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NEMA 17 with 5:! gearbox smoked Motorshield V2.2
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NEMA 17 with 5:! gearbox smoked Motorshield V2.2

by vwaterson on Sun Aug 04, 2019 4:56 pm

I was previously using a NEMA 17 with no gears however I had to use springs to enable to left a load vertically. It was suggested to me that if I used a NEMA 17 with a gearbox then thei would solve the problem

I did check the resistance on the coils

On the NEMA 17 with gearbox (See speck below) the resistance on each coil is 6.7 ohms. The resistance of each coils on the NEMA 17 without the gearbox is 42 ohms.

I have ordered another Adafruit V2.3 motorshield but am now concerned that will get smoked too.

Any thoughts on how I can drive this motor.

Thanks



Product description
This high precision NEMA 17 Stepper motor has an integrated Planetary gearbox with a 5.18:1 gear ratio, the resolution reach 0.35 deg. step angle.
It's a good solution in applications that need very low rotation speeds and/or lots of torque.

Electrical Specification:
* Manufacturer Part Number: 17HS19-1684S-PG5
* Motor Type: Bipolar Stepper
* Step Angle: 0.35 deg.
* Holding Torque: 2Nm
* Rated Current/phase: 1.68A
* Phase Resistance: 1.65ohms
* Inductance: 2.8mH+/-20%(1KHz)

Gearbox Specifications:
* Gearbox Type: Planetary
* Gear Ratio: 5.18:1
* Efficiency: 90%
* Backlash at No-load:<=1 deg.
* Max.Permissible Torque: 2Nm(283oz-in)
* Moment Permissible Torque: 4Nm(566oz-in)
* Shaft Maximum Axial Load: 50N
* Shaft Maximum Radial Load: 100N

Physical Specifications:
* Frame Size: 42 x 42mm
* Motor Length: 48mm
* Gearbox Length: 27.3mm
* Shaft Diameter: 8mm
* Shaft Length: 20mm
* D-cut Length: 15mm
* Number of Leads: 4
* Lead Length: 500mm
* Weight: 520g

Connection:

Black(A+), Green(A-), Red(B+), Blue(B-)

vwaterson
 
Posts: 70
Joined: Thu Oct 11, 2018 3:47 pm

Re: NEMA 17 with 5:! gearbox smoked Motorshield V2.2

by adafruit_support_bill on Sun Aug 04, 2019 5:17 pm

NEMA 17 is not a complete motor specification. It only a frame size designation that gives you the dimensions of the faceplate and where to drill the holes for mounting it.

The Motor shield uses a rather simple TB6612 driver chip that does not have any current limiting. So you need to consider the phase resistance when selecting motors and power supplies to use with the shield. https://learn.adafruit.com/all-about-st ... he-stepper

the resistance on each coil is 6.7 ohms.

According to the spec posted, the phase resistance is only 1.65ohms. This motor was clearly intended for use with a current limiting driver. Without current limiting, the supply voltage would be impossibly low and the performance would be terrible.

We do have a couple of driver options with current limiting. The DRV8833 and the DRV8871.

https://www.adafruit.com/product/3297
https://learn.adafruit.com/current-limi ... th-drv8871

Also check www.pololu.com for a wider range of current limiting stepper drivers.

adafruit_support_bill
 
Posts: 74326
Joined: Sat Feb 07, 2009 10:11 am

Re: NEMA 17 with 5:! gearbox smoked Motorshield V2.2

by vwaterson on Sun Aug 04, 2019 6:20 pm

Many thanks for your prompt reply.

The Polulu Tic T249 USB Multi-Interface Stepper Motor Controller supports 1.8amp per phase so its looks like this will handle the NEMA 17 5:1 geared motor. Just waiting for Polulu to respond.

Thanks again you have been most helpful.

vwaterson
 
Posts: 70
Joined: Thu Oct 11, 2018 3:47 pm

Re: NEMA 17 with 5:! gearbox smoked Motorshield V2.2

by adafruit_support_bill on Mon Aug 05, 2019 5:50 am

I haven't tried the Tic T249 yet. But the specs looks quite nice. My experience in general with Pololu products has been excellent.

adafruit_support_bill
 
Posts: 74326
Joined: Sat Feb 07, 2009 10:11 am

Re: NEMA 17 with 5:! gearbox smoked Motorshield V2.2

by vwaterson on Mon Aug 05, 2019 8:17 am

Thanks for the feedback which is most appreciated.

vwaterson
 
Posts: 70
Joined: Thu Oct 11, 2018 3:47 pm

Please be positive and constructive with your questions and comments.