Forum Replies Created
@pex12 yea great idea, never thought of using a drill press like that and there’s a huge old one sitting in the barn next to me. Maybe injection could be on the cards one day. For now I’m gonna just go for it free-hand on a wood lathe, I only want to make a set of wheels as proof of concept at this stage, though I would go like to along the CNC route eventually. But this is all off topic…
@s2019 Another thing I use is acetone which can help to get the glue off from the labels. It’s cheap and easy to find, and as chemicals go it’s relatively benign as far as I’m aware.
Had an idea earlier: HDPE detergent bottles sometimes have small amounts of leftovers inside, maybe this could be used to clean the motor oil bottles?
@s2019 Yea a paper towel is great to get most of the oil off and not really a big deal to burn; I also have no idea what the effects of traces of oil would be on reuse. However I do know that there are some plastics which are deliberately impregnated with oil for reduced friction applications.
thanks; I have looked carefully at different options for injection, but for the product I want to produce, I think the best method will be to make solid blanks or billets using a compression-type machine, and then turn them on a lathe to create the final shape. It is important for my product to be exactly round (yes it’s a wheel).
@s2019 I’m not at a stage to answer that yet I’m afraid, I don’t have any machines yet so I haven’t started using any of the plastic I’ve been collecting.
However it makes a lot of sense to me to clean the plastic as much as possible before shredding. With motor oil bottles I have found that leaving them upside down in the sun for a few days allows most of the oil to slowly drain out. Then I fill them with hot water to loosen and remove the labels, drain, then part fill again with hot water and a drop of washing-up liquid, and shake with the top on. drain and repeat 2-3 times. I have not tried yet but I wonder about adding a spoonful of sand to the water to give some abrasion.
I don’t know if this will get them clean enough to use, my plan is that after this i will cut the bottles in half length-ways and put them in for a cycle in a dedicated dishwasher, with mild detergent. If anyone has any experience recommendations of detergents I would love to know.
Of course the problem then is how to deal with the contaminants in the waste water, I plan a series of mesh screens followed my a sand/charcoal filter.
I see motor oil containers as one of the most promising sources of HDPE for recycling if these issues can be properly addressed.
Another way to remove oil is to use aerosol brake/clutch cleaner, which does a great job for occasional very oily items, but it’s not very nice stuff and not really in tune with our broader environmental concerns.
Edit to add: some info about brake cleaner: https://envirofluid.com/articles/tetrachloroethylene-a-deadly-danger-in-brake-cleaner/
For HDPE milk bottles and motor oil bottles, I find filling them with very hot water will usually soften the glue enough to peel the label off. Then I use the label to dab away any remaining glue. The hot water is also a great first pre-wash.
Another low-tech idea I just remembered which I saw in Africa once:
A pair of car wheels mounted on a steel beam in line with each other, about 50mm apart. One on a freewheeling hub, one on a drive shaft through a hole in the beam, which connects to your machine e.g. shredder. The drive shaft needs to be positioned as low to the ground as possible, i.e. dig a hole in the ground for the lower half of the wheel.
Build a small wooden ramp in line with the wheels.
Drive the front wheel of your car up the ramp and over onto the mounted wheels so that it sits between them.
Start the car and run in 1st gear. The differential in the car will send all the power to the raised wheel, in turn powering the drive shaft with very high torque.
Edit to note, it took several people to push the car back down off the ramp afterwards and the whole thing was rather dangerous!
A cheap idea for filtering waste water to remove microplastics- very fine mesh filter bags sold in sets of decreasing grades down to 25 micron: Herbal ice extraction bags
Even cheaper on ebay or banggood.
Might not be ideal for production processes, but could be useful for small scale stuff, or for counting microplastics of different sizes in wastewater?
I also want to be able to make moulds from 3d prints, I’m currently working on the idea of lost wax casting of aluminium. Briefly this would involve coating a 3d printed original with a thick layer of melted wax, separating the wax off in 2 halves when cool, casting the wax halves in plaster of paris; when the plaster is hardened, heat it to melt out the wax, then fill the void with molten aluminium.
I’m still only part way through building an aluminium melting furnace but I’ll let you know how it goes.
Edit @frogfall Annoyingly it’s difficult for us to access what people have posted before on the subject without a proper Search function on the forum 🙁
It’s not for me to comment on your relationships with other parties, just like it’s not for you to comment on my skills or background. But I am suggesting that a decentralized movement will be much more robust, reduce conflict and allow individuals to focus on getting the job done.
