foehnsturm
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Everything posted by foehnsturm
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Well unfortunately, due to the interfering rods the UM geometry is not the easiest setup for that. A H-type gantry would offer two sides where several tool heads could easily be docked without any interference with the rods :???: . -
That's exactly the point which distinguishes this idea from others. It's scalable. However, besides electronics, this requires smarter slicers and firmware as well. That's why I'm eagerly waiting for the new Cura. The fun really starts with different nozzle sizes and slicing settings for each extruder.
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What about laser cutting the flat, approx 3-4 mm thick part of the piece and using some washers in the corners? If you order say 5 pieces with 0.8 mm thickness an stack them that would be quite cheap and of better quality than laser cutting 3 or 4mm thick aluminum. I use cutworks.de but there should be similar job shoppers in Spain.
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It's the small version: 70 mm long, 36 mm high some more pics: http://umforum.ultimaker.com/index.php?/topic/9657-a-different-multi-extrusion-approach-um-tool-printhead-changer/?p=101813
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One advantage of this design is that the hotends always travel to the same position when not in use. So it should be relatively easy to add some kind of nozzle wiping / cleaning device on this path with no extra movement needed There are printers which have this somewhere in the back of the printer and move the printhead over it every time when changing extruders.
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My attempt too meet this one http://www.thingiverse.com/make:106961 Layer height 0.12mm, Faberdashery red and glow in the dark, 4 hrs printing time, no ooze shield / wipe tower etc. I'll stop with bi-colored animals now.
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This should be the last bi-colored animal for some time ... I wanted to see if I can meet this benchmark http://www.thingiverse.com/make:106961
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Regarding the (pickup) sound: Greasing the wedge shaped part works wonders! I used "Titanfett". Retraction: One of my two (supposed to be identical) hotends shows almost no oozing / stringing with a retraction of 2 or 3mm (direct drive!) when parking. No idea how the 2 or 3mm translates to with a bowden. The other one oozes with the same settings. :???: Congratulations for accomplishing this with an almost original UM2 setup!
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0.15 mm most times, 1.2 mm shell, 20% infill
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Yes, but I didn't install it yet. My modular system was designed for easy hotend change and the magnetic mount does this as well. So some space is occupied by a part which realizes a feature which is already there. If the magnetic mount proves its reliability I'll install the new part. But of course I'll keep the tried and tested modular printhead in reserve.
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The connection is 2.4 mm wide, 2.2 mm long, 15 mm high, FormFutura FlexiFil. It just bends. Stretching or lateral movement is virtually impossible.
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Another dual extrusion test http://www.thingiverse.com/thing:647840. Scaled to 40%, blue and orange PLA, layer height 0.12mm, printing time 58 min. Temp some degrees too high, especially for the orange. This one is not really optimized for dual extrusion. Scaled down like that, the orange surface is shallow (0.8mm, you almost can see the blue shining through) and consists of tiny bits, virtually just blobs of filament.
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The new tool holder. Printed with PLA and FlexiFil. It can bend a little, as the orthogonality of the x/y axes is already overconstrained which may produce additional friction IMHO.
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It's running at the moment, difficult to take a picture. This is from the video.
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Time for a short progress report. Spring steel strip to block the nozzle: bad idea Too weak to prevent oozing -> filament gunk conglomerates -> nozzle finally sticks to it -> disaster Rotating hotend in the groove mount to adjust height: good idea but with severe side effects The whole hotend assembly is not exactly centered -> adjusting height changes x/y offset of nozzle tip -> adjustment workflow turns into a serious nightmare Spring steel strips to push cartridge back into holder: brilliant idea The parked cartridge might start to move back a little (due to some force applied by the filament ...). If it moves too far the arm will hit its corner before picking it up -> disaster In the video you can see tiny spring steel strips which gently push the cartridge back into place before the arm arrives to pick it up. Direct drive and 3mm retraction when changing extruders -> no more oozing Next step: Adding small fans at the parking position. Right now there is less cooling airflow there -> PID lowers heating power -> when the hotend is picked up and moved into the cooling airflow the temperature drops some degrees -> the opposite is intended
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The 0.6 mm (0.3 on each part) will make a huge difference. I made a tight fit and used a drop of super glue. But you're right, if you want the magnets back you have to destroy the printed part. Linear bearings of lower quality can have horrible play in my experience.
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Macua85, Do I understand correctly that there is some play when the two parts should be locked together? Do the magnets really touch each other? The magnets will only act against forces which try to break their connection. They will not sufficiently inhibit lateral movement. That's the job of the cones. It should be impossible to move the two parts against each other except tearing the magnets apart. In other words: It's all or nothing. There shouldn't be any play at all as long as the print head doesn't fall down.
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At least I hope so. But I don't want to put any stress on UltiArjan :wink: As the magnetic mount is working flawlessly and the combination with the modular printhead is kind of duplicating features I'll replace this bulky part with a more compact design. This should save another 20 mm printing space in x direction. Just have to develop a design which contains some flexible parts so I can use double extrusion :smile:
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PLA with FlexiFil works well. Simple flexible button: Functionality inspired by https://youtu.be/mOWfX_b1jls?t=52s
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But z hop is not always a solution. With parts like the camouflage Ultibot the problem with the z hop is speed. The print would take endlessly unless it's a deltabot. I don't think blocking the nozzle for a short time is that risky. If one extruder pauses more then a few minutes then yes. But future slicers will have to detect this case because you'll have to do something then (lower temp ...) anyway.
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I tried to fight the oozing with additional cooling in the parking position. But the PID is a little overcharged with this. I ordered some tiny spring steel strips. The nozzle will be pushed onto such a strip when parked, the strip will flex a little and hopefully block the nozzle.
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You are correct. That's the standard sequence, generated by Cura. It means that the first layer with the new extruder will be printed at the same z-height as with the previous extruder. Then it does a z-move and prints the next layer with the same extruder. That's why adjustment of the nozzles is that important. But I would like to test a sequence with twice as much extruder changes but a z-move of layer-height / 2 between every "extruder-layer" (the post I'm referring to). Of course this is only of interest with my setup. It doesn't make much sense if you're carrying both nozzles around all the time. So I'm the first one to ask for it.
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Regarding speed: Compare this time for changing extruders with the commonplace nozzle switching + priming or wipe tower procedure :wink:
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Second print, 0.1 mm layer which is already close to the minimum for dual extrusion I'd say as nozzle height adjustment has to be very precise. I'd really see this implemented to have some clearance for the nozzle at any time: http://umforum.ultimaker.com/index.php?/topic/10337-dual-extrusion-turn-off-alternating-sequence/?p=100101
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I' love to bring this to the market. However, there are too many possible variants at the moment: UMO, UM+, UM2, UM-like printers stock hotend, Merlin, E3D, ... direct drive (NEMA8), flexdrive (bowden I'd exclude from the list) Evaluating these alternatives is essential if you want to narrow down the list. But this is beyond my time and budget as a one-man-show. So we need some sort of cooperation to bring this forward.
