This Fortnight's Project: Sticky Launcher

Decided to try compressing the firing mechanism used on the Rocket Launcher into a smaller space. As it stood, it used one mechanical pencil spring and one retractable pen spring. The goal was to simplify it down to a single spring for actuation and firing.

Mechanics
In reducing the size, I chose to use the smaller mechanical pencil spring (12mm uncompressed, 4mm compressed) as the propulsion method. Preliminary tests with the smaller spring yielded satisfactory results in terms of projectile range and speed.

The firing rod was also size reduced, with a diametrical drop from the Rocket Launcher's 3.175mm bamboo stick to a 3mm diameter Gundam part runner. The firing stroke was limited unlike the Rocket Launcher's massive 70mm displacement to a more modest 16mm. Previous experiments in firing mechanisms showed that additional stroke length did not appreciably contribute to projectile performance.

Actuation
This design uses a paper clip bent in a box shape to act as a flat spring. There are two "arms" that connect to an obstructing rod to block the head of the firing rod, with the remaining side fixed to the barrel. Actuation is provided by a 3m MtG laminated arch that depresses the paper clip arms, lowering the obstruction and allowing the firing rod to complete the stroke forwards. A very primitive mechanism, but it offered reliability.

The initial design used a fairly long flat spring, with arms 20mm long. It worked just as well after a reduction to 13mm in length. For this design, a shorter mechanism is ideal. A shorter spring provides a longer stroke and requires more effort to depress, giving the user more of a sensation of pushing a button.

Diagrams
Perhaps the most pointless part of the post, since none of you are ever going to try to build this. Posting it here as reference regardless. Only core mechanism parts are diagrammed. The model's fairly simple that you can half-ass the rest and still have it look decent.

Prototype Testing Results
The initial prototype cycled through several rounds successfully, but there was some sign of wear where the firing rod head contacted the latch spring. There was also a significant reliability problem with the initial design, where pushing the firing rod back with any ordinance met with some interference with the latch spring. To solve this problem, another step was added to the firing rod, so the latch secured a section in the middle of the firing rod head than at the front. Stroke travel was not affected.

Ammunition

 

For the sticky bomb, I used a clear Gundam runner and stuck the ball of spikey death on top. From estimates, a sticky has spikes that are 1/5 of the diameter in height. I wasn't concerned with accuracy of the sticky, but more of "will it fit in this stupid launcher". A 7mm ball with 2mm spikes barely worked, as my inner barrel diameter was 11mm. Had to trim them down a little to fit better. Also, for ease of loading, I opted not to put a spike on the front of the projectile. 

Prototype Demonstration (With test fire)

I really need to learn how to make videos that don't suck so bad.

Notes
In another case of "crappy TF2 modeling", it should be noted that the game model when viewed in first person vastly differs from the model viewed in third person, unequipped. The dimensions for the side plates on the ammunition drum changes. The part that I presume is an ammunition ejection port also flops sides. I suggest that one or the other be chosen for making a replica, and not both. I used the 3rd person, unequipped viewmodel for this project.

In terms of production costs, this model can be assembled for around 6 Magic: the Gathering cards and some generous amounts of cardstock. Not that you'd need one since no one else has a 12" Demoman, and this model's pretty bland, visually.

Revised TF2 Sentry Gun Schematics

Reworked all the original 1:6 scale Team Fortress 2 Sentry Gun schematics I had posted previously, so that people could actually use them. I was innundated by a single comment requesting the originals be refined. Should be fully documented to the extent that you could theoretically CAD and CNC your own parts. But would you trust the accuracy of a guy hand drawing part diagrams with a ruler, protractor and a circle template guide? Probably not!

There's 8 sheets to work with, 7 of which contain dimensioned drawings for all the individual components. They're designed to take advantage of common sizes when working with paper, so you'll see a lot of 3.175mm and 6.35mm diameter holes and tubes, corresponding to a 1/8" and 1/4" hole punch. Easier than cutting a 6mm circle by hand. Best built using 110lb cardstock and Magic: the Gathering cards.

