Author Topic: OK, I'm Hooked, but I need some help.... (Read 940 times)

flyfisher · « **on:** January 17, 2006, 11:18:14 AM »

I've been lurking in the shadows here in the mortar and cannon forum for too long......I'm Hooked!!

I've been thinking about building a golf ball mortar for the longest time, and I feel that I am ready to begin. Being a chemistry teacher, I've always been interested in any type of exothermic reaction. The logical thing seems to continue this interest with the development of a mortar.

Here's my situation: I have found a retired piece of solid steel shaft from one of my dad's manure spreaders. The shaft is about 6 1/2 to 7' long and about 2 1/2" in diameter. I think that it would make a great mortar. I have no idea what kind of steel it is made out of, but I know that it will be strong enough for a golf ball mortar. I have a friend who owns a machine shop and am going to have him put the bore and touch hole in the shaft for me, but I have some questions first:

1) What would the ideal length for this mortar be?
2) What would the ideal bore size for a standard golf ball be?
3) What would a good starting load be for such a mortar?

Any input that you guys can give me would be greatly appreciated. Thanks for all of the posts and pictures that are easy to get to here on Graybeard.

Thanks,
flyfisher a.k.a. Ryan

Cat Whisperer · « **Reply #1 on:** January 17, 2006, 12:32:36 PM »

flyfisher -

If it's an axel shaft it may be hardened. It is good steel, but IF hardened it will be tough to machine. It can be annealed.

Bore length - I'd go for 2 to 3 calibers long (inside of bore 2x or 3x inside diameter of bore. 1 caliber long will give you max range of about 8-10feet. 2 calibers will go 100-200 yards. 3 calibers into who-knows-where.

Bore size. 1.70" or a little larger. 1.75 works and is a little loose. Too little clearance and you'll clean after every shot. Too much, no big deal, just use a little more powder. 1/40 the diameter for 'windage' is a rule of thumb for clearance.

Starting charge for golf balls - FFg - 10 - 20 - 30 grains is the range. I use one to two .45acp cases full.

rifleshooter2 · « **Reply #2 on:** January 17, 2006, 02:38:44 PM »

exothermic reactions are cool :-D

Andy

flyfisher · « **Reply #3 on:** January 17, 2006, 04:14:18 PM »

Cat Whisperer,

The shaft is from one of the "beaters" on the manure spreader, which is usually softer than an axle shaft. I'll have my machinist take a look and decide what could be done.

I have seen a picture or two where a golf ball mortar had reasonably thin walls. I realize that the pressures here are not nearly as great as shooting a cannon with more dense projectiles...would it be possible to make a mortar out of let's say schedule 80 pipe?

Thanks for the great info.

flyfisher

Cat Whisperer · « **Reply #4 on:** January 17, 2006, 05:21:27 PM »

ff -

Here are two pictures of 4 different golf-ball caliber mortars:

On the left, made from two pieces of 1144SP (round and DOM tubing) and on the right from solid pieces of 4140. Big one weighs in at 28 lbs.

Two piece ones were products of the contest we held some time back. Adequate for light charges and only golf balls.

Octagonal/round one is hand-held! With golf balls kicks about like a .38SP.
Has about 1/2" thick walls; where the heavy one has 1"+ walls.

There has been much discussion here on strength, strength of materials and design. It will be well worth your while to take a couple of hours and read through selected threads on golf ball caliber mortars here.

Double D · « **Reply #5 on:** January 17, 2006, 06:19:54 PM »

Hey, CW is exothermic one of those bad words, Graybeard wants us to X out!

Cat Whisperer · « **Reply #6 on:** January 18, 2006, 01:21:47 AM »

Quote from: Double D

Hey, CW is exothermic one of those bad words, Graybeard wants us to X out!

Not at all. It simply means to give off heat from the reaction.

But *^&^%, ()%$%, $%#@, and (@#$%# are; and will not be tolerated.

