This is yet another revision of this design but it has been modified so that you can attach the dumpstercnc (www.dumpstercnc.com) Delrin lead nuts with anti backlash springs, or the standard flange nuts.
The screw pattern is for the 3/8-12 1 start nut flange. I believe any others have a different flange size. You could just modify the drawing if you wanted to use other sizes.
I should note, my setup has this - "Add a .860" (21.8mm) machined cutdown flange with (2) .173" (4.4mm) dia holes." on the flange, which makes attachment a bit easier. This was available from dumpstercnc
Like the previous revisions, It's designed to take advantage of the aluminium blocks on this carriage to bolt into, making a much firmer attachment. Stock, PB recommend you bolt the leadscrew supports into plywood holes on the carriage, which strip easily and flex a lot, causing banding.