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(Preview of FUTURE project) Plastic-Extruding, Filament-making Machine

This will be a (near) future project. I plan to finish the 3D printer before I worry about completing this plastic filament making machine, but I have a good start on it already.

I bought the auger bit that I will need to carry the plastic pellets to the hot-end to extrude filament (which I can then use in my 3D printer). I took the pieces over to my brother's house to show him and without having to ask him, he took the pieces of pipe out to his shop and cut the slot that I will need in the pipe where the plastic bits will drop in and get caught by the screw.

Having only a lathe and not a full milling machine, I had planned to just cut a slot in the pipe by using my grinding wheel and trying to clean it up with the Dremel hand-tool. He did save me a lot of work by putting it on his Milling machine and cutting the slot for me.

☺ Thanks, Ric !


In the 3D printer, it is extruding a much finer line to hopefully add better detail to extruded pieces. In this machine, I will be extruding a 3mm diameter strand, so a bit more plastic should be heating at a time. Since I will want this plastic blob to heat up nicely, I have a larger chamber to heat. Earlier I used a copper welding tip and an aluminum block, but since brass fittings are available to thread onto steel pipe, I will use brass this time.

  I've purchased a brass coupling and a brass end plug. These will be heated, probably with the same resistor method used before, although with a larger volume of metal and plastic to heat, it will take more than just the 2 resistors that worked before. You can also get band heaters, but I think they are more expensive. I will check that out later.

Now with the auger screw turning in the direction to push the plastic towards the extruder end, the action-reaction principle tells me there is be equal pressure trying to push the screw backward, out the other end. In my basement workshop (metal shop) I found a perfect cap for that end of the steel pipe. It is actually a collar ring that was previously in one of the bathrooms, holding the feed pipe to the faucet, (prior to changing to a different faucet which had a different size pipes). This ring is the perfect size to screw onto the pipe and have a hole through which the shank of the auger screw fits. That will keep the auger in the pipe where it should be to push the plastic through.

So now I have most of the pipe hardware I will need for this filament extruding machine, but there is still the electronics and the drive.

I still need a drive mechanism to connect the screw shaft to the motor. This may either be in the form of belt and pulleys, chain and sprockets, or straight gears.  A belt and pulleys may be the easiest to locate or fabricate. (And to think I threw out a couple old bicycles that I could have taken the chain and sprockets from...!) As to gears, I have never made nor purchased a rotary table with which I can make gears, so that idea is pretty much out the window, unless I were to find some on ebay that are reasonably priced. I will decide on how to drive the screw later when I figure out what is readily available.

As I mention above, this project is only just started, and will not be finished until later.

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I wonder if you have considered a grinder attachment for this machine. You would be able to turn failed prints, rafts, and old support material into the pellets that would feed the extruder. I personally have a small box full of such material.

Almost.  What I have been saying to my brother and others is that my next machine after the filament extruder, will probably have to be a shredder machine to chop plastic into small bits. :-)

Until then, I will have to get by with my manual "paper cutter" that I've had around since back in the day, when I had my own darkroom and did film and prints. I can see, however, that using the cutter to chop up all that plastic will get old real fast.

I have seen several different filament extruder designs on YouTube, and they are all basically the same.  While I am following the same basic design they all do, I am not specifically following Lyman's design. I would say I am building it basically from scratch, after having seen several designs that work just fine.

I willl likely make the hot-end similar to the one I made for my 3D printer project (with wire-wound resistors).



> The following is Strictly MY OPINION about the Lyman extruder winning the prize. <

I have seen the plans for the Lyman II extruder, but while I may respect his age (83) I felt he won the contest by being "less than truthful" about his costs to make it appear he was under the $250 limit. Virtually every item is listed at lower prices than the actual listings I find on the internet. Did every company raise their prices on every item? On the auger bit he used, he gives an ebay listing. Looking at that ebay listing he mentions, you will see the auger he says he got for $8.00 is actually listed at $12.29 from that company. Did the price go up? Did he get it on a bid price? He does not say. There are other inconsistancies, as well.

He lists a flat 10% allowance for shipping allowance, but you can often pay much more than that. [For example the order from hardwareandtools.com, I was at their page and got a shipping estimate of $6.87 on an order such as he listed (less than $9), which is a 76% extra cost. Shipping prices will vary greatly, but I do not feel 10% was realistic, unless he had bought all parts from the same place on one order.]

