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Request: Direct drive Extruder for the UM3, which supports 1.75mm filaments

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Well almost true.

And by the way i really like the ideas, and the mods you make for your printer.

I don't mind testing the Zero-gravity extruder on the UM3. But i can already see that the design will need me to change the mounting of the cable on the cores block. And will only work for a single extruder setup, and not for a dual extruder (because of the extension torque shaft).

And i'm also in the process of changing and testing a 1.75mm conversion  from Solex for their printcore. (custom settings in cura allow you to change diameter of the filament, so it's only an issue with the mechanisms on the printer).

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Oh um3. @gudo did some design that would work with an um3.

The problem with um3 for flexibles (not semi flexibles but ninjaflex/recreus) is that the too of both cores has a visible gap when they are inplace on the printhead So to print a flexible with reliability it would need a new design of the top cover of the printer.

But all this, in the end, depends on the complexity of the objects you need to print. There are less flexible tpu, like polymax, ultimaker tpu, etc, that will print decently on a bowden, even allowing some degree of retractions.

The main thing you will need to change is the extruder, since the um3 design (same of um2+) doesn't have a close path for the filament, so a tangle could happen at anytime. That's a basic requirement for flexibles, unless you go ofc for semi flexibles that have more playroom.

I did on my um3 change the feeders to bondtech and even @gudo made me two cores for 1.75mm (long before 3dsolex made his simple changeable nozzle core).

By the way, a small observation, I'm starting to be more and more sure than 2.85mm could print flexibles better, just because the filament is thicker and is easier to actually make pressure, but ofc that will have more dripping and back pressure from the filament itself xor bowden.

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I agree with you there Neotko.

But for me the main problem is i also tend to test proto-filaments which can be brittle or too flexible. And i prefer for the brittle stuff  to produce the filaments in 1.75mm instead of 3mm, it makes it easier to use, and less likely to break inside the bowden tube. Plus if the material goes through any expansion after production before printing i can still feed it through the 3mm bowden tube, and just adjust the material thickenss in the slicer software.

As for the indirect path in the extruder system i guess it's there for the purpose of being able to swap printcores. But still what stops an individual fitting a removable adaptor from the top to make it a continuous tube if you end up using 1.75 mm instead of 3mm for the whole installation.

Probably you would have some problems in retractions, or heat transfers from the hotend, but other than that i can't think of any other issues.

I like the UM3 because by the time we manage to test any new designs which requires specially made custom filaments it takes forever to do it on the Statasys Object printers (too expensive to fix if you break it), while i can advance alot quicker using the Ultimaker or any other Filament based printer.

Edited by Guest
spelling mistakes (the usual for me)
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Interesting indeed. The thing is that you might need something with less precision (on the drive gear) like a mk7/mk8/e3d hobb gobblin that can actually work with 1.75 & 2.85 filaments. If I where you I would design a titan extruder adapter with a pancake nema (ofc you would need to change some details on the firmware by gcode and use some tricks) but that should allow you to use almost anything with the downside that you would have extra weight on the printhead.

If you usefor example s3d, and adjust the start gcode, you could have that working in a few days. The main changes for a print would be motor amps (a pancake uses less amps), esteps (to adjust it to the titan) and not much more. A decent design should allow you to keep the second core as it is.

Ofc you could just mount a normal nema17 but that's a lot of weight, but if your objective is to print slow that could work too. And by adjusting the gcode start you could pretty much play with the setup really fast.

Ofc I dunno how much into modding a machine are you, but it's doable. Gudo zge is more focused on giving as much precision as possible, that why it uses bondtech gears, and that ones are for 1.75 or 2.85, but not for both.

The issue using 1.75 on a 2.85 system is that it can create problems on retractions, lack of 'push' force to actually push filament without snapping ona bowden it due hyateresis, etc. And ofc, push back pressure that can create retraction problems, specially on filaments that get hot fast. But if you just want to extrude plastic without a precise control, indeed that can work.

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