I've taken Lee's suggestion and moved the SBR20s to the top and bottom of the Y gantry and placed them on a 45mm ali bar which is just the right width for them. This has needed a redesign of the Y stage but it is now of the 'box' type with the ballnut on one side, and the router on the other.

I've also upgraded all plate ali to 15mm. Thanks for all the input!

Here is a cut away of it, does it look better:

Click image for larger version.  Name: router2.jpg  Views: 352  Size: 63.8 KB  ID: 11261