NEMA17 Stepper motor for extruder?

Hi, I found these:
[cgi.ebay.com]

For people in the US it might be a nice and cheap, already splined shaft. Not sure if it has the torque, but at this low diameter it might be enough. If so, it would make for a very light weight extruder!

When I buy 10 of these, shipping is still more expensive than the motors (>70 dollar!). So it's impractical for me...

---

Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]

I tried some old surplus versions of that stepper - at 864 g*cm, they have about 1/5th of the torque you need for a decent direct drive pinch wheel extruder. I could only get it to extruder 1 or 2 mm^3/s of PLA through a 1 mm nozzle.

I've been working on gearing down the 5 kg*cm Kysan stepper motors I've got - so far it looks promising. Details here:

[objects.reprap.org]

Wade

I've taken a different approach.

Since I'm using a Bowden filament guide, the weight of the motor is relatively unimportant (it's not part of the moving mass).
I printed one of my adapter plates ( [www.thingiverse.com] ) switched the NEMA17 with a Keling NEMA24 motor. This one won't skip for sure! I've already printed an object with it with a very consistent surface. But now I'm plagued with issues of extruder jams. Not sure why... the new extruder drive mechanism seems to have a lot more force. I'm using the same extruder end (barrel, etc). I'm thinking this is more of a problem than it is a solution...

---

Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]

Quote

I'm thinking this is more of a problem than it is a solution...

What are you referring to here, the bigger motor, Bowden, ... ?

---

[www.hydraraptor.blogspot.com]

I mean that more motor power revealed problems somewhere else (I've got NEMA23 motor, not 24 as I pointed out by mistake)).

I've solved the extruder jams by completely rebuilding the hot end. I also made a second one that seems to work. When I use PLA, everything jams, so I'm leaving that alone for the fourth time. Maybe in a month I will regain the courage. It gets to hot higher up the nozzle and start to create a plug, It gets compressed and widens, creating a lot of friction.

But with ABS it works GREAT... I can easily print at 50 mm/s. Even objects with very sharp corners, because of the Bowden cable.

Erik

ErikDeBruijn Wrote:
-------------------------------------------------------
> I've taken a different approach.
>
> Since I'm using a Bowden filament guide, the
> weight of the motor is relatively unimportant
> (it's not part of the moving mass).
> I printed one of my adapter plates (
> [www.thingiverse.com] ) switched
> the NEMA17 with a Keling NEMA24 motor. This one
> won't skip for sure! I've already printed an
> object with it with a very consistent surface. But
> now I'm plagued with issues of extruder jams. Not
> sure why... the new extruder drive mechanism seems
> to have a lot more force. I'm using the same
> extruder end (barrel, etc). I'm thinking this is
> more of a problem than it is a solution...

---

Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]

I notice that this is a 3.5v motor rather than a 12v. Dopws that make any difference or could 3.5v motors be hooked up to the reprap's electronics? And if so, what changes would be necessary to do it? I have a batch of 3.5v nema17 motors at the moment but I was not planning on using them for my Mendel since it calls for 12v ones.

3.5v motors are fine. Since the drive circuitry limits the max. current, the only result will be they'll move a little faster. They won't burn up, catch fire etc. Well, as long as you set the current control pot correctly. But this has to be done anyway, the steppers spec'd for the reprap aren't 12v anyway. There's more writeup on this elsewhere too.

---

--
I'm building it with Baling Wire

I'm new to all of this (electronics, extruders, stepper motors, etc.) but saw these on Ebay.

Ebay Nema 17

Can someone tell me if they would work for a Mendel with the MakerBot stepper driver controllers?

Thanks.

Scott

not enough torque, you want about 62oz.in (0.43Nm) for the extruder. probably fine for the axes though

---

-----------------------------------------------
Wooden Mendel
Teacup Firmware

I have the same on Wade´s extruder... works fine.

Wolfgang

Quote
ksmith5133
I notice that this is a 3.5v motor rather than a 12v. Dopws that make any difference or could 3.5v motors be hooked up to the reprap's electronics?

I'm not an expert, far from it, but I have spend a lot of time reading up on electronics and engines in the last couple of months.

From what I understand of the literature, a voltage mismatch between the controller and the motor isn't a big issue until you exceed 4x the voltage, and then the only effect in the beginning will be shorter engine life span. In fact, according to "Electric Motors and Drives" ISBN-13: 978-0-7506-4718-2, it the voltage spec of the controller should be at least 2x the rated voltage of the motor.

There are numerous threads dealing with motor vs supply voltage. Here's the short version:

As long as the motor driver/controller does current control, you can use any supply voltage greater than the motor's rated voltage. In fact, a large difference is advantageous to the top speed of the motor.

If the motor driver/controller does NOT do current control, you must use a supply voltage fairly close to the motor voltage (no more than 2x) or the motor will overheat and burn out its winding insulation or demagnetize its rotor or something like that.

The reprap axis drivers do current control, so you can use a 1v motor with a 12v supply quite safely, as long as the current is set correctly.

The (current) extruder controller does NOT do current control, however it does have a software-configurable "power level" which you can use to emulate a "virtual" supply voltage below the real one.

---

-----------------------------------------------
Wooden Mendel
Teacup Firmware