I have an old ender 3 that I have been using for small laser projects and recently need to add a rotary axis. Marlin does't seem to want to run a rotary axis with out having to do a bunch of firmware changes (and even then it doesn't play well.) I purchased a black box earlier this year for a build I haven't started yet. So my question is to set up the 4th axis as A axis do I just leave the slave jumpers off? All I can find in the documentation is how to set the forth axis as a slave to X, Y or Z, is it possible to run it as a true forth axis (a)? I think I may just run the black box to run my ender 3 hardware with a rotary axis util I get around to building my other frame. Any insight on this would be awesome!