I also felt he was misleading in another way. For example, he says he paid $8.80 for a bicycle chain, but since he only used part of it, he only added $4.40 to his list of costs. We all know he was not able to buy the chain for half price because he only planned to use half of it. Stores do not work that way. Since he paid $8.80 (plus tax), the total he spent should have been on his list of costs. Anything he had to purchase to build the machine, should have been added to his list of actual costs. To say otherwise is being dishonest. Therefore I felt he dishonestly adjusted his BOM (bill of materials) so he could win the contest. I also raise an eyebrow at the quotes from eMachineshop.com where the price is based on how much they are each if you buy 400 of them... Say what? So we should buy 400, in order to get a price that appears to keep our costs below $250? No individual is going to buy quantities like that. How much do they charge if you only buy one? Using the methods he did to make his costs appear to be within the contest limits, it is a shame the people judging the contest did not look closer at what he reported.

I looked at hardwareandtools.com where he got the pipe coupling, nipple and flanges. The prices are "almost" right. (floor flanges, he says $2.19 each. http://www.hardwareandtools.com/Worldwide-Sourcing-27-1-2B-Black-Pipe-Malleable-Floor-Flange-1-2-Inch-6102362.html The listing says $2.20, but only if you buy 100 or more. Individual price is $2.39. Pipe couplings 1/2" are $1.39, not $1.19 and the pipe nipple costs $1.19 versus his price of $0.99 http://www.hardwareandtools.com/Worldwide-Sourcing-1-2X31-2-Black-Pipe-Nipple-1-2-Inch-by-3-1-2-Inch-6456339.html

If you have to purchase a roll of kapton tape, you should list the entire outlay, even if you only used a few inches (or cms) of the tape, simply because you had to pay the full amount to get the pieces you needed.

Hmmm.... Auger bit inside of a tube....

Damn, ok, that's pretty good, my friend... 

Aye, the auger is 5/8" diameter and the pipe is listed as a 1/2" pipe. (Go figure.)

I have no clue why half-inch pipe does not have a single measurement that is one half inch...

That pipe is an old one that was laying around the house. (You can spot a lot of rough grooves on the outside of it. Those are marks remaining from some time in it's life that a pipe wrench was used on it.) It was a wee bit out-of-round. The auger bit went part way down it, but hung up about where the grooves are in the outside.  It had to have a 5/8" drill bit run down it and now the auger fits perfectly.

In the picture it looks like there may be a gap between auger and pipe, but that is just shadow. The actual fit is perfect.

Nice start!

Are you making a plastic extruder from scratch, or are you following an existing design (lyman filament extruder; filastruder ...) ?

Oops, your answer was posted above.

Man I just asked out of curiosity, but in the end I think your point of view is interesting!

Since you live in the States I can totally understand the rant about price inacurracies. However, I'm in the euro zone and consumer hardware stores around here don't carry the same stuff at the same price tag than, say, home depot or harbor freight... Sucks!

I'd also like to build a filament extruder; I had to go to 7 different hardware stores around (no reasonnable prices online) to find 1/2 inch steel pipes (water pipes around here are usually made either of thin metal tubes or ABS/PVC). The store I found had some (expensive) imperial thick steel pipes but few accessories to go with (no pipe flanges, brass plugs or smooth couplers).

Anyway, thanks for your answer, I actually have another question: is there a seam along the inside lenght of your tubes?

There is a type of pipe which, here, is called "black iron" pipe, which DOES have the objectionable seam in it. I know this, because I first bought a piece of black iron pipe and had to take it back to the store. That type is also refered to as "butt-welded" pipe.

Obviouly you should not buy the pipe with the internal ridge.

Instead, you need the other type of iron pipe which is called seamless steel pipe. It starts out as a solid rod or billet, then while hot and malleable, a "piercer" is driven through it lengthwise forming a hole in the center. There is a lot more to the process to check that the size in within tolerances and all that, but that is the basics of it. Seamless pipe does not have that objectionable internal ridge.

That is the type of pipe you need. (I doubt you will have a metal drill bit that can run the length of the seamed pipe and drill it out smooth. I don't, but luckily, my brother did, since the old piece of pipe I used for the longer piece needed honed/drilled out a bit to make a proper fit.)

Sorry to hear about the lack of iron pipe vendors. I presume you are in UK, since I doubt the other countries would even carry pipe in inch measures at all. I am guessing though, that there may be other pipe sizes which would be close to an available size of auger bit.

That place called hardware and tools (hardwareandtools.com) says it sells worldwide, but I do not know what the shipping charges would be for europe.

Anyway,  Good luck on your project.