By request, another member has asked that I recreate on this site my "how to" on how I built my carbide cannon. So here it is.
The finished product can be seen in action during the initial test firings via the youtube link in my signature block.
This will be kinda long, but it does come with pictures. Remember...this is a carbide cannon, not a black powder cannon. I wish I could attach the Word document I made up about it.
Summer of 2012 I finally knuckled down to build this thing. I'd rough sketched what I wanted and had been buying material a bit at a time over the previous several months for it. The basic criteria for the cannon were two-fold:
1. No "redneck" cannon. The cannon couldn't look like a bunch of PVC pipe glued together.
2. Following the general philosophy that "bigger is better" with respect to sound effects, the cannon couldn't be small.
I settled on making a replica of a 24-pounder off the USS Constitution. I've always had a fondness for the looks of that cannon design, and even made one about 8 inches long 0n a metal lathe in shop class during junior high school, some 40 years or so ago. I downloaded a drawing from the internet and used that to make all my scale patterns from.
The core of the cannon is made from Schedule 40 PVC and is assembled from a 6x6x4 Tee, a 6x4 adapter, a 4x3 coupling, and a 3 inch diameter pipe. You can see it in this picture, with the jig I made up to hold the cannon for the carving process:
The core was then layered with several pieces of 2 inch thick foam insulation blocks. The whole thing is then mounted in the jig, to which I fastened the patterns to be used for carving the foam. The carving was accomplished by using a "hot wire" knife, which is drawn across the patterns to guide the wire. The hot wire slices through the foam. After each pass, the cannon is rotated by hand a little bit to allow slicing off a new layer. This is repeated until the round body of the cannon is achieved. It took me about three hours to do this.
By the way, the hot wire was made using a guitar string held in a frame, and the string was connected to the output of a 25 volt transformer to provide the current to heat the wire. The temperature of the wire is controlled by a dimmer switch.
After the body was rough carved using the hot wire, the body was rough sanded for a few minutes using 80 grit sandpaper to remove the hot wire cutting marks and make the body round. Some hand carving was required around the 4 inch cleanout plug on the bottom of the Tee at the breech. A reference line was drawn down the length of the cannon and each layer of foam sequentially numbered. This was to allow me to remove and reinstall the layers of foam and to install the trunnions on the barrel. The trunnions are the "pivot points" of the cannon, which rests on the carriage and allows the cannon to be angled up or down.
When that was done, the body was primed using latex KILZ paint thickened with some drywall mud. This is required to "seal" the foam before spray painting. Most all spray paints will dissolve the foam, and that would suck after all that work. Some minor body work was performed with spackling compound to fill in cracks and minor defects, but no effort was made to make things perfectly smooth...cast iron cannons didn't have a smooth finish. Then a second coat of KILZ was applied. This was the result:
The finished product can be seen in action during the initial test firings via the youtube link in my signature block.
This will be kinda long, but it does come with pictures. Remember...this is a carbide cannon, not a black powder cannon. I wish I could attach the Word document I made up about it.
Summer of 2012 I finally knuckled down to build this thing. I'd rough sketched what I wanted and had been buying material a bit at a time over the previous several months for it. The basic criteria for the cannon were two-fold:
1. No "redneck" cannon. The cannon couldn't look like a bunch of PVC pipe glued together.
2. Following the general philosophy that "bigger is better" with respect to sound effects, the cannon couldn't be small.
I settled on making a replica of a 24-pounder off the USS Constitution. I've always had a fondness for the looks of that cannon design, and even made one about 8 inches long 0n a metal lathe in shop class during junior high school, some 40 years or so ago. I downloaded a drawing from the internet and used that to make all my scale patterns from.
The core of the cannon is made from Schedule 40 PVC and is assembled from a 6x6x4 Tee, a 6x4 adapter, a 4x3 coupling, and a 3 inch diameter pipe. You can see it in this picture, with the jig I made up to hold the cannon for the carving process:
The core was then layered with several pieces of 2 inch thick foam insulation blocks. The whole thing is then mounted in the jig, to which I fastened the patterns to be used for carving the foam. The carving was accomplished by using a "hot wire" knife, which is drawn across the patterns to guide the wire. The hot wire slices through the foam. After each pass, the cannon is rotated by hand a little bit to allow slicing off a new layer. This is repeated until the round body of the cannon is achieved. It took me about three hours to do this.
By the way, the hot wire was made using a guitar string held in a frame, and the string was connected to the output of a 25 volt transformer to provide the current to heat the wire. The temperature of the wire is controlled by a dimmer switch.
After the body was rough carved using the hot wire, the body was rough sanded for a few minutes using 80 grit sandpaper to remove the hot wire cutting marks and make the body round. Some hand carving was required around the 4 inch cleanout plug on the bottom of the Tee at the breech. A reference line was drawn down the length of the cannon and each layer of foam sequentially numbered. This was to allow me to remove and reinstall the layers of foam and to install the trunnions on the barrel. The trunnions are the "pivot points" of the cannon, which rests on the carriage and allows the cannon to be angled up or down.
When that was done, the body was primed using latex KILZ paint thickened with some drywall mud. This is required to "seal" the foam before spray painting. Most all spray paints will dissolve the foam, and that would suck after all that work. Some minor body work was performed with spackling compound to fill in cracks and minor defects, but no effort was made to make things perfectly smooth...cast iron cannons didn't have a smooth finish. Then a second coat of KILZ was applied. This was the result:
