It's always fun to get a new mold in the shop. This week, after a long wait, we received not one but TWO new molds. The first mold out of the box is a companion to our switchplate cover below... recycled outlet covers. 

These took a bit of designing from our friends at Sustainable Design Studios in the UK. Since the US uses a completely different power system than the UK and EU, we had to send several covers to Rory to take measurements from. Just like the switchplates, he created a model in Fusion360, which was sent to one of his UK partners for fabrication.

All this happens overseas, so the entire process took some time. But they finally arrived this week, and the finished product looks great. They're a perfect complement to our switchplates, and now that we have these in hand, we can start Rory on our next mold, which will be (by popular demand) double switchplates. It turns out that a lot of homes need these, and we've got a lot of requests. 

And just for good measure, we also ordered a pen mold. While this only uses a small amount of plastic, it's a nice item that will be good to have.

Up to now, our recycled items have only been for sale locally. But if you'd like to materially support the TybeeCleanBeach mission, you will soon be able to order recycled items from the Tybee Island Marine Science Center website. TIMSC has been one of our wholesale partners for a few years now. They plan to increase their web presence, and TCB is proud to be a part of that effort.

 One of the challenges that we have with recycled plastic is the longevity issue. Here in the US, we tend to view anything made of plastic as disposable... "use one time, throw away! (Which is a direct quote from a very old Chinese man my mom was talking to in Malaysia in 1973, but that's another story.) To put it another way, we are constantly asking ourselves, "what can we make that isn't going to be tossed into a landfill?" 

That's why we settled on the idea of switchplate covers made from recycled plastic. Once these are installed, they tend to stay in your house for a very long time.

But like most things, coming up with the idea is the easy part... executing is more difficult.

Our first attempt at switchplate covers involved a three-piece "sandwich" mold, laser cut from SendCutSend. In short, it didn't work. (It wasn't their fault, their parts arrived exactly as specified... the problem was with my design.) The finished result was sized correctly, but far too crude in appearance to be actually used. This was a mold-making job for the pros.


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The pros, in this case, live just outside of London, England. We have bought several molds from Sustainable Design Studios, who also supplied our two Injection Mini machines. We bought our first machine assembled, which was a mistake in retrospect. In overseas shipping terms, the assembled machine is fairly large and heavy, and our machine must have been dropped in transit. So I had to take the thing halfway apart and re-assemble, which took almost as much time as building from scratch... which is exactly what we did for our second machine. We bought the kit (more about the build process is coming soon)- but I digress.

We got in touch with Rory Dickens at SDS about designing a mold for us. We sent over a standard US-style switchplate so that he could take off exact measurements. After some time, he returned three 3D-printed examples- one percent undersize, one percent oversize, and one actual size. This was to allow for shrinkage of the plastic. All three worked, but the actual size print seemed to be the best fit, so we gave him the go-ahead to cut the mold.

Some months later, we received our mold. To say that I was impressed is putting it mildly... it's a beautifully-made, nicely-finished, expensive chunk of aluminum. After a few tries to get the temperatures and pre-heating requirements dialed in, we started to produce switchplates. That's when we learned that this product is an especially good fit for our Injection Mini. Rory's design is especially quick to use. The finished product clears the mold easily, so we can inject the plastic and clear the mold in about 60-90 seconds. 

And the finished product looks great. There's almost no flash to clean up, and the sprue is removed with two snips with a flush cutter. We make these with colors, as well as straight white and black. All look good. Early sales are indicating that these will be a fairly popular product... so much so that we've already contacted Rory about making another mold for us- this time, a matching outlet cover. 

We will need to sell a lot of these to recover the investment in the mold, but I believe it'll work. It was expensive, and it did take quite a while to get the project done. But it's a great fit to our core mission, which is to keep plastic out of the landfill.

It's always exciting when we get a new mold in the shop, even if the product isn't terribly different. This one is a large bead mold for craft projects. It's pretty much identical to our previous bead mold, it just makes larger beads. It is a little easier to use than the small bead mold, since there's a touch more room for the plastic to flow. We managed to get several fully-filled rings of beads on the first day, with no short shots. This wasn't the case when we tried our small bead mold, which has to be pre-heated... otherwise the plastic will solidify halfway through the injection process. We still get useable beads when this happens, but we don't get as many. We learned that when these molds are preheated (about ten minutes at 250 degrees F usually does the trick) and lubricated with a quick shot of silicone spray, they work like a charm. We followed this process with the new bead mold right from the start, and had no problems.

