Portable desktop injection machine
it was suppose to be an easy thing I thought but I spent then 3 full days on it at the end, lots of hours on the lathe, 1-2 hours welding and a little bit on the mill. I wanted the best result possible, tight tolerances, smooth plunge and an easy to extrude plastic with a flexible nozzle. (btw. I can’t recommend building this without lathe or mill, it really wants it accurate to get a smooth plunge).
In the next iteration I will try to have it spring loaded which is pretty difficult as I noticed.
here you go, full metal desktop injection (some part are hardened to maintain this nice blob sound in the barrel) :
The plaster mold worked well. It replicated the detail and survived a couple of injections (HDPE) without any apparent damage. The small round mark on the black shell is probably due to warm up. It was the first injection of the day and the nozzle may have still been a little cool. The metal tube frame protected the mold well.
Yes, I had a similar thought. As a follow up to the machinable wax suggestion, I wanted to see how the plaster mold would work. I wanted to make sure it was well reinforced so yesterday I cast it into a tube cut off as you describe. The plaster retained good detail. I will give it few more hours to dry and then try it. If it works well, it may make that cheap CNC engraver viable since I think it won’t have trouble carving (though slowly) the part in the machinable wax and then cast the mold in well contained plaster.
OK, I did a rev 2.0 on the wood mold approach for making a threaded bolt knob. I used some left over engineered wood floor cut-offs. Most of the cross section is homogeneous instead of grain. I drilled the 8 holes to to provide the texture and then hole-sawed out the main body. Sanded smooth and then used aluminum tape to provide the smooth surface. I used HDPE scraps (milk containers) so the color is not exciting but the surface is very smooth and usable. I did lightly sand the top to remove some light swirls. The bolt is 1/4″-20 (~6mm) for reference.
I actually need a 12mm version to replace a broken one on my miter saw. That one will get some fun colors.
In conclusion, the aluminum tape provides a smooth surface and the part releases very easily
I’m in the experiment phase. I was interested in whether it was easy to use simple available forms to mold stock shapes that could then be used for other projects (bushings, pistons, stand-offs, etc.). Right now I started with HDPE. Some parts do end up with voids, so right now I’m looking at temperatures, mold heating, and form plugs to see what works. I tried using a bolt to mold an internal thread (3/8″-16). That worked pretty well. Because of HDPE shrinkage I ran a tap through it afterwards but otherwise it worked. You can also see a small void in the bottom right corner, that I’m trying to get rid of.
Looks awesome, a bench injection machine is the next thing on my projects list 🙂
these are coming out great dude, i remember some time when i would have by this for no reason but for the colors, making little cute glass tables to hold my bong collection 🙂
btw. collection, i am still buried under crap but this goes soon into ‘best of PP, 2019’
@pporg , Funny, I’ve gone through the “apply your technical skills to making a better composter” directive. I used a large plastic barrel on rollers, it had internal blades to stir the compost as you turned it…blah..blah…blah…rubbish. Too much work and it made the worms dizzy. My technical ego was crushed when my wife had me cut the bottom off of a large plastic (~75l) bin and set it in the corner of the garden. Now we just throw kitchen waste in, no shredding, put the lid on, the worms come up happily from the soil and do all the work. A few months later we move it to a new spot. So much for clever engineering.
@donald …Some of the better uses for CNC https://hackaday.com/2015/01/14/choctopus-chocolate-printer-x8/ , https://hackaday.com/2016/11/24/open-source-pancakes/ I think you can buy these off the shelf now…..Failed prints are not a problem
funny you, i think you mean half deadly ninja choco knifes to throw at others, shredder knifes as boomerang, why not 🙂
@s2019, my wife joined the workshop a few months ago and she seems to catch up slow but good on what we are actually doing 🙂 She told me recently to make something useful out of the v3 shredder: put a wheel or handle on it and shred kitchen waste to make compost for our garden. Obviously stainless is pretty overkill but making one from PET or HDPE should be possible with the little arbor press you have done, no ? Larger pieces (side plates) could be done breaking them into puzzle pieces (interlocking) and glue or screw them together just. That aluminum folie mold technique you have there seems fully enough to make all parts of a plastic shredder, what you think, i dont see much trouble doing so .
