventilation.

Seems like hosting through a pi is the way to go.

Currently i am looking for one card with atleast 7 stepper drivers and “the usual stuff” and a second card with atleast 2 stepper drivers, 3 heater outputs, 3 thermistor inputs and 4 fan ports.

I could use two Manta M8P cards but started to wonder if there are better options since i probably need to host klipper with a pi anyways.

2

(Personal preference) I would avoid cards that use a compute module for a host.

It is not unusual to use a printhead board dedicated to one stepper motor.

You could wire motor driver chips to the RPi GPIO.

There are “servo motors” (stepper + feedback + integrated drive controller) that attach to the CAN bus.

The options are nearly endless. There are lots of cards with STM32 or RPi 2040 micro controllers that can be wired to stepper drivers.

The Pi can be replaced by a mini PC or thin client. By the time you add a power supply, case. cooling, and storage to a Pi5 the mini PC makes sense.

What is your budget? What is your use case?

There are lots of 6 motor boards. 2 of them would cover your current requirements.

3

Thanks

Well, no firm budget etc at this point. Just trying to look into different options so i hopefully end up with the most suitable setup. A mini/thin client does not sound like a bad idea at all, the rpi isnt exactly free either…

I looked a bit into closed loop steppers a few weeks and found some discussions where a few felt that the added complexity was more of a hazzle than the benefit of closed loop. In my case i believe i look at the same amount of cables etc regardless of closed loop can bus motors or “dumb” steppers?

The use case at this stage is just for hobby, but off course if it works out it could turn into something else. The main goal is to print body panels, mold flasks etc. But first I need to make it work properly which could be a project on its own…

4

The first thing I’d want to know is how heavy is the extruder? That drives the selection of the motion system. You may figure out that a stationary extruder with a 3 axis bed is indicated.