nate campbell published a new build:

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I used spabond which is a pre thickened rubber toughened epoxy that is used commonly in boat building. A good bit of effort went into make sure the two 20*60 extrusion ended up parallel. Ultimately I'm not sure how much of a difference it has made. The X axis is definitely extremely stiff though. Mostly I did it because I had some nice 3mm carbon plate laying around.

After running the machine for awhile I think if you want to push it hard stiffening the y axes is probably more important. If you are trying to make an aggressive cut along the x axis with the y axis in the middle there is definitely some vibration. It was very noticeable the other day doing some parallel finish of a curved surface. At the most aggressive part of the cut it was around 9mn deep with a step over of 1.5mn and a feed rate of 2000mm/min the cut started out great as it was near the beginning of the y axis but as the machine moved down the table it became an issue, especial as the cutter moved to a more shallow depth. If I was building again I would probably for go the plate on the inside if the y axis and attach the axis to the table. Maybe make a inside plate that attached to the top wheels and the x axis

 

The smaller one is for just the spindle cable. It seems to work just fine. Not sure what there is to be gained by replacing the two with one larger one.

 

I'm using cheap chinese LJ12A3-4-Z/BY proximity sensors that are available on ebay or aliexpress for $3-4 each. Haven't had any problems with them.