Sunday, August 30, 2009

J.Norad's Tutorial for Making a 1:6 scale Shotgun

Time to bust out those junk Centaur Veterans, Rock Jockeys, and Mudholes! It's gun making time! Today's agenda: I'm going to try to show you how to make a shotgun out of 110lb cardstock, bamboo sticks and Magic: the Gathering cards. Refer to this guide if you want to work with Magic cards as building material. This is going to use a few techniques most paper model makers might find handy, but it's mostly going to be knifing, bonesawing and Dremel-ing.

First, we need a stock image.This is the shotgun from Team Fortress 2. Simple model, compared to other things I've built. I'm going to show you how to get from this deceptively simple image to a solid model. For your convenience, this full size image is the exact size of the finished model.

Once you've obtained an image of your weapon in question, preferably a side view, you now need to formulate a plan.

From the above image, we can find three main components:
  1. The grip/receiver assembly : This is largely an extruded object: the part we need to make looks exactly like this from the side view, but pulled out so it's thicker. Think of what a cube is compared to a square. You'll be making it like a block shaped like this section.
  2. The Barrel: This is going to be one of the easiest, yet annoying parts to make. It's just a hollow tube, followed by a shorter, hollow tube, connected with some small rectangular spacers. Not to mention, some bracket thing on the front.
  3. The Pump: You're going to hate this part with a passion. Especially if you have the tooling capability of an Amish man with a metal allergy. Look no farther, ye of little machinery.
Once you've formulated what parts you need to make, it's time to draft some plans!
I've taken care of the hard work of figuring out how to measure things with a ruler for you. All dimensions specified are in millimeters, and are basic: meaning no tolerances attached to the dimensions. On the top right, that's my original plans for the shotgun. If you haven't caught on by now, I'm going to make the pump move. Static models are boring!

For part 1: the grip/receiver, you simply need to trace that section onto paper, cut that out, then trace it onto some 4-card stacks until you have 4 parts. This will be approximately 5mm wide, which is the width of our shotgun.

You can simply glue these four pieces together now and sand down the edges flush. Advanced methods involve notching two 5mmx3.175 notches to receive a 3.175mm diameter bamboo stick, as indicated in the lower image:

For the barrel tubes, you'll need to use this reference on making tubes, or this Excel file for making tubes and cones out of paper. That is, if you want to precisely make 4.5mm outer diameter/3.175mm inner diameter tubes. I like my tubes to be as close as possible to the desired dimensions. Cut them to length, and make some 1mm spacer blocks to hold the two tubes together.

Now for the hard part: the pump. This part involves the lower half of the schematic. The lower left covers the dimensions in third angle projection. The lower right covers the concept and upper assembly to hold the pump in place.

If you draw the leftmost figure in the above image to the specified dimensions in 110lb cardstock,then roll around a 5mm diameter rod, you'll get the shape of the shotgun pump. the dimensions were calculated using my cone frustum calculator. It uses the same principles listed in the tube making reference, but with some fun tricks. If you roll up a triangular sheet, you'll form a cone. If you roll up a sheet that has a lot of triangular sections like the one I drew up, you'll form a shape that looks like the shotgun pump, if revolved around the magazine tube axis.

After you've made this solid, you'll need to use your cutting tool of choice to cut out a V shaped notch on one side of the pump. This is shown in the bottom right of the schematic. I'd suggest cutting 2mm wide and flaring out to 5mm. Next, you'll need to cut out that U shaped rectangular piece shown below and fold it to form a U shaped trough.
This will form the upper part of the pump and also serves to hold the pump together from the top. I suggest using two layers of Magic card for this part. For those of you who added the notches into the handle, you can stick some bamboo sticks in there to hold the barrel to the receiver together.

Now all you need to do is add details. The trigger is made from a 3mm wide strip of Magic card, three layers thick. I simply curved the part to fit the drawing and glued it in place with some Loc-tite for extra quick adhesion. To smooth out the pump, I sanded mine down until it was relatively flush. I then used the cone maker formulas to create some cover parts to wrap around the pump sections. This took care of the major surface irregularities.

All you need to do now is add the little details, which should be easy compared to the pump. For the side ejector port on the left, simply cut out a 12mm x 3mm rectangle on the side as depicted on this screenshot:
Screencaps are great for video game model replicas. I took several in the course of making every item from Team Fortress 2. Use these to figure out what details you need to add. If you do a part analysis, they should be easy to make once you figure out of you need a block, tube or a strip of material to make it. when you're done with your model, coat it with some paint primer and finish it off with some nice paint. Then assemble your model, since it's easier to paint parts that move before assembly.

Remember: if you managed to get as far as a rough form, you've done pretty well. A static model was perhaps what my capabilities were limited to a year ago. If you managed to pull off this model and get the pump working, or even understand the schematics, you've done quite a good job. You deserve a medal, if they weren't all gone.

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