Guys and thanks for your comments. Well it's been 2-1/2 years later
and I've just upgraded my machines to 32bit, BLTouch and Titan Aeros.
What started the upgrade is that I began to print with higher temp
filaments which needed higher temps on the bed. This warped and damaged
the PLA carriage, notably where the extruder motor connected. This
allowed the whole assembly to sag over time. So I redesigned the
carriage to accommodate an 1/8" aluminum angle capturing the bottom
bearing and the back of the extruder. This time I printed out of Prusa
ASA filament, a much higher temp material, this stuff has great
qualities. Very high tensile strength which means great sanding and part
The double bearing/rail worked well for years, but I began to question
it when I was assembling the new carriage. I found that I had
intermittent snag/hesitation when test moving by hand. This happened in
different areas of the rail so it was not related to rail or bearing
geometry. I had the same problem with the initial assembly, but went
ahead with it and it never was a problem that I was able to determine. I
chalked it up to ball transfer in the bearings.
But on the new assembly I decided to change. The Titan Aero is a bit
heavier than the MK8, so i decided to eliminate moving mass by taking
off the TOP rail and bearing. This has the assembly essentially
"hanging" from the bottom rail, much closer to the nozzle than stock.
Movement is perfectly smooth with the single bearing. Subsequent prints
are just as good as the double and better than the the top single
original Folgetech design.
The new carriage is a bit of a better design too with replaceable cooling fan nozzles, easier to change that design if needed.
Let me know if you (or anyone else) is interested in the new design and I'll upload that too.
All the best, Don