X and Y step values

Hi guys,

I started with a Sunhokey acrylic framed i3 clone and it had X and Y step values of 80.5 to get the required scale in the printouts.

I have just completed a rework using Emotiontech's prusa i3 rework V1.5 and now to be able to get correct scale in my printouts, I needed to reduce my X and y step values to around 75.

I'm interested to know why I needed to do this.

My pulleys, stepper motors and belt pitch has not chnaged (although I did replace the belts) so the mathematical equation to arrive at the step values still holds true, but I am required to have lesser values otherwise my prints come out bigger than they should be.

I have my scale correct now but am interested in why my end step values don't reflect the calculation based on the hardware used.

Should I worry about it?

Cheers,

Steve

Because the hardware has some tolerance.
For example, step angle might be reported being 1.8°, but step accuracy is +/- 5%
So the real step angle is something between 1.71 - 1.89°

I'm guessing your real step angle is above 1.8°, so you need less steps/mm

I hear what you are saying mate, but the same hardware was running in the Sunholkey acrylic frame and I needed X and Y steps of 80 to get the scaling right.

Same hardware in a different frame, and I need to reduce X and Y steps to get the scaling right.

Cheers,

Steve

belt stretch is also a possibility

Thanks Dust,

I did replace the belts under the rebuild.

Cheers,

Steve

I looked at the Emotiontech's prusa i3 rework V1.5 specs on Thingiverse and the one aspect that would seem to make the difference is the different size bearing(s) in the Y-idler assembly maybe???. Different diameter may throw stepping off?? I assume the x-axis bearings are also a different size than the original too??

After thinking it through, the smaller idler bearing should not effect the step value. Are you using different pulleys (teeth count the same)?

A bit of a stumper...

Edited 2 time(s). Last edit at 09/09/2016 03:05PM by psneddon.