Red_Leg · « **Reply #7 on:** January 18, 2006, 07:23:10 AM »

Hey flyfisher we share common backgrounds---I am a retired Chemistry Professor----spent 38 years without losing a student in the labs---many burns and oops accidents---nothing reportable an no fatal results. I taught Freshman Chemistry to all (hopeful) Chem Majors, Enjigears and Pre-Meds ( the latter being generally a sorry lot). I've been retired for 15 years now, and have been a lifetime flyfisher and fly tyer as well as a BP & gun nut. Nice to meet you here---ever since my 8 years in the US Army as an Artillery Officer, I maintain a fanatical interest in the Artillery---specially the old timers. :grin:

flyfisher · « **Reply #8 on:** January 19, 2006, 01:58:21 PM »

Very nice to meet you here as well, Red Leg. It seems as though we share many of the same past times, and great past times they are. I am a lowly Chemistry teacher in a small public school here in PA. Been teaching for seven years now, started straight out of college. I am proud to admit that I have yet to lose a student as well...only had to use the eyewash station one time in my career, and that was no big deal. No explosions (except the ones that I make on purpose). No matter the age, the old hydrogen and oxygen balloon really is an attention getter. Can't wait to go flyfishing as well, I've had little time to tie here this winter...our first child (a girl) is on her way (March 17). I am trying to find time to work on a new project, as you can see. Maybe this Spring or hopefully earlier. Stay in touch, it's pretty rare to find two crazies like ourselves in the same place, and I look forward to hearing about your artillery experiences as well.

flyfisher

GGaskill · « **Reply #9 on:** January 21, 2006, 10:03:24 PM »

...would it be possible to make a mortar out of let's say schedule 80 pipe?

Possible--yes, desirable--not really. Pipe is not a desirable material unless one can guarantee that high density projectiles will never be fired from it. Even then there is the seam inside that has to be removed which is an immense pain in long barrels. And it is not guaranteed truly round.

Bored/drilled-from-solid or seamless tubing are the preferred materials for cannon barrels because they are stronger and less likely to have corrosion-induced failure.

Powder keg · « **Reply #10 on:** January 22, 2006, 03:53:40 AM »

Quote from: flyfisher

would it be possible to make a mortar out of let's say schedule 80 pipe?

Remember, Pipe is for Water, thats it. Not good for anything else. Thanks for pointing that out GGaskill. I missed it the first time through.

Later, Wes

Cat Whisperer · « **Reply #11 on:** January 22, 2006, 06:46:46 AM »

Quote from: Powder keg

Quote from: flyfisher
would it be possible to make a mortar out of let's say schedule 80 pipe?

Remember, Pipe is for Water, thats it. Not good for anything else. Thanks for pointing that out GGaskill. I missed it the first time through.

Later, Wes

I used to make 'cannons' from 1" water pipe when I was in high school - good thing that I used my own crudely made black powder!

claypipe · « **Reply #12 on:** January 23, 2006, 08:25:18 AM »

Quote from: flyfisher

would it be possible to make a mortar out of let's say schedule 80 pipe?

You might try looking into what is called hollow stock or hollow bar. But , as others have pointed out, schedule 80 is water pipe, not gun metal.

flyfisher · « **Reply #13 on:** January 24, 2006, 04:57:36 PM »

I thank you gentlemen greatly for your advice. I am going to stick to the steel shaft idea and create the mortar that way. I took the shaft to my machine shop guy and he says that there should be no problem creating a bore in the shaft. I'll be posting later on the progress of my project. Thanks again for all of your advice and suggestions.

flyfisher

Cat Whisperer · « **Reply #14 on:** January 25, 2006, 12:10:41 AM »

Quote from: flyfisher

I thank you gentlemen greatly for your advice. I am going to stick to the steel shaft idea and create the mortar that way. I took the shaft to my machine shop guy and he says that there should be no problem creating a bore in the shaft. I'll be posting later on the progress of my project. Thanks again for all of your advice and suggestions.

flyfisher

My first mortar started out as a billet of hot rolled steel - rough hard surface - wore out (from resharpening) a tool bit just turning it to size. Bored the thing with a 3/4" bit - only tool I had to use - drilled it and then took a few thou at a time using the bit held in the tool holder. Beer-can caliber. Looked so good (to me) I took it to the local plating plant and had it bright chromed!