The longer the motor, the more indusctance it will have, and will requre more volts to get it going.
Also the 80mm long motors are not in stock and will not be for at least 8 weeks, this is at MCP and also Zapp.

I am not in the office at the moment, but will get you the datasheet later today, but this image may help you :)

www.slidesandballscrews.com/pdf/sy85 torque curve.jpg


Quote Originally Posted by Robin Hewitt View Post
Hi Gary
That was jolly good of you sending that
I am quite happy to upgrade all the stepper drivers and power suppplies to higher voltage, but I want to start with the 40 volts because it is already fitted and working.

Next one up in the Changzhou Fulling range is the 80mm length, largest I can fit, have you got a pdf for that one? Do I want to wait?

Much ta

Robin