Falcon rotary roller technical specification

Hello,
I’m have a Creality Falcon laser 10W + Falcon rotary roller.
I try to setup the rotary in Lightburn 1.7.06.
Does someone know the mm per rotation and the Roller diameter for the Falcon rotary, I can’t find this information anywhere.
I have tried are (40.29mm per rotation / diameter 16.80mm) and (41mm per rotation / diameter 17mm).
The 41/17 parameters give the best result i.e. the actual size of the frame is equal to the definition I did on Lightburn. However the engraved text is not perfect, the space between some letters is unpredictable.
I don’t if this issue is linked to the parameters or it’s a physical issue with the rotary itself such as release or tighten the synchronous bell.
I would appreciate any suggestion to resolve this problem. Thanks