Does anybody else dial in their rotary using the "User" tab (4th tab over from Work, Output etc.) and playing with the circle pulse setting? You can click the "read" button (with your machine powered up) and then scroll to the bottom and turn "Enable Rotating" on and off here. You then press the "write" button to send settings to controller. I just set the "diameter" value to the calculated diameter that the program would turn 360deg when the stepper motor itself turns one full rev. This came out to be (roller diam 24.22 x (32t/20t) = 38.75) and then I fiddled with the "circle pulse" setting while cutting out 10mm x 10mm test squares from toilet paper rolls and tweaking.
HOWEVER, I did get a weird thing once where I was engraving a glass and the first 20% of the program ran with the glass surface advancing a little faster than normal (resulting in a stretched out engrave). The last 80% finished normally. It was very weird, as slip would not make the surface move faster!
Actually, upon revisiting my math realized I did the pulley ratio backwards.
Now I'm not sure that it matters but I went and looked at the stepper driver and found that it is set to 2000 pulses/rev. I will try setting the "circle pulse" to that number and then adjust diameter to get a scaled image and see if anything improves. Then the settings will line up with what I was trying to calculate in the first place! Oops.
I watched the RDWorks learning labs on the rotary and will say that I prefer using an approach that doesn't require scaling of the job just before output, and this is for two reasons:
- convenience: why bother? what if you want to make an edit and have to scale back again? Image quality loss could result
- vector cutting/tracing: if you output a short line that actually physically moves as a longer line, then you dont get the same cutting speed at your part's surface. Duration of the move is the same while the distance moved in the real world is greater. X-axis cuts will be more vigorous than rotary axis move cuts.
The nice thing about this approach is that since the 3-roller rotary effectively drives the SURFACE of a workpiece rather than the center axis, this is a one-shot setting. All you need to do is toggle the "Enable rotating" on or off.
I've also used the User menu to solve the problem of having too little "Y-axis" travel when using the rotary. I think it manifests as "over slop" or something similar. If you move up the User menu a bit, you'll find a setting for "Y Auto home". I turn this off when using the rotary axis and back on when using the full gantry. This means that when you power up the machine, it only homes X and just leaves Y alone. No waiting around for the home routine to time-out and leave you with too little travel. Instead, my controller sets the Y position to something like 10000mm. Basically you have unlimited rotations, as you should!
Careful if you don't turn this back ON when going back to the gantry because the machine won't know where its ends of travel are and will crash into the brackets at the ends of the Y axis rails! Ask me how I know!
So, now I will try to calibrate my machine using 2000pulse/rev and something close to 15.14mm diameter and see how that works out. Hopefully more reliable! I also think it would be worthwhile to try to take some of the backlash out of the axis drive belts and see if I can get more consistent "texture" to my large area engraves.
Happy to post some photos if anyone is interested in my results and how I set up to do conical-shaped pint glasses
