I've been making changes to UMMD's Z axis. I swapped and flipped over the bed lifting brackets on the Z axis linear guides raising the bed aout 50 mm. That let me shorten the extruder carriage. I also made some changes that allow easier maintenance/modification of the Z axis/bed system.

The awful, old way of releasing the belt clamps from the Z axis, and the old lifting brackets:


The new belt clamp attachment- easy to reach with a normal screw driver, and the new lifting brackets:


The shortened extruder carriage:



Now I'm working on a new bed support design. The old design used a 4040 t-slot tee with PTFE blocks to hold the leveling screws mounted in the slots of the tee. I recently found some instability in that construction so I redesigned it.

The new design uses a 1" square t-slot tee with PTFE blocks to hold the leveling screws, but the blocks don't fit in the slots- they are bolted to the tee using 1/4-20 carriage bolts. It's a much more stable way to mount the PTFE. I find the 1" square tee is a little more flexible than the 4040 used in the original design, so I may go back to the 4040 tee (with redesigned PTFE blocks) after some print testing, depending on the results.



I was out of PTFE so I built the new design using nylon blocks, but found that they gripped the screws too tightly for them to be readily adjustable. I've ordered a big block of PTFE and will remake the parts as soon as it arrives. Each block is held in place by a single carriage bolt (which allows for some adjustability in their position) and has a tang that fits into the t-slot in the tee to prevent rotation.

I'll be recementing the heater that is coming off the bed plate. I contacted Keenovo about it and they pointed me at a couple interesting links that say you should seal the edges of the heater with silicone after sticking it to the bed plate. Maybe that would prevent it from letting go of the bed as mine is doing. Maybe it would be a good idea to do that around the PEI that's held on the bed using the same adhesive...

Edited 1 time(s). Last edit at 04/26/2019 01:17PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

For everyone else who looks at that link and wonders where it says to seal with edges with silicone, there's a link inside it to a PDF, and it's that PDF that has that suggestion.

I did wonder.

Is that the Loctite 5399 ?

I ordered a brick of PTFE and made some new leveling screw blocks to fit the 40 mm square t-slot support frame. The leveling screws are much more secure now, yet very easy to adjust. Each block is held in place using a 4mm screw and t-nut.





Edited 2 time(s). Last edit at 04/28/2019 09:59PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Blog post on the changes...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]