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3D printing shredded failed prints with a prototype pellet extruder
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- Опубликовано: 18 авг 2024
- I have been trying to recycle waste 3D prints for some time now, so I jumped at the opportunity to borrow a prototype Bravo pellet extruder from Polylab. This video takes you through my experiences.
Plenty of hours went into this but ultimately I ran out of time to get it all working as I would like. My results here were mixed, but I think with more time things can be improved. The product will also inevitably be further developed, including documentation on slicer quirks and other aspects I struggled with.
I will continue to pursue pellet extruders such as this as well as filament making machines.
Thanks to Chris from Polylab for lending this extruder and for his support throughout testing.
Polylab website: polylab.org/
Thanks to Mark Mitchell from Proto Hub for his help selecting the HRC coupler for my shredder: / protohubau
Archimedes screw wiki article: en.wikipedia.o...
My first video on shredding plastic: • Recycle waste 3D print...
My second video on shredding plastic: • Recycling waste 3D pri...
0:00 Introduction
0:57 What is the Polylab Bravo? Interview with Chris Larkin
3:26 My current 3D print shredding setup
4:48 Unboxing and installation
8:39 Differences from conventional FDM 3D printing
10:40 Testing, results and troubleshooting
15:32 Conclusion
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Seems like a better solution would be to have an independent extrusion system that essentially creates "homemade" spool of filament. Rather than trying to go from trash to print right on the printer itself. You could theoretically achieve higher extrusion rates and more consistent feed as you only need to create the filament with the parameters under which it will deliver a uniform diameter, without adding in all of the variables necessary for actual printing.
That would be ideal but its significantly more cost effective to just directly extrude the plastic. Extruding and making spool filament with the required tolerances will require a separate larger machine all by itself.
@@infernaldaedra I disagree. A Filastruder and Filawinder set up is considerably less expensive than this thing is expected to be, and getting filament consistent enough to print with isn't really that hard, considering most printers can handle a pretty wide variation. As long as you're not expecting production quality filament, it will be a lot more reliable than this extruder.
But hey, it's still a prototype. It's essentially a scaled down filastruder, but with the main problem that when extrusion slows down due to material delivery issues, the printer doesn't know it, and doesn't slow down accordingly. A Filawinder will only wild when needed, so the extrusion can speed up and slow down, and still have a continuous spool of filament as a result.
@@infernaldaedra I disagree. You need to produce the filament with an extruder with a much larger hot area with 2 zones, the first with a small nozle and a second with a large (filament size). Pressure and temperature need to be constant in the second one.
Heating and cooling cycles break the polymer chains of plastics so as direct recycling additive manufacturing (DRAM) matures, it will eventually produce higher quality prints than recycled filament ever could.
@@brawndo8726 I won't argue the chemistry, as that information is quite common in these discussions. All I know is that I've printed with recycled ABS, which means it's been through at LEAST FOUR cycles... original extrusion from pellets, printing, re-extrusion from ground up scrap into filament in my Filastruder, and finally printed again. This is assuming that the original process that created the original pellets did not involved heat. If it did, that's 5 cycles. Some of the stuff I've printed is already back in the scrap bin to be recycled again. I honestly expect it to be fine. I've seen people doing the same as me with stuff that's been through nine times. I certainly won't be putting this stuff to use in prints where the original characteristics are necessary for the items functionality and safety, but this still beats the hell out of sending it to the landfill, never to be used again, other than as a microplastic to help kill the planet.
That said, I do agree that *IF* this can be made to work/print reliably, it will be nice to cut at least one cycle out of the process.
Just got this video suggested as I was looking for recycled filament videos. Have to say this is the first inline, direct to printing system I've seen. I hadn't considered that. I'm impressed.
Grind consistency is key. Bits that are different sizes will progress through the melt zone differently.
Yeah.... I think running scraps through some sort of... pelletizer.... lol would help a lot.
Just like coffee, the better the grind consistency the better the outcome.
