can anyone tell me how or where to find out how to build a beer can mortar. thank you
Here's a quick overview - perhaps enough to get you started in the right direction. All take some machining by one means or another. There are advantages and disadvantages to each.
1. Make a split pattern - generally wood - have it rammed up in the flask (cope and drag) with green sand. Remove the pattern and the plugs put in for sprue and riser, use moulding spoons to cut a pour hole and then reassemble the flask; pour in the molten iron. Advantage - cheap when you're making many copies. Disadvantage - still requires machiing of the bore, trunions and touch-hole. Disadvantage - takes skills and equipment not generally found in local machine shops. Disadvantage - strength of iron (or bronze) is questionable. Most organizations require a steel sleeve inserted into the bore for strength.
2. Take a steel tube (4140 or 4130) that is precisely made (DOM - drawn over mandrel tubing) of the correct size bore and sufficient strength. Make a plug for one end. Thread both, assemble, weld (must be preheated to some 700 degrees F. to preclude cracking - good luck!). Trunions can be added by welding or fitting a ring around the tube or a ball-end that fits into a socket in the base-plate.
3. Start with a solid round billet of 4140. Turn on lathe. Bore the hole. Cut the vent. Attach the trunion. This is how I make mine. Limiting factor - boring the hole - hard to go deep, time consuming. See avitar on left of my 4.5".
You will see beer-can caliber mortars in the price range of 500 to 800 bucks. After you make a few you'll think that's cheap!
If you're going to compete you want to look into the rules for the organization - most will require that they be a particular caliber and be patterened after a particular model - full scale too.
There is, of course, the consideration of safety. How thick should the walls be? Is it going to be of a Coehorn style (powder chamber in thickest part of the tube (for strength)? This is where the ENGINEERING of the design comes in.
This is a most serious game. Once you've seen a supposedly well designed cannon blow up (up front and personal) your whole perspective on design changes.
Again, good luck. Make a decision as to what you want and what direction you're headed with this - that'll make advise easier.
