I just received my X7 and am trying to figure out what the best setting are on LightBurn for cutting 7oz leather.
I had it set up at 5mm/s at 100% for 5 passes. The outer cut for a keychain was fine, but when I had it cut for the key ring hole it seemed to melt the top half of the hole. If I speed it up, it doesn’t cut all the way through. Just seeing if anyone has any insight for this engraver.
I am not sure, but i think there is some settings you can select on lightburn cut/engrave properties precisely to avoid that issue. 
I wouldn’t think Leather would melt. Is it releasing some waxy water-sealant or something from the hide-tanning process?
Air assist may help cool the cutting area significantly. You’ll probably be able to cut faster or make fewer passes. It’s worth trying.