Interesting article on Cannon founding/archeology

[Littleneckhalfshell]

while continuing my search for information on Trunnions and Dolphins, I came across this article dealing with The Guns of the Santíssimo Sacramento

by JOHN F. GUILMARTIN, JR. This ship sank in May of 1668, the article deals with gun founding practice and has some nice diagrams. Of particularly interesting note is that many of these guns were cast with wrought iron core locating devices, something I had never heard of before. Though the diagrams show both on centerline trunnions and off centerline trunnions and Dolphins, I am still no closer to understanding the place of the placement of trunnions and dolphins on the timeline of ships guns of the 17th Cent. But those interested in Cannon, may find this article enlightening. At the very least I have learned to spell trunnions correctly ;-)

http://www.angelfire.com/ga4/guilmartin.com/Santissimo.html

Edited April 5, 2009 by Littleneckhalfshell

[Cascabel]

Bravo, Suh !!! A most interesting article...

>>>> Cascabel

[Crudbeard]

Bravo, Suh !!! A most interesting article...

>>>> Cascabel

Indeed, aexcellent article. I have printed it out for myself; I want to save that one. On the question of trunnion placement, my information is that moving the trunnions down below the centerline of the cannon barrel was a fairly recent inovation by the British, designed to make the recoil motion better. Also I understand it didn't work as intended.

The cast iron rods holding the core in place in the article are now called "chaplets", and they are very evil things. When a gun founder wants to save casting metal, they can form a core out of hardend sand and hold it centered in the barrel mould with chaplets, which end up cast into the gun. The evil nature of chaplets is that they penetrate the barrel wall at right angles, and even though they are usually headed like a carriage bolt, they have a very wicked tendency to eventually erode and fire like bullets out to the side of the piece. This is one of the reasons why modern period artillery rules require a steel sleeve in the bore.

Crudbeard

[Capt Thighbiter]

OK from what I have read now, it seems the trunions were placed lower then centerline because prior to the creation of trunion shoulders, placing the trunion lower increased the amount of metal in contact from the trunion to the barrel. Once cannon makers have figured out how to add shoulders the trunions started to migrate up to centerline. Also, putting the trunion at centerline reduced the the tendency of the barrel to want to 'flip' over. It also allowed the barrel to be flipped over in the carriage if the original top surface got too corroded from the elements and extending the life of the barrel.

But as far as an exact date when the switch was made - impossible to say, as each country and cannon maker had his own idea of what worked best. THe best I can say is that by

1780 or so, most but not all trunions were being placed on centerline.

Just to cloud the issue up - carronades have NO trunions and the pivot for the barrel was directly under it. From what I read, carronades had a wicked tendency to want to flip completely over, hence the wood and metal slides that were used with them. `

Dophins are just lifting rings made fancy, and they started to show up on cast barrels early on. Rare on iron gunsnot sure why, but likely due to casting limitations of the time.

As cannon handling techniques improved, dolphins started to be left off. Again no hard dates for that.

[Crudbeard]

OK from what I have read now, it seems the trunions were placed lower then centerline because prior to the creation of trunion shoulders, placing the trunion lower increased the amount of metal in contact from the trunion to the barrel. Once cannon makers have figured out how to add shoulders the trunions started to migrate up to centerline. Also, putting the trunion at centerline reduced the the tendency of the barrel to want to 'flip' over. It also allowed the barrel to be flipped over in the carriage if the original top surface got too corroded from the elements and extending the life of the barrel.

But as far as an exact date when the switch was made - impossible to say, as each country and cannon maker had his own idea of what worked best. THe best I can say is that by

1780 or so, most but not all trunions were being placed on centerline.

Just to cloud the issue up - carronades have NO trunions and the pivot for the barrel was directly under it. From what I read, carronades had a wicked tendency to want to flip completely over, hence the wood and metal slides that were used with them. `

Dophins are just lifting rings made fancy, and they started to show up on cast barrels early on. Rare on iron gunsnot sure why, but likely due to casting limitations of the time.

As cannon handling techniques improved, dolphins started to be left off. Again no hard dates for that.

Thighbiter, that's interesting about the lower trunnion placement having to do with the casting. Makes sense. Thanks.

I re-read my earlier comment and realize I wrote the opposite of what I intended. What I meant to say was that the center line placement was recent, originated by the British. Another interesting arcainia on trunnions is the "gunnade", a carronade barrel cast with trunnions instead of the lug on the bottom. These smaller caliber pieces were made at the very end of the muzzleloading era, and used a lot for frontier defense in Canada and Alaska, as the guns were lighter than cannon to transport out to the forts. I'll have a model of one at Buccaneers and Privateers in New London April 24th to show ya.

[Littleneckhalfshell]

Another bit of trivia on Trunnions. Well anyway, something that I found odd.

When the Trunnions are cast off center, apparently people don't always get it right as to which side is supposed to be up.

At Walt Disney World, Magic Kingdom, near the Columbia Harbor House Restaurant , there were two cannon by a planter near a tree mounted on naval carriages, but they had the Trunnions on the high side of the center line!

I mentioned it to the main office, but I don't know if anyone ever corrected it or not, or even if the cannon are still there.

[Commodore Swab]

That was an intestering article and It can relate quite easilly to the smaller pices I am casting with a core. My core is made up of a very hard sand that I hold in place with 2 stainless screws. The screws go into the sand (not the bronze) and the sand holds the allignment of the core. Once poured the screws are picked back out of the sand easilly to be reused. Finished weight is right around 6.5 pounds but I use 15 pounds of bronze to pour ensuring a dense bronze as the article mentions.