Steps to Degrees with 3325_0 - 42STH38 NEMA-

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zuppaman
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Steps to Degrees with 3325_0 - 42STH38 NEMA-

Postby zuppaman » Wed Jul 30, 2014 3:01 pm

Hey,


I'm doing a test with a
3325_0 - 42STH38 NEMA-17 Bipolar Stepper with 5.18:1 Gearbox
http://www.phidgets.com/products.php?category=23&product_id=3325_0
And a 1067_0 - PhidgetStepper Bipolar HC

I'm trying to figure out how many steps are needed for a full 360 rotation.
From the documentation I figured the following.
360 degrees * 16 (microsteps for one step) * 0.35 (Step Angle on the engine page).

At first sight this seems to work but after every turn I have small offset.
Anybody has an idea what's wrong in this calculation.

Thx in advance.

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mparadis
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Re: Steps to Degrees with 3325_0 - 42STH38 NEMA-

Postby mparadis » Thu Jul 31, 2014 9:26 am

Your calculation is off by a little bit because the 0.35° spec is rounded. For accurate calculations, use the base step angle (1.8 for most steppers) and the fractional gear ratio. For this motor, the gear ratio is 5 2/11. So the real gear ratio is 1.8 / (5+(2/11)) = 0.347369...

The more digits you're able to use, the closer you'll be to the true gear ratio.

zuppaman
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Posts: 2
Joined: Wed Jul 30, 2014 1:38 pm
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Re: Steps to Degrees with 3325_0 - 42STH38 NEMA-

Postby zuppaman » Thu Jul 31, 2014 12:09 pm

Hey,

Thx for clearing this out so fast.
I tried the gearbox calculation myself but the notion was a bit confusing.

Thx for explaining this.


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