These molds use such a small amount of plastic, they can be used pretty much continuously. In other words, you can inject the mold, add a little flake to the injector, and then remove the product. By the time we get the product out of the mold and tighten the bolts, the injector is ready to go... no need to wait for the plastic to melt. What this means is that we can really crank out the beads. This is a good thing, because beads are a fairly low-cost item and we can't ask a whole lot for them. So the quicker we can make them, the better.

Just a quick note to let folks know that TybeeCleanBeach will be fundraising at the Tybee Island Farmer's Market on Monday April 8th from 3:30 to 5:30 or thereabouts. Stop by and say hi, and have a look at our #5 recycled coasters, herb pots, soap dishes, coasters, and other items. Remember, 100% of our proceeds go directly towards expanding our recycling efforts... like our NEW Injection Mini machine that will be exclusively used for #2 plastic... more on that coming soon!

After last week's post, I spent a fair amount of time in the shop adding extra bolt holes around the perimeter of some of our letter/number sets. I brought these into the shop yesterday for another test.

I'm happy to report that these are much improved, but not fully fixed. I ran two different letter dies in the mini to check the results. There is still a small amount of flexing in the aluminum around the center of the mold, which allows some plastic to leak around the center of the letters. While these letters will be salvageable, it is going to require a good bit of cleanup... something that we can't afford to do on every single letter that we make.

The next correction will require another order to our friends at SendCutSend. We are going to have a new bottom plate cut from thick steel, at least 1/4". It will have all eight holes located and burned, but since these holes are very slightly tapered, I'll drill them out to the final size on my little drill press. 

I'm also going to tap these holes for 5/16-18 threads, rather than using nuts on them like we currently use. It's a bit of a pain, especially since I have been plagued by a run of broken taps lately (more on this subject will be coming later... I'm still researching). But having tapped backplates should add a bit to the speed of the process, as it seems like I'm constantly chasing nuts around the floor.

A friend, Dave- who has a great deal more machinist experience than I do- suggested a further improvement. By adding a very slight crown or dome to the backplate, we can concentrate the clamping pressure on the center of the mold. We're talking about maybe a few thousands at the most. I can get this with a couple of passes of a flap wheel on a side grinder to the outer two inches or so. It's quite possible that this won't be necessary, and I plan a few test presses first. I'll be sure to post about the results, so stay tuned.

Some time back, I designed a set of letter and number plates for our large Precious Plastic design injection machine. In hindsight, and to put it politely, I made a few choices that I would do differently were I to do it again. To be blunt- I screwed 'em up.

We have a lot more experience with molds than when we had these cut, both with in-house designs, as well as out-of-house designs. I like to think that everything's an experiment, and any experiment can fail. Right now, these molds are falling into the "fail" category. But there's almost always a fix, and that's what I'm in the process of now. But first, let's have a look at these molds:

The screenshot above seems pretty good at first glance. We specified aluminum for these plates in an attempt to keep the weight manageable. We are making more than one letter or number at a time, which is good from a productivity standpoint. And the layout has a central injection point and corner bolt holes that are all in the same position. This means these dies can be stacked- creating four or even six letters or numbers at a time. We arranged the letter combinations to minimize "closed" letter shapes, like A, P, Q, R, O, D, B, 6, 8, and 0. These letters need a dedicated backplate with the centers either welded, or in our case, riveted into place. The other letters can use a plain backplate, reducing the total number of plates required. This, in turn, reduces the cost.

But the thing that I've learned is that injecting molten plastic creates a huge amount of hydraulic pressure... enough to deform 1/4-inch aluminum plates if they're only held at the corners. When that happens, plastic squeezes out in between the plates, creating a huge cleanup problem. To prevent this, we need more bolt holes.

And here's where my layout mistakes become apparent. If we simply add four more bolt holes in the center spaces between the existing holes... well, that's OK for some of the dies, but not all of the dies.