14:41 *Benchy result comes out.*
Teaching Tech: *Visibly disappointed* "YOU'RE GOING BACK IN THE DEATH MACHINE!"
Aww. :( now I feel bad for the sad, ugly little benchy
@@BRUXXUS That's the circle of life. Or one could call it "The whirlpool of benchy". :D
Very informative. The recycling of our waste is an area that I hope to see many more solutions coming from familiar and new suppliers.Thank you Michael.
This is awesome, looking forward to a video from the final production version when ever it is out.
Paint ball has solved the jamming of pellet/ balls issues long ago with a agitator in their hoppers. One could use their design inspiration for this purpose.
First i would put a weight pressing down on the beads from the top. Then add a agitator closer to the entrance of the auger.
That weight would cause issues when dispensing more material live wouldn't it?
I would think that an agitator would cause vibrations that would affect the quality of the print.
@@drkline69 google how a paint ball hopper works. Its a tiny servo motor that turns a 3 blade paddles to force the balls into the feeding mechanics.
@bluephreaker its a 1kg hot end whats another 80g more LOL.
To be honest its not a smart idea in the first place to put a bead extruder on a hotend. Its better to make known size material like filament and use that to print.
I can always count on this channel to put me to sleep when I need to be ready for work in the morning. Thank you.
I believe this concept would need some kind of pressure sensor in the meltzone, to automatically compensate for pellet flow incinsistency in real time.
That is similar to how our industrial extruders operate, in which a PID controls the pressure, and you adjust your temperature to the compound in use. On an industrial scale, it seems pretty consistent. It seems like it would be scalable.
The size of the waste plastic should be reduced too..those seem rather large for that small setup
@@Gearhead73 That might work, but do features like the layer hight influence the pressure at that position? And do sensors of that size exist? If there is model, so the needed pressure is known, I guess that might fix the current problems.
@@merkatorix The sensors are around, even at that operating range, but they are expensive for the application. www.mouser.com/ProductDetail/Measurement-Specialties/M3031-000005-10KPG?qs=6mErgoZBfVIodfSpkT4ApQ%3D%3D
@@merkatorix I guess I should have looked a little closer,that sensor that I linked is only rated up to 85 degrees C.
Hello,
we are also working on this kind of extruders. Whatever the model, the problem is always the same : the output depends on the speed of rotation, but not only. The flow rate is also a function of the time variation of pressure. There are many cases where there is a variation of pressure during printing. When the nozzle moves in Z to make a free path of deposit for example. Moreover, there is no linear relationship between the speed of the archimedean screw and the flow rate, so it is necessary to be able to take it into account in the slicer.
It's really a big challenge to make nice impressions with this kind of material. It is likely that the focusing will be very painful for you too.
There are many alternatives, for example direct3D or mahorxyz, which provide alternatives. Mahorxyz starts at 330€, which is much more affordable.
A cell phone vibrate motor mounted on the hopper would do it! You could power it off your 5 volt output too.
Thanks Michael. I really like the idea of being able to recycle failed prints. I'm not sure about adding a vibration motor. Introducing vibration to the printer seems like a bad idea. I reckon they could add a secondary auger to the bottom of the hopper geared off the main auger. This might even be cheaper and lighter give the assembly is already heavy at 1kg.
I would like to see them do a cost effective filament extruder. I think that would really help to separate the issues. I've been looking for a while for a option that won't break the bank. Even if it's slow. I could live with slow.
As long as it's faster than my printer eating up all the filaments I would be good with it.
Right, but filament extrusion is also complicated to do well. Lots of hobbyists and small companies have been working on this for years.
I very much want the idea of recycling failed prints come into fruition. And to be able to done in your own home is the end goal. I feel guilty to throw out my failed prints. I've kept all I've ever done. Waiting for such an invention which can be affordable to the average Joe. When I was watching the video I already thought in my head it needs some vibration to assist in consistent feeding. I'd love to see an update on this later on down the track. Very much interested.
