Author Topic: 1 pound mortar (Read 1410 times)

Evil Dog · « **on:** June 26, 2004, 05:43:53 PM »

I finally have my newest toy just about finished. All that remains is deciding on what type of elevation mechanism (if any) I want to use. I've had the barrel for a few months now bracing it in place when I wanted to play. It's a 1.75" bore and I found a mold for 1.70" cannon ball fishing weights so will be getting rid of a rather large pile of wheelweight one pound at a time.

Double D · « **Reply #1 on:** June 27, 2004, 12:50:15 AM »

Nice looking gun!!

You don't need an elevation device on that gun. Range is adjusted by the powder charge. Increase charge for more range and decrease less range that how it was done.

Did you build the piece yourself or buy it some where. Tell us about it.

Evil Dog · « **Reply #2 on:** June 28, 2004, 02:52:49 AM »

Hi Double D.... yes, I built this one myself (my first). The barrel came from a machinist in Arkansas. Spent a few month firing it by bracing the barrel up with sandbags until I finally got the base finished.

Was out playing with it yesterday using mainly the 1 pound wheelweight ball. The powder chamber in this barrel is 1" diameter by 1 1/2" long. I make up foil wrapped powder charges that size by using corn meal as a filler... just have to be sure the powder cartridge is marked to indicate which end has the powder in it.

With the barrel at around 60 degrees either a 50 or 60 grain charge of FFg would send the ball approximately 75 yards down range. Going to 75 grains would send it approximately 110 yards. With the ball painted a flat black I could see the entire flight from "bang" to impact. Don't think that I will be shooting too many golf balls as I have probably 500 or more pounds of wheelweight laying around the shed to get rid of.

I still like the idea of being able to change the angle of the barrel. To that effect I scribed a line on the end of the trunion parallel to the centerline of the barrel. Then marked the trunnion cap at 45, 60 and 75 degrees. Not exactly precision aiming but close enough for play time.

Blaster · « **Reply #3 on:** June 28, 2004, 03:26:41 AM »

Evil Dog: Hey, you did an excellent job on that mortar. That carriage looks just perfect. Wish I had the talent to complete a project like that.
If I had one that looked that good, I'd hesitate shooting it for fear of getting it scratched up. Enjoy it!! Blaster (Bob in CO)

Evil Dog · « **Reply #4 on:** June 28, 2004, 03:42:15 AM »

Hi Bob.... After playing with it yesterday I had to take it apart for some minor repair. Not sure what the correct name is for that piece of wood at the tail end but I had to take it off and attack with a belt sander. Several burns were caused by pieces of burning fuse falling on it. The same thing was reported in the "Yorktown Mortar" thread. Next time I will put several layers of foil over that wood block.... hopefully that will prevent it from happening again.

Next project will be a cannon...... I've always just wanted one. Guess that is reason enough.

Double D · « **Reply #5 on:** June 28, 2004, 04:26:18 AM »

First shorten your fuse you only need enough sticking out to light. Second upen up your fuse hole more a little . The fuse should be a loose slip fit into the hole. When the gun fires the fuse should be blown out of the hole. A long fuse drags and falls on the carriage.

That's why in the mortar shots mortars re required to have shield.

For elevation make wedges of different thickness/angles. Make the wedges just slightly narrower than the width of the front transom. On the bottom of the wedge attach a cross strip or make an undercut. When you the slide the wedge in it will stopped by the undercut catching on the top of the transom.

Wedges were a commonly used elevation adjustment device.

Evil Dog · « **Reply #6 on:** June 28, 2004, 05:01:23 AM »

Thanks for the info on the wedges.... will be making some up shortly. Should be a lot easier to use than my current method. Also will definitely shorten up the fuse so that there is between a half inch and an inch hanging out. Currently I have been cutting fuse allowing for up to 3 inches of protruding fuse.

Double D · « **Reply #7 on:** June 28, 2004, 10:24:11 AM »

Cut yourself a length of fuse one foot long. Light the fuse and time how long it takes to burn up.

Now give someone the watch and have them say ready set go, and start running, when they say go, then when the amount of time passes that it takes for the fuse to burn one foot have them yell stop....call the EMTs to bring oxygen. (If you are a smoker have some one bring a cigarette)

Now back to the serious....divide the time by twelve and you have the burn rate per inch of fuse. From that you can compute the time the fuse will burn until it reaches the powder. That will help establish how long you need your fuse.

Cat Whisperer · « **Reply #8 on:** June 28, 2004, 12:37:48 PM »

Quote from: Double D

First shorten your fuse you only need enough sticking out to light.

I like to have from 1/2" to 3/4" sticking outside the hole minimum. That way (more so with a mortar than with a cannon) there is less risk of the fuse igniting any powder that may have worked it's way out through the fuse hole when the ball is loaded. If it were to go off I want to be a safe distance away, not right much close.

Blaster · « **Reply #9 on:** June 28, 2004, 12:39:00 PM »

Evil Dog: As Double D stated, just open the fuse hole (vent) just a little to allow the fuse to easily slip down into the charge. Got to be careful not to make the hole too large so that sparks could possibly drop down along side of the fuse and into the charge before the fuse can burn all the way to the bottom. I used to take a little wad of modeling clay and gently pack just a tad around the fuse where it enters the hole. Was always wondering how long it'd be before I'd have a dropping spark causing a premature bang. At one time, when I was especially worried about starting a forest fire, I'd cut a piece of aluminum pop/beer can and wire it over the fuse and around the tube after the fuse was inserted and laying flat. Didn't work at all as the fire shooting out of the vent melted the aluminum and the molten fuse still went where it wanted to. I have seen some folks who'd take an old frying pan and poke the pan handle into the ground behind the vent to prevent the fuse from being blown wayyyyy back. IMHO. Blaster (Bob)

Evil Dog · « **Reply #10 on:** June 28, 2004, 01:05:05 PM »

I haven't measured the existing fuse hole but I believe it to be right at 1/8". Green visco fuse slips in with just a very slight pressure. As Double D had suggested, I think that I was just cutting the fuse too long allowing molten fuse to drip down. Will start cutting it to where there is between 1/2 and 1 inch of fuse protruding from the vent.