I took another try at a wooden mold for the injection machine. I have use for a large robust clip/clamp. I started with simple softwood pieces out of the bin. I took some care that the dimensions defining the part were accurate and that the edges were sharp (first image). I taped the interior surfaces with aluminum foil and used a bushing for the sprue (second image). When I injected it with HDPE (some of my wife’s plant pots) I clamped the sprue during cooldown, maintaining some internal pressure. The part shrank primarily in length and maintained some of the other dimensions (third image)
@btmetz, no, but the sunglass guys are around the corner 🙂 And yes, anything automatic coming out of PP in the desktop format would be great. Marlin and the like are great but the difficulty is to enable people adding or changing parts to the system without much programming. I wrote an visual editor one day where you drag ‘commands’ (ssh, serial, udp, arduino direct, printers, …) on visual objects like buttons and so on and the export the thing as web-app, more likely a touchscreen running off an RaspberryPI. If you like, you join this efforts in another topic (‘automatic desktop injection’), this days ..
@s2019, yes, keep going! This looks near perfect to me; apparently this could go into the library, if you don’t mind to open another topic ‘arbor mini injection’, we could start making drawings when there are enough detailed pictures, instructions as well component selection in a way others can reproduce this; as well making a commercial version, ready to be build by builders for the bazar.
pporg, are you the guy doing the sunglasses in Spain from the videos? Andrei told me he met the sunglasses guy the other day.
I been looking at that arbor press design although at the moment no budget to experiment aside from CAD drawings on it.
I have also been looking at the automated molder someone posted a video of.
Seriously considering that as my next line of building after the polyester fiber factory is built.
I am thinking a great product to make for the local market with the automated injection molder is buttons. The kind for shirts and pants.
Seeing as the injection molder can be made with Arduino/Ramps/Marlin firmware as the controller, a couple SSR to run the heater bands and I found some small compression screws for 100usd (with barrel) that will be the next project I hope to kick off here.
yup, we’re started right now 2 small scale sets for 2 clients in the field as pilot projects. as often those guys don’t know actually what they want nor what to do with the machines. many come up with the idea to let the kids bring plastic and currently I have to push them back already from their idea to recycle PET bottles (fume, hard to recycle,…), makes me headaches because apart from shopping bags there isn’t much left the kids could bring from home. Shampoo or ‘fairy’ bottles are pretty hard and would exceed the machine limits (2Kw) and also may require dangerous pre-cutting. Ultrasonic cutters come to mind but a nightmare in the class room 🙂
more or less that are the 2 major tasks to solve with or for them : the missing PP manuals (there’s lots to do, localized) and the actual workshop plan. the machines are more less clear to me now : for people from 1.30 – 1.70 meter high with little muscles and complete enclosures, water prove, and a door for the shredder as well all the measures we’ve mentioned recently.
I could of course just ‘send it’ but I’d love to work this out. There are some similar activities I came along on instagram but i have the feeling all this is at the very beginning. i don’t see much educational value in 1. shred some plastic and 2. inject a pre-made mold and send the kids back home with a spinner ..
way to go.
These really look great. From some of the other threads, it looks like there is an educational institution demand that these would be ideal for. I hope that works out.
yeah, I could easily need a whole set of these. I am so messy sometimes that I search the whole house for a particular mallet/hammer…
using the injection as regular press: fantastic, you’re right. we call this in germany as “can’t see the tree because of soo much forest” 🙂
and yep, larger volumes are getting quickly a problem. i am still in the trial phase but it turns out that my 2 Nema-34 steppers (1600 oz) need a very specific leadscrew and a transmission to max this out. doing this with custom made parts on the lathe & mill isn’t much a big deal, but reproducing this with common available parts yes 🙂 possibly i better open another thread, looks like a black hole to me these little injections. my idea about was there at least one full-automatic machine available to PP users, below 1K, printing $$ non-stop. there is enough market. btw. there is a larger cooperation here in europe and elsewhere i think who bought all major and small producers and now they do price fixing. I had recently a catalog of small plastic parts (bricolage stuff) and I was shocked how expensive this small stuff actually is. anyway, soon more about 🙂
I love that mallet. I made some larger stock in the past using the oven, tube, and C-clamp approach. They came out OK but took a long time and I got dirty looks for using the kitchen oven. I think there is an option of using the injection machine actuation to compress a mold heated with cartridge mold heaters. I’ll have to try that in the future.
