Reduce friction on the rods and bearings

Reduce free play at the head rod ends

It gives a smoother movement and less noise when the directions changes forth and back.

I originally designed this to reduced a bit the useless friction that the standard plywood losanges were applying to the bearing and/or the X/Y rods.

This may not be significant. Also, a hole in the object would allow the bearing to be oiled also. To do so, you can also use the batman derived object on thingiverse(!), or as below:

Update: switched to these better end caps

Better, with a Nylon hub and free play adjustment (jwag55's excellent upgrade)

I printed the inside hub in Nylon to benefit from its nice properties (less friction, no wear, a bit of flexibility).

It is also a very good illustration why open licences such as Creative Commons are good, since this is a design by jwags55 inspired by mine (above). So I benefit from a free smart upgrade because I did not ask for money not prevented anyone from improving it.