# Thread: 1mm position accuracy for timing belt

1. Good day all,

I am a student doing a design project on timing belt and pulley with design considerations.

I need to achieve a position accuracy of 1mm. Initially, i thought that a 1mm pitch will do the job, but apparenatly, the pitch and the position accuracy is two different issue. I am very confused of how to achieve it.

Do i need to find a smaller pitch size pulley? (I tried searching but to novalid.)

My current design
Given Centre Distance = 1500mm
Calculated Minimum Diameter of pulley = 3.074mm
Ideally Gear ratio: 1:1

Would apperciate if someone would give me some light about it. Thanks

2. Surely the position accuracy is not so much a function of the belt but more to do with the stepper motor angular movement ? or whatever is driving the belt.
Also you don't say where the required accuracy has to be measured ? belt position, driven ball screw, item connected to ball screw via ball nut, etc.
Last edited by EddyCurrent; 31-01-2015 at 09:57 PM.

3. Originally Posted by EddyCurrent
Surely the position accuracy is not so much a function of the belt but more to do with the stepper motor angular movement ? or whatever is driving the belt.
Also you don't say where the required accuracy has to be measured ? belt position, driven ball screw, item connected to ball screw via ball nut, etc.
hi eddy, thanks for replying.
What do you mean by the stepper motor angular movement ??

By position accuracy i meant the motion accuracy and reliability of the belt position.

4. Originally Posted by motomage
hi eddy, thanks for replying.
What do you mean by the stepper motor angular movement ??

By position accuracy i meant the motion accuracy and reliability of the belt position.
Well something has to be driving the belt, the belt is just to transmit power therefore it's position is determined by the prime mover.

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