This riddle is perplexing

My rotary is somewhat working…

Problem - When doing a circle it comes out as somewhat of a circle but not completely - see image

It is a GRBL 1.1h board, rotary is tested on both Y and Z axis - same problem. When I test my rotary it makes a complete 360 turn.

Anyone care to make a guess at how to solve this?

This looks a lot like backlash. I assume you’re engraving a circle in one sweeping motion.

The sharp corner shown with the arrows (down and to the left) is produced when the machinery is a little loose, reverse direction and the machinery ‘takes-up’ the slack. The soft predicted corner (opposite - arrows down and to the right) is generated as the engraver is continuing in one direction.

If you have a machined flat on a shaft and the set screw is slightly loose the motor will move without moving the gear causing symptoms similar to what you’re seeing.

Please check set screws and other possible loose components and report back. :slight_smile:

thank you.

I have retightened all screws on the pulleys, retightened the belt - I am sure nothing is moving that should not be moving :slight_smile:

and then I redid a circle.

And I am still perplexed…


It was indeed backlash, however it was well hidden in a bearing in the rotary device. I swapped it and circle are now actual circled :slight_smile:

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