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Author Topic: Does pulleys affect config?  (Read 2764 times)


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Does pulleys affect config?
« on: October 10, 2015, 18:53:58 »

Hi Tom,

I must confess that I have a lack of understanding regarding the pulleys used with my mount.

I use 40 tooth on mount side and 20 tooth on stepper motor side. Step angle of my NEMA17 is
0.9 degree. And I own a EQ5 mount. Does this affect the settings in the config utility? --> see attachement please

Do I have to change my settings? And if yes to what values?

« Last Edit: October 10, 2015, 19:09:00 by AustroNoob »


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Re: Does pulleys affect config?
« Reply #1 on: October 10, 2015, 20:05:33 »

Hi Martin,

The "Motor Gear Ratio" is the ratio of the large pulley to the small pulley. So in your case this is 40:20 = 2:1, so enter 2 in the box.

The "Worm Gear Ratio" for an EQ5 is 144, so that stays the same.

The "Motor Step Angle" will be 0.9 for you as your motors are 0.9 degrees step angle.

"Axis Reverse" may have to be enabled. The only way to tell is once you run it, if you find the motors are going in the wrong direction (e.g. when sidereal tracking is enabled the stars move twice as fast), then you'll need to run the config utility again and click on the axis reverse button so it says 'on'. Depending on your wiring you may need both on, both off, or one on one off. Trial and error here.

Once the settings are entered, click update for each axis to calculate the correct ratios. When you are done, you can use the 'save' button to save the configuration to a file (in case you want to change it later), and the 'done' button to upload the settings to the EEPROM.

Tom Carpenter (AstroEQ)


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Re: Does pulleys affect config?
« Reply #2 on: October 11, 2015, 22:47:35 »

Perfectly easy explained. Thank you very much Tom!


Felipe Prado

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Re: Does pulleys affect config?
« Reply #3 on: September 22, 2017, 00:29:53 »

Hello! I wonder if this stepper engine is compatible with AstroEQ, and if it is just connect the RJ11 cables and everything works?
 NEMA 17 PM-K049B Engine (new model)
first engine for 3D printer (search the model).
Bipolar - 4 wire - Touch 2.7kgf
Product Type Hybrid Stepper
Step angle 1.80 degrees
Nema Size 17
Outside diameter 42 mm
Rated current 0.70 A
Resistance 6,2 Ohms
Steps 200
Rotor inertia 37 g / cm²
Torgue 2.7kgf
Motor mass 200 g
motor length 34.0 mm