About this 3D model

SGK did a great job of integrating several good ideas into another good idea. Using this instead of separate bearing holders and belt clamps turns a lot of fiddly alignment and measurements into a trivial 5 minute install with perfect results every time with no measurements, and also fewer holes to drill. I've added a few more tweaks to his design. The previous design had the belt entering flush with the print bed which isn't quite right. This one has a parameter for space from the bed to the belt so the belt doesn't travel at an angle. Also, there's no need for two belt tighteners, so one of those is removed. The SCAD code has been cleaned up and commented a bit. The belt clamp module has been unified so that the one module can make any of the required shapes by providing the proper parameters (and global variables). A bridging layer has been added in the belt clamp nut traps for cleaner printing. The STL provided is an SAE model for #6 screws and GT2 belts. Modify the SCAD for other screw or belt sizes. The belt-to-bed spacing should only be different if you're using different bar clamps or bearings than the standard Iteration 2 Prusa parts. NOTE that the linear bearing holder SCAD file does not use configuration.scad so the screw dimensions need to be changed there as well.