Portable desktop injection machine
This topic contains 142 replies, has 12 voices, and was last updated by Anonymous 1 week ago.
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) :
oh dear, i said LATHE, not toy. if you add ‘Chinese’ in front, it’s not a lathe! even old tony can’t fix this #$%@#$%, nor does Chuk2009; anyway, gotcha, was just trying to get most & best of out you 🙂
Let them out of their boxes, they will each dig a really good rabbithole for any spare time (and some cash) you may have.
@pporg , not sure what you mean. When I chuck up a bar of HDPE, I can take the same cut This Old Tony takes in stainless.
A few days ago I mentioned frivolous decorations. Well every patio needs to be protected. Though we like the European gargoyles as solution, these work as well.
So I needed a secure way of mounting each Tiki lamp. The first image shows the “kit”. An internal plug (HDPE – milk jugs) clamps the ceramic lamp to the base. The base (HDPE- plant pots) also adds a bottom clip that clamps it onto the pergola beam. The image also shows the simple molds that provide the geometries. The base clip itself was made in the wooden mold as previously. The mold is holding up well with repeated use
The second image shows it mounted in position. With a solar/LED cap, it is on duty day and night.
While this is successful, it does take quite a bit of time to go through the steps to get to finished parts. I think anyone planning a sustainable work space should consider the throughput that they can achieve.
So you spend all this time tinkering with that plastic melting gadget in the garage, your spouse looks in every once in a while and just shakes their head..What do you do to salvage some legitimacy to your activities……
Fix something of theirs! (some free gray-haired wisdom here)
This was an otherwise nice cast iron plant stand that was a bit rusty and had a busted wheel. Well, a little spray paint and that clever threaded knob made in the wooden mold in the Feb 10 post, and I achieved temporary hero status. Since we don’t take our plants for walks, the wheel function was less important.
The nice thing about using recycled plastics to make replacement/repair parts is there is no concern about plastic costs so you can make them robust. I’m guessing this solid HDPE part will hold up well, If not, I can make a bigger one.
I have been thinking of ways to get rid of the need of cnc milling machines in the mold making process. Mold making is always the difficult of part of IM and expensive.
Look at this article: it may be helpful. https://www.3dhubs.com/knowledge-base/3d-printing-low-run-injection-molds#why
If you use conformal cooling channels connected to a water source like a tap you could get some interesting results. You should be able to cool the mold down enough to do 100 of units. If you could get a desktop extrusion printer to print molds it would be a powerful tool to increasing product development and outputs.
let me know what you think!
Thank you for the great link. Making a temperature resistant mold in the DIY environment/budget is a challenge. I’m planning some more trials with the plaster technique. That may be a way to bridge to 3D prints.
I think my favorite high temperature 3d print application is the guys 3d printing molds out of sand for casting engine blocks.
I wanted a plastic pre-processor to deal with the thicker source material (bleach bottles, plant pots, etc.). I went with using the metal shear approach suggested in this thread https://davehakkens.nl/community/forums/topic/precious-plastic-version-4-%f0%9f%98%ae/page/5/ . I got one of the 30 cm metal shears. First off, the thing is a beast. In my defense, it looks smaller on the computer monitor and the cost savings for going smaller wasn’t that great.
Well, it works great. I squish the bottle using user mass and gravity and then a few chops later it is sized to fit into the injection machine.
For those with a shredder, it is an easy and safe way to get down to single ply material for the thicker stuff.
I will be making a shorter, forward angled handle for use with plastic.
I replaced the original handle that was way oversized (78 cm) for plastic to something more compact. I also angled it so it does not swing past my forehead like the original. Of course, I adopted the PP.org standard of contrasting colors for machines.
I wanted to try making a bar using nearly the full capacity of my injection volume. I used my wood and aluminum tape mold approach. The results are shown in the images below. The resulting bar (HDPE) is about 10 x 38 x 320 mm and weigh 114g after the sprue is removed.
A few things I found interesting:
The black material was in the barrel first and then was filled with the white, and yet the ends are white, and relatively symmetrically so. Even the cross section of the sprue is black. I cut my source material into medium and large strips , not shred, so I’m not sure where the material ends up during compaction, but the result is consistent.
The shrinkage was predominantly axial and the cross section is fairly consistent until the very end. I may have run out of material but the ends are square so they probably reached the end at one point. Also the gaps on each end are very similar. I was not sure how well injecting from the middle would work but it turned out OK.
