GT2 - T2.5 Belt loop end pull tensioner

Whilst upgrading my printer, I needed an effective way to tension my X Axis.

I have made a few before, but this one is much more rigid, and uses less material than my previous designs.

At the moment it does have a slightly wide slot for the pulley,
but 2 - 3 washers will fix that, and give a little freedom for alignment.

it uses 5-11-4 bearings MR115ZZ, or the fanged version MF115ZZ,

the hole for the bearing is tight, which is good after all.