Wednesday, July 29, 2009

Developing and Constructing the Team Fortress 2 Force-a-Nature Shotgun

In developing the Force-a-Nature shotgun, I had to get some standardization in how I scale up my reference images to 1:6 scale. There isn't much sense of scale from an in game object, since we don't know what the exact size of the in-game surroundings and models are in Team Fortress 2. However, we do have one handy bit of insight on how big to make something: ergonomics and established design.

I have established a few set of rules based on observation of other model firearms in 1:6 scale. I've referenced a few model firearms, notably ones with fixed stocks. The sample pool included a SPAS-12 (folding and fixed stock, Dragon), an M-1 Garand (Soldiers of the World), AK-47 (ZACCA), and the De Lisle carbine (21st Century Toys). I've compiled my observations into the following standard I will now be using for all future endeavors: The G-43 standard.

Figure 1: The Gewehr 43

I chose the Gewehr 43 as the basis of the standard due to the initial similarities with the Force-a-Nature's construction, and that it was a handy representation of a wooden stocked firearm. First off, from Figure 1, I've taken note from the sample pool that the distance from the trigger to the rear of the stock was about 55mm, with a tolerance of around 1mm. This measurement is useful in approximating the size of weapons with fixed stock lengths.

The G-43 Standard encompasses the following principles:
  1. The distance from the trigger to the rear of the stock is 55+/- 1 mm.
  2. The trigger guard is around 10mm long from front to back.
  3. The handle thickness is a nominal 5mm wide.
  4. The grip thickness is around 7mm to be "wieldable" by a 1:6 scale figure. Larger sizes render the model un-wieldable, and smaller ones necessitate special features from the user's hand (spring loaded fingers) or extra tooling (rounding of the grip) of the handle.
I've previously used the last two pieces of information after purchasing my ZACCA AK-74 in making my StG-44 and M60 models. Those turned out ok, much to my surprise.

Figure 2: Rough Schematic for the Force-a-Nature Model

Armed with the knowledge of what makes a comfortable and usable stock-gripped firearm, I figured out the scale of the Force-a-Nature. The results of my measurements can be found in Figure 2 above. Units are in millimeters, because Imperial units are the fancy of a king's foot fetish.

The top part demonstrates ideas of building the hinge locking mechanism. The actual mechanism I copied can be found and better understood here. The sketch covers my implementation of the locking lever, but naturally, I tend to store 50% of the information on a sketch, 20% by the finished product, and 30% in my head. Not a good way to document things. The aforementioned link does a good job of explaining what the notches and recesses in my barrel are used for. The actual lever itself is a "Z" shaped paper clip section that rotates and obstructs the square cornered part of the hinge from swinging out.
Figure 3: The Blueprints for the Force-a-Nature

In my attempt to better clarify how it works, I drew up rough sketches of all the major components to the Force-a-Nature. The bottom right shows an idea of the rotating lever locking mechanism. Should have drawn that in isometric view. Oh well. I hope you have a good idea of mechanics and a good physics engine in your head. For those of you who can't mind-read, here's some photos of the mechanism.

Figure 4: The Barrel Notch

Figure 5: The Sliding Lever

The sliding lever is limited to an overall travel of 9 degrees. I originally chose for a larger range of 18 degrees, but centering the lever exactly to lock the barrels was a silly idea, unreliable and tedious. The lever end in Figure 5 is barely visible due to the nature of the size involved. There is a bit of play with the barrel assembly, even with the superglue trick to thicken the parts involved. However, post painting, I found a little bonus that corrected that problem.

By sheer luck, I designed the barrels to accept Dragon shotgun rounds. Placing these in the chamber filled up the gap causing the play, making the model a bit more solid to handle when locked.

Regarding the stock curvature and contours, I achieved this by laminating approximately 20 layers of Magic: the Gathering card together, then using a Dremel to shape the stock. Not also do you get a nice shape, but post painting, it looks like wood grain!

Monday, July 27, 2009

Celebrate July 27, Portuguese "Build A Shotgun That Sends Deer Flying Into The Woods" Day

Time to showcase some new toys. Today, we have a sawn-off shotgun, otherwise known to you Team Fortress 2 fans as the Force-a-Nature shotgun for the Scout. Normally, I'd have the Scout show off the weapon, but due to his previous existence as Shia LaBeouf, he will be forever hated in my heart. Actually, his "Bonk" arm action prohibits me from making fun poses with the Force-a-Nature, which is a shame. Too loose to pose with.

