Building a Spring Firing Cannon

In this entry, I will illustrate the steps I followed to make a cheap plastic cannon into a matchstick shoot artillery piece suitable for an FLW game.

I actually started with two cheap plastic models. The grey, “Civil War” cannon is the model that was actually converted. I used the spring and plunger from the green model (this green cannon would be perfect for playing FLW in 28mm on a tabletop. Since I have 5 more of them, I may fix them to fire better and use them that way.). Aside from the Gun model, spring, and plunger, I needed a 2 ¾” piece of 3/16” brass tubing, super glue, and some epoxy putty. For tools, I used some wire cutters, a hobby knife, and the dental picks I use for sculpting.

Step 1 – Remove the old barrel.

I used the wire cutters to clip away the original barrel, saving the breech and trunnions. With the hobby knife, I cut away any other excess plastic to smooth out a spot for the new barrel. This method of barrel removal works well for soft plastic models. Because this model was a semi-hard plastic, it cracked at the breech end. I will fix the crack with super glue and epoxy putty.

Step 2 – Glue on the new barrel.

As the title of this step implies, I super glue the brass tube on to the trunnion/breech piece.

Step 3 – Fill in the gaps.

Using the epoxy putty, I filled in the gaps between the trunnion/breech piece and the barrel. I also built new bands over the barrel at the breech and trunnions.

Step 4 - Drill a hole in the breech.

I drilled a hole through the breech into the barrel. The end of the plunger will pass through this hole.

Step 5 – Insert the spring and plunger.

I dropped the spring and plunger down the muzzle end of the barrel. By jiggling the barrel and pushing on the plunger with a skewer, I was able to get the plunger end through the breech hole. I then bent the plunger end 90 degrees to form the handle.

The cannon is now ready to be painted, put back on the carriage, and used in a game. If you do not have access to a ready-made spring and plunger, these can be made or acquired from other sources. For the plunger, I use a wire coat hanger. Clip off a straight section of the hanger and build up one end of this. I use nested aluminum tubing in 1/8” long segments which I super glue then epoxy putty in place. For a spring I use two springs from retractable ball point pens stacked one on top of the other. I’ve found that this works better than a single ball point pen spring. If you do you the ball point pen spring, you will need a slightly larger diameter tube for the barrel.