It's great to see someone has made advancements with recycling, I have a wheely bin half full of purge strips and failed prints, I am thinking of making a brush from the purge strips and PLA sheets from the failed prints but it looks as though printing from failed prints may not be a pipe dream!
I think there is a big potential in extruding the shredded plastic an pelettising it. The run it through the bravo. Or even a filament making machine.
Nice approach eventhough. I look forward to recycle my failed prints at home 👍
I totally had the idea of adding in some type of vibration agitator system and then that's when you brought up their comment on adding one in lol.
I had a simple solution in putting that idea to good use, to keep a nice steady flow of the recycled bits to ensure that there aren't any air gaps in between causing the intermittent under extrusion ...
My Very simple and straightforward idea 💡↙
**What I was thinking as a temporary substitute until they either send one out or implement a more commercialized one, Is combining the cooling fan or placing an additional little 40X40 or 50X50mm cooling fan and cutting out 2 to 3 of the fans' fins, causing the balance to be thrown out ever so slightly that it now turns itself into a 2 in 1 problem solve lol Implementation I feel would be simple to just 2 simple steps.**↙
#1. Print up another bracket for a mounting solution.
#2. Fix to the Recycle Hopper however you deem fit.
#3. You will now reap the rewards 💲💲💲of no more under excursion all while being able to Cool/vibrate those pellets down to where they belong!!💯💯
Good luck and happy printing!! I hope you find some use in my idea and if not, You've most likely come up with one much better anyways lol 😆
I'm just wondering why you haven't gotten (or made) a Filastruder.
We experimented with a prototype we built and found there are a lot of hurdles to cross potentially making the cost effectiveness not viable in our case but it is a cool idea. Two possibilities for your most obvious problem we solved, the supply feed. The backyard approach increased the acceleration so that directional changes caused a small jerk to reflow the pellets, the chute design may need some tweaking to support this better so there is no pellet splash out of the hopper. Of course it will cause corner issues and possibly ghosting depending on how much jerk is needed to maintain the flow rate. The more complicated version used a secondary screw in the feed side to keep the supply stirring off the main screw motor, definite chute design changes. This however did not completely eliminate the problem it just reduced it. We even tried a feed tube with a screw in it going to a very large hopper on top of the printer. Obvious issues like tube wear with a screw turning in it. Other issues were things like air bubbles trapped in the extrusion, the plastics extrusion industry has spent millions on screw design to help eliminate this with very complicated variable pitch screws and flow tips to allow the air to flow back up the barrel and only plastic down the barrel, their still not perfect. As a secondary problem we found it needed a fair bit of babysitting and trying to refill the hopper while the printer was running since it is not practical to have a hopper that will hold 1 KG or more of pellets for the larger prints. Stopping or pausing the print was problematic with a oozing nozzle causing a pressure loss due to the increased size of the melt zone ,the re-pressurizing created another hurdle while the nozzle was oozing. Typical gantries and frames just would not handle this as an upgrade as this is heavier than the frame is designed for. One of the methods to resolve some of these problems in the extrusion industry and filament manufacturing is multiple heat zones but there is a size issue here as well as existing electronics not supporting 4 heaters in 1 heat block. We came close to trying micro induction heating but that did not get off the drawing board before the project was stopped.
Good luck to the manufacturer, I'm cheering for you to overcome these hurdles. I know it can be done, we just gave up too soon.
12:30 shows that while this device might not be practical for 'final' prints, it looks like an absolutely stellar solution for prototyping. For example, I'm working on a stand for my phone, and I've had a few iterations - a few at the beginning of design and testing, and another two after months of use with small features added/adjusted. It would be absolutely BRILLIANT to be able to take the prior prototype and instead of simply printing a second one, merely crush up the first one and re-use the plastic to print a new one.
One correction pellet extruder have a plasticising screw which hypothetically would be a Archimedes screw that not only pulls water but also increases it speed. In case of the plasticising screw there is compression as well which help in melting and mixing as well.