Sheet 1: Deals with the center support post.

 Sheet 2: Front legs and rear supports

 Sheet 3: Mounting plate for miniguns and ammo drum

 Sheet 4: Ammo Drum

 Sheet 5: Rocket Turret assembly

Sheet 6: Miniguns

Sheet 7: Rear legs

Sheet 8: Miscellaneous Assemblies

Next time: tips on weight reduction and building techniques using these diagrams!

TF2 Minigun Documentation

Doing a bit of housecleaning on this mess of a blog. Realized that I've never posted the drawings used to build the Heavy's minigun.  The drawings were used as a backdrop for the finished model. It's like I suddenly had a minigun built, without any construction progress documented at all. Not too useful if I for some reason need to rebuild one. Luckily, I've re-drawn 95% of the parts properly, so that even you have a chance in hell of reproducing the minigun!

 There's four sheets of diagrams total to document each part. This model can be built entirely out of 110lb cardstock and 1/8" diameter bamboo sticks, with little or no Magic: the Gathering requirement for strength. You'll need a good understanding of how to read an engineering drawing, otherwise parts may get confusing. All dimensions are in millimeters.

Assembling them all together is left up to you using a general idea of where the parts go. Shouldn't be too hard. I haven't split up the parts into basic components, so how you go about it is up to you. There's a lot of weight for the model, so you'll have to get creative in saving weight. It won't be a good beginner's model, but handy if you need to draw most of the gun using CAD, and wanting the result to be in scale. 



EDIT: Thanks to wargrounds for pointing out some errors in the schematic that make the assembly ambiguous. The updated schematic is here and the old one taken down.

This sheet details the spinning barrel assembly.  Details how the inner and outer assembly are made, along with the end cap to allow the inner assembly to stay in place while allowing for rotation.

 Miscellaneous decorative elements and the supports for the carrying handle.

 Main handle assembly and small view of how the barrel is assembled using the featured rod.

All these parts deal with the  ammo drum and the six barrels. The center item with the multiple specified lengths of tube to make deals with the individual sections of the barrel. These fit over the 115mm long rod, and are spaced out with the four disks and the muzzle.

 It looks huge, but it is 1:6 scale despite what I thought it was. This will help you figure out where everything goes.

I'm in the process of cleaning up some old drawings to save folder space. Nothing like having a folder stuffed full of schematics for 1:6 scale junk no one wants to build.

This Weekend's Project: 1:6 Scale Pancor Jackhammer MK3A1, Version 2

This weekend's project is part of the continuous improvements tasks, where I blatantly don't try to build anything new and revisit older projects since I have little incentive to go forwards. A little under two years ago, I built a 1:6 scale model of the defunct Pancor Corporation's Jackhammer automatic shotgun. That model was pretty good back then. But that's like saying "You did a great job there building that hovel with those rocks and twigs, but you could have used this shovel if you knew how to back then and make it suck less."

So, with Disappointment Depot behind us, let's move onto another Bad Tutorial! Last time, I attempted to teach you how to build a TF2 shotgun. Now I'm going to semi-attempt to tell you how to build your own Pancor Jackhammer. Chances are if you can't build the first one, you sure as hell aren't going to make it far on this one! With the demeaning taunts done (or am I), let's get to the schematic.

For this task, you'll need the following tools:

• Stack of Magic: the Gathering cards (or structural equivalent, Yu-Gi-Oh! cards need not apply.)
• X-Acto knife and a cutting surface, and regular scissors
• 110lb cardstock and regular printer paper
• ruler
• Sandpaper (coarse grit at a minimum)
• Tweezers (by Yawgmoth almighty, you'll want these badly)
• Elmer's glue (any strength, but not a Glue Stick), and Super Glue of any type
• Paper clips, and preferably a 1/8" diameter rod
• Dial calipers (oh hell yes you need this unless you're a savant)
• This excel spreadsheet from this explanatory post explaining how to make cylinders out of paper
• Guide to building with Magic: the Gathering cards (optional)
• Pliers (recommended unless you're a badass)
• 1/16" hand drill (highly recommended, but completely optional)

 That's a lot of tools, no? You'll need every single tool here unless you're a badass. I'm not a badass.

