Author Topic: new ideas for small cannon (Read 1029 times)

rampa room artillery · « **on:** December 11, 2010, 04:03:22 PM »

on my long hours of driving today i had time to get my head clear and think of ideas. on small cannons i know most people press fit their trunnions?

how about boring the center of the trunnion out. then welding from the inside with a mig welder?? more strength and a better look, smooth, you just fill up the inside and then grind it smooth.

any thoughts???

rick bryan

oh and i have lots more ideas but they have to be fine tuned in my head. ....... aka need a glass of rum.

rick

Double D · « **Reply #1 on:** December 11, 2010, 04:15:13 PM »

Why go to the extra work? It's a lot simpler to weld out side than inside.

rampa room artillery · « **Reply #2 on:** December 11, 2010, 04:21:15 PM »

that way there is not welding bead on the out side of the trunnion. on a one inch gun a weld would look way out of place unless you ground it all the way out flush,

rick

GGaskill · « **Reply #3 on:** December 11, 2010, 04:23:03 PM »

How about boring the center of the trunnion out. then welding from the inside with a mig welder??

You are describing what is essentially a plug weld, The disadvantage of this style is you don't have much metal at work, only the small diameter of the plug. By welding the rimbase perimeter to the barrel, you get much more material holding things together which gives you a stronger weld, and being at the outside, you get greater "leverage" on the recoil force. Not as easy to make pretty but a better attachment.

rampa room artillery · « **Reply #4 on:** December 11, 2010, 04:30:46 PM »

I am not talking about large cannons, and yes I would and have and the outside of the trunnions welded on my big guns. I am talking about an alternative to people that are just simply pressing their trunnions in with no weld. I remember there were several gun that people had done that way. I am looking at making a 1 inch cal. rodman and i am going to give it a try on a piece of steel and then stress test the weld see what it takes to break.

rick

GGaskill · « **Reply #5 on:** December 11, 2010, 04:52:11 PM »

So how big would you drill the trunnions? They should be about 1" diameter for a 1" bore. On a Rodman, the rimbases are faired into the barrel so you don't want a sharp joint. Welding on the outside would make the fillet you need anyway.

rampa room artillery · « **Reply #6 on:** December 11, 2010, 05:58:33 PM »

1 inch trunnion, I would drill it to 5/8 and fill it in with weld.

rick

GGaskill · « **Reply #7 on:** December 11, 2010, 06:12:00 PM »

If you are a good enough welder that there would be no voids or other faults in the bottom half inch of the weld, it would probably be OK. Although I would be tempted to countersink the bottom of the trunnion so that there would be weld farther out.

rampa room artillery · « **Reply #8 on:** December 11, 2010, 06:18:52 PM »

yea that sounds like a good idea, my plan was to use my gas mig welder turned up pretty high for first part of weld to really get into the barrel, then the rest is truly just filler. well, I will try it on a plate and then do the old beat it with a hammer till it breaks test. then try welding from the outside and test again. I will post the results. with pics.

rick bryan

GGaskill · « **Reply #9 on:** December 11, 2010, 06:35:28 PM »

Probably be a good idea to drill the bore last. What kind of material will you use for the barrels?

Victor3 · « **Reply #10 on:** December 11, 2010, 10:43:37 PM »

I have a mig welder but truth be told, I'm not that good at mig. I've usually had access to a tig welder so don't use mig much.

Aren't you gonna have to extend the wire way out past the torch to get to the bottom of the hole, where it may arc to the sides? Seems to me it might be difficult to get a good fill all around the diameter before the entire area fills up, possibly leaving voids.

Hey, it kinda reminds me of my favorite game as a kid

(image credit - blogs.smarter.com)

Cat Whisperer · « **Reply #11 on:** December 12, 2010, 12:42:07 AM »

If it's 4140, I suggest a certified welder.

Double D · « **Reply #12 on:** December 12, 2010, 02:21:17 AM »

Part of the purpose of welding the trunnion is to stop movement in the pocket between pocket wall and the trunnion when the trunnion flexes. If there is movement the hole can and will elongate. If you weld inside the out side can stillmove.

I have told this story before about the My Cairo cannon. This barrel is made of 4140. The Trunnions have a threaded stud on the bottom and the rimbases are interference fit in the pockets. They were put in with a barrel wrench. I had fired the gun for about a year. I was living in Redding California and went to a cannon shoot there. The would not let me shoot my cannon because the trunnions were not welded. Area cannon maker and a Millwright Doug Titus offered to help me out. We pulled the gun off the carriage. Both trunnions were loose and could be unscrewed by hand and one had a bent threaded stud. The trunnions pockets were elongated--remeber this is 4140 steel. Doug did the preheat, welding and anneal on the barrel and every was fine after that.

Zulu · « **Reply #13 on:** December 12, 2010, 02:46:04 AM »

Rick,
One thing to consider:
Most of the folks here are making their guns for themselves, and they use several different ways to secure a trunnion. Some better than others.
It is my understanding that your intention is to sell these guns. If that is the case, you face the inescapable liability issues that the others don't face.
Choose wisely my friend.
Zulu

rampa room artillery · « **Reply #14 on:** December 12, 2010, 03:35:06 AM »

ah, yes, but if anyone here makes a guns to sell. i have talked to two lawyers that work for your company. the best way to protect yourself is easy.
do not drill the vent all the way. just drill half way. then you are not selling a weapon. just a model.

testing will begin next week.

I will let you know.

rick bryan

Double D · « **Reply #15 on:** December 12, 2010, 04:11:33 AM »

Quote from: rampa room artillery on December 12, 2010, 03:35:06 AM

the best way to protect yourself is easy.
do not drill the vent all the way. just drill half way. then you are not selling a weapon. just a model.

rick bryan

Any good attorney will tell that is nonsense.

Zulu · « **Reply #16 on:** December 12, 2010, 04:51:06 AM »

Liability goes far beyond "legal" liability when making a cannon. Moral liability takes precidence.
Zulu

rampa room artillery · « **Reply #17 on:** December 12, 2010, 06:02:43 AM »

well of course, i would never sell anything that i had not tested and I will always keep the first of any production. if somthing doesnt work then i wont do it. there should alway be a safety factor of 4 times. my barrels will be able to shoot 4 times the powder then i will rate them at. the 4x is a osha and safety industry standard. like ladders, yes a 6 foot ladder is only rated for 300 lbs. even tho they can hold 1200 lbs. that way when people push past the safety rating they will still be in a relative safe area.

and mostly i am making cannons for me. if i sell any it will be for friends and family. no commercial intent yet.
I make enough play money selling lead to pay for my sport. these small cannons are mostly for me.

rick bryan

Zulu · « **Reply #18 on:** December 12, 2010, 06:10:52 AM »

Rick,
What are you making out of lead? Cannon balls?
Zulu

rampa room artillery · « **Reply #19 on:** December 12, 2010, 06:21:56 AM »

lead pellots, and bullets for my rifles most of the n-ssa shoot lead pellots in rifled cannons. and everyone shoots soft lead in our rifled muskets smoothbores carbines and revolvers. no lead cannon balls, that would be to heavy for our safety standards. zinc is used for cannon balls. / some shoot turned aluminum bolts in the 6 and 12lb field guns. they seem to shoot very well.

rick bryan

GGaskill · « **Reply #20 on:** December 14, 2010, 02:41:33 PM »

On a one inch gun, a weld would look way out of place unless you ground it all the way out flush.

On a gun of one inch bore, a typical TIG weld only needs the dimes smoothed out. The joint shouldn't be a sharp angle anyway.