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foehnsturm

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  1. foehnsturm
    The first files are available on Youmagine https://www.youmagine.com/designs/um-magnetic-printhead-changer More abstract, generalized versions will follow.
  2. foehnsturm
    Magnets: I used these https://www.magnet-shop.com/neodymium-magnets/blockmagnets/blockmagnet-120-x-70-x-20-mm-n44h-nickel-holds-15-kg::53.html 12 x 7 x 2 mm. I'm pretty sure you can use any other similar magnet. As far as I know China is the main source for Neodym magnets. They should be available in China as well.
  3. foehnsturm
    The next step would be a Flex cartridge. The NEMA8 direct drive is too tricky to adjust right now because of varying stepper shaft lengths and the required adapters. As I already notice a huge order backlog at my regular businesses, I can't spend much time on this subject the next 4 weeks. However, I would like to see this project growing. I can put some files for the magnetic mount parts online. Maybe in two different sizes. Anyone interested to participate?
  4. foehnsturm
    So, Mutley3D, :wink: What would be the smallest possible footprint for a Flex cartridge? Just the worm gear box with knurled wheel, idler arm and a standard reprap hotend mount. 30 x 30 mm?
  5. foehnsturm
    If so, I would expect at least a complimentary UM3 :smile: Indeed, if you take both topics ("Best of two worlds - Flexdrive" and this one) together, this would be my concept for a - let's say - UM4. A modular system: housing, x/y/z motion system, electronics and a standardized magnetic mount up to 4 connectors for feeder/hotend cartridges various types of cartridges (perhaps Flex as default) even of other manufacturers, an entirely new market Future-proof and flexible. In my opinion this FDM segment needs a disruptive move, some outside the box thinking. Don't cling to the plug & play idea too much it'll never be that completely. But instead open up a whole new world of possibilities. So, if UM won't do it, maybe someone else.
  6. foehnsturm
    I would call that a success You can literally throw the cartridge into the holder. Anyway, it will be picked up reliably.
  7. foehnsturm
    Will be able to report on step a) (repeat accuracy) hopefully this week.
  8. foehnsturm
    I keep getting bad results. Tried the entire temperature range from 240° to 260°. With and without fan. Bed from 65° to 75° C. Using reasonable print settings: 0.15 mm layer height, 30-50 mm/s Below 250° there is bad layer adhesion. At 260°C I can print the shell but some corners get round (temp too high?) some show underextrusion. Sparse infill, even at the same speed as the shell, becomes a mess. I tried two different hotends - no success. I'm perplexed. Last spring in Erfurt I got samples of what was said to be a pre-production of the new XT batch. However translucent red, a color I can't find anymore for XT. It printed like a charm. :?: Note: I'm using a highly modified setup, Merlin hotend (tried also Prometheus), crossflow fan, direct extruder. But other filaments print perfectly.
  9. foehnsturm
    Thank you! ... http://www.wok-it.de (both in German) I just asked Mutley3D about his retraction settings. I think mine were too fast, so I had issues now and then. And yes, it's because of the challenge as well. :wink:
  10. foehnsturm
    That's cool. I think I was a little too fast then because I had these artifacts especially with many retractions and only little extrusion in between. Will revisit this.
  11. foehnsturm
    So what is next? a) Repeat accuracy testing with a NEMA8 direct extruder cartridge which has to be finished. b ) Building a second cartridge and cartridge holder Ideas so far: another identical direct extruder or a direct extruder with 1:20 gear and for 1.75 mm filament or a flexdrive cartridge 1.75 mm is interesting but a later dual extrusion test would require identical filament diameters afaik. c) Prepare for dual extrusion: electronics, firmware I didn't take a closer look into gcode generating for dual extrusion so far. Extruder switching would require a short roundtrip between the two cartridge holders and coming back to the initial position (with the usual dual extrusion offset, as I would use a two sided gripper). Cura Plugin? d) Replacing the bulky modular printhead gripper part with a most compact all-in-one design. e) laser cartridge, ink / felt tip cartridge for painting perimeters after printing ... Obstacles: Two main professions ...
  12. foehnsturm
    Sounds good. You want to have an area within the mounting surface where you can attack with a wedge shaped part for unlocking (or find another way how to break the high holding force of the magnets with comparatively low force). This linear move - wedge - shear force trick is actually the idea I'm really proud of :wink:
  13. foehnsturm
    Looks pretty good! What retraction settings did you use, the UM2 default as well?
