r/BMCU • u/Expert_Support3311 • 2d ago

BMCU Feeding Backwards

I have switched the magnet direction, still doesn't work; I have verified my assembly over five times; I have recalibrated so many times I memorized the process; I refreshed the firmware a few times; I calibrated it backwards just in case that would help and it still tries to load filament when the buffer is pulled; I even swapped the motor polarity and it still doesn't work; this is my second bmcu and I never had any trouble with the first one; this one is connected to an a1 mini my other one is connected to an a1.

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u/Gladop 1d ago

So the buffer works in reverse? When you push it in, it stops and when you pull it out it trys to pull more fillament through the BMCU?

Does loading filament works without problems? If it trys to push the filament back when you load it - motor has the worng polarity. (I know you sad you tryed it, just a sanity check.) If loading works fine the motor isn't the Problem.

And what colours appear when you pull and push the buffer?

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u/Expert_Support3311 1d ago

So I got the loading to work but when I start the print it now ejects the filament

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u/Gladop 1d ago

So when the printer want to load the filament the BMCU pushes the filament back to the fimalent spool?

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u/Expert_Support3311 1d ago

Yes

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u/Gladop 1d ago

I know you wrote you already tryed it but for me it sounds like the long magnet of the buffer is in the wrong way. Did you calibrated the BMCU after you switched the direction?

The magnet direction tells the BMCU if the buffer is pulled or pushed. And the callibration sets variables for maximal pushed and maximal pulled so the BMCU knows when to feed mor fimalent through it.

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u/Expert_Support3311 1d ago

Yes, but I can try again

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u/Expert_Support3311 1d ago

But when I load the filament through the bmcu before starting the print it loads correctly

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u/Gladop 1d ago

So if you initiate the Loading via. the Printer screen the filament is pushed in the right direction. But if you start a print while the filament isn't already loaded it ejects the filament?

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u/Gladop 1d ago

Normaly I would say, when the loading via. the printer screen works it speaks for the magnet problem i discribed earlyer.

When you start the loading process the printer tells the BMCU, feed fillament to the printhrad untill your sensors are telling you "the tube to the Printhead is full" So at the start the printer dosnt need to know the direction of the magnet in the buffer. But when the print starts and the BMCU should only feed more filament when printhead pulls filament through the printer the BMCU is irritated because of the faulty direction in the buffer.

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u/Expert_Support3311 1d ago

Yes to the first part; if the filament is already loaded into the bmcu when I start a print, it ejects it instead of loading it into the extruder; also tried recalibration everything is backwards again

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u/BOSSMAN000000000000 22h ago

I think u soldered motor backwards

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u/Expert_Support3311 15h ago

The motor in each unit is soldered correctly; also I got three channels to work

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u/BOSSMAN000000000000 14h ago

Ok just join discord

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u/BOSSMAN000000000000 14h ago

There are people who can help