Nema 17 for HEVO CoreXY

bartolomeus · 31 Jan 2018, 15:38

I have a fairly standard HEVO 300x300x300 with 10mm steel rods on the X-axis, and a remote extruder (Nimble), oc with a Duet Wifi.
I am looking at upgrading my X and Y motors. I would like to have versatile motors, quality over printing speed. What would you chose based on the listed specs (both have 48mm long bodies)?

Nr 1, from Stepperonline
Step Angle: 1.8 deg
Holding Torque: 45Ncm(64oz.in)
Rated Current/phase: 1.68A
Voltage: 2.8V
Phase Resistance: 1.65ohms
Inductance: 2.8mH ± 20%(1KHz)

Nr 2, Wantai
Step Angle: 1.8 deg
Holding torque: 4800g-cm (66.6 oz.in)
Rated current: 2.5 A/phase
Voltage: 3.1 V
Phase resistance: 1.25 Ohm/phase
Inductance: 1.8 mH/phase

timcurtis67 · 31 Jan 2018, 15:48

These motors are good ones http://openbuildspartstore.com/nema-17-stepper-motor/

bartolomeus · 31 Jan 2018, 16:42

Thanks for the tip. I'll llook into those aswell.

I have done dome reading prior to my post, however threads tend to get very technical to the point that I get lost.
I've also read the wiki recommendations. Problem is I don't have a clue how much holding torque the printer needs.
Also, I don't know how to compare motor specs. The stepperonline motor looks nice as I can run it at a lower amperage for the same torque as the wantai. However, the wantai has lower inductance (at least on paper). So, how do I compare these motors?

dc42 · 31 Jan 2018, 19:39

Have you read https://duet3d.com/wiki/Choosing_stepper_motors ?

This one
https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html is also a good match for the generation 2 Duets.

bartolomeus · 31 Jan 2018, 20:22

@dc42:

Have you read https://duet3d.com/wiki/Choosing_stepper_motors ?

This one
https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html is also a good match for the generation 2 Duets.

Yes, I did read that. Based on that, I am looking for Nema 17 1.8 degree motors with <4mh iductance. However it still doesnt clear everything up (for me). If you have two motors that fit the criteria, is lower inductance better or lower amp rating? However, thanks for that tip, it didnt show up in my search on that site.

Phaedrux · 31 Jan 2018, 20:37

@dc42:

Have you read https://duet3d.com/wiki/Choosing_stepper_motors ?

This one
https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html is also a good match for the generation 2 Duets.

I'm glad you've linked those David, as those are the motors I chose for my i3 build, and I went for the 0.9 degree version for my CoreXY.

dc42 · 31 Jan 2018, 20:46

On a Cartesian printer the inductance isn't normally very critical. It's more of a concern on deltas using 0.9deg motors.

On the page I linked to there is a link to a spreadsheet, which you can use to check whether the motors will provide full torque up to the maximum speed you are interested in.

bartolomeus · 31 Jan 2018, 21:59

@dc42:

On a Cartesian printer the inductance isn't normally very critical. It's more of a concern on deltas using 0.9deg motors.

On the page I linked to there is a link to a spreadsheet, which you can use to check whether the motors will provide full torque up to the maximum speed you are interested in.

Thanks for clarifying. Regarding 0.9 degree steppers in the post above, I read that for a CoreXY there really isnt an difference in print quality. Or, as I am geeting new motors, I might as well get 0.9 degree steppers?

Phaedrux · 2 Jan 2018, 02:54

I wondered that myself. In the end I decided to go for a 24v system and 0.9 motors and figured that would help even out any loss in torque and might provide slightly better surface quality. The price was virtually the same.

Using that spreadsheet in the choosing your motors wiki page I should be getting around 150mm/s peak and 125mm/s worst case with the 0.9 motors, and 250/180 for the 1.9. That's not bad at all, and that's pretty close to what I found when I went through all those calculations manually when I was choosing them. That spread sheet sure makes things easier though!

bartolomeus · 2 Jan 2018, 10:23

Thanks guys. Searching around the internet, discussions about 0.9 vs 1.8 are highly theoretical, I haven't seen any proof of an advantage of one over ther other (for X and Y on a CoreXY). Question remains, how much holding torque does my printer actually need. There isn't much info on that. I found one mention of a mendel printer requiring app. 13.7 N·cm torque, and one recommendation for at least 45N·cm torque for a HEVO. So, I am going to order the ones recommended by DC.

The openbuilds motors look nice, but they are in the US, so shipping and customs costs really add up to the total cost.

jiusrugok · 13 Oct 2018, 10:18

You can have a look at this one:
https://www.oyostepper.com/goods-50-Nema-17-Stepper-Motor-Bipolar-59Ncm-84ozin-2A-42x48mm-4-Wires-w-1m-Cable-Connector.html is also a good match for the generation 2 Duets.

deckingman · 13 Oct 2018, 11:04

@jiusrugok I'd guess that as the last post was 9 months ago, the OP will have found something by now.