Since it's getting harder and harder to build things to impress the two of you out there who follow this blog, I had to do something extra with this model. Time to unveil ... THE GIMMICK!

The Magic: the Gathering Force-a-Nature model actually breaks open. *YAWN* Not too exciting.

I conveniently accidentally designed the Force-a-Nature to accept Dragon 1:6 scale shotgun shells. Gives this model a bit more fun factor. That's great and all, but that's nothing a normal bored engineer can't do. What does a bored engineer who inhales Magic: the Hallucinogenic Dust do to make something special?

They add a functional locking mechanism. There's a lever located on the stock for latching and releasing the front barrel assembly. I'll go into the details in the next post on how that works. No point making the barrel hinge open if you can't hold it shut. No more losing shotgun shells randomly after handling/dropping it.

The Force-a-Nature boasts the ability to launch the user into the sky if fired in mid-air. Naturally, Hotaru wants to try this out. Or rather, she doesn't have a choice this time.

Simply aim down and prepare for lift-off.


I've always had a fondness for a double barreled shotgun, ever since seeing Demolition Man where Sylvester Stallone reloads his shotgun by breaking it open, flinging it over his shoulder to eject the shells, then calmly reloading it. Now, I can relive those glorious moments in fabulous 1:6 scale, thanks to Saxton Hale of Mann Co.

Saturday, July 25, 2009

This Weekend's Project: Playing With Switchblades

Bit of a long overdue Spy update: finally made a knife. My Spy has been forced to go "Revolver spy" since September 2008 since I never made him a butterfly knife. No backstabbing for him.

Until now.

Naturally, what fun is it if the Spy's knife is static? Of course it works! It's perhaps one of the most fun melee weapons I've made in 1:6 scale next to the Soldier's entrenching tool. I'll go over the finer elements of the butterfly knife if you feel compelled to make your own for your Spies.
With all projects, we have the obligatory schematic. The knife is made of three main parts: the blade, and the two halves of the handle. I've taken care of the hard work of designing the parts for you. All dimensions are in millimeters, since Imperial units are for things made by Texans with large wrenches. The handle is made of the usual Magic: the Gathering card, created by folding a card in half and gluing another folded card over the first. An additional two layers were placed on both sides of the handle half for extra rigidity.

The blade, this time, is actually made of metal. I opted for metal in this case for simplicity of a strong and thin blade. You can use sheet metal bought from a craft store, but it should ideally be 0.05mm(0.002in) thick. I used the aluminum sheet that comes from electronics breadboards that I had obtained from my college days. No idea why they package a sheet of aluminum with them, but hooray for me! Draw out the blade with a marker and trim it out. You'll need a 1/16" drill bit for the hinge holes. For the hinge pins, a paper clip will suffice.

The silver paper circles are actually there to hide and retain the paper clip pins. They won't fall out normally, but it's nice to know they won't later on. You can optionally try to dull the blade so you don't do what I did and accidentally stab myself with it. But hey, if you're smart enough to make this, you have every right to make it as functionally sharp as possible.

Now with his own knife at last, he can do what all of us have been doing since the Sniper/Spy update: camping and trying to stab snipers and katana wielding girls. (The katana is incidentally from Final Fantasy VII Advent Children's Sephiroth figure, if you wish to obtain your own. It makes a surprisingly great 1:6 scale item despite it being 1:8.) Happy stabbing!

I'm going to gut you like a cornish game Aeris.

Sunday, July 12, 2009

Why No One Built a 1:1 Scale Sentry Gun

Only half a year, and I've figured out all the issues that anyone trying to make a 1:1 scale exact copy of the Team fortress 2 sentry gun would have. I would like to point out first that if you do for some reason decide to build a 1:1 scale model, you're going to enjoy all the problems I've had, but on a larger scale.
This is the TF2 sentry gun in its current repaired state. I've completed all six legs and corrected for the bending issue caused by the inherent design flaw of placing a massive weight on a thin moment arm.
Figure 1: A Force Analysis

Figure 1 illustrates the crux of the problem with the design. What looks aesthetically pleasing in the virtual world doesn't necessarily correlate to a practical design in reality. Left, we have the side profile of the sentry gun. The middle shows what the model essentially looks like from a force analysis: two "real" ground supports, one distributed load, and one concentrated load with a pivot at the intersection of both leg supports. The right shows the resulting problem: the rear assembly starts to deflect if the support isn't properly reinforced.

