Cog wheel, belt size design help

[TeknoFreek1284]

Hello all, I am new to this forum, and I have mostly a software background so mechanically, I'm a little lacking. Anyhow, I have a stepper motor that steps 1.8 degrees/step and I need it to move a transport shuttle between 8 different positions 0.875" apart via a cog(timing?) wheel and belt system. What I need to know is how do I determine the size of the wheels and belt. I would like to keep the driver and idler pulley equal, but it's not necessary. I guess what I'm looking for is a formula or algorithm (must be my software-minded thinking). Any help would be appreciated.

 

[desertfox]

HI TeknoFreek1284

Depends on how many steps do you want the motor to do between the different positions for example:-

for 8 positions over 360 degrees = 45 degrees between each
position

and that would equal 45/1.8 = 25 steps of your motor per
position.

so 0.875/25 = 0.035" per step

now to find radius of pulley "r"

0.035= r * angular step of motor in radians

0.035= r * 2* 3.142 * 1.8/360

0.035*360/(2*1.8 * 3.142)=r

r = 1.11394" so 1.11394 * 2 = 2.22788 dia


so pitch circle dia for driver and driven = 2.22788" dia


regards desertfox

 

[strokersix]

Yes, but the timing sheaves will most likely be specified as number of teeth instead of pitch diamter. You will have to pick the closest available tooth count sheave and adjust number of steps between positions accordingly.

Mike