ok, first attempt using sketchup 8

[irving2008]

OK OK.. I should have qualified that thought process with 'theoretically'...

On a serious note, the laws of physics don't change, so if you're not getting within 70 - 80% of the theoretical numbers then something is very wrong. Now I don't profess, Jazz, to have your experience (or John's) of building these things, I'll admit I'm an amateur in the CNC world, but I've built, tuned and fettled enough race engines and other electro-mechanical systems to know that things generally, in my experience, behave the way I expect them to. For example a 10mm pitch ballscrew should generate 50N of force per Nm of torque and thats enough to accelerate a 50kg mass at 0.1m/s^2 i.e a velocity of 6m/min after 1 sec and 12m/min after 2sec. Now I'll accept that the error in the theoretical calculations above is an assumption of infinite travel. Of course, in reality on a 1m bed you'll need to start decelerating after 3secs in order not to run off the end (assuming your stopping torque is the same as your running torque), at which point you'll theoretically be doing 18m/min - assuming your motor is still producing sufficient torque at 1800rpm. So your overall transit time over the metre is around 6 secs minimum (probably closer to 7 or 8sec), which is an average speed of 7.5 - 8.5m/min, close enough to your 9m/min.