[HN Gopher] Programmable Filament Gives Even Simple 3D Printers ...
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Programmable Filament Gives Even Simple 3D Printers Multi-Material
Capabilities
Author : headalgorithm
Score : 88 points
Date : 2020-10-31 15:28 UTC (7 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| leowoo91 wrote:
| Nice, this would be precise if start mark could be verified, so
| to prevent any shift error between transitions.
| teraflop wrote:
| Yeah, the paper mentions that the only way the authors were
| able to get reasonably accurate alignment was by manually
| adjusting the offset during the printing process.
|
| On my printer, the extruder uses a toothed gear that grips the
| filament by biting into it. The exact length of filament that
| gets displaced for a given amount of gear rotation depends on
| how deeply the teeth penetrate, which in turn depends on how
| tightly the gear and filament are pressed together, the
| filament's stiffness, ambient temperature, and probably all
| kinds of other factors.
|
| It seems to me that you could solve this problem in principle
| by printing a toothed pattern into the filament itself, so that
| the gear teeth automatically align it to the correct position,
| instead of deforming it.
| mrfusion wrote:
| You should write to them. That's actually a great idea.
| jepler wrote:
| Various people including me have proposed mixing filaments by
| printing the filament. However, there are some good ideas here
| that had not occurred to me. I suspect forms of this have been
| invented multiple times. I know of two: My design was
| deliberately gradient in nature:
| https://www.thingiverse.com/thing:3609741 and was inspired by
| someone else's design for an even mix of two materials:
| https://www.thingiverse.com/thing:3565827
| punnerud wrote:
| The was a Indigogo project that did not take off, where they
| demonstrated making filament from pellets using an extruder. Had
| this been extended with multiple color feeded to the extruder at
| the right time, it would make this technique a lot more
| practical.
|
| Maybe also more high precision because you can have the extruder
| closer to the printer, to match filament type with what is
| printed at any given time.
|
| I proposed the this technique about 5-6 years ago here on HN.
| Nice to now se it in real life.
| IgorPartola wrote:
| The problem is that an extruder that makes filament is
| something that can easily take up a room. It requires vats of
| water, wheels multiple measurement sensors, tensioner,
| spoolers, etc. And it still is unlikely to produce consistent
| filament compared to a commercial operation. I love the idea
| but I feel like you might be better off injecting viscous dyes
| into the hotend instead.
| punnerud wrote:
| Room size? Several examples that is home made and about the
| size of a hand (this from 2014):
| https://richrap.blogspot.com/2014/12/no-more-filament-
| quest-...
| lxe wrote:
| That's cool and all, but wildly impractical. Just thinking about
| swapping the filament dozens if not hundreds of times to print
| the intermediary filament that's capable of making each layer of
| the final product is making me tired.
| jstanley wrote:
| This is a really cool idea. I think the limitations are that you
| can only make filament rolls that are small enough to fit on your
| bed, and the precision with which the colours match the intended
| part depends on how much oozes out when you're priming the
| nozzle.
|
| I noticed that some of the parts shown in the video appear to
| have a wipe tower next to them. Presumably this is because the
| G-code was generated with Cura or similar, but given that the
| filament is one continuous piece with colour changes in exactly
| the right places, it seems like you could skip the wipe tower? Or
| maybe it's better to keep the wipe tower because it reduces the
| precision required in priming the nozzle?
| adrianmonk wrote:
| > _can only make filament rolls that are small enough to fit on
| your bed_
|
| I suppose you could print filament of arbitrary length by doing
| batches that get pieced together.
|
| Here's my best idea so far how to do it:
|
| (1) Instead of a spiral, print in a double spiral. Meaning a
| spiral that starts on the outside, goes to the middle, makes a
| u-turn, and then goes out to the edge again. (For the u-turn, I
| assume filament has some minimum turn radius and as long as you
| stay above that, it's workable to straighten it out.)
|
| (2) Pause printing, put a clamp over one end of the printed
| filament, yank the rest off the bed and wind it on a reel.
|
| (3) Resume printing, and repeat as many times as necessary.
| miahi wrote:
| I think the tower is still needed because when the filament
| changes you will have a blend, as old melted filament inside
| the head will combine with the new filament, it takes a bit of
| time/material to clear.
| orasis wrote:
| This is a good example of bad system design. It claims simplicity
| and elegance but will have a serious cost in robustness. Simple
| is only simple if it increases the robustness of the system.
