Saturday, December 11, 2010

Finishing up the VSS and Case

Last time, I covered building the VSS "Vintorez" sniper rifle. This time, I'll highlight the carrying case.

The build is similar to the Golgo 13 gun case, with the exception that I have no idea what the rest of the case looks like other than the inside. The walls are 4 cards thick, with a 2mm overlap between top and bottom covers. The case seems to have different latches and handle, so I'll be using a newer design for those.

I have a ton of leftover foam from the Golgo 13 case. Absolutely annoying to trim and cut. What I did was trace out a template of the parts arrangement on some paper, then attempted to cut that pattern on several layers of foam. The case is fairly deep, and it required three sheets of foam.

Each layer of foam differed, requiring the three different patterns shown above. A larger block of foam would have been extremely annoying to cut out in this case. As usual, the foam is completely different colored from what the inside of the case is, and visually showcasing black gun parts on a black background is terrible.

The handle looked like a double hinged attachment, so a bent paper clip tacked in place with some cards worked fine.

I had more liberty with experiment with hinge sizes this time. The hinges are composed of two 2mm wide strips of 110lb cardstock glued together using loc-tite to strengthen it. They were then folded over a paper clip to form the hinge hole. The sections were then staggered and glued together to form two hinge halves. The overall thickness of the hinges was under 3mm, closer to 2mm.

I could not find a feasible method of reproducing the latches on the actual VSS gun case. Mostly because I couldn't tell what they looked like. So I went with generic suitcase latches. The overall width was 3mm, requiring some narrow strips of cardstock. The construction method is the same as the rear case hinges, but uses two narrow 1mm strips for one side, and one narrow 1mm strip for the latch. These had to be strong enough to not snap off after 5 uses, but not bulky. I fixed that by effectively soaking the sides of the hinge pieces with super glue and letting them sit.

As great as the prototype colors look, I had to eventually ruin the project with my crappy painting skills. At least, just the gun part. The case may not see paint for a while. Onward to failure!

This gun used mostly flat black enamels. The stock was a nice mix of dark red, flat brown, and "rubber" enamel. Turned out better than I expected (meaning it didn't look like complete crap). I have no idea how to make textured surfaces like stucco, so the grip is a smooth finish. Anyways, here's some more images of the completed sniper rifle.

So, Golgo 13 has a choice of covert sniper rifles to use. Options are always great.

For the people completely uninterested in reading blocks of any text at all, here's a video demonstrating the case.

Wednesday, December 08, 2010

This Month's Project: 1:6 Scale VSS "Vintorez"

This month's project could be tied to the game S.T.A.L.K.E.R. - Shadow of Chernobyl, but I actually chose it on other merits. The VSS Vintorez silenced sniper rifle is an interesting weapon for a few reasons. Its existence as an integrated silenced sniper rifle alone is notable.  It also is a fully automatic sniper rifle. I was more interested in the idea that it was capable of being disassembled and stored into a carrying case for Spetsnaz operatives to use. The goal this month was to design and build a 1:6 scale VSS Vintorez that can be disassembled and stored into a briefcase.

Since there's a whopping one image of the briefcase, it was a tough job. The goal is to replicate the configuration of this case, down to the specific scopes used. In this case, there are three 10 round magazines, one 1P43 scope, and one MBNP-1 night vision scope. The MBNP-1 was reverse engineered with the help of this site, and the 1P43 scope was built with the lone side view offered by this site. Most images of the VSS feature it with a PSO-1 scope, which was not one of the scopes in this case.

First, we get some helpful side profile images as usual, then scale them down. For this, I mapped out each section and how they'd integrate with each other. The toughest part was devising a means to attach the stock to the receiver.  Otherwise, this gun is a very mediocre and easy build.

This is the base, composed of simple laminates, a box for the magazine well, and a rolled up paper tube fitted over a bamboo stick barrel.

Next, it's time for adding single sheets of 110lb cardstock to thicken out the smaller details, and carving off sections to form rounded areas.

Smaller pieces like the sights and safety were done with two sheets of Magic the gathering card thickness (in this case, X-Men TCG cards were handy).

 The VSS has some side rail mounting system that I can't replicate in 1:6 scale, since I can't build a clamp that small. I however could copy the aesthetics with a single layer of MtG card and a lot of zealous gluing. Loc-tite and other super glues aren't good in shear, so I had to compensate by using MORE GLUE. Plastinating the entire section worked out ok.

 Here's the major portions broken down. The magazine up to this stage is a placeholder.

 The attachment mechanism worked out better than I hoped. It was a simple paper clip rod inserted into a groove covered by a single card. It was sturdy and had a very low profile.

Using the sites mentioned above, I was able to create close replicas of the scopes in question. I have a bit of uncertainty about their actual names, but I'm fairly confident I have the dimensions done right. These were done using my spreadsheet for making cones and solid cylinders. The goal was to have clear lenses as well, so they're hollow in the center with proper recesses to allow fitting of plastic lenses.

