Project Highlander - General

[IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0332_zpsd14f73d0.jpg[/IMG] [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0333_zps0408f1a4.jpg[/IMG] IT BEGINS I printed out some graph paper at work a few days ago and spent my lunch break doodling and revising some basic plans. Some parts on this are obviously very rough, the main point of the diagram is to have plans for the frame assembly (which is to scale- each square is 0.5"). The construction will be three layers of 0.5" MDF, with the triggers, latch, and other small parts build from 0.25" MDF and superimposed as necessary. The main thing not on the diagram is the stock, which will be a Mossberg wood stock that I should have access to next weekend. I have never worked with MDF and have some concerns regarding its durability, but I plan on reinforcing the trigger mechanism with brass or aluminum sheeting bent to shape to form a frame and help the pieces resist deformation. This weekend I will be doing basic prep work. Next weekend I will have my Dremel, drill, and vice, and the real work starts.

I feel like MDF is going to not work out very well. What about cutting steel sheet?

[QUOTE=Fish Muffin;42336999]I feel like MDF is going to not work out very well. What about cutting steel sheet?[/QUOTE] Don't have the tools to cut it, and would be much more difficult to build since the thickness of these pieces allows a layered construction. Keep in mind that this is essentially going to be 1.5" wide solid wood, bound together with machine screws, with at most 0.5" gaps cut out of the middle layer for the moving parts. I'm not worried about the upper frame breaking, I'm worried about the stress points present on the lower frame (the part supporting the barrels) and the triggers (which are thinner and have strong axial forces), which is why I'm planning to reinforce them with aluminum or brass banding to distribute the shear force and prevent compressive forces from snapping the pieces. The trigger guard, for example, will most likely continue all along the bottom of the frame until it reaches the hinge. Using steel sheet would require me to cut and shape it to form a box- fine if I had a welder and full machine shop, but not so good with mostly hand tools. A grenade launcher is an extraordinarily simple design for airsoft purposes, so I want to see how easily I can build one. If I can do this, anyone can. Also, I went with MDF mostly because I'm concerned about plywood separating once cut and sanded as I intend to do. I will be layering and sealing it with lacquer to retain a hard exterior and resist damage.

I didnt mean cutting the sheet and then forming it into a box, I was talking more along the lines of just cutting the triggers out of like, 1/4in sheet with either a dremmel or hack saw. McMaster-Carr has a lot of steel for very cheap. [URL]http://www.mcmaster.com/#standard-steel-sheets/=opgxka[/URL] [editline]28th September 2013[/editline] the shape you have for the triggers would not be very difficult at all to cut, and if you have a friend with a band saw, you could have that done in ten minutes.

This is constantly subject to revision, so thanks for the link and I'll keep it in mind. If reinforcing the triggers doesn't do the trick then I'll definitely look into alternatives. Unfortunately, I do not have access to a band saw. My intent with the triggers was to cut out the rough shape, then use a sanding bit on my Dremel to refine.

Oh, yeah, I meant only the triggers from the beginning. The frame should hold up just fine. I mean, if you re reinforcing the triggers with metal anyways, why not just make them out of metal to begin with, you know? [editline]28th September 2013[/editline] You can get metal cutting bits for dremels [editline]28th September 2013[/editline] also mc master-carr has literally everything, great source for mechanical parts and such. check out their home page.

Now that I think about it, I have some very thick brass sheeting that will probably do the trick. Definitely going to look into that. Either way I have this big board of MDF so I'll probably end up using it to build a practice balisong or something.

I'm equally excited and skeptical, as I'm sure you're well aware of by now. GODSPEED

I cant wait for it to malfunction and wipe us out in a violent detonation of PVC and BBs

What about putting the hinge on the side, like a double-barrel with the stock turned around.