| ChuckMcM wrote:
| This is a really cool result. Basically you know how much
| filament you're going to feed into a print, so you can back
| compute what part of the filament would be in what part of the
| print, and then construct a filament with the right materials in
| the right places. That it works as well as it does is pretty
| neat.
|
| I expect it also makes for some interesting print failures when
| you're print/filament registration is messed up. :-).
|
| If this becomes a 'thing' then you could design a filament making
| machine that would make a custom spool of filament. Even if you
| had a printer with a 'belt' for the bed, then you could make as
| much filament as you wanted.
| daemonk wrote:
| There is a commercial solution that fuses multiple materials on
| the fly as it feeds into the the printer:
| https://www.mosaicmfg.com/
|
| From what I've heard, there is a lot of filament waste still. But
| the results looks decent.
| rkagerer wrote:
| The approach in the article is novel, but multi-filament
| splicer/feeders like the one you linked seem much more
| convenient.
| moepstar wrote:
| If they'd work decently - ask people who have them, i "know"
| at least two on a 3d printing discord and what they have is
| basically a pretty expensive paperweight...
|
| I once saw some video about the buffer and the way it is
| flawed - also don't expect any print speed if you're using it
| :S
| maddyboo wrote:
| Am I the only one thinking about cascading the output of 4 of
| those machines into the input of another? You could achieve 8,
| 16, 32 color prints!
| jjoonathan wrote:
| Next step: pneumatic fast-change arm!
|
| https://youtu.be/G9ZdMgCMsV4?t=23
|
| ...with gigantic magazines!
|
| https://youtu.be/oTz2P5RaoDk?t=427
| teraflop wrote:
| This appears to be the Instructables post that the authors
| briefly mention as "inspiration":
| https://www.instructables.com/DIY-Rainbow-3D-Printing-Filame...
| ris wrote:
| Neat idea. Still needs a purge block of course, but I wonder if
| it could be altered to extrude it into another "purge filament"
| which could be used again as scratch filament.
|
| I guess there might be a limit on the number of times material
| can be extruded from a hot end before it starts to degrade?
| fabian2k wrote:
| Sound like an interesting idea, but probably quite limited in
| practice. They write that you can produce 20m segments of
| filament on a 30x30cm bed. That is already a somewhat large
| printbed, and 20m is not that much filament. So it seems like the
| use case would be small objects only.
|
| 3D printers can be very finicky, and I'd worry that the filament
| diameter and properties would be variable enough to cause issues
| here.
|
| My impression is that multi-color printing is far more limited by
| the amount of effort one is willing to spend on tuning everything
| until it works than just money.
| mrfusion wrote:
| This is neat but I don't understand how it saves time/effort
| compared to simply pausing the print at the right times and
| changing the filament then?
|
| The article addresses this but I don't understand their
| explanation.
| fabian2k wrote:
| If you have multiple colors per layer, you have to switch
| filaments at each layer. A typical 3D print has hundreds of
| layers. Manually switching is only an alternative if you print
| a continuous part in one color, and then switch to another
| continuous part in a uniform different color.
|
| In this method you have to only switch to each color once (if
| the filament length you can print is enough for your object).
| mrfusion wrote:
| Hmm. I'm not getting the switch each color once part. Why is
| that?
| fabian2k wrote:
| Printing the filament like in the linked article is
| essentially in 2D (not really, but for this point it's
| close enough). So if you have 2 colors, you can first print
| all color 1 segments, and then manually switch and print
| all color 2 segments.
|
| In a real object your print is 3D and consists of layers
| that are ~ 0.1-0.2mm high. In a typical multicolor print
| each layer has several colors, and you have to finish a
| layer before printing the next one. So you have to switch
| between all colors that are present in each layer.
| fentonc wrote:
| To create the 'programmable filament,' you only switch over
| to each color once as they generate the toolpath in such a
| way that the nozzle doesn't interfere with previously
| printed filament (and the printer resets the z-axis back to
| 'layer 0' each time it switches colors).
|
| For making relatively small, multi-material / multi-color
| prints, this really is a pretty clever system that looks
| reasonably practical on a wide variety of existing low-end
| 3D printers. With good software support, I could imagine
| being able to make things with interesting physical
| properties by making hybrid rigid / flexible materials
| (integrated hinges or other deformable parts, for
| instance).
| mrfusion wrote:
| I finally get it! That's really cool.
|
| This is what I wasn't getting:
|
| > resets the z-axis back to 'layer 0' each time it
| switches colors
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