Super intresting video 😃 Looks like the development of a sustainable recycling system is well on its way
This is a REALLY fascinating idea to recycling. I'd never even thought about a direct(?).... batch melt of plastic. Not unlike how chocolate or concrete 3D printing works.
Seems like this would work a lot better for big nozzles and printing very large parts. I'd imagine that could help reliability and somewhat smooth out any little gaps in the stock feed.
Definitely a cool idea and one I look forward to see developed more. Filament recycling has been super tempting ever since I started 3D printing like... 8 years ago. It always kind of breaks my heart to throw away a box of scraps.
I wonder if there’s a measurable torque difference on the feeder when missing flakes.. maybe it’s possible to detect with something like stallguard and feed based on resistance instead of volume.
When you first started to talk about under extrusion due to jams i was like just super glue a tiny weight to a blade on the extruder fan to vibrate the hopper.
I would honestly love to see what this would do to the print itself, as it would be shaking the whole carriage.
@@richmondrivet Have you ever tried the "fuzzy skin" feature in Cura? :D
@@peterkiss1204 , hah. I haven't, but I have seen Chuck Hallebyuck's video regarding it. That's probably a decent representation of what it would do.
I use a screw to push material through the hopper. I giggled when TT suggested it.
Captain Obvious' color suggestion: 'Recycled filament mix'
16:05 loved your smile at the end mate. You should always sign off like that 😁
The main problem on this is the size of the pellets needs to be small and round to feed proper into the small system. I suggest instead of waste direct print we should focus with some 3D printer parts to come up with an filament maker. once we can make a filament maker you can use than your normal 3D printer and print with the material. I been working on this for some time and right now sourcing parts for the build. Perfect Plastic and others do have a nice solution but they all lack of consistency and part sourcing is still an issue but we working the kinks out.
You get much better results if you first run your filament thru an extrude which prints only 2mm big dots onto the surface and than you take those and pump them into the hopper for printing. Flakes always have a tendency to stick and entrap air into your filament process when not using a big compression screw.
Ghost benchy, the black Pearl benchy, Pirates of the benchy, Davey Jones benchy
Interesting for sure. Keep in mind running recycled materials will always be a challenge. It’s something injection molders struggle with even when
using the same grade of material. I’d focus on how well it works with virgin pellets first then move to same material waste and then make evaluation. Also vibration of the hopper is a good solution, but may need a way to apply a consistent weight on the pellets. Worry static is adding to the troubles. Adding some mineral oil may also help.
The same way you printed a fan mount for the bottom, you could print one for the top, and paste a weight on one of the blades to create the vibration you mentioned.
Perhaps a bed that performs the X and Y movements would solve many problems on the extruder. The extruder can then be improved uncompromisingly because the weight is only a minor factor.
Pollen has a delta printer with a fixed extruder and moving bed. It's pretty cool.
Its a game of tradeoffs. Making a reliable and "cheap" X/Y moving bed is substantionally more difficult or expensive than an X/Y hot end like the ender 5 or a X/Z hotend like the Ender 3.
@@viet0ne Here is a cheap finished design for an XY-Bed: ruclips.net/video/oS0z1R73aas/видео.html
I think this would be the easiest way to run a reliable pellet extruder. Many problems with the pelletextruder could be solved now (because weight is no longer an issue). The only new problem would be the additional mass of the printbed. But here you can first reduce the speed.
May I suggest "Oil Spill" for the colour ? Wasted chips extrusion is a complex subject. I gave up back in 2013 because I did not manage to get a flawless extrusion. My two cents: you probably want a fixed extruder or an extruder that only move on the Z axis, because you can't build a compact chips extruder. So an inverted delta should be the right machine structure with a fixed nozzle and a bed moving in along the 3axis.