Before you guys go shittin' on ShadowSocks, we're cool, it's a friendly jest. We go to the same college and he's meeting us for HC5. YCheez, I'm not sure I follow. You mean like a sideways break-action that opens like an M320? Also, small update: It is becoming apparent that MDF is not up to the task, so I bit the bullet and ordered a few sheets of (freakishly expensive) styrene plastic. This stuff is easy to cut, easy to shape, sands nicely, takes paint perfectly, and glues astoundingly well. The only issues are it tends to bend and then snap (shouldn't be an issue when no stress-bearing part is thinner than 0.5"), and that it's so expensive. Well, we'll see how it goes- next weekend I am focusing on getting as much of this done as possible.

Yeah, like an M320.

[QUOTE=YCheez;42363904]Yeah, like an M320.[/QUOTE] I guess I could, I just don't see the point. Mechanically it's slightly harder to design and a little harder to align properly. I suppose the main advantage would be reduced traverse to open for loading, but at that point I might as well use a side-by-side design and break top normally.

[QUOTE=catbarf;42363993]I guess I could, I just don't see the point. Mechanically it's slightly harder to design and a little less compact overall. I suppose the main advantage would be reduced traverse to open for loading, but at that point I might as well use a side-by-side design and break top normally.[/QUOTE] I guess so. I just thought the hinge would have a lot of stress and with the side hinge you could retain the over-under design. Or you could go for a three-barrel design in which the barrels are triangular but I have no idea how that will work out.

[QUOTE=YCheez;42364017]I guess so. I just thought the hinge would have a lot of stress and with the side hinge you could retain the over-under design. Or you could go for a three-barrel design in which the barrels are triangular but I have no idea how that will work out.[/QUOTE] Or he can leave it exactly how he designed it because your input is bad and over-complicating things for no reason.

Triangular was one of my first design ideas, actually, but it's not worth the geometric headache. The hinge I'm not worried about, I intend to take two long bars of 0.25" card, cut each along a 45 degree angle (so that they form a 90-degree V shape when put together), and then fit the barrel to that gap. Then drill a hole, and use two arms, each 0.5", reaching back to the frame. Even though the joint is going to bear the weight of the barrels, I'm not concerned about it breaking- I'm using a bolt for the hinge, so that won't go anywhere. The most likely failure point will be where the 'arms' meet the rest of the frame, so that area is going to be the most reinforced. [editline]1st October 2013[/editline] [QUOTE=Herfjotur;42364043]Or he can leave it exactly how he designed it because your input is bad and over-complicating things for no reason.[/QUOTE] Hey, all input is valuable. Even if it's not the best suggestion, at least by asking he can perhaps learn. I'm not an engineer, I have no engineering background, I learn through trial and error. Every question asked and answered is a little less error the next time.

In today's news, the order I placed with McMaster-Carr on Sunday evening is scheduled to arrive at my house today (!), which is pretty awesome. Unfortunately living away from home at the moment means that I won't have access to it until this weekend. Sunday is when I'm planning to get as much done as possible. I've also cut and glued together the barrels, treated with primer, and sanded- I'll have a picture of this up later.

