[GilchristT]

Hi, not having a problem per se, just looking to educate myself a bit.

I'm running Mach4, a PDMX-411 USB smooth-stepper and a GeckoDrive G540.

My machine was originally a Shapeoko 2, upgraded to X-Carve and a few other bits and bobs. I've rebuilt it lately for Mach 4 and some new wiring harnesses I've built.

Anyhoo, as part of the reconfiguration I'm having to fine tune the counts per unit. Using standard calculated values I'm out by about 1/2 a centimetre over a 30cm distance. Not massive and I have the tools to calibrate it but it got me wondering why this is needed.

I'm using GT2 belting and wheels. If the stepper motors are a set number of steps per revolution and the wheels and belting are a set distance per tooth, while I wouldn't expect them to be 100% accurate surely minor inaccuracies should even out?

I guess what I'm asking is where does the inaccuracy creep in or is that like asking how long is a piece of string?

Just wondering.

Tommy

[jalessi]

Tommy,

If you calibrate across a small distance a small inaccuracy is cumulative across a larger distance.

Calibrate over the largest distance possible and the error will be much smaller.

See attached video for some insight.

https://www.youtube.com/watch?v=ZAQHNYSYR2I

Jeff...

[ger21]

Those tiny belts can stretch a bit.
And I would say that 1/2cm in 30 is a massive amount.