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I’ve been thinking about having different sized piston hot ends for different types of molds. Making the large clips, I need as much volume as possible. Filling a large cavity through a large diameter nozzle requires less pressure and I can use a larger diameter piston. For small items, with smaller diameter sprue, it needs more pressure, less volume, and potentially a smaller piston. @andyn mentioned that he uses what I think was a bushing in his system to get to a smaller diameter. I’m not sure of the details of his implementation. I think in your design with a little modification, you could have the hot end and a length of the piston be a drop in replacement with the electricals connectorized appropriately. This would give the smaller user (that does not have quite the user-mass advantage I have) a chance to make some smaller items. Actually, in your desktop design, if the middle beam was replaced with a pair of back to back C-beams with a gap in between you could have both hot ends in place and just slide the one you want to use into position. That may also be a way to increase the low throughput of the injection machine.
I’m going to make a mount for my earlier smaller hot end so I can use either in my machine.
Searching “efficiency of pulley drive”
Lots of good info and design guides out there such as https://www.grainger.com/content/supplylink-industrial-belts-save-energy
So it depends on your design. Handbooks provide the minimum pulley size and separation to avoid slippage.
Thanks for the link to vanplestik. In their product descriptions it says 100% recycled. I think the boutique furniture and decor is a place where a workspace can do well.
@donald I’m not sure I would depend on complexity providing the safety filter in the machine builds. The compression oven and injection machines are within the DIY capability even without broad technical expertise. Judging by the number of “melting plastic in your kitchen toaster” videos, the safety risk is out there.
@pporg thanks for taking this on. If you are planning on hosting this on your site, that would be great. I truly appreciate Dave Hakkens providing this forum and the current moderators flushing out the spam, but as a data repository, it is fairly transient. I’ve seen posts where the forum is to be ended and replaced with some other platform, though the V4 folder does not have much information on the data architecture of this new platform. My expectation is that if the V4 team gets immersed in Project Kamp, it is such a large endeavor that it will be all consuming for the foreseeable future. So managing this information on a site that is unaffected is a great offer.
Let me know if I can help with some of the content.
If you can find/make a metal fan blade and connect it with a motor on the outside, convection should help quite a bit.
The “I’m new, I want to get started saving the world” checklist
Model business plan..i.e. Reality check
The “What can go wrong” list
V3 machine capabilities
Case study examples of actual workspaces (if possible include one with positive cash flow – unsubsidized)
@mvenson , Sorry that thread meanders a bit. I used it as a collection of ideas rather than a description of a point design.
The particular post (22/03/19) where I used the aluminum tube as a compression mold was an experiment to see how well the aluminum tube would distribute the heat from a single clamped-on cartridge heater and to see how well the arbor press could be used for compression molding. It worked well so I ended up using it in my current version show in the 06/05/19 post. I used the cartridge heaters because I had them, and I had the aluminum tube. Since they are cheap (I just bought a bunch for a couple of dollars each) I plan to use them for other things like heated molds etc.
I have not built an extrusion machine but, for that, getting a good dimensional match between the tube and the auger is important. I would stick with the steel tube and band heaters. I’m not sure what you mean by aluminum tube and steel pipe as barrel but directly heating the steel barrel should work well.
If you are using the typical threaded tip thermocouple sensor that comes with a lot of the PID/SSR/Thermocouple bundles, a convenient way to mount those, especially on a relatively thin walled tube, is to use a small block with a through hole tapped for the thermocouple thread and a couple of mounting holes or a hose clamp to mount the block. This way you thread the TC sensor into the block until the tip is pressed against exterior of your tube. You can see an example in the thread I linked.
You can see the approach I took for both the heater and the temp sensor in this thread https://davehakkens.nl/community/forums/topic/portable-desktop-injection-machine/page/3/ . Using aluminum for the barrel makes the cartridge heater more effective.
Yes, even though I’m not quite in windmill country, when it blows, it can be pretty strong, I made the clips long enough that I can put plates across the bottom to fully capture the beam. The clips are chunky with each leg about 12.5 x 38mm. I screw directly into the HDPE with sheet metal screws. I drill an undersized hole and then drive the screw in and out a few times with a cordless. The screw heats up and seems to form a thread in the HDPE.
