1 Topic by 2n2r5

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Topic: Nema 8 or nema 11 Extruder Stepper

Hello all. It's been awhile since I have lurked on here. I wanted to run a mod idea past everyone and see if this might be worth trying.

I was looking to setup one Nema-14 stepper at the reel like you are feeding Bowden style but have a helper stepper on the carriage handling the actual feed. The one on the carriage would be a nema-8 or nema-11. Though, I don't know how much force is needed to get the filament through the hotend reliably.

My reason for this is obviously to reduce weight on the carriage and allow for more accurate prints while still maintaining the benefits of direct drive. Or, that is the hope at least.

I welcome all feedback or suggestions. Before I dive into this, I want to see if anyone else had some ideas on why it won't work.

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2 Reply by carl_m1968 (edited by carl_m1968 2017-10-26 20:50:15)

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Re: Nema 8 or nema 11 Extruder Stepper

2n2r5 wrote:

Hello all. It's been awhile since I have lurked on here. I wanted to run a mod idea past everyone and see if this might be worth trying.

I was looking to setup one Nema-14 stepper at the reel like you are feeding Bowden style but have a helper stepper on the carriage handling the actual feed. The one on the carriage would be a nema-8 or nema-11. Though, I don't know how much force is needed to get the filament through the hotend reliably.

My reason for this is obviously to reduce weight on the carriage and allow for more accurate prints while still maintaining the benefits of direct drive. Or, that is the hope at least.

I welcome all feedback or suggestions. Before I dive into this, I want to see if anyone else had some ideas on why it won't work.


You are going to have an issue with the helper motor keeping up with the extruder motor. That motor does not run at a consistent speed but varies depending on the feed-rate needed. So if it runs too long at a slow rate then your helper motor may feed too much and allow twisting and tangles. If it feeds too little due to the extruder running fast for too long it may actually cause misfeeds or even break the filament.

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3 Reply by Tin Falcon

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Re: Nema 8 or nema 11 Extruder Stepper

The first thing to remember the frame size and torque are not directly related.
the second thing to remember is that the stack length can vary the longer the motor generally the more torque.
That being said the most common way to reduce head weight is a pancake(short Stack ) motor usually of nema 17 size as these directly fit available extruders go with a smaller motor frame and you will need to redesign your extruder.
Hope this helps

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4 Reply by justsomeguy

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Re: Nema 8 or nema 11 Extruder Stepper

Another option is a remotely driven extruder. Are you aware of flexdrive?

https://flex3drive.com/flex3drive/

I think there are some other vendors with similar solutions.