The mounting method was tough to plan out, given the small workspace. The requirement was to have something 1mm thick, but rigid, and also have a means of attaching it to the side of the VSS. Paper clips are about 0.8mm thick, and alone weren't enough to fill out the frame. I turned to an unlikely resource that I had accumulated: hard plastic card sleeves. Gaming resources unite! Two sheets of hard plastic card sleeve glued with Loc-tite made a fairly stiff sheet. Gluing this to a bent paper clip allowed me to make a thin but sturdy component.

For mounting the scopes, I ended up having to cheat. I drilled two 1/16" diameter holes into the side of the gun, and put a mating pin into the scope mounting brackets. I used more paper clips to serve as attachment rods. The original goal was to have the holes be hidden near the mounting rack things on the gun, but they were placed in not convenient locations. As a result, they're noticeable without a scope attached. However, the end result is stable, and the mounting rails catch the bracket frame on the scope to align the scopes up with just one pin.

VSS with the MBNP-1 scope attached.

The other scope was built in a similar manner, but with less overall complexity.

Next time, I'll cover the briefcase construction.

Sunday, November 21, 2010

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.

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.

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.

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.


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.

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.

Sunday, November 07, 2010

Assembling a Sentry Gun

Doing some more clean up with documentation. The TF2 Sentry Gun paper model is very under documented. Magically jumps from a base stand to a level 3 within four days.

I've recently uploaded revised schematics to replace the very ineffective ones posted about two years ago. However, there's no documentation of how the parts were assembled. Time to fill in those gaps.

Building a Sentry base
The base needs to be stiff. 110lb cardstock without special treatment methods will be ineffective in supporting the loads this model will encounter. Recommend using 110lb cardstock only for tubing and using thick laminates of Magic: the Gathering to assemble every part on the base.

Magic cards offer good strength for little material. Treat them like sheet metal when building the front legs. Use thicknesses of 8 cards to create 2.5mm thick sections. The curved side frame posts were built in that manner. A thickness of 4 cards was used for minor sections like the upper parts of the front legs.

 110lb cardstock is weak when used as a plane sheet, but when rolled up with or without support of a 3.175mm wooden rod, it's sturdy. The main post and rod running through it were done with both methods: using a wooden inner rod and without.

 These rear legs are very troublesome. You're going to have minimal adhesive holding these parts together. Recommend making biscuits and joints to connect the sections. Super glue is recommended for these parts.

 Tubes, Tubes, Tubes
 A lot of the sentry will be large sections of material. The trick is to lighten up the material as best as possible. The ammo drum was built almost like a papercraft model, with lots of empty space inside. Making the drum solid would contribute excess weight to an already unstable model. Here, there's the inner drum (left), outer support drum (middle), and the outer shell (right), which is composed of a tapered cylinder. The outer shell fits alongside the outer support drum to stiffen one side, while providing the tapered shape on the other side. Magic cards were used for the flat backside, offering good planar stiffness with minimal warping.

 I built the ammo drum support arm in sections. Don't do that. Build this section as stiff as possible, and out of as few pieces as possible. This part is very problematic as it supports a lot of load and will be subject to constant bending for the rest of the life of the sentry. Don't even try using 110lb cardstock without some inner support material. Stiffer the better.

The minigun assemblies are designed to spin, but also designed for weight reduction. The arch shaped supports are fleshed out using tubes on the curved ends, and troughs made of Magic cards. Tubes offer stiffness with shape, and the cards offer stiffness with flat surfaces. The only time something needs to be completely solid is for shapes 3-4mm thick or less.

For the barrels, they span a length of 40mm, but you can support them on the edges with 12-16mm of material. This lightens up the parts significantly.

For this build, I considered using pre-existing plastic tubes to minimize friction when rotating. Not a big issue in the long run since it won't see much rotation. The tubes offered strength and volume for little effort. The barrels themselves need rework, but I've drafted new plans for a stronger set in the newer plan revisions.

 There's a bit of sag from the barrel weight, since rolled up 110lb cardstock is still heavy. There's little room for a counterweight, but adding more mass to the supports only loads the center mounting plate more. The goal is to minimize overall weight as well as keeping it balanced. The first objective helps with the second.

 The Turret
The rocket turret is another part that requires lightening. The image above demonstrates how it was built: four tubes running along the length, with tabs on the sides to allow for a cover to be placed around it. Build this like sheet metal and not like a milled object. 

These support arm parts for the turret were built light and stiff. They may appear thick, but they're mostly hollow inside.  
The amount of "large mass supported by a thin strut" situations on this model are numerous. Luckily, this is the least severe of the situations. The white support base is made of several layers of 110lb cardstock, but can be done with Magic cards. The trick is to use the thickness of the material to your advantage for small details.

Wiring the Sentry
This wire assembly can be tough. You'll need to find wire with a sleeve diameter of 3mm, or make your own by rolling printer paper around some thin wires. Printer paper is soft and bends easier than 110lb cardstock when rolled. Goal is to keep the rolled thickness to a minimum. Thicker the walls, harder to bend. 

Attaching the wires to the plate can be done by leaving bare wire on the ends and threading it through a sheet. Just glue another sheet to sandwich the wire ends in, and they should remain in place.