Good luck with your new build. I wonder if a larger volume, lower pressure pre-melt stage could handle the V3 flakes. An arduino could synchronize the transfer to the injection stage.
calculator: i did, i am so lazy and just wanna mess around 🙂
did you know this video. it’s plastic color g*ng b*ang o*gie
@btmetz, great. I am afraid i just understood the first half only of what you said, btw. your keyboard’s enter key seems jamming often 🙂 Anyway, i am looking into it this weekend.
@s2019, awesome work again ! this looks really promising so i went ahead with the screw idea : M20 acme rod and thread and bad a** hand wheel, it pushed PLA effortless through 25 mm tubing – almost on it’s on own since the handwheel was more of a flywheel. unfortunately my rushed welds were too bad so the thing broke apart the last part but it was enough to fill a flat cylinder. i gonna build this bigger and better this weekend. To me it seems this is a serious candidate to replace the plunger and even the arbor press driven injection, for larger things at least 🙂 I just need to kick the handwheel gently only and this thing keeps spinning whilst extruding, lovely.I turned also trapezoidal a screw now my self on the lathe, 25 mm diameter with a optimistic pitch to speed things up. I guess I will make the nut in plastic as well (Delrin again).
no, i didn’t but thanks for the hint and link, looks really neat and tempting, but managing this spring over there seems a little overkill, no ? i also afraid that anything ‘sophisticated’ like this doesn’t justify the involved on part work anymore. i could easily get lost full 2 weeks on it 🙂
let’s see how well it does, i have the slight fear that the transmission needs an extra gear…
apart from that, it’s was 3 days full-time work in a row, lots of mistakes done but the next one is pretty stream lined and cheaper to build for sure 🙂 So there will be 4 heatbands (one inside the bar), a 300 Watts, on the nozzle, 6 cm ID, on a brass sleeve going on our standard 35 mm).
i think this can be all done with basic tools: drill press, welder and angle grinder, if you’re good with hands, i won’t be that accurate as the lathe, cnc but good enough.
anyways, 150 Euro in materials, consumables and electricity, not too bad, 33kg steal.
seeya around soon, just ordered plaster and a shit load of expoxy 🙂
i just finished our own arbor press’s housing (see left). as often I bought too big; the rack is module – 3 (3cm x 3cm x 50 cm long) and the gear was 40 Euro only, I hope i get a good and flexible connection to an extendable plunger. this all has to fit in a hydraulic press like frame, a little tricky. i will weld a disc on the shaft to place some solid bars to make large hand wheel, 60 cm diameter or so. no idea how much power this gives yet but should be still way stronger than anything else i had 🙂
about the molds again, i could finally finish the first shapes : cylinder & hexagon in one cylinder (see right). i gave up on the piston, it caused to much friction and the plastic got it all badly. i still don’t know about the cap and clamp but i think i will go for 2 quick clamps which hold the upper cap (mold entry = M20 nut) on the cylinder. there is a little M10 thread on the bottom of each mold. i hope it acts as an ejector without too much damage. i also went for thinner walls, in hope it’s cooling down faster 🙂
soon more, I have to catch up with all your recent thoughts (expoxy, plaster,…)
see you in a bit
amazing! gives me another idea on how to have a height adjustable plate to place the mold under the nozzle. pilling up a some extruded cylinders connected via shoulders or ACME rods, should do the job.
about the abor press again, there are 50CM long hydraulic cylinders (5T, car jack section) on Amazon, for peanuts. Only problem with them is that it takes ages to expand them. i saw a guy who made hacks on a habor freight press (20T, 150$) via air-compressor. looked quick promising. alternative is a module rack & pinion based press but you need to build a special housing (i just did) and something to extend the rack for the plunger (updates about soon in another thread).
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