Are you saying you have different stepper motors for X and Y?
Unless you have a Y<>Rotary switch, you normally plug into the cable to the motor.
I had wondered on the standard EZcad2 board which has two outputs for stepper motors, if you could just simply change the jumpers there at com 4, to effect the following change I explain otherwise. There are two sets of four wires for stepper motors but only one of the sets, pins 1,6 and 14,15 on the left side can be used for lightburn rotary. The way my unit was configured from JCZ China, these pins originally went to the programmable Z for their software.
My Y uses 2 motors and drivers, my X only uses 1. The lightburn rotary setup only has y,z,a no x. The manufacturer said i could damage y drivers if i only use 1 y driver leaving the other unattached to accomodate single motor rotary. I just want to have my rotary chuck or rollers run plugged into the X driver.
This is because the rotary should have the least travel, with the primary motion being in the Xaxis. Do you have a 4-pin connector on the controller board for a Zaxis drive? If not, someone with your type of machine will have to jump in and assist.
I have two sets of four pins on the standard ez2 board lmcv4 and they are found on the 15-pin din
The rotary should always plug into the cable from the motherboard to the Y axis motor . Unplug the cable from the Y axis motor and plug the rotary into the cable that comes from the motherboard. Unclear from your post why you cant do that? Send a screen shot of the Lightburn Laser Tools screen.
If your y has two motors i dont think the rotary is going to work.
Maybe is was wrong. Check out this link that has directions on how to use a rotary with a 2 motor Y axis machine. I cant get my head around how this would work but look at the instructions in the link below
Check out this post from a while ago. Someone had the same issue. I didnt read through it to see if there was a solution here
Here’s another link that might help
Considering all the available evidence, I have no idea why your manufacturer (actually distributor) would say this. My DLC board has 2 Yaxis connectors, but my gantry machine only has 1 motor moving it.
I believe the scenario OP is describing is different. He’s saying he’d have one of the 2 Y-axis motors still plugged in. And replacing one of the motors with the rotary. That means both the rotary and one of the Y-axis motors would be driven at the same time. That could lead to a mechanical issue.
@Odlaw, you could try working around this by not enabling Rotary function in LightBurn while connected to X-axis. Just use the normal flat mode. This will require you to manually adjust steps/mm on your controller for X-axis for each job. You could setup a macro to do this.
Not what he quoted, although that might be what he was thinking. Of course, I had no way of knowing what he was thinking. 
I just reread it and I can see your reading of it.
The key ambiguity here is the word “unattached”. I interpreted this to mean that the other driver is unattached to the rotary but still attached to the other motor. I think your reading is that it’s unattached entirely which may be the more obvious reading now that I revisit it.
Thanks all for the help. I will try using X and adjusting steps for 360 deg rotation of object to be lasered. I also will switch the angle which at 0 now moves x for lasering then y for increment. Since my rotary will be 90 degrees from a typical Y setup, I will change the scan angle to 90 to laser while moving y and increment using X. This cuts down on constant rotation moves. It is interesting to note that I have seen pics of other lightburn screens rotary setup that does have x as an option. Must be part of machine info on some. Believe it or not.
Where have you seen this?
That’s the rotary setup for galvo machines. Very different situation.
I guess my point is why isnt that option available for diode machines?
Can’t say for certain but likely because it’s uncommon and unconventional.
Thanks for your input and I agree. Its just a matter of workspace layout for me and my wife bought the wrong all in one rotary for xmas present. I dont want to tell her to send it back. Ill get it to work. Just wanted an easier solution then changing settings etc.
Happy wife, happy life!
If it has a chuck, with only one exception I have seen, they all look pretty much the same. Make it work, she will be impressed.
If you setup a macro this shouldn’t really be any more steps than any other rotary.
If you have 2 drivers for the Y, the stupid easy trick might be to get another stepper motor and attach the rotary to one of the y drivers and attach the other (loose) stepper to the other drivers.
I’d disconnect at the motor ends (usually more accessable).
This way both drivers are loaded and shouldn’t know the difference and you have it working the same as everyone else.
nema23 can be had pretty cheap, or if like many of use you might have one laying around – I usually have 6 or 7 spares JIC
But then I have 3 3d printer, 2 laser engravers and a 3018 CNC