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After having some of my blaster parts laser cut in acrylic I needed to jump on the strip heater to bend them into shape. It's a nifty device with an infinite variety of practical uses when manipulating plastic so I thought I'd share a quick "How To" for anyone unfamiliar with the magic of a strip heater. A strip heater is pretty much a long heating element (similar to the kind you would find in a toaster or electric home heater) that has an adjustable cover made of thick steel. This adjustable cover lets you expose just a "strip" (hence the name) of heat source at your desired width, which allows you heat specific sections of you plastic piece without affecting the rest of it. Unlike a heat gun or an oven you can heat very precise lines and very small areas individually, which allows for bends, sharp turns and shaping in only certain areas of the plastic. Think of taking a flat piece of any thermo plastic and bending it into an L shaped bracket for example. Of course, in my infinite wisdom it didn't occur to me to actually take a picture of the strip heater as I was working the parts, but basically they look like this: And work like this: It's an incredibly simple machine, and although it takes a little practice and care to get used to the plastic your working with, the heating times and the cooling times etc you can do some pretty nifty stuff very easily with this bad boy. So where do we start? First adjust your gap to the width that will suit the sharpness of the bend you are looking for. Obviously the wider the gap, the larger the area of plastic that will become flexible, so a small gap will make sharper turns, while a large gap will make larger softer curves. If necessary place some additional blockers to shorten the strip length wise as well, and place you piece of plastic on the bars, with the area you wish to bend directly above the exposed portion of the element. Here I am doing it with the flat cut out of the folding stock butt template: The length of heating time depends on the material and the thickness of that material - this 3mm acrylic took about 10 minutes to become fully pliable. You will know when it's ready as the plastic in that area stops being smooth and takes on a strange almost wavy appearance, as seen here: Don't worry - it's much easier to see in real life than it is in a photograph. At this point the plastic will take on the consistency of a stiff rubber. Remove the plastic from the heater and simply use your hands to bend the shape you want: The smaller the strip the more the plastic will naturally bend toward the intended crease. If you heat a wider area you must be careful to get the curve exactly where you want it. You have to work quite fast here as the plastic stops being flexible much faster than it seems to cool. (ie; it can still seem very hot to the touch long after it has lost it's flex and gone hard again) If you keep applying pressure too long it's likely you will crack the plastic. Much like working with a heat gun, It also helps to push a little further than your intended shape as there will be a little spring back. Once you've got the position right, hold it until the plastic has no more movement in it to ensure it stays where you want it. This is hard, as at this point the hot plastic will be burning your fingers, so don't wuss out here... The great thing is that once you've done one part, the strip heater will heat the next part while protecting the bit you just worked on from reheating and losing shape. Thus you can do one part at a time. This is my butt (oh ha ha - grow up <_< ) after heating and bending two sides: With a wider strip setting you can heat a bigger portion of plastic and bend softer curves like this: Of course this requires more holding and shaping with your fingers than a simple bend so you are really, really gonna burn your fingers doing this (if anyone says why didn't you wear gloves, it's because I'm really tough ) I also found that the smart thing to do was have a score line in your plastic where you want tight folds. It not only helps line up the piece on the strip heater, but it will bend more naturally where you want it to: (See the state of my hands? I repeat: your fingers will suffer and hate you - ignore them. They don't understand how cool it is to blend plastic to your will...) Now we understand the principle here's a quick series of photos showing it in action to make the arms for the folding stock: Rough test fit of the parts: You'll note the underside of the butt piece is a touch flatter than is accurate. I should have (and will soon) given that a slight curve by placing it underside down on a wider setting on the strip heater. All in all this a great piece of kit. It's much less strenuous than working with metal bending and using plastic allows for much more precision in shape. It would be ideal for making inner drop boxes too, or getting a better fit on your crotch tab. If you don't have access to a strip heater they are actually really quite easy to make (and let's face it: no workshop should be without one). They cost about $300-$500 but there's a great tutorial on how to build one for under $30 here: http://www.mp3car.com/fabrication/111936-how-to-build-a-heater-strip-to-bend-acrylic-for-30-bucks-or-less.html I hope this encourages other to give it a shot - if only because it's so much fun! Zero Over and out
Well I finally got a moment off work over Christmas and had just enough days to get obsessively stuck in to a new E-11 build. I'm building this one totally from scratch with the exception of a grip casting and a mag casting I had lying around. The rest of the build is my laser cut plastic parts and some found items. All my reference and measurements come from the "Best Sterling Templates Ever" thread that can be found here. I have used the actual templates we built up and relied entirely on the measurements and reference photos so generously provided by the team of real Sterling owners who contributed to that thread - sskunky, Christian, Lichtbringer and DaveJ - so a huge thanks goes out to them for giving me a chance to do a scratch build with accurate specs and skip the BBC plans altogether. Another huge thanks goes to Andy PlayfulWolfCub who made some corrections to errors I made in the blueprints and sent me literally hundreds of reference pics of his Sterling for me to work from. For those of you wondering when these templates are going to go public, the answer is soon. This build has allowed me to correct a few small errors and as soon as I'm done adjusting the template booklet I'll post it for all to grab Well without further ado - onto the build. I didn't get as far along in the four days I worked on it as I would have liked but these things always take longer than anticipated don't they? Here's what I've done so far anyways... THE TRIGGER ASSEMBLY I started with the trigger assembly. I know this is unusual but I have a