From the schematic, you'll need to make a few templates out of cards or 110lb cardstock to trace out sections of the gun. I've drawn some diagrams of how some parts need to be assembled, but you'll have to fill in the gaps. It's like woodworking, or shop class, except my shop class experience was a lot of New Yankee Workshop episodes on PBS and no actual building.


I've fortunately done most of the hard work for you, mapping out all the major components. We'll break down the gun into regions to work on. We have the following zones and sub components:

• Magazine (1x 9mm outer diameter, 2mm inner diameter 110lb cardstock cylinder, 12.5mm long; 10x 3.175mm inner diameter, 4mm outer diameter printer paper cylinders, all 12mm long)
• Grip/receiver (Magic: the Gathering cards, to be documented later))
• Pump (2mm diameter rod, 75mm long, made from a paper clip and covered with a roll of printer paper glued with loc-tite super glue; lots of MtG cards)
• Magazine housing (13mm wide x 32mm long MtG strips glued together to form a 10mm radius half arc; 2x MtG card covers built to schematic specs, 4 cards thick)
• Stock (2x 8mm outer diameter, 3.175 mm inner diameter, 16mm long 110lb cardstock tubes)
• Carrying handle/sights (MtG cards, to be documented later)
• Barrel and muzzle (45mm long, 3.175 inner diameter, 7mm outer diameter tube; compound tube with a 13.5mm long, 8.5mm outer diameter first section; transitioning to a 10mm outer diameter, 3.5mm long second section, uniform 7mm inner diameter throughout; 100lb cardstock)

Good Galacian, that was a lot of stuff to build. Here's what most of that junk looks like:

If you thought that was hard, well, the rest is more of the same. Time to explain the receiver/grip and the pump. For this model, we're going to make the model have a sliding pump to release the magazine like the real one supposedly does. You can skip parts of this if you wish, and it'll make the job obscenely easier. I'll note the options you can skip if you want a static model and describe anyalternate steps in italics.

The top part shows the template for the grip/receiver. Trace out this on a 4-card thick lamination of Magic cards.  Cut a 2mm wide groove along the receiver, above where the trigger guard is, but only cut it 3 cards deep and not all the way through to the 4th card. Glue two of these together to make a 8 card thick block of Magic cards. Add two 3-card thick panels of 33mmx13mm to the sides of the receiver to thicken it to 5mm.

The pump needs a template too. Of the 9mm tall section, you'll need just 6mm of height, as the center region will mate with the barrel's underside. Do the same as the receiver and cut a 2mm wide groove on the bottom of two 4-card thick sections of the pump. Roll printer paper around a straightened paper clip until you reach a diameter of slightly under 2mm. Glue this rod to the pump groove, and only to the pump groove. Highly suggest using loc-tite or super glue to coat the rod to enhance durability. Make 16 cards thick worth of the center part of the pump, then another 3 card section of the full profile to do the side grips. The additional 3mm will overlap the barrel, and needs to be bent outwards slightly. Tweezers helps a lot with this task.

The magazine.

I want my magazine to be removable and to be able to have ten 12 gauge shotgun shells be loaded into the chambers. If you're making this model static, simply build a 18mm outer diameter tube with any reasonable inner diameter and a height of 12mm, and skip the rest of this step.  Glue 10 of those 3.175 ID/4mmOD tubes around that 9mm tube. Fill in the crevices with some wedges made of MtG cards or anything handy. I offset the 10 tubes by 1mm from the center one so the shotgun shells sit flush with the cylinder face. After this, sand the outside smooth and cover the outer perimeter with printer paper.

