[Closed] extruder motor specifications  

Re: extruder motor specifications

Thomas

1.8 degrees. There should be a number on the motor which you can google to get the specs.

I am sure Jeff will be along shortly...

Peter

Re: extruder motor specifications

I cannot find any number except the Prusa label.

I read some posts here in the forum to upgrade to an 0.9° stepper. Is this recommended or is it oversized ?

If I buy a new motor then it's also easy to buy an 0.9° stepper.

Thomas

Re: extruder motor specifications

Thomas

LDO NEMA 17 motors: http://ldomotors.com/products/show/42mm-hybrid-stepper-series

If you can measure the coil resistance and length, you should be able to determine which of these it is and then you can find an equivalent.

Personally I would love to go 0.9 degrees, but it just won't work with the MM upgrade, because the speed would be halved. That's my biggest issue with the MM upgrade, the 140 steps/mm.

Peter

Re: extruder motor specifications

I'm wondering about the variety of these motors (exspecially fur the extruder). I read many posts in different forums, is there no generic extruder motor for our printers ? 😯

Peter, yes. I'm tending to the 0.9° stepper too. I will not upgrade to MM (because I found the concept not coherent, I don't like bowden extruders).

OK; what I have found :

- Nema 17
- length about 40mm
- about 40Ncm torque
- current > 1A
- resistance about 1.5 Ohms
- inductance about 3mH
- 4 wires, bipolar

Thomas

Re: extruder motor specifications

Yes, anything with similar specs to the one on the LDO site will work fine. You just need to determine the voltage and current rating.

I don't like Bowden either, but after using it for a while, it does work as well as the direct drive.

Peter

Re: extruder motor specifications

sorry for browsing this thread with a delay.
but Thomas is right, a standard NEMA17 stepper with 1.8° and 40mm (x 42mm x 42mm) dimensions will do the job. torque should be above 35Ncm.
consider that it needs to have a shaft with a flat side.
this one will do the job.

by the way: the current is limited by the stepper driver at the rambo, so the voltage will never exceed the voltage rating of the motor, as long as the current is lower than the limit.

Re: extruder motor specifications

Great !

I've ordered this one 😉 and for playing around with the 0.9° this : http://www.ebay.de/itm/231657793068

The picture was a nightmare ! Filament builds a knot on the spool, spool jammed rotating. Printer lifts up to the spool holder until it crashes against it. I used ABS, so it's a relativ strong filament. The force must be very heavy, the filament tear up and the printer must be dropped down about 10cm or so. After then prining continues but stopped again because of the knot in the filament. Extruder motor becomes very hot and this maybe damaged the motor. It still works, but it has no torque anymore. Maybe it is loosing his magnetism because of the hot.

Yes, the 0.9° stepper has relativ high resistance, but Ohm law tell us : 6 Ohm x 0.5A (max. current form the Rambo) = 3V -> should work well :geek:

Thomas

Re: extruder motor specifications

...
Yes, the 0.9° stepper has relativ high resistance, but Ohm law tell us : 6 Ohm x 0.5A (max. current form the Rambo) = 3V -> should work well :geek:
Thomas

you've got it !

I've an 0.9° stepper here as well, dedicated for a test as extruder motor... but haven't tested it until now.
another point to mention: when a 0.9° stepper is used the retraction/extrusion precision will be increased by factor 2, but at the other hand retraction speed will be reduced as well. which might cause more stringing...

Re: extruder motor specifications

but at the other hand retraction speed will be reduced as well. which might cause more stringing...

Or it might even reduce stringing...

The idea with retraction is to move all the molten filament out of the nozzle orifice. If retraction is too high, then it will leave some behind.

The actual amount of retraction needed for this is very small; the E3D nozzles have an orifice length of twice the diameter (standard: 0.4mm / 0.8mm) and that is why E3D recommend only very small retractions.

Of course, you also have to take into account other factors such as last extrude volumetric speed, filament (cold) elasticity, (hot) viscosity and the distance from the motor to the nozzle.

Peter

Re: extruder motor specifications

hmm.... if you pull the honey-spoon out of the pot, you'll get more "stringing" when you do it slower as if you do it fast.
just a thinking model.

Re: extruder motor specifications

hmm.... if you pull the honey-spoon out of the pot, you'll get more "stringing" when you do it slower as if you do it fast.
just a thinking model.

Yes, but you leave more behind. Idea here is to empty the honey pot in one go...

Peter

Re: extruder motor specifications

Jeff

Have a read of Michael's excellent blog: http://www.sublimelayers.com/2016/10/some-musings-on-retracts.html

Peter

Re: extruder motor specifications

Jeff

There is also one more thing to consider and that is acceleration.

If your retraction is set to 0.8mm, the maximum retraction speed will only occur at 0.4mm. I really don't want to start working that out (it would probably kill my brain), but of course with the MM upgrade, retractions are much greater (4mm) and they may approach the MAX settings within firmware.

Peter

Re: extruder motor specifications

Jeff

Have a read of Michael's excellent blog: http://www.sublimelayers.com/2016/10/some-musings-on-retracts.html

Peter

💡 yes, good explanation. thank you for that link !

Re: extruder motor specifications

Hmmmm, thread going a little bit offtopic 😉

Thomas

Re: extruder motor specifications

Thomas

SORRY 🙄

But ir was all to do with the extruder (motor).

Peter

Re: extruder motor specifications

Peter,

it's OK, I also benefit from it 😉

Thomas

Re: extruder motor specifications

I have seen a lot of people trying to find replacement motors and so many others giving out incorrect information about what to use, so for those of you looking for THE exact motors that Prusa uses, here you go: (because accurate information should be free!)

XYE motors are 6.5v 1.0a P/N LDO-42STH38-1004A

Z motors are 8v 1.0a P/N LDO-42STH34-1004L321E