This 12pdr Coehorn Mortar was built about 5 years ago. It was my first full scale mortar. I was lucky enough to have access to a large lathe, milling machines and welding equipment at the time.
Total cost for materials was about $300-$350. I would say that it took about 80 hours over the course of a year and a half to complete not including design time. It is a fairly involved project and requires a wide range of skills.
Materials:
Barrel:
7.00” dia. x 12.63” long hot rolled 1018 steel (1 req.)
(cold rolled would have been better but hot rolled was cheaper)
2.25” dia. x 10.13” long steel (1 req.)
0.25” steel plate (2 req.)
Base:
2” x 8”x 8’ long framing lumber (3 req.)
Hardware:
0.50” dia. x 12” long steel bar (6 req.)
1.25” dia. x 1.5” long steel bar (6 req.)
1.00” square x 0.5” steel (6 req.)
0.75” square x 0.4” long steel (4 req.)
3/8” x 6” carriage bolt (4 req.)
0.13" x 2.00" flat bar x 2.0" long (4 req.)
0.25” x 2.00” flat bar x 10.0” long (4 req.)
0.25" x 1.63" flat bar x 4.75" long (2 req.)
Tools / Equipment:
Lathe (as big as you can find)
Milling Machine
Band saw
Drill press
Welding Equipment
Skill saw
General hand tools
Wood carving tools
This is my first instructable so please let me know if there is anything I can do to make improvements.
Total cost for materials was about $300-$350. I would say that it took about 80 hours over the course of a year and a half to complete not including design time. It is a fairly involved project and requires a wide range of skills.
Materials:
Barrel:
7.00” dia. x 12.63” long hot rolled 1018 steel (1 req.)
(cold rolled would have been better but hot rolled was cheaper)
2.25” dia. x 10.13” long steel (1 req.)
0.25” steel plate (2 req.)
Base:
2” x 8”x 8’ long framing lumber (3 req.)
Hardware:
0.50” dia. x 12” long steel bar (6 req.)
1.25” dia. x 1.5” long steel bar (6 req.)
1.00” square x 0.5” steel (6 req.)
0.75” square x 0.4” long steel (4 req.)
3/8” x 6” carriage bolt (4 req.)
0.13" x 2.00" flat bar x 2.0" long (4 req.)
0.25” x 2.00” flat bar x 10.0” long (4 req.)
0.25" x 1.63" flat bar x 4.75" long (2 req.)
Tools / Equipment:
Lathe (as big as you can find)
Milling Machine
Band saw
Drill press
Welding Equipment
Skill saw
General hand tools
Wood carving tools
This is my first instructable so please let me know if there is anything I can do to make improvements.
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I have had an interest in cannons ever since I was a kid. Several years ago I participated in a civil war reenactment and I was hooked. After doing some research I decided that a mortar would give me the most bang for my buck. I came across a small mortar called a Coehorn Mortar. The design was originally developed by the Dutch engineer Barron Von Coehorn in the late 1600’s. Variations of the design were used in the American revolution and Civil war.
My mortar is based on the 24 pdr Federal 1841 model used during the American Civil war. I decided to build mine as a 12 pdr. The size refers to the weight of a solid shot. The shot for a 12 pdr is half the weight of a 24 pdr but about 80% the size.
Technically my mortar is not full scale but at 12pdr I still consider it full size. The confederates did have 12pdr mortar but I liked the Federal design better.
I want to note two things before continuing. First, this mortar is not a toy. It is a very real artillery piece and should be treated as such. Second this mortar 100% legal. It is not considered a “destructive devices” and does not need to be registered in the US. For more information see the National Firearms Act, sections 26 U.S.C. 5845 and 27 CFR 479.11, both can be found on the ATF website.
My mortar is based on the 24 pdr Federal 1841 model used during the American Civil war. I decided to build mine as a 12 pdr. The size refers to the weight of a solid shot. The shot for a 12 pdr is half the weight of a 24 pdr but about 80% the size.
Technically my mortar is not full scale but at 12pdr I still consider it full size. The confederates did have 12pdr mortar but I liked the Federal design better.
I want to note two things before continuing. First, this mortar is not a toy. It is a very real artillery piece and should be treated as such. Second this mortar 100% legal. It is not considered a “destructive devices” and does not need to be registered in the US. For more information see the National Firearms Act, sections 26 U.S.C. 5845 and 27 CFR 479.11, both can be found on the ATF website.
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Good luck in future Battles and may your projectiles fly true.
I have made quills using a strip of tape and a straw. You take some 1F or 2F powder and sprinkle the sticky side of a piece of tape about 4” or 5” long. This is then placed in a paper straw. About a half inch or so is left sticking out of the top. The finished quill is placed in the vent and ignited with a slow match. The idea is that, once ignited, the flame travels very quickly between grains due to the air space in the straw. Ignition is almost instantaneous.
Fascinating project - I too would like to see a video, assuming you can find something safe to fire, and somewhere safe to fire it.
It must've been hard work making one of these in the 17th. century. At least you don't have to worry about the whole thing blowing up because of an undetected flaw in your barrel.
Thanks for sharing that with us.
This also falls into the “don’t’ be stupid” category. If you act suspicious you will be treated as such. It is unlikely that every municipality will know all the laws in detail. I have a copy of the federal regulations in my powder box. If there are ever any questions I can bring it out for reference. It is also still a firearm so all local regulations need to be followed. This is not something you could fire in you front yard anytime you want. I would recommend contacting your local police department if you have any questions.
Some states also classify cross bows and draw bows as a fire arm.
As written, your title coupled with the discussion of the device's use by the Confederacy is tinged with irony :-/
I've stood near black-powder cannon firing "blanks" (actually a lump of wadding an straw), and you don't so much hear them as feel them go off.