Now it really feels like I’m making progress! I have thoroughly tested Logan’s 45 Degree linkage system 
I really like the new calibration routine for triangular kinematics. I was quite easily able to establish quite tight tolerances across the entire bed. Scored 1.58 : 0.5 for my calibration benchmark. Below are the results of the benchmark test:
So I dove right into the more tortuous test. I was quite pleased that the sled stayed stable during the entire program. I didn’t have to babysit the chains and make sure that they didn’t skip. Here’s the results of the test:
One thing that I found interesting is how I lost a lot of X-Y tolerance at the center of the bed. My guess is that I’ve calibrated it for the long dimensions, not the tight tolerances in the middle. I’ll have to spend some time messing around with the simulator to see how I can tighten my tolerances a little.
As far as assembly, I thought the kit was a little more involved than the top mount version. The top mount you bolt together a handful of components and mounted them to the sled. The 45 degree linkage kit I did much more prep work on. Sanding and assembling each of the components took more time. However, the assembly is solid. The parts move smoothly, and there is very little slop to the system.
The other design consideration is that the lower right mounting point really crowds the Z-Axis. It’s not impossible to fit both the standoff and the axis’s brake, but it’s something to be aware of:
All in all, I like the 45 degree system from the testing I’ve done today. The above tables would suggest that it has better accuracy than what I was seeing with the top mount. However, the last time I ran the top mount was before the chain sag calculations and the new calibration system, so the jury’s still out on that one.
Next weekend I’m planning on testing that 