Two approaches are possible. Classic or pressurised. With the classic approach, you want a large screw. Maybe 30mm or more, because you always get a small percentage of voids and the larger the screw the negligeable the voids. Second you want your chips under pressure before to reach the screw. I tested the double screw method (1 screw for the extruder, 1 to push chips in the screw). Last, you want to increase the melted plastic pressure or you won't get a consistent density of plastic on the deposit. Professional pellet extruders uses special screws with constant pitch but reducing conduit (the groove of the screw gets smaller gradiently near the output nozzle). This is an engineered part to get the right density and pressure at the nozzle. It's expensive and out of the skills of a hobbyist.
The pressure way differs and is an original answer to the consistency problem. It's inspired from injection molding technology. You want a melting chamber to get a good amount of pellets fluid, a piston pressurises the plastic and a solenoid valve allow the plastic to get to the nozzle. For continuous printing, you use alternately a second chamber. Once again, it is probably not reachable fo a hobbyist.
The reason why I abandoned is budget. Even if we produce a huge amount of plastic waste, filament spools are so inexpensive that the budget and efforts do not worth it. At the fablab we recycle by making boards for future projects. No shredder needed, just an oven and a DIY press. Easy enough.
Glad someone is trying this, but there is a reason things like filastruder exists :)
That adds so much mass and variables it's going to be really difficult to get working consistently and fast.
Hello,
I think your main issue is with the pellet locking. We face this issue and we solve it creating a macro that shake the head at the end of each slice, choose the direction where your printer is the most rigid ! Using Cura, you just need to tell it to call the macro each time you finish a slice. This really solve this issue.
The other issue is to be sure that the material is not to hot before entering the archimedes screw, if it is over the glass transition, you will have issues, then, just decrease the temperature. Using linear advance really improve the results, and we use your method to tune it !
Best regards
this could potentially be useful as a way to repurpose old PLA for reuse as support material, rafts, and maybe infill for decorative prints on a dual extruder system. it'd be pretty cool to peel a part off, break off the supports, shred them, then reuse them for supports on the same print again.
If you need help, I work with large format pellet printing. I would suggest for them either mechanical/air agitation like you mention, with "yard trimmer line" or something reaching in closer to the auger
Honestly, I think the biggest improvement will be made with smaller pellets. The pellet size is an issue in my eyes and needs to be smaller and more homogeneous. I would add a special type shredder to create smaller particles, at least 20% of the current pellet size for more reliable extrusion. Not too small as this could cause caking of the small particles before they reach the extruder. With this setup you definitely need a vibration motor to make sure there are no hiccups.
I think the better way to do it is make a separate diameter controlled filament. The material in the hopper, and therefore the screw is not a common density, therefore each turn of the screw will feed out a different amount for each layer. This is why you will get good/bad/good prints. You need a completely constant infeed and outfeed of material. Thats why its so important to have low error filament to get really good prints.
I think the idea is good, but it shouldnt be part of the hotend assembly.
Also to comment on that, being part of the hotend it gives it more inertia/momentum on its movements. So the motors have to work harder to move it, and they also will have more trouble with stopping the movement at the end, so you will get more of a lip at corners unless you tune it way down.
I think a good test would be to take it off completely, drill out a 1.75mm hole in a nozzle, and see if you can just make filament. You'll have to experiment though because there are dimensional changes in the filament as it cools.
I think the only way the hopper idea would work would be with pretty much powederized filament with a vibrating hopper to ensure constant feed.
call it "soylent green"
I can see how this could be a lot more efficient than re-extruding filament before printing. Perhaps if they look at how filament systems manage to create a consistent product they could apply those techniques.
One obvious issue seems to be the feed system, maybe the auger needs to be larger to allow the chips to pass through easier.
the bowl looks awesome the random colour thing is cool.
Melt the leftovers. Pellitize them . then use them . This will give you the advantage of not having to make a hard to make consistent filament, but instead a easy to make pellet of a size that is usable and constant size pellet to use in your extruder .
