I apologize in advance if this is the wrong place to post this.
I have an ebay style black/blue chinese 60W machine with a Ruida 644XG controller, using Lightburn 0.9.15. I have been engraving rotary items recently, and I’m currently on a job with some tumblers that have thick paint. I wasn’t getting through all of the coating with 100%/50mm/s, so I dropped my speed to 10mm/s in Lightburn and after that noticed it did not seem slow enough at all. I set it again to 2mm/s just to see, and again it was definitely not going 2mm/s. The Ruida display shows the correct speed, but the machine is not following that… I can set it down to ~30mm/s, but I see no signs of slower movement at any speed setting less than that.
I thought it might have been a 0.9.15 bug, so I rolled back to 0.9.14, but still getting the same thing. I know for a fact that I have been cutting/engraving down to 2mm/s without the rotary, so maybe it’s just a rotary setting that I’m not seeing?
Does anybody have any idea about this?
Here are my settings -
There’s nothing in LightBurn that would do this, but it’s possible that your laser has some minimum in it, in the firmware. I am not aware of any low-end speed limit, but it’s possible. I will say that there is no difference at all between jobs sent in rotary mode and flat work - the controller does all the conversion on the fly - so if you can run the job with rotary mode off and it runs at 2mm/sec, but with rotary mode on it doesn’t, then it’s likely something internal.
First off… holy COW that was a fast response. Faster than any support “live chat” I’ve used. Talk about customer service!!
I’m not seeing anything at all related to minimum speeds. These are all the same settings I see when I read with RDworks too…
Your “X Start Speed” for engraving is 40 mm/sec. You could try that one. (to be clear, this is an educated guess, but it’s a guess)
Yep! That was it! I set X start to 5mm/s and it seems to be working perfectly now. I should have had the insight to try that myself, but thanks so much!
Hah - I’ve apparently ‘internalized’ how the Ruida engineers think, which shouldn’t surprise anyone I suppose. Happy that was all it took. 
Hey now - mind out of the gutter, this is a family friendly forum. And you’re crowding me.