The Magazine housing.
Didn't take a damn picture, so here's what you're ultimately trying to get:

It's a hollow section made of two walls and a half circle arc made all of Magic cards. Trace the front profile of the magazine housing from the schematic and make it 4 cards thick. With two 13mm wide, 32mm long strips of Magic cards, glue them together to form a half circle and glue that to both halves. You want the bottom open area to be the side that is completely circular and not the side with the weird dome. Fill in the top dome with 110lb cardstock and sand flush with the sides.

At this stage, you'll want to make the grooves on the side of the magazine. Make some right triangles with 7mm height and 5.6mm width for the side facing the barrel. Make a series of "L's" 6mm tall and 5.6mm wide for the other side. Printer paper works fine.

Barrel and stock assembly: 
Barrel's just two tubes as described earlier, but you'll need to cut the muzzle at a diagonal. Join the muzzle with the barrel and leave 40mm of the barrel in length unobstructed. To attach the barrel to the receiver, go nuts with the super glue or add a 3.175mm diameter rod to the receiver to support the barrel.


For the stock, you'll use two of those 8mm diameter, 16mm long tubes. Flatten the sides of one of them by shaving off material with a sander/knife. Glue the two to the oval looking shape from the stock's drawing. That section needs to be 12 cards thick. Add the little details for the stock at this point. Should be trivial at this stage.

If your gun looks remotely like this, you're doing great! Time to make heat dissipators!

To make these, I used two 8mmx33mm cards glued together, and curved slightly. I drew a 18 hole array onto the sides and drilled them through with a 1/16" hand drill. You can simply poke a crude hole or make a dimple with a ball point pen. To glue these to the gun, glue three 2mm wide strips of MtG cards to the sides of the upper receiver, and stick these on those. See the photo for a reference.

Carrying Handle.

 Trace the template but leave just a 1mm tall section above the holes instead of tracing the full template. Make two identical 2-card thick sections with that template, then glue those to another set of 2-card thick sections. This time, leave the bottom 3mm hanging off, so that the part with holes lines up with the edge of the Magic cards. This will need to be bent outwards with tweezers. I recommend scoring the fold first.

Glue both halves together and rejoice! You've completed the hard parts. Complete the handle by making two 3-card thick rails and gluing them to the upper 1mm wide section above the holes. Should make sense if you look at the schematic. Now it's detailing time!

 The muzzle isn't cylindrical, apparently. I added some flats using 110lb cardstock, and cut slots with a knife to represent the flash diverter things. You can add the trigger and the oval handguards now. I cut a triangular groove in the pump handle sides which may be noticeable in the photo above.

This part sucks no matter who you are. The stock has a separate region that tapers off. I made it using about 22 cards worth of thickness, and cut it to shape using an X-acto knife. Then, I added the little ridges using tweezers. There's a little circle at the bottom of that end piece which I'm uncertain about the purpose of, but it's there on the photos. Have fun doing that.
 

 So, after a whole week wasted for you guys later, you'll have a 1:6 scale Pancor Jackhammer! Since no company makes a 1:6 scale model of this, this is currently one of few ways you have to obtain one. If you opted to make the moving pump version, go celebrate by buying some 1:6 scale shotgun shells or make your own! You now have the most badass 1:6 scale Pancor Jackhammer model money can't buy (or if you built it poorly, the most crappy model ever!).

 

 Now go equip some infantry and enjoy using excessive force.

This Week's Project : 1:6 Scale ТОЗ-34/TOZ-34 Hunting Shotgun

 This weekend's project comes from the pile of inactive projects I have lying around due to insufficient tech to advance. The list results from ambitious project ideas that have been stopped by one or two major problems that prevent finalization of construction. Oddly, the one stopping this week's project was something fairly simple: a hinge mechanism.

