Summary I had a old prusa i2 frame lying around as i used up most of the parts for my mendel max. I thought that a great way to bring it back to life would be to convert it to a corexz ( the one made by Nicholas Seward ). That way it would get rid of all the z screw issues. I get a printable area of 190 x 200 with this setup. I have used 625vv bearings and 18mm aluminum spool.