Figure 2: Support arm

Figure 2 demonstrates all the key points of interest in making the arm that supports the ammunition housing for the sentry gun. Due to the angled shape of the arm, there are multiple points of interest where the builder will need to take into account material shear and deflection. The bottom pivot pin takes on a substantial lateral load and not much concern for axial loading. Threading a rod through a circular ring solves the problem of shear located where the pin meets the support arm.

At a small scale, there are not many ways to reinforce a series of thin rods connected to cylinders. I've resorted to Loc-tite glue to be a pseudo welding compound. Works fine, but for larger versions of this model, the rods would need to be solid components with the cylindrical sections. The right half of figure 2 illustrates the only method of corrective action taken to counter the lean: reinforcing the arm base with a wooden rod. The component in that region had begun to deteriorate and delaminate. The rod strengthened the region.

I still feel that the sentry gun's legs are ridiculous. The rear legs with the large circular feet are almost purely cosmetic. They cannot bear a load well, due to the fact that they are not bearing loads axially with the leg supports, but actually causing a bending moment around their attachment point. This causes a great potential for shearing at that region. The middle two legs are actually the most important legs of the 6. They bear the greatest load being near the base of the support column, and don't have a tendency to split away from the other legs like a ladder without the center folding bracket.

What of the sentry gun's front legs? They're slightly worse than the rear legs, since they are actually held onto the main column with pin supports that are actually not rigid in position. Their structural strength lies in the support struts connecting the base of the front legs to the bottom of the support column. I would advise anyone making a 1:1 scale model to put extra consideration into the strength of the strut brackets and to actually convert the pin connections at the top of the front legs to fixed joints.

Friday, July 10, 2009

J.Norad Reviews ZACCA 1:6 Scale RPG-7

Welcome to part 3 of 11 of J.Norad's "we've got money, so let's buy small fascimiles of illegal arms" series. Today, we'll be looking at the RPG-7, one of the blind boxed models in Series 2.

The model comes in four pieces and measures 24.5cm long. There are no moving components, and the rocket unfortunately is molded with the front half of the rocket propelled grenade launcher. Not too great if you're childish and love being able to launch your ordinance at things.

The model is fairly detailed, with what constitutes "aging technique" for the aluminum colored parts. The grenade part looks like someone went overboard with the black paint for the crevices. Heavy lining that helps you find the details easily, but looks like it's been drawn with a black sharpie than painted. The wooden rear section isn't really made to look like anything except extruded orange plastic. For $5, it's not a bad model.

The Soldier's rocket launcher in Team Fortress 2 somewhat resembles the RPG-7. The elements are mostly there: two hand grips, wooden rear section, and a conical rear black exhaust port. Unfortunately, no optical sight (the front dust cap is NOT rubber and should not be moved) for the TF2 rocket launcher.

If you're looking for an RPG-7, there's a version out there packaged with the Resident Evil 5 Chris Redfield figure. Haven't seen it in person, but I'm certain it's probably sturdier for play than this one would be. Product images so far show a lot better quality in terms of paint, and similar build quality. The ZACCA version needs some adhesive to keep the rear part on securely. I had to apply Loc-tite around the circumference of the interface to thicken the part.

Overall Meaningless Scores and Stats

Price per unit:
MSRP: $5
Price shipped: ~$10
Competing prices: Hot Toys' Chris Redfield figure, ~$140. Expect figure scalpers to be selling the RPG-7 separately for somewhere around $12-$16, if they for some reason decide to.

Build quality:
If you're looking for an RPG-7, there's a version out there packaged with the Resident Evil 5 Chris Redfield figure. Haven't seen it in person, but I'm certain it's probably sturdier for play than this one would be. Product images so far show a lot better quality in terms of paint, and similar build quality. The ZACCA version needs some adhesive to keep the rear part on securely. I had to apply Loc-tite around the circumference of the interface to thicken the part.
I would be confident dropping this off a bookcase, since there's very few delicate components. 7/10.

You have two options for getting a 1:6 scale RPG-7: ZACCA or Hot Toys. You're not going to be buying the Hot Toys version en-masse at the price of $140+. You're forced to buy the ZACCA model, but it's pretty good and sturdy for posing and play. How sturdy is it? Enough to go outside and do some shooting.

"Boys, I see the signs of a BLU base! We must attack at once and crush the enemy!"

"A Pepsi plant? Sweet! Now that's what I'm talking about!"


"We must stop that BLU cart from getting past this point, boys!"

"This is my street! You are not welcome in my street... Hmmm. Maybe you are welcome in my street. I'm going to get going now."