For example, take a look at the 4&5 die. Adding four more bolt holes in between the existing holes is no issue at all, and should fix the problem. This remains true for most of the dies. But a few are going to be a problem. The most obvious example is the I&M die, where I was trying to squeeze two letters in a space that, really, should have been left as a single letter. The cutout for the I running across the top of the die presents a real problem. Other trouble spots include the K&L, E&F, and W dies.

These could be corrected by adding two new holes across the top & bottom, for a total of 10 new bolt holes. But this won't work for all of the dies... it will interfere with some of the other letter cutouts. Again, I was trying to squeeze letters and numbers that were too large into a small, compact space. The dies have to be a certain size in order to spin onto the machine, Plus, smaller dies are easier to handle that larger dies.

Two of these dies are a real problem (even more frustrating because it's a problem of my own making.)... the S&T die and the M&I die. As far as I can see it, I have solutions, but none of them are really good. 

One fix is making a custom top and bottom die plate with a custom bolt pattern... expensive and a bit of a pain to keep up with. Another fix is to recut the letter plates for individual letters... expensive, and a little painful since we've already spent a lot of money on these dies. A third fix would be to make larger steel top and bottom plates, with bolt holes that fall outside the outer edge of the aluminum. This might be the cheapest option, but it would result in a heavy & bulky die stack.

So for now, I'm adding four new bolt holes to the existing dies. That should solve the problem with 15 of the dies, leaving 5 unresolved. I think I'll sleep on it for a few nights before I decide how to fix the others.

 As I've said in previous posts, we have two plastic injection machines in our shop. Our first machine is the Precious Plastic designed injection machine, built for us by the Sea Monkey project in Malaysia. This is a great organization that we were really proud to support, and we use our machine a lot.

While this machine has a host of advantages (for example, a larger shot size and higher manually-controlled pressure), there are some downsides. Mainly ergonomics... the PP design uses a threaded barrel. Molds are screwed onto the barrel, forming a tight, high-pressure seal. This method is simple, cheap, and works fine.

BUT...
It isn't perfect. The threads can wear out over time. This is exactly what has happened with our first square flower pot mold- it no longer attaches to the barrel. Normally it's a simple matter to weld on a new pipe nipple to replace the old one, but this is a stainless mold, and I don't have a TIG welder.

The second problem has to do with us. Our workshop is staffed (if you can call it that) with all retirement-age technicians. Of these, only one of us has the knees/hips that allow getting on your hands and knees in order to screw on the molds. It's further challenging to hold a heavy, stacked steel mold flat while lifting it up to the barrel in order to get the threads to properly catch, and cross-threading is a problem that has to be guarded against.

There is a solution to this problem, and it's partially why we bought our Sustainable Design Studios mini injection machine. It uses a smooth tapered nozzle that fits into a matching recess in the mold. When held under pressure, this forms a seal that doesn't leak. It's self-aligning and quick, and I'm starting to prefer this type of attachment.

So here's the trick: most of our molds use the screw-in type of attachment. What we needed was a way to use both our machines with our existing molds.

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What I came up with is a simple- in theory- aluminum nozzle adapter that can be bolted onto a steel plate. I have a supply of  3" x 1/4" aluminum bar that I saved from the trash awhile ago, as well as a few small aluminum rounds that will fit in my small 7 x 14 lathe. 

Machining these little sockets is time consuming, but not too difficult since the aluminum is relatively soft. I suppose it would be theoretically possible to design a cutter similar to a countersink. You could chuck this into a large-ish drill press, to machine this profile in one go. That's probably beyond my machinist skills, though there may be something at Grainger that might work. In the meantime, I cut these manually. As I said, it's time consuming, but it does work. (Note: stay tuned, I may do some more research in this area shortly.)

I'm certain that the folks at Sustainable Design Studios or Easy Molds could fabricate something functionally similar but a lot nicer, but these work for now. ​

If you look around the Precious Plastic website, you'll find three main methods for recycling plastic- injection molding, extrusion molding, and sheetpress. While we are very busy with our injection machines, we're also looking into the other options as well.

A sheetpress is- again- very simple in theory. You bring the plastic up to melting temperature in a specialized oven, and then squeeze it to get rid of the voids. What could be simpler?