I've documented the ammo belts here, and with the rest of the new diagrams, that should cover all the miscellaneous aspects of building the sentry gun.

Now.. Just need to properly present the completed model this time around.

Saturday, November 06, 2010

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!

Sunday, October 31, 2010

This Weekend's Project: Reworking the TF2 Rocket Launcher

This weekend's project comes from the pile of "looked ok 2 years ago, but looks like crap compared to newer stuff" programs. The Soldier's rocket launcher has been a simple and primitive build. The paint has been very lackluster. However, there was little improvement possible for the build, leaving just a new paint job and maybe a few extra polygons.

Here's the 2008 prototype model (top), compared with the 2010 production model (bottom). Major changes include the less-half-assed construction, increased weight due to a liberal use of Magic: the Gathering cards for a stiffer build, thinner inner barrel diameter, and the addition of a firing mechanism.

Yes, this model fires out projectiles.

The Mechanism
Let's go build ourselves a working paper rocket launcher, shall we? First, let's explain a few things. This mechanism is a simple, using a total of two moving parts: a trigger and a launcher rod. There's two springs, easily obtained from mechanical pencils.

 The mechanism works by the use of this odd shaped metal wand and a wooden 3.175 diameter dowel with a 6mm diameter head. The barrel diameter is 6.35mm, giving the rod enough clearance to move around freely.

 The rod fits in a slot that runs through the diameter of the barrel.

 The part that dips low at the top between the "ears" obstructs the head of the launcher rod from moving. Pushing the metal wand upwards into the slot in the barrel allows the dip to slide into the barrel wall, leaving the barrel clear. It's a simple mechanism that is reliable and fairly easy to build. The downside is that it requires a large diameter barrel to make good use of it.

The Build
You'll need the following schematics for the major components:

You'll need the following tools:
  • This excel spreadsheet from this explanatory post explaining how to make cylinders out of paper 
  • 110lb cardstock (don't even bother using printer paper)tack 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
  • ruler
  • Sandpaper (coarse grit at a minimum)
  • Elmer's glue (any strength, but not a Glue Stick), and Super Glue of any type
  • Paper clips (smaller the diameter, the easier)
  • One 1/8" (3.175mm) diameter wooden stick
  • Guide to building with Magic: the Gathering cards (optional)
  • Pliers (Jewelry Beadmaking pliers HIGHLY recommended, regular needle nose pliers mandatory)
  • Badass paper clip bending skills
The level of involvement of Magic card use for this project is minimal and borderline optional. There's only one part that requires cards, and it's pretty easy. The biggest challenge will be your ability to bend a paper clip to this following component:

 This is the key to a successful construction. The closer you are to the dimensions, the better the result. The two legs of the wand have a little protrusion for holding the end of the spring between the head and the middle of the wand. Without that small protrusion, the wand will slide out of the handle, and the spring won't have anything to push against. Your success will depend on whether you can replicate that out of a paper clip. Hope you bought that 100 pack. Don't even try it by hand.

About building the wand: Use a beadmaker's jewelry pliers with thin rounded tips to initiate small bends. After the bends get close to a "U" shape, compress the entire "U" together with needle nose pliers. You'll have two chances to get it right. You can usually undo the bend once before the metal is too fatigued and snaps apart with a second attempt.

About the spring: start from the wand's open end and take the termination end of the spring coil and thread it around the two legs. Spin the spring around until it eventually screws into the region. You should be able to compress the spring while it sits in between the wand head and the protrusions in the middle without any obstructions.

Building the components

 The center object is the trigger housing. The housing preferably should be made of Magic cards. The side wall is 2 cards thick, and the thin walls are 3 cards thick. A plastinated wall made of 110lb cardstock and enough super glue permeating through it may be acceptable, but is very messy. The center of the trigger housing has two walls protruding inside the trigger pathway. This is there to keep the trigger from falling out too far. May be critical if your spring is too stiff or too long for the wand. This, and the bottom of the trigger will be the only parts that Magic cards are helpful for, but can be done without.

 Now if you've built all the pieces, you should now have the following items:
 These are the major components needed. Anything not mentioned in the drawings is stylistic and not structure critical. Depending on your spring length, you may need to either trim it down or change the dimensions by pushing back the rear end stop into the conical part.

The sight works better if you use Magic cards. I did it with 110lb cardstock 2 years ago and it was acceptable.

 The rear part of the launcher is made of three conical sections. You can put them together by making cones or carving down a cylinder. Not structurally important, as long as it stays together.

The build is mostly tubes and squares. A simple project by normal means. I recommend doing some test fires before gluing both halves together. Always good to verify the mechanism works reliably now than have to redo a section later because of a failure. The mechanism isn't the best, but it's effective. You will need to push the trigger in as you load the rocket launcher so the head can clear the obstruction. I haven't tested out other means of assisting the load mechanism, but there's some room for improvement.

After you've assembled the rocket launcher, you'll want some rockets. I recommend making generic projectiles 5mm in diameter and fairly long so you can push the launcher rod in with it. They go fairly far using mechanical pencil springs, despite my reservations.

Happy blasting! (Now with video!)