I made two cuts, each one 25mm from the center. The cross sections are shown below. Yep, it looks like a Mounds candy bar. The initial (black) plastic coats the walls and the rest squeezes through the center. Very surprised that both pieces look almost identical even though they are from different sides. Still can’t explain why the sprue is the black plastic. On future parts, I will try to really mix colors well and use smaller pieces to see if you can get that cool multi-color result without milling the surface.
Overall I’m happy with the result. My desktop machine is limited in height/stroke but I think the arbor press design that PP.org has https://precious-plastic.org/home/library/machines/arbor-injection-press-2/ could be sized up to produce parts at least twice that size, which would become interesting lumber.
captured and added to a special page. amazing results, thx @s2019. Could you try making a gear that way please, ‘Module 2’ would be sufficient enough to drive stronger stuff as in Chinese mini lathes 😉 if you don’t have one, i send you one 🙂
I made some process improvements to get more interesting patterns and to control the shape better.
For the better patterns, I reduced the size of the flakes to about 1-2 sq. cm and mixed them well (see container in picture). The black and white were equal by weight.
To control the shape, I reduced the length of the mold by adding a 2 cm block on each end to make sure my shot volume would fill the mold.
I am happy with the results. The bar maintained thickness and width. The length recessed but did so after establishing a square end. The pattern mix came out much clearer and the surface is smooth and does not have the texture you get with room temperature metal molds. You can see a few wrinkles in the aluminum tape due to axial motion. The mold is from really old scrap plywood and the tape does not stick to it as well. I’ll probably switch to some flooring remnants I have.
Unfortunately this will make me start shopping for a longer rack for the arbor press to get even more stroke volume.
I wanted to revisit the plaster mold at a larger scale. Back in February, I posted some promising results using a plaster mold to replicate a seashell. Sticking with the ocean theme, I found a cast steel starfish that looked like it would make a good mold. I used plaster in a plywood frame for the mold and plywood/aluminum tape for the lid. The results came out pretty good. Some small amounts of plaster did stick so I’m researching ways to seal the plaster that will take the hot plastic. The second image shows the back. Other than a few wrinkles (the plywood is old and the aluminum tape does not stick as well) it shows the smooth gloss that the aluminum tape surface provides. You can see I had to inject near the end of one of the arms because the mold frame was too big for my machine, but the mold filled well. This size (125 g of HDPE) is about the limit of my machine.
I don’t plan to repopulate the oceans with my starfish, this will be one of a kind, but the results make the plaster approach promising enough to keep exploring it.
I wanted to try out the 3D model => 3D print => low cost mold => Injection molded part process. My wife has a gardening event coming up and some custom buttons would be welcome (and of course justify the new 3D printer).
The first image shows some of the results. The background colors are from various blends of HDPE (though the black one apparently got the glittered). The ones on the right my wife enhanced with nail polish and ink to make the lettering and flower stand out. The rest will get the same treatment.
The second image shows the process flow. I put some nail polish on the 3D print to help smooth out the texture and help it release from the plaster. The plaster is actually a useful step because with just light rubbing with sand paper you can get rid of much of the 3D print raster lines and smooth small defects. I’m still experimenting with different sealers and releases for the plaster. Right now, I’m getting a couple of prints out of a mold, but plaster is cheap (though apparently I need to have the patience to let it fully cure) and I only have a few to make. We still need to come up with a more robust way to paint and protect the HDPE (the nail polish comes off if you scrape it).
But for now, mission accomplished.
If anyone has tips on low cost ways to get from 3D to injected part, please post
Actually, a few years back I made a small propane aluminum furnace and created my small pile of casting muffins. I plan to dust it off soon to make at least mold blanks.
For this 3D => ??? approach I was trying to start on the cheap/easy end and work my way up. For some things, just being able to have a single use path to make a PLA print into a HDPE or PP part is useful to me.
This is what the buttons look like after my wife got done with them. The funky tie dyed backgrounds are provided by various HDPE sources. The only parts that were painted were the flowers and the letters (and the black button got glitter bombed). I think they provide a fun organic look that fits well with the gardening event.
These will be given away to volunteers that contribute but I could see a potential for some workspace catering to providing interesting, low volume items for groups and events, especially if the groups are environmentally themed. I think there is a path to making these effectively, starting with a 3D printed master. The mold material development still needs work, but I think there is a low cost solution out there.
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