I don't know if anyone else has suggested this, but if it were me, I'd consider using a blender, like the will-it-blend 1 (or home made equivalent) to get a nice fine powder to feed the extruder with.
really good for a new concept I love it it's awesome
A few attention points:
Lookup Dyze Design pellet extruder
L/D ratio barel/screw should be around 20 in order to get good mix and consistent extrusion
A non- linear screw it's preferred for high enough pressure buildup
I love this! Just found it in 2024. Have you had any other experience with this? Love the idea of printing from all my junk prints.
Very interesting concept and am keen to see it as it further develops 🙂, ... coming from a constructive place I wonder whether we are asking too much of our 3D printers in something that they have mastered quite well with a spool. As others in this post have noted maybe a filament making machine would be a better pursuit. Making the filament would be less of a stretch than going from raw materials straight to print ?
it is called MIRAFIL OOS edition, for sure (MIchaels RAinbow FILament, out of shredder edition) Grays Almanac tells it became a huge success, back in 2022, after only 2 years of fiddling with an abused 3d printer, and 5 zillion benchys, most of them with more holes than one could imagine ...
Input choper should have vibration motor on it and should be connected via vibration absorbers with extruder. That should provide more stable stream of incoming material to heater.
I think anything you can do to improve the consistency of your shredded bits will help a lot - sifting your shreddings through a series of meshes to sort them by particle size for example and excluding all the bits that are above a certain size. Also I imagine the stringy bits in your recycled material probably aren't helping as those could get tangled up in the screw.
It is a nifty system for sure.
Hi brother. Class I am also doing in this direction, Greetings from Russia!
If you first feed the scraps to a separate (not neccesarily high quality) extruder and then chop that intermediate filament to uniformish, rounded, pellets?
this is going in the right direction ... maybe it is more effective if we ( the makers ) are able to produce our own filament off wasted prints on spools ....
Awesome video! your defiantly leading the Development Space which is greatly appreciated! My thoughts are that maybe a larger nozzle diameter would take advantage of this more. It appears the general idea and technology behind this is that of a typical Plastic injection molding machine. Air in the heat zone is the biggest enemy. This would be great for a .8 or 1mm diameter extruder. Injection molding meets 3d printing,
Super cool, Thanks for the Update!
It is a very good idea very cool thank you
Really interesting idea -- I'd love to see a system in which waste plastics become material for large scale prints -- imagine (as an example) a council based system that could produce benches, bin, shelters, etc on demand.
I think one of the hardest parts in using shredded pellets is irregular shape, sharp ends, etc. Prior to use, if they were smoothed somehow (say.. run through a sand tumbler), I think it'd increase flow consistency through a machine significantly overall.
There is that German guy now, how created another prototype, which looks like even works!
I wonder if we one could print a shredder for filament out of rigid and heat resistant material, PP maybe, then heating the PLA parts meant to shred to maybe 65-75C and grind them down while warm. It shouldn't get so hot that it would get sticky but enough to make it really weak. Also the shredder should be made out of a material which PLA doesn't like to stick to, assuming we want to focus on recycling PLA. The cutting parts could also be hardened by glueing carbon fiber to the edges using some resin.
I guess finding the right amount of heating would be the problem with that plan, since the size of the material to recycle could quite differ. However, without even having a cheap shredder I won't recycle that stuff anytime soon. I'll wait till I have around 100-150 kilograms of waste or so, then it might starting to be interesting.
Another factor may have been how dry the plastic regrind was.
I'm all for recycling, but a better system would be an add on module that creates filament from the shredded material plastic in real time that then feeds into the printers extruders. I would be OK with a second printer sized machine that I can dump or shred waste products into a have it as a standby hopper of raw material for my next print.
I would check out the 3Devo Composer or 3devo Precision. They're filament making machine that are self contained and mostly automated, plus it auto spools the filament for you. 3D printing nerd did a video on it last year and was able to get up and running with it with little setup and no issues.
nevermind that product has a price tag of over $6500, YIKES! But it works and pretty quickly too. But yeah not gonna find that laying around a maker space without a year of fund raising or something.
