Build Your Own SLA/SLS

I would really appreciate your guys' help.

My printer has a simple vat tilt down -> Z lift -> vat tilt up -> Z lower sequence. I'm using an UNO and GRBL. Currently every G1 code has its own separate line but I'd like to start the tilt up and z lower motions at the same time to reduce the total print time.

If I put both tilt up and z lower motions on the same line with just one G1 code I get an unexpected result (unexpected for me anyway), both motors seem to try to sync their arrival at the destination or something. It seems like one of the motors is slowing down to match the other motors total travel time. I don't think it is just the F setting because I have tried changing them and even just using one F setting that should be ok for both motors.

Any idea what is happening? Anybody know a way to just start both motors moving at the same time? Maybe there is another G Code code?

I think you might want to look into G0 instead of G1.

If I'm not mistaken, it isn't possible to set a feed rate with G0. I still need to control the tilt and z speeds but just have them start at the same time.