I agree that the community needs to be able to control it’s own web presence, but there’s nothing to stop anyone setting up their own website and negotiating a co-operation.
Clearly people are getting worked up and distracted, which is why I would encourage people to focus on the job in hand with their own projects. With regard to getting funding and support, as the original thread suggests there is definite potential to get help from existing companies, grants and other sources, but there are challenges in demonstrating the viability of individual projects in order to negotiate funding. This is why I am advocating a conventional small business model, self-sourcing of funding and investment for each project, an element of market research, testing etc and driven by financially rewarding participants and investors rather than relying on their goodwill (and ability to not fall out with each other).
@pex12 In my opinion it is not the responsibility of Eindhoven to support individual projects, and attempting to do so would only ever lead to conflict. I think it is better if individual projects source their own funding and resources. Although it is challenging, the process of doing so helps to shape each project and to ensure commitment from it’s participants. If financial support were ever to be a possibility, I would imagine it could only be delivered to projects which have already demonstrated some success anyway.
It’s great that some individual projects are getting exposure through the PP site and I believe this will continue. In the mean time, my approach would be:
1. Have a good idea of a product to make from recycled plastics, and establish the valid need/purpose for it
2. Research existing industrial production methods
3. Develop an appropriate DIY method for your product
4. Manufacture the product
5. Sell the product via the PP Bazar
6. Share your experiences and methods developed via the forums
7. Use profits to recompense your time (pay yourself as an employee), and invest further into your product
This approach avoids all the political conflict you seem to be experiencing.
@pex12 I don’t know or really care about the politics with PP Eindhoven, I see no reason why anyone should feel constrained by them, or any other part of the movement. In my opinion we should be grateful that they have given us all so much to get started ourselves independently, and even to make money, and so now it’s up to us to do that. I’m suggesting the best way is to start as a more-or-less conventional business, making things and selling them. Instead of looking for support from Eindhoven or anywhere else we should be figuring out how to do it on our own. And when the raw material is free there are really no excuses, we just need extremely good product ideas which add actual value to discarded plastic. That is the real challenge.
Hi, a simple design for a wet scrubber I read about a few years ago, sounds similar to the ones mentioned:
Large plastic barrel; 100mm plastic pipe fume inlet cut through the side at the bottom, with a 90degree bend pointing down on the inside at the mid point of the barrel; 100mm outlet pipe of your choice cut into the lid, with inline fan to draw air upwards through the barrel.
Hose with garden sprinkler atatchment fitted upside-down on inside of lid. Outlet for waste water at bottom to separate sand and charcoal filter.
Fill barrel almost full with ping-pong balls or other small plastic items. This creates a huge surface area for fume gasses to be collected or neutralized.
In the example I read, they used a Lye solution through the sprinkler, but this may not be appropriate for plastic fumes.
The financial side of operating a plastic recycling enterprise is still difficult for me to figure out too. On one hand, we are trying to address a problem of waste, and on the other hand we are trying to make money by selling our products. There is a philosophical conflict between the two ideas, some people even feel that it’s not right to benefit personally from recycling plastic. This is understandable perhaps, since most people at this stage are engaging in this voluntarily and all profits go back into making machines.
However I feel that this mindset will be the biggest limiting factor to success in addressing the plastic problem. If people are unable to gain financially from the activity, the only ones who can afford to give their time to it are the (relatively) rich. Therefore I think it is vital that plastic recycling initiatives are treated as small enterprises rather than loosely organized voluntary activities. Using the structure of a company, even if it is a not-for-profit company, ensures a robust business strategy which seeks to deliver financial return to reward participants and to develop further. It should also help to focus manufacturing principles towards creating products which are actually useful and in demand, rather than simply more useless plastic objects.
By forming a small company, we can then engage with other local and existing companies on the same platform and format, and interactions such as inter-business loans, investment or support are much more straightforward.
And it shouldn’t be too difficult, we are talking about setting up a manufacturing process which uses a raw material which is free. 100% added value. We all share the same environmental ideals, but I strongly feel that only the potential for financial reward for participants will enable this movement to survive and grow in the long term, and I think we can only achieve that if we focus on discarded plastic as a huge opportunity, rather than a problem. Then we can see that way to interact with ‘Industry’ is to recognize and accept that we are part of it, and arrange ourselves accordingly.
excellent yes, thanks I hadn’t seen that video. What I’m planning is basically the same idea but with a lost wax investment casting instead of using greensand. I am keen to try both methods, but I think lost wax might be better for my needs because I want to retain as much dimensional accuracy as possible. Also investment casting means no mould lines, because you just smash the plaster of paris to get the casting out.
