Rostock Finally working Accurately- YAY!

Well I have been slack of late and never got around to debugging the Rostock printer.
I have had a long outstanding issue where prints were not perfect dimensions in X and Y
If for example I printed a large square 200mm x 200mm it would not be perfectly square. It would be out by a couple of mm in 1 corner.
I tried all sorts of measurements but could not work out the issue.
As I had a few days off over new years weekend, I decided to bite the bullet and fully rebuild it.

I totally dismantled it and cut new base and top boards. Assembled and squared everything up making sure everything was square and all rods are exactly the same length from the print centre, both Top and Bottom.
As mentioned in a previous post, I also replaced the printed rods and joints with manufactured Heim joints.
This time it all works very accurately.
Things that helped that I did not have as an early adopter for the first build:

• A good set of precise dimensions for the base and top boards. Previously its was all angles and distance from centre etc. Very difficult to get perfectly accurate. This set of dimensions lets you locate all the key points just by measuring from the top left of a rectangle board.  http://www.thingiverse.com/thing:34359 .  I still calculated the build centre point which is 175 In from the left and 175 in from the back. Lines going out from the centre point at 120 degree angles intersect the midpoints between each of the whole pairs.
  An important note about the diagram is that the holes on that are marked as 8mm. This is wrong they are only 3 or 4mm and are used to secure the plastic parts that hold the rods. The rods do not go through the board they are on the outside edges of the board.
• A good calibration guide: http://minow.blogspot.com.au/  This is an excellent source of information that clears up so much of the black magic. Thanks minow :-)
• A second try :-)  My experience from the first build made the rebuild easy. Basically it was done in a day.  

This time around I did not add the threaded rods for support. I am going to add some sides on the left and right sides that extend a couple of inches beyond the the back of the unit. I will then add a threaded rod X across the back for stability.

I will post an image once I have completed the build.