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) :
Just for fun, This is what the small annular cavity fill part (right side) looks like with a little clean up.
Yes, these were done with the setup I showed at the beginning of the thread. I used a small arbor press (1/2 ton) just because I had it. The next size up (1 ton) is still very cheap and manageable in size and weight but has a longer stroke. I may upgrade at some point to get the extra volume. I still think, with a little bit of cleverness, one could (in the US) build this for around $100 using a saw and a drill press (hand drill with great care).
dude, i am blown away! that’s pretty much the best thing i’ve seen here since long. congrats ! really, i copy & paste this here, even though finding a plastic shell at the beach may be quite an awkward moment 🙂
so from what i learned, people could do this with some basic tools (did you this with your abor press hack?). all what’s needed is some press (ACME & Cylinder), an oven and basic shapes which serve as mold enforced containment. congrats, you’ve made my day.
see you in a bit, let me try this as next after i managed to have piston like base mold, followed by an adjustable rectangle mold 🙂
I also tried a couple of cavity fill trials. The one on the right used the steel bushing inside the aluminum tube to form an annular cavity in the bottom portion of the mold. This was to see what it takes to fill narrower channels. It worked OK but the flow stopped about a half centimeter from the bottom. So either the injection temperature needs to be hotter or the mold needs a little preheat. Even without a taper I was able to tap the HDPE part off of the bushing. For larger diameters the bushing may need a taper or maybe be aluminum.
The second part on the left was to see how well a relatively large diameter cavity can be filled (the nozzle is about 5mm). Worked well but you can see that the outer surface cooled into the swirls (HDPE). May try some with a wood plug and/or preheat of the form. May also need a bit more material.
thank you both!
@s2019, thanks to your overwhelming (you’re a book on legs 🙂 input I think I figured now a how a flexible mold for a potential mini PP starter kit could look like. I was toying around with all that scrap cylinder cut offs today and realized I need only a bigger cylinder with 90% inner diameter. then, i do a piston like object which enables adjustable height. then i just need to make different sleeves to enable diameter and whatever shapes.
i have boxes filled with those cut off cylinders, finally i can turn precious metal into some precious plastic thingy 😉
greets from the shop, Sunday is my favorite to be here 🙂
Looks quite interesting.
I too had issue with wood splitting when I tried a CNC routered mold using soft Canadian pine.
Another mold material that works nicely is steel epoxy and marine epoxy.
I tried mixing black iron oxide (sludge leftover from the CNC Plasma table to extend the marine epoxy and got nice results also.
I understand that it will get several hundred shots, although I have not done more than around 30 some shots with a epoxy mold.
good thoughts and work! keep going 🙂
I just ordered 2 pieces of the paper shredder seen below (the strong one from Amazon). And about the bottle problem, well the PP v3 shredder isn’t doing well on this one either 😉 Even with plunging it’s a pita. Apart from that, no idea yet how PET can be of use, the HDPE however makes the best fit for what i want. as soon i have the paper shredder hacked (better entry), i will post it here…
the results of your wood mold look promising, i guess this has to polished anyways, no matter what 😉
Right now, I’m rethinking the shredder for the hobby set up. In my injection configuration, it is much easier to stuff larger strips into it with needle-nose pliers that it is dealing with small chips.
I like the paper shredders, except that you still have to cut the bottles to be somewhat flat. I’m not sure that they can handle just a flattened (double thickness) detergent bottle.
Earlier I said that the captured form plate can be wood. Well apparently not the soft pine I tried. The goal was to make a knob with an embedded bolt. There are youtube videos where they make a nice aluminum tool. I wanted to try a simple wood form. Since it it was a trial, I didn’t sand or prep it, just drilled and hole-sawed the main features. The pine split but the knob came out pretty well and solid. Using plywood or some other material that won’t split and doing some prep work smooth the form, a nice usable knob can be made easily.
I also made a couple of shallow wedges to position the mold under the nozzle and eliminate the need for shims. This worked well. The end grain has enough friction that the wedge holds under load. I was originally looking for a low profile scissor jack but for now this works great.