If you go with the injector, just be aware of the size limitations on the parts. Mine has a cylinder swept volume of about 200cc, I can get maybe 130-140 g of HDPE into a part. The larger bottom clip is about the limit.
For my injector I use cartridge heaters (also called mold heaters) but it means a modified design. Amazon should have the band heaters as well.
@wellsforzoe I was surprised that you wanted to build the injector first. While it is one of the easier machines, it produces fairly small items and does not consume much plastic (probably less than 150 g per shot). You also need the capability to make molds, which can vary in difficulty.
Integrating the injector design with a solar concentrator has some challenges. If you are going to try for direct heating then you will need to configure the injector cylinder accordingly, you will also have the sunbeam in the same place where the operators are working to fill and compact the plastic in the cylinder. If you go with the remote collector and hot circulating fluid, you will need to design a heat exchanger at the cylinder and you have to come up with a hot fluid pumping approach. Both can be done, it just means some engineering needs to happen to come up with a modified or new design.
By comparison the compression oven should be easier to adapt to solar heat and there are similar designs already out there from the baking application.
Have you tried band heater in ebay and amazon?
Depending on how big, how many, and how perfect, I would consider trying a split mold that forms the shape. If they are large, maybe one mold that repeatedly squeezes the correct shape (kind of like a pair of pliers) and drops it into water. If there are a lot of small (airsoft sized?) pellets, maybe a mold with 10 or 15 in a row and the extruder bead is place along the row and then squeezed. If it is a standard size, this could be made with a ball endmill. For a limited number, may be even cast it in plaster or equivalent.
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.
It may be worth writing down some top level requirements to establish the scale of what you are trying to do. I’m guessing you will end up modifying the basic injector concept significantly. It may also be worth keeping a hybrid concept as a possibility where some of the power and control are electric. PV solar panels are relatively inexpensive.
Yes, a freelance designer should always have a plan for managing their designs and other intellectual property. It may be easier to do with an engineered CAD file for a product mold than for a sketch of a chair. I think this forum and PP are promoting an open source environment but I’m not sure there are any restrictions about advertising custom design services in the Bazar.
I would like to hear of one workspace that is making a profit once reasonable salaries and payback on capital expense is accounted for…If it exists, they should post the secret.
I wonder if an application there the obvious recycled look is a great benefit would be to make recycle bins (for sidewalk collection?), maybe 100l, some frame and slat design using the V4 extruded beam techniques.
There is a link to a low cost example PID, thermocouple, SSR bundle at the end of this thread https://davehakkens.nl/community/forums/topic/ssr-relais-for-injektor-extruder/ . The control requirements are not very sophisticated so I don’t think you will need to tune the PID parameters which you can’t do with some low end units. If you already have the SSR and temp sensor, just make sure that the PID is consistent with them. With the lower cost SSR you probably want to have lots of margin on current.
If your use requires industrial quality equipment similar configurations are available at a significantly higher price.
Nice clean design. I wonder if you used an I-beam for the moving table and put the guide holes in the flanges, you could avoid the dreaded ” @pporg : yeah, I ended up welding anyhow” admission.
I wonder, when you add support feet to make it less likely to tip, you may be able to end support your bottom C-beam and then use a dial indicator on the center as your force measurement. Probably should run some numbers to make sure you don’t yield at 8 tons, though you could move the support points in as needed.
As far as using plywood as a isolator. It is not clear from your pictures how much is in contact with your hot plate but take a look at this page https://www.performancepanels.com/thermal-properties and see if the concerns apply.
Not sure what your temperature and force cycle timeline looks like but one option if you spend most of your time heating is to use some springs to support the hot plates and have the support transition to some lands (blocks) once you apply high pressure. I’m not sure about the concern of heated molds. The heaters are cheap and cable management should be doable.
@pauldufour , As before great work. The results for the degraded plastic (HDPE?) are very encouraging. I’ve been trying to figure out what to do with crumbly flower pots, etc.
Were the samples on the display board injected? Are those temperatures the body temperatures or the nozzle?
You’ve posted a lot of great results, are you planning on collecting them (along with some detail) in a report of some form?
