Long X-Axis

Yellow superstructures on both sides don't provide enough stability. They're planned to be replaced by aluminium bars. 

Based on Richard aka. rbudding's feed-back, I tried the railway wheels with rubber band.

They match perfectly on the aluminium bar.

The idea about the X-axis is to improve stability and reliability. 

The all-plastic solution I used previously was fine but the moving deck wasn't easy to locate with precision. The X-axis motor, actually an encoder-motor, was on the moving deck, making it big and heavy.  

So basically, the X-axis motor should be stationary and the moving desk carry only the Y-axis motor. 

To achieve such a goal, I performed various tests, using long metal axis for guiding and moving, and aluminium bars.