Color name suggestion: the perfect-for-prototyping color
I think this is a match made in heaven, 3d printers are great for prototyping parts, and the prototypes that don't make the cut can be recycled to make even more prototypes because color accuracy isn't important for those
Great idea. I personally don't like tinkering, so this is a big nope for me.
If you could melt the old 3d prints into beads first I believe the extrusion would be MUCH more consistent.
IIRC this is a suggestion i made on your last video regarding the recycling of filament, but if you have the time, you could possibly look into the "lyman filament extruder" on thingiverse, there's a few versions of it i think. And its not a direct from scraps to print like this one, but rather a scraps to filament machine all built using off the shelf stuff. Love your content!
the vibration motor is a good idea but they would need to introduce a pressure sensor at the nozzle. the pressure would need to be used for the print speed, as low pressure means lower molten plastic and high pressure means more molten plastic. not sure how easy it would to implement the sensor and implementing it into the firmware
Teaching tech: explain bravo in one sentence
Polylab guy:sure 1:18
The hopper size looks small for larger prints; but bigger hoppers full would add even more weight. Unless there is a hopper filler as well.
Great video as always Michael. Great to see some innovation from an aussie company. Not really sure I'm convinced by an expensive kilogram lump... which makes you use a bed slinger, when what I'd really like to do is make filament to feed into a much higher performance printer. But we know that's pretty difficult and expensive too... here's hoping I can finally make use of a massive box of ABS failed prrints, test prints, prototypes etc...
actually, you could *print* filament. It would take ages and you'd be limited to small coils I guess... but I'm kind of curious if you couldn't print filament coils on coils and snap them apart...
Vibration could cause some quality issues - in paintball some guys used to have worm screws in the hopper to agitated and "pull" the pellets through.
I wonder if you could use jerk to shake the material in the hopper more aggressively. Maybe even a zigzag model on the print to force to it to shake somewhat violently every layer.
For calibrating the esteps, instead of using length, you're going to have to use mass. Everything for calibrating this machine is going to have to be via mass instead of length of filament.
3d nerd has a video of a convention that had a delta machine that uses pellets instead of fillament. That company might be able to help you with calibration.
Trapped air bubbles may be causing some of the under extrusion. The vibration motor may help to minimise this issue (if it is one) as well.
Maybe the ground bits should be screened so you are only putting in bits that are below a certain size and even shape., doesn't go through the screen, back into the grinder. I also wonder if the ground bits might not benefit from going through the chopping blade of a food processor. In my Cuisinart, it will turn even the hardest nuts into a paste in a short time. Might work well for plastics. those finer particles will be less apt to bind and jam I'd think.
Vibration motor might leave artifacts in the surface finish. Might try air instead.
nice thing with misses on a system like this is they're almost free. Grind it up again and throw it back in, the stuff was previously destined for the landfill
Looking promising! But you can see some undeextrusion probably caused by the inconsistent feeding of pellets. Looking forward for more updates on this one! 😀
I still think that the intermediary step of producing filament gives the system much more control and allows for inspection of the filament. It that was combined with a few optical sensors... that would be the optimum solution as software can react to filament quality.
I can’t see this working reliably as designed. Depending on the material, the density of plastic to air will vary wildly.
The only way to make it viable that I can think of is to sense the pressure in the melt zone above the nozzle, then use that as a feedback to the screw to maintain a certain pressure. This would vary depending on the material being extruded, but could at least be set by the FR multiplier in the slicer.
I just watched the building of the shredder video. I wondered if you had done an update. Product seems capable but needs a lot of refining still.
Did you see that Precious Plastics has a filament extrusion machine? Would love to see how you would get that running.
I always thought the nozzle on that extruder was too big for 3d printing but for some reason I was thinking if a 0.4mm nozzle. If it does 1.75mm it might be quite suitable.
@@TeachingTech I think when you build it you can select the size filament it produces.
