Linear rail question

[njhussey]

There is not much price difference between 15mm and 20mm the trouble with 15 mm is it can be very tight in the z axis unless a lot of material is milled away. The Chinese stuff is fine you can buy it all at the same place including screws and bearings etc this is one place BST http://es.aliexpress.com/store/314742

I've got 15mm on my Y & Z and if I was doing it again I'd buy 20mm all round. The Z axis I've got round by using a 40mm thick plate and recessing it for the ballscrew and mounts so I could put the bearing carriages flat on the back plate...