How to send carve toolpath to machine?

As long as you have the commands on the same line, it doesn’t matter what order they’re in.

M3 S12000

works just fine for me.

In UGS, type $$ and look at line $102. For an M8 rod I believe it should be 302. If it says something way off of that, change it and carve something in air to see if it’s closer to accurate.

sorry to be such a noob, Erik, but where is the machine control tab in Easel?

That was in Universal G-Code Sender, not Easel…sorry…