I'm not sure if this is the right thread for this but I will ask anyways.
I have a stepper motor 1.8 degree per pulse and 200 pulses/rev.
I have a stepper drive set for 2000 pulses per rev.
I calculated the circumference of my pulley to 100mm/rev.

My question is how do I figure out how many pulses do I send my stepper drive for the pulley to turn 30 mm or 40 mm?
And do my calculations change if I set my motor drive to 400 steps/rev?
Any suggestions would be great.

 

You're better working in degrees rotation, that way just divide the angular distance by 1.8 this will give you how many pulses/steps to use.

So your pully is 100mm circumference @360deg, thats 1mm per 3.6degree so 2pulses per mm travel.

 

So to get 30mm 60 pulses?
How does the scaling on the drive effect this? I have the drive set for 2000 steps/rev.
How do I calculate how many pulses do I send to the drive to move the 30mm?

 

As said earlier,,,, 30mm is 60 pulses, your settings are 2000 pulses per rev thats 10times the amount,

1pulse is 1.8degrees or 0.5mm travel...

 

You say the circumference is 100 mm (Dia about 31.83mm) and 2000 pulses give 1 revolution or 100 mm travel.All you need to do is scale it so for 30 mm travel it is 30/100 x 2000 =600 pulses or for 40mm 40/100 x 2000 = 800 pulses

If you set it for 400 steps per rev then the calculation is
30 mm 30/100 x 400 =120 pulses 40mm 40/100 x 400 = 160 pulses

Les.

 

The term "pulses" is pretty generic. If your stepper controller supports micro stepping (multiple pulses per step) then that's something you need to consider in your math.

 

Thanks.

 

Yes it is micro-stepping.

 

OK so then your math would be .5mm travel per step. Stepper controllers are different, so read the docs for yours. If your stepper controller handles microstepping for you then you just tell it how many steps to travel, i.e. .5mm * steps = travel. If your stepper controller requires you to add pulses yourself for microstepping, then you would multiply/divide; .5mm * steps / pulses-per-step = travel.

 

Put a piece of tape on the motor shaft to act like a flag, set the stepping speed for something slow enough that you can count revolutions. Send it some steps and see how far it rotates.

Note that if your pulley has some inertia, you might have to gradually speed up the motor from a stop, then gradually slow down from full speed. Otherwise the motor might miss steps. Google microstepping, there's a ton of info.