Woo, triple post. Update time! On Saturday I began a small test of paint method on some scrap PVC, and the results came out way better than I expected. I've always had problems with paint chipping on my creations, and nothing ruins the realism of a prop more than ugly white plastic showing through the paintjob. I was especially concerned about PVC, which has a reputation for not taking paint well. Well, after a bit of research, I found that high-temperature barbecue paint comes recommended for painting gun props, so I thought I'd give it a shot. Here's the overall process I'm going to use. The only part not on the sample below is the very last step. -Sand thoroughly with 120 grit sandpaper, to give a good surface for the paint. -Spray with Rustoleum High Heat Black. -Sand with 200 grit sandpaper. -Spray again, a little lighter. -Sand with 400 grit sandpaper. -Spray again, very lightly, just enough to solidify the color. -Buff to a gentle shine. -Rub with graphite. I took some graphite from a mechanical pencil and a small piece of sandpaper, and sanded it down to a small pile of the stuff. I then rubbed it onto the piece with a wadded tissue until I had full coverage, then rubbed it hard with clean tissues until no more graphite came off. -(Not in picture) Spray with semi-matte sealant. This should cut down on the shine to give a more realistic look, while still allowing some of the metallic tone to come through. I didn't do this on account of not having my spray paint while I'm away from home. So, aside from that last step, which will dramatically cut down the shine, here's the result. What do you guys think? [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0334_zps3abd964c.jpg[/IMG] Most important, though, was the durability. Well, even though it's not fully cured (generally takes a week, sometimes two, for most enamel paint to be 100% cured), I am very pleased. Scratching it with my thumbnail doesn't take off any paint, just the layer of graphite, which is only noticeable because the paint is less shiny. I had to scrape it with a knife to get any of the paint to come off, and even then it was minor. I'm calling this a success! Next, here is the promised picture of the barrel assembly, all purple'd up. The purple, for those who don't know, is a priming solvent used for PVC. It eats into the PVC, dissolving away the top layer of protective plastic and finish, allowing glue to secure a stronger bond. For my purposes, getting rid of that top layer makes it easier to sand and helps the paint adhere. [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0335_zps5d028714.jpg[/IMG] And lastly, Timebomb and I have been collaborating on ammunition. I have ordered a six-pack of Matrix Eagle Force 40mm grenades from Evike, and am looking forward to seeing how they perform on CO2, as [URL="http://www.airsoftohio.com/forums/showthread.php?p=422786"]an interesting guide[/URL] recommended them. However, one thing I want to try working on is the ammunition, as firing footballs is my primary use for this gun. In real life, the Minie ball was developed in the early 1800s as a way to drastically improve musket accuracy. It's a conical projectile that had a flared base, allowing it to be muzzle-loaded easily, but still expanding to fit rifling when fired. What a lot of people don't know is that the design of the projectile itself also improved accuracy. The conical design keeps the weight forward, but still retains enough aerodynamic surface to correct any tumbling in-flight, like a shuttlecock. This effect is also used in airgun ammunition, and modern tank rounds. I believe that by improving the tail surface of a pocket football, which normally provides the same function to a degree, it may be possible to strengthen this effect. The implementation I want to test is using a length of plastic [URL="http://www.findtape.com/images/product-450x450/Berry-Plastics-771-Surveyors-Flagging-Tape.jpg"]flagging tape[/URL] to form a tail not unlike that of a kite. The tape, which I have ordered in bright orange coloration, will wad up between the shell and the football in the barrel. When fired, it will serve the dual purpose of acting as an aerodynamic surface (imparting drag to stabilize the projectile) and an additional visual cue to highlight it in flight, as often players don't realize they've been taken out by a rocket. I have no idea whether it'll work or not, but I figure it's worth a shot. Like I said before, this weekend is when the real fun begins.

Really cool idea! Reminds me of this: [IMG]http://images3.wikia.nocookie.net/__cb20130701032260/teamfortress/images/7/7f/Loch-n-Load_item_icon_TF2.png[/IMG]

That was pretty much the idea, yeah. Although it's funny to note that the sights on that model are backwards and could not work in real life.

[QUOTE=catbarf;42404761]That was pretty much the idea, yeah. Although it's funny to note that the sights on that model are backwards and could not work in real life.[/QUOTE] haha, I can imagine someone adjusting the "front" sight as high as it can go and shooting it into the ground :v:

Functional ladder sights are definitely a priority for this project. I'm going to try building them myself, but if I can't get sufficient durability (a must, since they like to catch on things), I plan to order an M203 leaf sight and use that.

Have you considered adding an extractor?

[QUOTE=Slavaboo;42414743]Have you considered adding an extractor?[/QUOTE] Yes, however, mechanically, it's a lot simpler for me to just have a cutout on each barrel to allow the shell to be pulled free. Today I went home and received all the parts I ordered. The only setback is that the adjustable CO2 regulator I received is dead on arrival due to a faulty gasket, so I'm getting in touch with the seller since I can't find any websites selling replacements. Hopefully I can get started tomorrow anyways.

