Need to replace replicator 2 extruder motor

[Chris Spurgeon]

The extruder stepper motor on my Makerbot Replicator 2 has started stuttering. I completely removed the motor from the extruder mechanism and the problem still happens, so I know it's nothing to do with a blocked nozzle or a clogged or stripped extruder gear or anything like that. And I checked the continuity of the wires between the extruder motor and the circuit board underneath the chassis and the wires all seem fine too.

So I thinking it must be the motor itself. (Could I be wrong on that?)

Looking on the back of the extruder stepper motor, here's the designation I see...

MOONS' STEPPING MOTOR

TYPE 17HD4063-03N

60285194 13/07/15

I can't seem to find that exact model online anywhere. Does anyone know of a compatible motor I could use?

Thanks!

[Jetguy]

#1, Yes, doubting it's the motor. You can test the cables until you are blue in the face, the point being they flex millions of times over the life of the printer and the strain relief setup was not ideal on these printers leading to failure of the cables. As such,it's likely an intermittent fault making static bench testing hard to see this fault.
Second part of doubting the motor, if you tested the wires, did you not test the very motor connector and basic coil pinout???
#2 Makerbot custom ordered those motors but that doesn't mean you cannot find a match.
This motor is the identical ratings (1.8degree, 34mm long NEMA17, 5mm shaft, 0.84A rating) https://ultimate3dprintingstore.com/collections/brand-new-2017/products/ultimate-3d-printing-store-parts-department-wanhao-duplicator-4-series-xy-axis-stepper-motor-d-shaft
Identical spec motor from a FlashForge http://www.flashforge.com/product/motor-for-x-axis/

MakerBot stepper motors are the comon 6 pin connector but ONLY 4 pins are used.
So, coil 1 is Pin 1`, skip, 3, and then coil 2 is 4, skip, 6 So just check for continuity at the connector.


This $12 cable is what I would replace long before even thinking it was the motor https://store.makerbot.com/parts-accessories/replacement-extruder-cable/

[TobyCWood]

And... it could be the limit switch cable. All in the bundle should be changed.

How to test? Swap the x with the y.

[Chris Spurgeon (gmail)]

Great, thanks for the info!

Yeah, the motor seemed unlikely to me too. Following up on your reply, I checked the continuity on the motor itself, and the only pins that show any connection via my multimeter are pins 1 & 3 (that’s counting from the left when looking at the motor from the front). I would expect a normally functioning stepper motor to show two connected pairs, as you pointed out.

I’m going to go ahead and replace the cable since, as you said, it’s pretty inexpensive and can’t hurt. (I previously had one of the x/y axis cables fail, so there good reason to think that even if this one was ok its days may be numbered.) If that doesn’t do it I’ll go ahead and snag a replacement motor. 

Thanks again!

[Chris Spurgeon (gmail)]

I don’t think it has anything to do with the limit switch cable. The X, Y, and Z movements all seem just fine, and the axis limit switches are firing just fine. I really think this is something to do with the extruder stepper motor, the cable connecting the extruder motor to the circuit board, or (worst scenario) the board itself. But thanks for the suggestion!

[Jetguy]

I would unscrew the back off the motor (you may have to tap the aluminum housing with the handle of a larger screw driver to knock it free from the laminations), and just check for an obvious bad solder joint to the connector PCB if the motor did show lack of continuity to one coil at the motor connector directly.

Stepper motors are insanely simple devices. They have what I consider one moving part- the rotor in the middle. Yes, it has 2 bearings, so maybe you call it 3 parts, but again, no brushes, no contacts, no sensors. There is not one thing "electronic" in it.
It's 2 coils of wire that are wound into the stationary stator of the housing. I'm not saying one could not "burn out" a stepper, but there would be evidence- smoke, bad smell, melting anything attached to the motor since the entire motor would be smoking hot. So an open circuit coil to the connector is most likely a bad solder joint.

[TobyCWood]

Swap the motors. 

Motor go bad? Yours would be the 1st I'd ever hear of. Only way they go bad is if they are somehow damaged via inputs or wiring.