plan to create a functional trigger assembly that will allow the bolt to be cocked and fired when the trigger is pulled. As a result I needed to build the rest of the blaster around the trigger assembly to be sure that everything was slotting together correctly. First I drew up my plans for how I thought a working trigger assembly might be constructed. This is basically a modified version of the real Sterling trigger function, greatly simplified after the manner of a toy dart gun: Basically the trigger should push the bolt catch down far enough to release the bolt and have it slam forward: Now heads up here: I have no idea of this will work. It's purely theoretical and until the whole thing is assembled I won't know if it succeeds or not. If it doesn't it's no big loss, I'll just have a static prop. If it works however it will add some fun. I started out with all my appropriate cut parts: The laser cutter cuts very sharp straight edges so I had to use the sanding drum on my dremel to shape the front portion of the trigger with the correct rounded edge. You can see the shape in this pic better: I glued the inner workings onto the right hand face of the trigger assembly in order to install the parts and rubber bands: I made short video of the parts in action but I can't embed Mobile Me gallery videos for some reason so if you're really keen to see it, you'll have to click here: http://gallery.me.co...3/TriggerAction This is the finished "sandwich" of parts: I've only painted the parts of the trigger assembly that will end up exposed after final construction. This is simply because paint and glue don't play well together and I want to be gluing plastic to plastic, not plastic to paint, for durability. The next step was to prepare the grip mount, which is this bit here: You can see in this image from Christian that, whereas most parts of the Sterling were butt braised on, the grip mount was flange braised: So I needed to create the flange edge for my grip mount pieces. I needed to make sure that the angle at which the flanges spread fit the barrel casing perfectly so I came up with this system: I took the plastic grip mount pieces and sandwiched them between two pieces of wood and set them in the oven for ten minutes Then I wrapped my receiver tube in foil to protect it from any heat transfer And literally pressed the tube into the soft heated plastic until I got a flange flare I was happy with: Then I had to set about making a trigger guard. I happened to find a strip of copper hanging around my man cave that was the correct 1.6mm thickness. I transferred the trigger guard template flat onto the copper strip with a pencil: Once I was satisfied with the measurements I clamped the copper strip down and cut it to shape using a jewelry saw: Lather, rinse and repeat for the other end and we're ready to go. The tricky part was the bending. The copper is soft so bending it is easy enough, but getting the precise shape of the Sterling trigger took some concentration. Initially I printed the trigger guard shaping template and bent the strip while laying it against this shape on the paper, but ultimately the best way to do it was to bend it in position against the trigger assembly using reference photos and some tricky yoga positions. This trigger guard shape varies slightly from the real Sterling trigger guard in that I've removed the small curl at the top front. It does however insert properly into the trigger group like it should, but will be held with glue instead of a swiveling pin: All that was left now was to paint everything up. It may seem odd to paint the entire grip and trigger assembly up before it is attached to the barrel casing, but as this section layers black pieces on top of silver I needed to do it prior to assembly. Again I've taped up the pieces to prevent paint spray reaching the parts I want to glue: Painted the grip while I was at it just to maximize my fume inhalation opportunities: Here's a pic of my finished trigger assembly next to a photo Andy PlayfulWolfCub's sent me of his real trigger assembly: and here it is with the whole shebang assembled and the selector switch in place: You can see in this pic the great texture that the hammered black spray paint Seantrooper put me on to gives the parts. Very close to the wrinkle paint (sometimes incorrectly referred to as parkerizing) used on commercial Sterling L2A3's, and a pretty convincing metal simulation. The actual Hammered Black is gloss so it requires a satin overcoat to knock it back. THE SELECTOR SWITCH The selector switch was an easy part. Again I need to use the dremel to shape a curve into the base but then it was a simple assembly and paint job: I painted a layer of Krylon Crafters metallic on first and let it dry. Then I gave it a coat of the black satin and while it was still wet, I lightly whipped a piece of sandpaper over the switch to produce the weathering.
Well guys I finally did it - I found a ready source (in fact several ready sources) of accurate pipe or tube for Sterling receiver tubes for E-11 builds! The whole problem seems to be that we've been looking for the wrong thing. We've all been using or shopping for PVC tube (possibly as a legacy of the BBC plans) which only comes in a 40mm OD. For those who don't want to use metal pipe, because (like me) they live in a country in which this could cause legal issues or because (like me) they have no metal working skills, having an accurate pipe but in plastic, is a god send. We should have been looking for polycarbonate tube or butyrate tube which comes in, not only a 1.5" (38.1mm) OD but also has the accurate wall thickness of 1/16". This means the outside diameter, inside diameter and wall thickness all match the original sterling receiver tube perfectly! No need for any more inaccurate 40mm pipe builds! Here is a link for the polycarbonate tube: http://www.usplastic.com/catalog/item.aspx?itemid=27235&catid=841 And the butyrate tubes: http://www.usplastic.com/catalog/item.aspx?itemid=35305&catid=704 And for anyone just looking for a quick order of a small amount willing to pay just a tiny bit more it's even available on Amazon: http://www.amazon.com/gp/product/B000OMHJGW/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=1278548962&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000OMHI0E&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1D1CHZ8Z7TY4SBVWS6FB It's slightly tougher to drill or cut than PVC pipe but is also much tougher and crack resistant in the long run. It's also available at many other suppliers - just google it. With this info in hand there's really no reason why we should even need the 40mm templates anymore since it was just a default choice anyway. Having made the tube templates recently I can safely say that this tiny 1.9mm difference in OD does actually make a big difference in accuracy once you spread the receiver details out across the new circumference. So what are you waiting for? Get ordering!