[QUOTE=catbarf;42414905]Yes, however, mechanically, it's a lot simpler for me to just have a cutout on each barrel to allow the shell to be pulled free. Today I went home and received all the parts I ordered. The only setback is that the adjustable CO2 regulator I received is dead on arrival due to a faulty gasket, so I'm getting in touch with the seller since I can't find any websites selling replacements. Hopefully I can get started tomorrow anyways.[/QUOTE] ...what is the c02 regulator for?

[QUOTE=Fish Muffin;42422557]...what is the c02 regulator for?[/QUOTE] Filling the Co2 shells?

Green gas is extremely unimpressive, as ~120PSI isn't a lot, while straight unregulated CO2 is a little much at ~850PSI and tends to blow seals. But it's fine for a shot or two, like testing today, when the football flew fifty feet, knocked over a garbage can, and ricocheted another fifty feet into the air, spewing surveyor's tape as it went. How did it fire? That's right, update time! First, I had to cut my two sheets of styrene into usable slabs. Each is 0.25", but the core is intended to be 1.5" wide, so I needed six sheets there, plus another two for paneling and details, so eight 12"x6" sheets it is. Cutting straight lines with a jigsaw requires clamping wood as a guide, a time-consuming and laborious process... [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0337_zpsddb5bb6a.jpg[/IMG] ...but the results are well worth it. This is the cut side facing the camera. [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0338_zpsa2236a8c.jpg[/IMG] After cutting them all in half again to get eight panels from four, I clamped four panels together to make the outer walls. The design here is very simple- two outer walls, 0.5" each, each composed of two 0.25" panels, sandwiching an inner layer containing all the moving parts. I've roughly cut out the outline with a hacksaw (the jigsaw likes to wander and bend on parts this thick), and I'll be attacking it with a Dremel before assembly. [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0339_zpsdef2846c.jpg[/IMG] Here's a mockup of the gun. I'm going to need to experiment as it comes together to see whether the 'hump' right in front of the stock is going to cause problems with reaching the triggers, but I can always shave it down if need be. Still not sure if I'm going to square off the top, or see if I can shave it down into a rounded top (like the China Lake Grenade Launcher or Browning A5)- collective input is always appreciated. I also will likely include a handguard extending forward of the hinge point, as per the initial diagram. I'm also set on sanding down the stock and refinishing it. That wood finish does nothing for me. [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0340_zps8e08a685.jpg[/IMG] Lastly, I carved out the barrels with my Dremel, and cut out extraction channels with a cutting wheel. Extracting spent shells is a piece of cake and they slide in and out freely. [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0341_zpsd29e9c48.jpg[/IMG] This was all about two hours of work, hopefully I can dedicate most of tomorrow to getting as much done as possible. All comments appreciated.

Have you thought about posting this in the Maker Mates forum? I feel like they'd be very interested in this sorta thing.

Today I basically woke up, got to work, mowed the lawn, did more work, took a short lunch break, did more work, fixed Flash on my stepdad's PC, did more work, and then drove three hours back to where I'm living for actual work. Well, it's gettin' there! There's been a slight setback as it turns out the wooden stock has a stupid design that means I need a foot-long screwdriver to take it on or off, so I'm going to have to use a different (synthetic) stock for the time being, but the internals are all roughed out (just need to be filled and sanded), the firing mechanism works, the hinge is all set, and the body is held together quite durably by screws. I know it's looking EXTREMELY rough right now, but that's the beauty of styrene- it's very easy to shape and adhere. The firing pins, for example, started life as two rectangular blocks. I used a Dremel to sand them into octagons (30 secs), then sanded by hand to make them round (2 mins). Once the gun is all together I'm going to alternate sanding and gap-filling until the whole thing is one big, smooth piece. That goes for the internals too. [img]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0344_zpsc96d93ec.jpg[/img] [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0345_zpsfcd52ec2.jpg[/IMG] [img]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0346_zps61d7016b.jpg[/img] [img]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0347_zps06f445b3.jpg[/img] [IMG]http://i99.photobucket.com/albums/l296/catbarf/Airsoft/100_0348_zps83e26f52.jpg[/IMG]

Do you have plans for any kind of extractor, or are you just going to unload it by hand? And what're you planning on using to keep the barrels closed?