Time to go vertical.!

[JAZZCNC]

Presumably before Jazz 'went vertical' he had a decent safety margin in his X-axis feedrates so he just used up some of this.

Yep Exactly.!

I think the short answer is "it all depends". clearly the ideal(ish) option is for the gantry to traverse horizontally in X so the Y is vertical and only the cutting head/Z-axis has to be lifted against gravity, but then you lose the benefit of having the chips fall into clear space. Unless your X-rails are space out from the bed in some way.

Of course, you shouldnt be running near the stall point anyway, there's a high chance you'll lose steps on fast direction changes if you do...

If you see my first post it explains how it came about being in the vertical position. It wasn't my first choice and if building from scratch then I'd run the gantry horizontal has it's a no brainer to why. . . . Other things aren't so obvious untill you've run it in this position.?
Little things like avoiding chip collection areas so need careful thought re-covers for Z axis, ball-screws etc to stop chips building up on rails or end bearings. The ball-screws on X axis will be better positioned behind the bed again to protect from falling chips. Not a problem in the vertical position.

I presume the weight of the gantry and Z and spindle will have a greater effect on the motors when used this way up ?

If you were pushing the motors to the limit when horizontal, then surely they would stall when up on end ?

Yes would have an affect if at motors limit but then Like Irving points out that's a bad idea in any case or machine. Pushing the max is one of the most common causes of missed steps and positional errors.
My machine is capable of nearly 12mtr/min but I run it at 7mtr/min in favour of acceleration. I always leave a minimum of 10% safety on velocity and often more like in this case when wanting higher acceleration. In all the time I've run this machine it hasn't ever missed a step or lost position unless I've caused it by hitting something, even then it takes a lot to stop it which wouldn't be the case if I run it anywhere near the motors corner speed.

When tipped vertical it made no difference to performance and still has enough torque to cut heavy depths. The video of it cutting 10mm single pass was 5mtr/min but it actually cut another at full 7mtr/min and then for the final test it cut full material thickness of 12.5mm single pass @7mtr/min with no problem until the really really knackerd cutter snapped.!! . . But the machine didn't stall it just kept on going like nothing happened.!!