After moving off to other games, I ended up playing S.T.A.L.K.E.R. : Shadow of Chernobyl with the 2009 Complete mod. Bad idea. Mostly because it ended up crippling the AI and giving me the most lopsided and overpowered weapon in the game's programming: the Hunting Rifle, otherwise known as the ТОЗ-34 double barreled shotgun. So I had fond memories of using my Russian beatstick to take down mutant dogs, SPETZNAZ and other hostilities using a variety of buckshot, slugs and the occasional flechette. Thing is just absurd with slugs.

Anyways, to properly give tribute to my trusty pal that stood by my side for 90% of the game (the 2009 Complete mod gives you this shotgun fairly early in the starting zone), I had to recreate it in 1:6 scale. To understand what the gun is like, here's a Russian tech spec for the gun. The hinge mechanism is composed of a ring and guide rails, so there's no traditional hinge pin type joint. The issue is that the center of rotation isn't somewhere convenient, as it becomes located near the bottom surface of the barrel assembly, where there isn't enough material to support a pin. A fairly simple problem and one that prevented it from going anywhere for about 3 months. I decided to do an approximation that put the pivot somewhere close to the original but used a traditional pin to hold it together. I used some tricks to hide the hinge so you can't tell offhand how it's done.

First, the schematic! (A very poor one)

 This is all you're going to get. It's not a very complex model in theory, but I had some additional plans. For this model, in addition to the expected break action and lever lock mechanism, I wanted to go one step further and add a working shell extractor mechanism similar to the one on the actual shotgun. For that, I needed some extra shotgun shells, since the Force-a-Nature and Sledge's Shotgun are tying up the remaining shells I had. Hence, the endeavor to build my own shotgun shells last post.

The barrel is hollow, and to make one strong enough to withstand minor bending and light play, I chose to use one layer of Magic: the Gathering cards wrapped around a 2mm diameter compressed air straw, surrounded by printer paper for a final outer diameter of 4mm. Process is fairly simple, I'm sure you know how to roll a paper around a tube. I had to make two of these for the upper and lower barrels. I had to sand them down flat where they'd join for extra contact and to minimize the overall height of the assembly.

 The stock is the standard 4-card lamination combined to form 16 cards' thickness worth of material. Nothing exciting here. Had to remove a chunk off the template to account for the latch mechanism, but that's about it.

The latch mechanism is the same from the Force-a-Nature shotgun: Z shaped lever pivoting around a tube embedded into the stock, then sliding to engage a 1mm wide notch.

This is the hinge piece. The top notch is for the hidden hinge mechanism, which will be composed of a paper clip bent to a "U" shape with a inner width of 3mm. The bottom notch was something I didn't use in the final assembly. The middle piece shows the notch that will be used to engage the latch mechanism.

Here's the hinge mechanism. The "U" shaped paper clip glued to the stock will ride on top of the groove in the hinge piece, rotating around that point. The barrel will sit on top of that block, securing the pin in place. The structure is fairly narrow compared to the rest of the gun, so I can hide the hinge with the rest of the gun's structural components. This does make the hinge integral and irreparable if something goes wrong, but it's a low risk. So much for that holdup that I described. This next part should have been my excuse for the holdup, but I accomplished it in an hour or so.

The way the barrels are situated, there's a groove where they meet due to the curvatures. Normally, I'd fill in this material to get them flat, forming an oval shaped cross section. I decided to use a paper clip to fill in the gap, and use it to slide a small piece of material along the barrel axis to function as the shell ejector. The actual TOZ-34 has this mechanism, and uses these prongs to engage part of the main body to pull the ejector outwards. This piece was easy to replicate, due to how things were going.

I did have to cut away a piece of the barrel assembly after gluing them together, since the ejector was an afterthought that was born from convenience. Not hard since I was removing soft printer paper and not a durable Magic card. I had to replace the missing section with a similarly shaped piece of printer paper, with the same curvatures. Gluing the two paper clips to the sides was easy with the resultant grooves.

