OB1.4 open beam single z motor

This replaces the 2 z motors with a single motor mounted on the top. The motor mount is based on the X motor mount from http://www.thingiverse.com/thing:1001437

You also need 2 * http://www.thingiverse.com/thing:1926143

There is the z motor mount and a bearing holder to replace the current Z motors (2 needed).

I have used some pulleys i had spare and used the gluing method for the belt http://www.thingiverse.com/thing:1814419

You need a couple if M8 bolts and nuts and 6 * 608ZZ bearings.

2nd plate made to lock bottom bearing in place. Place on top of Z_Bottom_Bearing.stl and bolt down. I'll upload a picture shortly.