Quote Originally Posted by Ians View Post
If I could ask a burning question straight away, Maybe it sounds a bit big but I'd like to build it to the dimensions of Y=1500mm X=1000mm Z=350mm with Ball Screws and Linear bearings, Would 2005 C7 Ball Screws on all axis with (fixed support bearings on both ends) be a bit overkill or should I use a 2005 on the Y axis and 1605 on the others?
There's no point getting 20mm screws if you're not exceeding the critical speed of a 16mm screw - it will only serve to reduce your maximum feedrate and acceleration.

With angular contact bearings on one end and standard bearing on the other end with 16mm the critical speeds will be 7000mm/min and 3000mm/min. With 20mm 8500mm/min and 4000mm/min (approximately).

Remember that with 10mm pitch screws (RM1610 for instance) you will of course get twice the above feedrates. Since it's not that useful to have one axis (except Z) a lot faster than the others I think 10mm pitch, 16mm diameter on Y and 5mm pitch 16mm diameter on X would be a good setup (7000mm/min and 6000mm/min ... assuming your motors have enough torque etc...)

It might be worth doing a rotating ballnut set-up like I did on my 1700mm (2092mm screw) X-axis on your longest axis. Depends how fast you want to go.

A 350mm Z-axis makes things tricky ... see my router (400mm Z)! You will want to either make it shorter or not have gantry sides.