Mendel 90 remix

First, I wanted to have a solid 3d printer for as cheap as possible. So I choose the model mendel 90 because there is not that much printed parts and the body is made of mdf and I'm used to work with it.
So looking at the plans and "vitamins" I realized it was going to be hard to make it for cheap: as I am in Canada (Québec, sorry for my English!) It was hard to find metric stuff. So I decided to work on plans to make it with imperial stuff for rods, bolts, nuts. etc.
Before I get started, I also removed from the original design every thing that is not essential to get printing. This printer can be built for less than 300$.
So here are my main changes:
1. I used 5/16 smooth rods instead of 8mm (7,94mm)
2. I used lm8uuaj: ajustable linear bearings
For this reson, every bearing mount is designed to be screwable. So you screw the bolt and nut just enough for it to be stable but not too much so it can move freely.
3. I redesigned the extruder to fit 6-32 screws and be more