As people have mentioned elsewhere on the forum, mould making is often the most challenging part of the process – which makes it the most interesting!
yes lost wax casting is nothing new, but I don’t know if anyone has tried it for making aluminium moulds for plastic? I’m part way through building a furnace to melt aluminium, as I want to make prototypes of my product in aluminium too, but my end goal is to make the product in recycled plastic so maybe I can make cast aluminium moulds with lost wax casting direct from a positive pattern?
My funds are limited so I can’t develop this method as fast as I’d like, maybe someone else out there would like to give it a try?
@donald Amazon sells a small degassing vacuum chamber for under £50, for use with casting resin, I’m guessing melted plastic would behave in a similar way to resin in a vacuum, but I have no practical experience with any of this yet, I am still developing a technique that will work for my goal
Also another option I’m developing for detailed moulds:
– 3D printed original pattern object (positive) or similar – could be hand made of wood etc.
– Attach paper divider to form separation point of mould, lubricate lightly with vaseline?
– Melt candlewax and paint onto outer surfaces of pattern object to gradually build up layers
– when sufficient thickness has been reached – at least 30-40mm, and wax is fully cooled, separate wax negative from pattern
– attach wax sprues to negatives to form pouring inlets and smaller gas outlets
– submerge the wax negatives in plaster of paris in a plastic bucket and wait until it completely sets
– remove the hardened plaster of paris lump from the bucket, bake upside down in the oven on a baking tray until all the wax has poured out
– remove wax in baking tray; turn plaster of paris upside down and bake for a few hours more to remove any traces of wax and vapour
– remove from oven; melt aluminium and pour into inlet holes while plaster of paris is still warm
– wait until fully cooled; smash plaster of paris and retreive your aluminium negatives of your original pattern object.
-Use these to make moulds for recycled plastic injection/compression moulding
Any thoughts? A bit long winded perhaps, but maybe more accessible for some than CNC-ing aluminium moulds…
Edit to note -the reason you need to build up the wax in layers is because if you cast a heavy block of wax it shrinks so much that you would lose the correct shape of the mould
@donald I love the idea of using a vacuum to get rid of bubbles and get a uniform material. What about even more lo-fi, I’m thinking to form solid heavy cylindrical blanks for turning:
– Find saucepan with lid
– Cut hole in lid and fit some kind of pipe attachment
– Add some kind of rubber gasket around the edge of the lid to form a seal
– Melt plastic in oven, in the saucepan with the lid off
– Remove from oven and put lid on
– Attach vacuum cleaner to pipe connector on lid and suck.
– Hopefully don’t fill vacuum cleaner with molten plastic lava
– Cool and remove de-gassed plastic blank
What do you think? I’d like to give this a try
This is a great thread! I am currently experimenting with mouldmaking options involving lost wax casting of aluminium, cast plaster, or hand machined aluminium.
My addition to the thread, in relation to posts higher up about CAD design of moulds, is that I’ve found STEP files to be the most commonly used especially for 3D printing. I’m a Sketchup user, but the free version doesn’t allow export of STEP files only COLLADA files; but I’ve found that online convertors work fine to translate a COLLADA file into a STEP file you can download. I have sent these to Meshlabs.com for printing and they work fine, you just have to be careful that your units are correctly set to inches or mm so that your print comes out to scale.
Also looking into hydraulic rams from tipper trucks which can be found cheap; come with their own pump, have a long stroke and might be powerful enough to be use individually. I thought about forklift rams but these often run on a shared hydraulic system so I’d need a separate pump. But that would be one hell of a stroke, a very long barrelled machine!
Better to keep them separate, otherwise the product cannot easily be recycled again in the future.
Also they do not blend well together to make a uniform substance
yes I have watched the videos and I have been researching different ways to produce a product which I have in mind. At this stage I just need a proof of concept of the actual product, not the production method, so I don’t want to commit to building a machine yet.
From what I can gather, some crock pot slow cookers on the highest setting can reach around 250deg Fahrenheit which I believe is just about hot enough to melt HDPE. I do understand that the thermostat and temperature sensor need to be replaced in order to maintain a stable temperature but I think this should be possible. One advantage would be that the pressure could be delivered by simply placing a heavy weight on top of the mold.
Alternatively just to melt the plastic into a dough to be pressed into a separate mould..