How to reverse the wiring of an extruder motor? - Afinity A9 printer

[biggnou]

Hi there,

This is a 3D printer question, not sure the forum category I chose is correct.

I recently bought the Afinity A9 3D printer from RobotShop (https://www.robotshop.com/ca/fr/kit-imprimante-3d-graveur-laser-a9-afinibot-assemblage-partiel.html?utm_source=rb-community&utm_medium=forum&utm_campaign=afiniti-a9-user-manual-and-drivers).

Assembled it, made the initial tuning, looks good. Pushing filament manually does extrude, no issue with temperatures at all. Me happy!

The issue is that when I try to print, the extruder motor goes backward. Instead of pushing the filament into the extruder, it pulls it. So the printer does everything good it seems, but there’s no plastic going out, so it produces an “air print”

Seriously, I looked here and there, found out that it’s a commun wiring error for pre-assembled printers, I now “just have to” rewire the motor. Me love computers, me not into electronic builds

But OK, no problem, I’m a grown up, I committed to buy a 3D printer, I can do that. Hopefully. Now here is the thing: There are 4 wires. Which ones should I rewire? I looked into the manual, it’s not specific enough, and it’s in Chinese (a beautiful language I unfortunately do not practice).

This is what I have:

I assume I will need to invert two of those bad boys, so the question is: Which ones?

I’m adding the wiring diagram (yeah, no joke, that’s what I have):

Bonus question: Why 4 wires? I understand two of them, that would be for for push and pull. But what are the other two for? ELI5 please

Thank you!

Alex.

[dialfonzo]

Stepper motors do not work like that, it’s effectively two coils inside (to make it easy).
The direction is not set by polarity like in a brushed motor, you have to swap the two coils.

Here is a GENERIC idea of how to do it:

I don’t have the wiring diagram (so be careful) of the motor controller used in the afinibot but it might be something like that:

[biggnou]

Hi @dialfonzo,

So I just did that and it gives me the exact same result, which I find interesting. I thought it would either not work at all, or blew up something

But nope… the extruder motor is still pulling filament instead of pushing it.

Should I try to inverse the wires within the pairs? Like instead of moving black to red and green to blue, should I try red to blue and green to black?

Thank you.

Alex.

[dialfonzo]

Can you please take pictures of the control board where the connector is?
Top and bottom so I can look at the traces and understand the pinout.

[biggnou]

Hi @dialfonzo,

I too pictures of the board from above. I can’t unmount it from the frame, one of the screws is too tight, I can’t unscrew it.

Is this enough to debug?

[dialfonzo]

Thanks for those nice pictures, it does help.
After confirming with an electrical engineer here, you have to swap only one “coil” to reverse the direction.

So from this picture you have 4 pins and only the first 2 will be “swapped” like this.

[biggnou]

Hi @dialfonzo,

So I did that, reverse just a pair, and tried to print. The extruder motor would not push nor pull, nothing. Very frustrating. So I inverted the other pair, and it works now.

God I’m ignorant when it comes to electronics, but hey! I’ll take it. I’m printing my first 3D object right now!

Thanks a bunch sir!

Alex.

[dialfonzo]

Good news after all.
It’s seems like the manufacturer did a mistake in the making of their cables as another one posted a “review” on our website talking about the same issue on the extruder.