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Can any help with commissioning a Prusa 3D printer with megatronics board. Answered

I have completed the build but require assistance in testing and commissioning, can anyone help me, located in Perth, Western Australia.


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1 year ago

Other side of the continent but the basic shouldn't be too hard....

I assume you have Marlin or similar running on it.
First order of business is to define endstops and directions in the firmware so it matches your hardware.
Check the G-code references out there to get the corresponding commands to get the basic info back from the machine through a serial command.
Or in simple words:
Make sure all endstops are free - check what the machine gives as a result.
If machine says all enstops are off then fine, check for on one by one.
If machine says endstop(s) are on while they are off or the other way around then reverse the endstop logic in the firmware.
Your printing software might support all this through a graphical interface, so use that if applicable ;)
Next is the movement directions.
The endstops are always at the homing position and the axis should move away from them.
Either way the machine logic must be follwed in the firmware.
For example a positive value should move the X- and Y axes away from the endstop.
The Z-axis on a Prusa has Zero at the lowest point - where the nozzle touches the bed height and again should move away from the endstop.
Keep steps short until you sorted the stepping otherwise your motor might crash into the end of the axis - if in doubt kill the power before it happens.

Stepping not only defines your arrucy but als in many cases the possible speed.
There is good guides to calculate the stepping based on your pulley/lead screws.
I say guide here as not always these calculated values match realities.
Is not so much the teeth on a pulley but the actual diameter defining the resulting steps you need to get a true 10cm out when you ask for it.
I prefer to use digital calipers where I fix one end to a fixed point on the machine to get accurate readings about the movement of the print head or axis.
Once you have close values repeat with about the max travel your machine supports in 10cm increments.
You want the actual motor steps to be calulated so the resulting movement matches what the head does.

Now you only need to get the extrusion rate set properly.
Same principle as above.
You measure what goes into the head and compare that to what you told the machine to extrude.
Works great without the hotend and calipers.
Last bits would be the finetuning, temps, first layer height setup and actually printing something....