 Here's the mechanism in place. It consists of two paper clip guide rails using the barrel grooves as the guide. It slides in and out fairly well, with some fine tuning of the dimensions required to get a smooth consistent operation.

 The mechanism doesn't extend very far in the real shotgun, and doesn't need to go far for this gun. I won't be getting any fancy things going like having the shells fly out of the barrels when I break it open.

This is the engagement mechanism. It consists of another set of paper clips on the edge of the blue regions to engage the extractor tips on the sides of the barrel. Chose paper clips since it'll take longer to wear out, despite being much easier to shear off after repeated use. Nothing a lot of glue can't fix.

After adding the rest of the bodywork onto the gun, here's the near completed gun. 

 There's a few small details on the latch. Mostly a raised portion at the end for easier manipulation, and what I presume is the safety switch selector.

 Here's the gun with a coat of primer on it. These Obitsu stands are great for displaying new projects.

 With the right amount of friction, I can get the ejector to move and engage the rims of my poorly machined shells, and pull them out slightly. I'm happy with the end result.

This shows the level of movement the lever can be displaced. Unfortunately, there isn't a detent for the closed position to hold the lever in place. I think it should be fine. 

And that is the TOZ-34, a fine addition to my wall of increasing firearms. I'm thinking of not painting this model since everything I paint turns to crap. I'm best at building the prototype and getting it functional, but I'm absolute rubbish at painting. Rather than ruin a well executed model, I'll leave it in the prototype primer color for now until I get some motivation.

I've learned to appreciate the level of detail a toy manufacturer can get into a model after attempting to get the shell ejector mechanism working. This model would be costly and fragile if it weren't for the metal components, and even then, it has a lot of delicate features that aren't good for a frequently handled item. Best as a showpiece.

This Month's Project: Reclining Chair Mechanism

This month's project is a reclining chair. Was going to originally make a wingback chair, but that wouldn't have been fun at all. To start the program, I needed a mechanism. A bit of digging, and I found this auto-reclining mechanism on a european supplier site:

Unfortunately, this was the only image I could find that was workable: semi-profile view and a clear view of all the components. It's simple but also a good start. Time to draft schematics!

I started off by attempting to draw the mechanism in workable views to get an idea of how the parts worked. Since I was using Magic cards to build this, I decided to build all struts and members with 3mm wide cards and 1/16" holes to fasten them to each other.

With the preliminary drawings done, I drafted some mockup parts to test out movement.

Leg rest mechanism folded. The initial build didn't fold neatly as I'd like, so I changed one of the angles on the curved arm to better fold the assembly.

Here is the mechanism extended. Worked out fine, except I didn't know what the round disc element did early on. Turns out, that piece allows the back rest to recline further. I learned that this mechanism lets you extend the leg rest by reclining back, without the use of a switch or lever.

With the main mechanism finalized, I proceeded to cut out two sets of parts out of 4-card thick stacks of Magic.

To fasten the parts, I bent paper clips into U shaped staples. To lock the parts, I threaded the paper clips through 1/16" holes drilled with a manual hobby drill, and bent the ends like the ends of a staple.

Paper clips worked well in holding the struts in place, but there's a noticeable lack of support along the axial direction of rotation due to the small area. To rectify this, the two sets of parts will need to be linked with a cross bar to keep the parts centered.

This diagram served to plan out how the parts would overlap. Since there's quite an amount of parts, I needed to sort out how they'd overlap and how they'd be joined to the main frame parts. After some gluing and shimming, we get the following result:

Well, that worked out way better than I hoped. I didn't expect this thing to actually work out at all, structurally with Magic cards. Time to draft schematics for the sides of the chair!

From here, it's all "wing it". I modeled the chair off the actual chair's finished appearance, with the exception that mine's a lot more crappy. And I've also designed zero other reclining chairs ever in my life. Won't stop me from continuing on with this project.

Next time: we make large slabs of cards and sew some cushions!