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Motor shield stepper forward and reverse go the same directi
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Motor shield stepper forward and reverse go the same directi

by morrisford on Fri Mar 19, 2021 10:15 am

I have a motor shield v2 connected to NEMA 17 stepper running the sample sketch on an Arduino UNO. When I run the sketch, the full step part rotates but only one direction. The other parts of the sketch just make the stepper sort of jiggle about in one place. The steppers I am testing with were removed from a couple of 3d printers that ran fine until I stopped using the printer. I am using a 75 amp 12v power supply ( actual voltage 13.5 or so). Suggestions please.

Morris Ford

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Re: Motor shield stepper forward and reverse go the same dir

by adafruit_support_bill on Fri Mar 19, 2021 10:19 am

Sounds like it could be a motor compatibility problem. Please post the electrical specs of the motors you are using.

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Re: Motor shield stepper forward and reverse go the same dir

by morrisford on Fri Mar 19, 2021 1:41 pm

Thanks for responding.
The printer these motors were in was driving with RAMPS 1.4 using A4988 chips.

The code on the motor is
42bhh48-050-24a

The specs (from a 150 instead of 050)that I found are:

5.5 kg-cm (76.38 oz-in) 4 Wire NEMA 17 Stepper Motor with "D" Shaft

Specifications:
Popular for 3D Printers Similiar to Kysan 42BYGH4803-DC
Step angle: 1.8°
Voltage (V): 4.2
Current (A): 1.5
Resistance (Ohms): 2.8
Inductance (mH): 4.8
L0 Dimension (mm): 48
L1 Dimension (mm): 42
Holding Torque (kg.cm): 5.5
Control Wires: 4
Insulation Resistant: 500V DC 100 MOhm Min
Ambient Temperature: -35°C~+40°C
Operating Max: 110°C
Wiring Diagram:

That is what I could find.

A few questions:

What determines if a motor is compatible with this motor shield? Where can I find such information?

Is the shield compatible with the NEMA 17 motor that Adafruit sells? If so, I will buy one for this part (researching) of my project. I want to use Adafruit feather/wing for this project and I need motor control.

Thanks for the assistance.

Morris

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Re: Motor shield stepper forward and reverse go the same dir

by adafruit_support_bill on Fri Mar 19, 2021 2:14 pm

Resistance (Ohms): 2.8

That is not a good match for the shield. The shield uses simple TB6612 H-bridge drivers and does not have active current limiting circuitry. Using a 12v supply, the worst-case current draw would be about 4.3A per phase (8.6A total) That exceed the ratings of both the motor (1.5A/phase) and the shield (1.2A/phase). You could use a lower supply voltage, but performance would likely be pretty anemic.

Based on those specs, I'd conclude that the motor was designed for use with a current-limiting 'chopper' type driver like the DRV8825 or Trinamic chips used on many of the 3D printer driver boards.

For more on the subject see this guide: https://learn.adafruit.com/all-about-st ... he-stepper

The #324 NEMA-17 motor in the store has a 35 ohm phase resistance. So at 12v, the worst-case current draw is about 350mA/phase (700mA total)
https://www.adafruit.com/product/324

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Re: Motor shield stepper forward and reverse go the same dir

by morrisford on Sat Mar 20, 2021 8:42 am

Could you point me to a compatible NEMA 17 motor that is actually in stock? I know that amazon among other places has those kind of steppers but without some indications that a certain stepper is compatible with this shield I will continue to thrash around until I find a workable motor by accident.

Thanks
Morris

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Re: Motor shield stepper forward and reverse go the same dir

by adafruit_support_bill on Sat Mar 20, 2021 9:45 am

Sparkfun has a very similar motor here: https://www.sparkfun.com/products/9238

And Amazon has this one: https://www.amazon.com/STEPPERONLINE-17 ... ef=sr_1_10

One caution about ordering from Amazon. We have seen motors from Amazon mislabeled. Do check the resistance of one of the coils before powering it up. It should be about 30 ohms.

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