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Re: Stepper motors with 7.5deg steps?

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7.5degree is 48 steps per rotation (full step)

This directly translates it to the accuracy of the machine

Presuming a standard belt driven axis using 2mm belt pitch and 8 tooth pulley and 1/16th micro stepping
1.8 steppers, 200 steps/mm gives you a theoretical resolution of 5micron
7.5 steppers, 48 steps/mm gives you a theoretical resolution of 20.82micron

On m5 leadscrews this translates to
1.8 steppers, 4000 steps/mm ie 0.25Micron
7.5 steppers, 960 steps/mm ie 1.04166666Micron

I don't think you will ever notice the difference.. Please try it

Right, the 1.04166666666666666.... - on the x/y (and z, technically, but that's not so important) this would leave an infinitesimally small fraction of a micron left over, shifting each layer by that much, correct? I know visually it wouldn't be noticeable between each layer but with a tall enough object / enough layers it would add up and lead to a small deformity every x number of layers. (poorly attempted ASCII illustration below)

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that 0.000001 something microns would stack up and after enough layers it would jump back to start, leaving a more noticable difference, and a weird pattern where one is not intended. That is how he explained it to me, I believe.

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That said I have been lurking various forums/threads and I think I'll give it a shot with the 7.5 steppers, worst case I just buy some 1.8's, best case I have a functional printer without buying new motors! :D

Thanks for the help.

Further discussion is welcome.

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