Thanks again for the update.
It looks like one of these https://www.harborfreight.com/12-ton-air-hydraulic-bottle-jack-94487.html or ebay/amazon equivalent.
It is funny, we were in a gardening store picking up some fertilizer and I saw they were selling a heated press for the errrrr…. cultivators…. I’m ignorant of that universe but these rosin presses are well finished heated presses that range from a few hundred https://www.rosineer.com/products/rosineer-rnr-mv2-manual-rosin-press-dab-machine-with-tools-for-best-plant-oil-extractions-dual-element-heating-plates-heat-plates-with-food-grade-stainless-steel-cover-easy-operation-with-manual?variant=40342718404 to a few thousand dollars. They look well capable of hot pressing things other than duckless duckweed.
As was mentioned, beyond the basic machines the equipment list depends on what your capabilities are and what you are going to outsource.
Are you going to build and maintain the machines yourself? Are you a mechanic/machinist/welder? Are you going to do all the sheetmetal fabrication? Are you going to do all the electrical/electronic assembly and diagnostics? All of these have some general purpose multi-use tools and some specific tools that you only use during the build. It may not make business sense to try to acquire all of them or to do all the steps in-house.
How are you going to acquire and process the materials? Do you need to provide collection bins? Are you expecting a broad mix of dirty consumer and industrial plastics? Do you need equipment to wash them beyond just tubs? Are there any requirements on what to do with the contaminated water? Do your products depend on carefully sorted plastic by type and by color, will you need lots of individual storage?
How are you going to create the molds? Do you do the CAD work and then outsource to CNC. Do your molds require welding?
Do your products require any additional processing after they come out of the mold? Trimming, assembly, heat welding? Will you be shipping most of your products? do you need shipping scales, packing equipment, moving carts, storage racks? Do you expect to have a storefront? Do you need display cases, racks? Lighting, counter, transaction equipment?
One thing to keep in mind as you work your capital requirements and cash flow estimates is that the PP V3 designs are not really high throughput designs. If you are making 10 euro items but you can only make 3 of them per hour, that is a tough business model.
It can be brutal and humbling to have your business plan reviewed and picked apart but if you are investing your own money, it may be a good idea to post at least the summary of your business plan and let people critique it. There is a broad range of business and technical expertise present here that can help you avoid some pitfalls.
Unfortunately I have not seen the PP effort generate a model business plan. There are some cost spreadsheets but not either a business plan or a successful case study.
It might help if you said what the purpose of the workshop is (produce a specific product?, education? pilot program for a larger municipal program? etc.). Does it need to make money or do you have a sponsor? If you are at the “there is too much plastic and I want to do something stage”, you may want to work out the detail objectives and business plan. After that, planning the hardware should be much easier.
Well you can always go for a record http://www.guinnessworldrecords.com/world-records/largest-tape-ball …that should raise awareness. Especially if it becomes public art that everyone can add to.
Yes, for that simple mold the next step would be to redesign the aluminum block that forms the 90 degree turn at the entrance to have a more positive seal.
One thing I’ve done both with the injector as well with some press molds is make a collection of stock material that I use on short notice to make some simple items. Yes you can buy Delrin, Nylon, or HDPE bar or rod from a plastic supplier, but it takes time, shipping costs, etc. The other option is to make it out of aluminum, but then I have to go to the metal supplier, dive into their cut-off bin, etc.
For example the test parts I made a few posts ago already got used to repair a glass/LED garden decoration where the original steel support base rusted out and a new solar panel mount was needed as well. I could have made it out of aluminum but why? And the bright yellow color matched.
I think in combination with some simple tooling, it just becomes another tool in the shop.
I tried 210 C for the garden stake. It came out well but I could only push out about 65 cm before the nozzle end of the mold leaked under high pressure. To go further I would need to change to more positive connections. Not going to pursue that at this point, but it was a good capability test.
I need to get back to making more of the large black clips for the top of the pergola (from a week ago). There are more things that need to be attached that those will be used for.
@davidsharma777 I don’t have experience with the labels, but I found this that might be helpful. http://www.plasticsrecycling.org/resources/reports/sleeve-label-study