The other discovery was that for me the solution to reducing or eliminating voids is ….. patience…who knew? Giving the plastic extra time in the chamber to fully melt gave me much better results.
found this one, shreds up to 18 sheets, dvd covers, 30 mins long, super reviews : https://www.amazon.com/Fellowes-Powershred-Proof-Cross-Cut-Shredder/dp/B000YGO7HW/ref=lp_172591_1_8?s=office-electronics&ie=UTF8&qid=1548890277&sr=1-8#customerReviews. It’s originally 600$, now at 214$. A better entry and this should be enough for doing fun stuff with little house hold waste.
oh that’s neat, thanks so much for the input.
let me summarize in short what a mini PP station would involve:
– credit card shredder : 50e (somebody here makes it looking possible, https://www.instructables.com/id/50-Plastic-Shredder-Grinder-Recycler/), on amazon it’s about 35$, in europe maybe cheaper
– heating segment: about 30 euro, 1 PID, 1 SSR, 3 heatbands (china stuff). possibly 50-60 when going for a larger diameter and better heat bands
– abor press about 70 Euro, new
– metals & wood : 50 Euro
– misc. stuff: nuts, bolts: 20 Euro
clamping/molds: if lucky scrap metal, sold per kg
so that’s about 300 Euro, possibly cheaper with some little efforts.
(not included : hand and power tools, around 300 for the complete set: angle grinder, welder (2nd hand), drill press. relative cheap stuff after all)
ok, so at this point we can recycle small stuff at home, shampoo bottles, caps, plastic bags; not too bad 🙂
about the ‘universal’ clamps: let me try something -) I was playing with the idea of a 4mm metal sheet and a whole patterns on it, so you you arrange some bars in the way you like and bolt it down and close it with another sheet (holes covered by a thinner sheet). the mold entry could be almost always a plug just, no idea, will have to play more. see you in a bit and thanks again,
A small shredder would be nice, I only use scissors for the thinnest material (milk and juice containers in the US) for everything heavier (detergent, etc) I use a utility knife and cut it into strips. This is relatively quick (for experimenting). I’m tempted to try one of the credit card capable paper shredder hacks.
btw. does anyone has an idea on how to make adjustable molds with basic tools. from what I see now with this little injection, I’d love to have just a few primitive forms: box, cylinder and triangle. I guess this could be done with wood, nuts & bolts and a screw driver and later on from plastic. no idea… i am just guessing but yeah, a kind of lego like system would be cool, made of house hold waste
well, about the no-shredder I gave it another thought, actually I’d happy to have a little shredder (hand driven) in place. Cutting this stuff with the scissor makes the idea of a ‘micro recycling center for everyone’ less attractive but that’s another story (will try a shredder box with 5 blades only, hand wheel operated).
haven’t tried PET yet, I figured even those quality heat bands (100 Euro for 4) have a difficult time to get on temperature. let me try with 35 mm instead 🙂
Yes, no shredding. I found I can fill most of it with fairly large 1-2 cm wide strips and then feed some small pieces to top off (needle-nose pliers keep the burning skin to a minimum) . The large pieces make cutting up a plastic bottle by hand pretty quick.
nice, i was running similar tests against my desktop machine, with pretty much the same desire as you: little level jacks, pistons, etc..
i pretty happy actually with the results:
– plastic bags didn’t turn out well, but i guess i have to wait longer, i really want this thing to work for house hold waste 🙂
– bottle caps : awesome, i know now i have to enlarge the entry just, with a bigger heat band around and so I just need to push that caps without any shredding, cutting or folding into the injection.
– lever could be more powerful but i guess i replace this against a rack and pinion as in the abor press sometime soon.
so yeah, a small machine turns out pretty fun and useful after all, i have to ask the neighbors to get plastic waste, wtf. :-O
@s2019 ah that’s neat, impressive that this works. makes me wonder one could create universal mold building blocks (3d printed goes well too) out of a few shopping bags. ideally this thing could be a small plastic milling machine too, just plug a hand drill and mount a guide and here go, a small plastic carpentry 🙂
@xxxolivierxxx, yeah i will keep you posted here. after a bag full of sleep i figured a few minor improvements i should do.i also think that PP definitely should work on something for the small pocket 😉 I was always amazed that these guys on youtube managed to ‘recycle’ with a few simple house tools like a mixer and a toaster.
the inspiration I’ve got from this machine :
I made more of the large clips in two sizes. The large size (130-140 g) is at the limit of what i can get out of my injector volume. The wood and aluminum tape molds are holding up well. The parts are very repeatable and provide a nice friction fit onto the bars they are designed for. The plan was to use them for a convenient solar panel mount and they work great. Normally I would have made those out of some wooden or aluminum assembly. Once the wooden molds were made, these were easy to make and I’ll be making more,.
The point of posting them as an example, is that sometimes just making parts instead of an end item is a good use for the plastic lumber.
I would like to claim that the solar panel will help save the planet but in truth it will just power some patio lights and frivolous decorations that i don’t feel like running line power to.
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