@@TeachingTech I was just pondering this, if you think of the build of the extruder like the hot end of a printer you could construct it to accept the extruder nozzles of a 3D printer.
Very interesting! Needs work of course. Shredded PLA needs a second pass through another shedder? Or perhaps pelletizing? Instead of vibrator to stir hopper how about a piece of kinked filament extending form a motor to just short of the screw feed. As it flops around it might do a better job of preventing logjams.
I think you need to have more consistent size for your shredded material. I think this can cause some problems for you as well. I guess I’m a little surprised that you did not use some virgin material to get everything working properly before attempting to utilize reused material.
I think these guys are onto something this looks very promising some sort of small vibrating motor might be a good idea to help keep the filament moving down. I look forward to seeing this becoming a product
Your shredded pieces are funny shapes. You need to partially melt them to get them round. I suggest a kitchen pressure cooker. You would need some kind of digital heat control though. A way to keep it stirred so you don't end up with a blob qould be nice, but i think thats asking too much. Obtw hot water is how they make shredded grocery bags useful.
Did you dry and clean the pellets before using? That seems to have some effect on the outcome. Having dirt and gunk on the pellets may block up the nozzle and build up, causing that under extrusion and failed prints
WOW, that kind of scratch will buy a lot of brand new clean ready to get filament? I'll be passing.
I see a Problem in this system. When mixing different brands of PLA you will mix different meltingtemps and materialproperties because the different brands are not mixed equally in the hopper. better to create a mixed spool which is consistent in it's properties. When using only one brand and one pla type or pellets it could work.
Suggest try using the biggest nozzle you can find to print something large as might be easier to push more filiment evenly through a big bore nozzle?
I actually really like that color of the benchy.
Don't mix your colours, find a way to bleed some excess cooling air onto the auger and back into the hopper. A vibration motor or clipping a tiny bit off a fan blade might work though.
Still think a separate filament recycler would be a better option; direct pellet extrusion makes more sense for much larger scale printing where the inconsistencies will matter less due to high flow rate.
Maybe you could add vibration to the hopper by modulating the speed in the g-code?
Also 3D print some sort of scooper that fits directly into the hopper as not to spill the pellets
I guess you really need to melt your waste once and let it "drip" or get it in any other way into uniform bead form. These unevenly non round shreds will be the mail problem for feed jams. Maybe just build a heatzone melting your scrap and a stepper ? rotating blades around the nozzle ?
I say move the motor to the side instead of on top the barrel. Have it turn the screw via a gear, and have the hopper a direct drop into the screw. I think then as much as possible would just fall directly into the hopper and you would need no vibration motor.
Maybe sending the bits thru a blender to reduce the size and get rid of stringed material would help.
I too had wondered if the string like filament particles would add to jamming in the bin and feeder.
I’ve been tinkering with the idea of using my waste plastic to cast parts. Print out a part with a funnel on it, make a mold of it in plaster and melt more plastic into it until it’s solid. My fails at using plaster for the first time have been embarrassing and I haven’t even got as far as testing the idea yet.
I think filament stock is essential to pull back material when travelling. Home made shredder/extruder/printer would be a revolution though.
I think you'll need to shred your prints to a far smaller size.
Side question, earlier on (almost a year back if memory recalls) there were recycle "extruders" that allowed you to make just the 1.75mm fillment. I feel that this would be more effective. Reason is the simple size of the print head module. the size would/might impact the print quality itself with such a large hopper.?
Why not have a larger melt chamber that is kept pressurized by a constant inflow of extra pellets, to smooth out the flow and avoid gaps? (might need some sort of valve to cut the flow when needed)
On the current system do me a big favor. Get a 1/4" ~ 6.3mm ID tube which goes up above your bar into a much bigger hopper funnel. this way material is fed better down via gravity into the extrusion screw allowing you also to load much more material because the hopper on top can be holding up to 1KG or 2lbs and remove's the weight from the Z axes. PM me if you are interested. Olaf