In practice, though, it's much more complicated. The Precious Plastic sheetpress design is a complicated build, and our metal fabrication facilities are extremely limited. To put it another way, I'm our metal fabrication facility. I have a stick welder, but that's about it. There's no space to build such a machine, and no room at our Tybee Island shop to put the thing if I did build it. But on the other hand, a sheetpress can use a lot of plastic flake at a time, and we have a lot of flake to use.

So I wanted to try some kind of small-scale sheet press operation- something that is cutting board size or smaller. If we can find an oversize toaster oven that isn't too expensive, then we could match that with a small flat press to squeeze the "sheet." We still don't have the toaster oven, but I went ahead and designed & built a press that is slightly larger than a cutting board. 

The main thing I was after with this design was low cost. It's made mostly of angle steel and 1/8x3 flat bar. I had an old bed frame that I squirreled away some time ago that provided the angle steel, and I had about eight feet of flat bar from a previous project. The plywood for the bed was also scrap... someone was moving and cleaning out their woodshop, so that was another zero cost item. The only thing that I needed was a small auto jack, which I bought for around twenty five bucks. Even if you had to buy everything new, I'd guess the cost would come in at around a hundred dollars.

The photos below show the basic process. In order to speed up the operation of the jack, the hand crank was removed and replaced with a bolt. You use a battery-powered drill with a socket drive to raise and lower the bed.

The "mold" for this... I really shouldn't call it a sheet because it's so much smaller... is just four pieces of 3/8" square welded into a rectangle. I used 3/8" because it's what on hand. Some sheet aluminum from an old road sign forms the top and bottom surface of the sheet.

I can't tell you how well- or even if- this approach works, because we don't have a heat source large enough to accommodate the mold. Another trick of this approach is bowls using male and female molds. The trick is the molds- they need to be very accurately made in order to get consistent wall thickness. This is a back-burner project that I hope to get on shortly.

Look for an update soon.

One of the issues that we have at the TybeeCleanBeach recycling workshop is the issue of what to make. Our machines are comparatively small, low-volume, low pressure affairs. This means the items that we make are going to be fairly simple.

We also want to break the mindset that plastic is a "use one time, throw away" material. The landfills are full, and burning it isn't very environmentally conscious. Plastic has a long lifespan, and we want to make things that will last and be used for a long time as well... making more plastic spoons is not our mission.

So what we started with were a few of the Precious Plastic designs for sea animal outlines, a coaster, and a square flower pot. Since then, we've expanded to include letters and numbers, and most recently, soap dishes, round flower pots, and small beads for craft projects.

This brings us to the problem of molds. Right now, we use two primary types of molds- stacked molds and true 3D molds.

The "sandwich" type of molds are the simplest. Described in simple terms, these consist of a top plate with some form of injection point, a bottom plate which is usually solid, and a middle plate containing some form of outline. The results of this type of mold- with exceptions- is basically a 2D shape of a consistent thickness, with some kind of outline. For example, our manatee mold is a 2D outline of a manatee. We make these into necklaces, keychains, and fridge magnets.

The exception is our coaster mold, for example. These have a dedicated bottom plate with a shallow, solid circle welded on. This becomes a depression where your glass goes. On the other side, we have a thin laser-cut plate with "Made from recovered plastic, TybeeCleanBeach.org", and then the top plate. 

These sandwich molds are comparatively inexpensive to make- we use both a local waterjet company and an online service to do our cutting for us. I have a diode laser engraver that I use to proof the designs. While I suppose that it would be possible to design molds without this step, it greatly improves my confidence level when I can hold up a cardboard mockup of a mold before we commit the dollars to have it cut from metal.

The other type of mold is a true 3D mold. These are much more complex to design, and expensive to execute. We have a few that we got from Sustainable Design Studio, and they are beautifully made and make an excellent product. When we one day get a grant for a gazillion dollars, we'll have them design and make all our molds... they really know what they're doing.

Even so, these molds are nothing compared to the high-pressure molds used by the plastics industry. It's not uncommon for a professionally made mold to cost ten to twenty thousand dollars. As Sir Alec Guiness said in Star Wars, "These aren't the molds you're looking for." Or something like that, it was a long time ago.

So molds are a big part of any plastic recycling workshop. We spend a great deal of time thinking about molds. Often it's the determining factor when we decide on a new product- where will we get the molds?

​We'll talk about them in more detail in upcoming posts

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