Quote Originally Posted by charlieuk View Post
just to add to thins the weight of the z axis is aprox 14kg and its on a 1605 screw and a 3nm nema 23. I ran it at 50% and it actually cut out sooner. I have got another set of pulleys coming which will give a 3.8:1 ratio so hoping that may help and in the mean time Im going to try taking of the spindle to reduce the weight and see what that does.
Charlie from what you told me regards velocity and Acc settings being so low and with 2:1 ratio then it should handle the weight without stalling or missing steps.
When my machine was vertical the gantry was much heavier than 14Kg and a single 6Nm nema34 which turned twin 5mm pitch screws via belts that where geared 1:2 to give speed so actually lowering torque by aprox half easily moved gantry. This means you actually have more torque than I do.!

If your absolutly sure there's no sticktion on the linear motion side then Things to check First is if the motor is wired correctly and performing properly.? Have you wired it in parallel or series.?

With 3.8:1 ratio you will be quite low on speed and Acc you'll reach which for 3D work you may want.? So I would try to find the cause.
Counter balance/Strut arrangement can't hurt if you have room to fit so I'd do this any way just to help take the the strain.