  14. foehnsturm
    There is enough room for an adapter. You can use both, it depends on the length of the shaft. The second NEMA8 I bought hat such a short shaft that I had no other choice as to use an adapter.
  15. foehnsturm
    With a simple lever which increases travel to 60 mm one could lift a tool magazine in a way that it wouldn't interfere with the x/y rods anymore.
  16. foehnsturm
    Just posted the stl and step files at Youmagine https://www.youmagine.com/designs/modular-printhead-nema8-worm-gear. But still no BOM due to the reasons I mentioned earlier in this thread.
  17. foehnsturm
    Yeah, the Merlin hotend is easy to adjust because it features an outside thread and can be rotated against the aluminum mounting part. The more generic approach of course would be to design a slim mounting adaptor with slotted holes which can be attached to whatever hotend you like. Some procedure like: Mount the hotend with the adaptor to the gripper, loosen the screws, let it drop down to the print bed, retighten screws ...
  18. foehnsturm
    That'll be the next step. However I'll have to finish a second NEMA8 / worm gear extruder for that and this will require some free time which I can spend at my lathe. Don't want to disassemble the working one every time.
  19. foehnsturm
    Holy shit that's precise. It would be interesting to find out how much clamping force is possible with my lock/unlock idea. It's basically a linear movement onto a wedge which produces shear force to overcome the break away force of the magnets. Followed by a perpendicular movement to move away (or the other way around). Right now the stepper / belt setup has no problem at all with the required forces.
  20. foehnsturm
    Right, you can virtually add any kind of tool head if its z-height is properly adjusted. I'll use the free space in both right corners. It's a two sided gripper. There is approx 30 mm clearance between the x/y rods and the frame. So I won't loose noticable y travel. In fact you can use almost full x travel in the middle area you just have to avoid some area near these two corners (like the UM2 bed clamps).
  21. foehnsturm
    Just started: http://umforum.ultimaker.com/index.php?/topic/9657-a-different-multi-extrusion-approach-um-tool-printhead-changer/?p=94033 :wink:
  22. foehnsturm
    What impressed me most is that the tiny magnets work exactly as intended. There is no need for generating an additional signal or having an actuator. Just a simple movement pattern in the x/y plane.
  23. foehnsturm
    Space requirements: I'll go for the difficult job as I want my NEMA8 direct extruder to be the tool head. The "cartridge" will measure 30 x 40 mm, not that big for a direct extruder... The final gripper with a cartridge attached will be roughly 55 x 45 mm. The current one is big because I'm using my modular mount to be able switch to my standard printhead within a minute. Of course the parking lots take up some print space. I'll loose 50 mm of one axis. But that's only a prototype. If you go for a bowden setup , especially with a tiny hotend like the Merlin, it would be easy to have a cartridge with 20 mm square and the reduction of print space should be approx 30 mm in one direction. And even better: If you don't need multi extrusion, you could simply take out the parking lots and use the entire printing area. Oozing: The final parking places should feature some kind of heat resistant and soft material where the nozzle tip sits. And at least, the oozing doesn't harm the print. Durability: PLA printed parts might degrade due to wear and tear. But there are so many tool changers out there which are carrying really heavy tools heads with precision in micron scale. It should be quite easy to find optimum material combinations for this tiny mount (PTFE / Aluminum ?) Required time: One could park all heads closely together in a magazine but that would take up a lot of space. Anyway, I think the time for reheating the previously unused hotend is in the same scale as the required time for moving.
  24. foehnsturm
    I've been following this dual extrusion discussion for some weeks now. The more I read the more I get the impression that the usual approach doesn't fit for UMs at all. Too bulky, too heavy and so many well known flaws, like oozing and having the second nozzle knocking down prints. It simply makes no sense to me to carry around a second hotend all the time. So I suggested independently moving heads or a tool changing mechanism like CNC machines are using. I couldn't resist ... Just a proof of concept right now but way better then I expected: 0.0 positioning play within the mount, more than enough clamping force, no additional actuators needed C'mon, if I can get this far in two days ...
  25. foehnsturm
    Regarding extrusion control and preciseness I would consider the Flashforge at least one step ahead of the UM. The direct extruder and the firmware should be responsible for that. This would be even of more value without the echoing which can be seen after sharp corners. It's as always, the lightweight UM head should give you better positioning quality at higher speed but the current extrusion system falls behind. The Flashforge extrusion system could deliver super sharp corners at high speed but the heavy printhead causes other issues which will limit max speed.
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