Our apologies for the absence of recent posts to the cannon blog. Historic Trades’ attention has been focused on the Armoury project and a host of smaller undertakings around town, but a group of folks has been working diligently behind the scenes to get ready for another pour.
After our failed pour of June 2010, the Historic Trades brickmasons removed the entire superstructure of the furnace down to the melting pan. Examining the mass of bronze there did not reveal anything conclusive about the failure, but reinforced the probability that the metal simply was not hot enough when we tapped the furnace. Based on that, the founders, gunsmiths, and masons made some changes in the furnace design, and beginning last autumn, the masons rebuilt the furnace accordingly. The new design also incorporates a wooden shed, built by the Historic Trades carpenters. This shed will cover the kiln to protect it from the weather on an everyday basis, provide some protection for the furnace should it rain during the firing process, and t better support the hoisting gear with which the molds and castings are handled.
Cutting up the hunk of bronze left in the furnace so that we could reuse it was more difficult than expected. After a couple unsuccessful attempts, rescue came in the form of Newport News Shipbuilding. Several of their employees picked up the mass, hauled it to Newport News, used some of their specialized equipment to cut it up, and returned it to us in pieces that we can set directly into the furnace.
While all this was going on, the founders and gunsmiths completed another set of light three-pounder molds. Their experiments with new loam mixtures led to much more satisfactory results than in the past. When they removed the core and burned out the wax, they ended up with sharp, clean interiors, and the molds seem to be more sturdy than earlier ones. They will take the molds over to the College of William and Mary on May 7, where Professor Mike Jabbur will fire them to a “redware” hardness and ensure that they are completely dry.
So, we are ready to try again. With some extremely helpful advice and hands-on assistance from Andrew Eshelman and Stephan Williams of Newport News Shipbuilding, we are planning to pour on Thursday, May 24. We will be preheating the furnace much longer than in the past, and will be using a modern pyrometer to monitor heating more accurately and better understand how the furnace is operating.
The proposed schedule — all weather dependent, of course — from now until then is:
May 7: Load molds in ceramic kiln at the College of William and Mary
May 9: Pick up molds
May 14: Test fire furnace
May 21: Load bronze in furnace and start preheating
May 22: Continue to raise furnace temperature
May 23: Continue firing. Bury mold
May 24: Build tapping channel. Bring bronze to pouring temperature. Pour.
May 25: Excavate mold and open
From May 21 until pouring, this will be a round-the-clock operation. As before, it all will be happening adjacent to the parking lot across from the Visitor Center and adjacent to Great Hopes Plantation.
Hi Cannon Crew,
Ok you were able to use the Newport News Shipbuilding to cut up the brass mass. What did the 18th century cannon forgers use to cut up a large mass of brass or did they simply melt down any large scarp?
They were using much larger furnaces, so they could use larger pieces of scrap, including retired barrels. But, when they did need to cut brass or bronze, whether to reduce its size for melting or, for instance, to remove the deadhead/feeding head from a casting, they did it using large, framed metal-cutting saws.
The Verbruggen drawings show four men at work using them, two on each end. According to Dartein in Traité Èlèmentaire sur la fabrication des bouches à feu d’artillerie, and as translated in Carel de Beer’s The Art of Gunfounding: “…in nine hours of work they manage to saw off the feeding-head of a 24 pounder gun…” and “…for [the feeding-heads] of twelve inch mortars, cast about a newel on top of mortars with a bed-plate, have demanded four days of unremitting work, carried out by eight men wielding the saw without interruption, four of them resting by turns.” I am guessing there are a huge number of folks in Trades who are very relieved we don’t have the saws.
Thanks for the information.
I will be watching to see how the pour goes. Good luck and HUZZAH!!!!
To the Cannon Crew,
Much is to be said of good neighbors. A big Huzzah! to Newport News Shipbuilding for their help. Glad to hear that local or nearby businesses support CWF when the 18th century way, just will not do.
Will you please post more pictures of all the activities. If possible, maybe the moveable webcam from the Armoury can be moved for a day or two to the cannon site if there is electrical power at or nearby. Living in the Chicago area makes getting there for such wonderful learning opprotunities hard.
Folks in the Historic Trades live the CWF moto - That the future may learn from the past. You yourselves learn from each pour and change things accordingly if needed.
Good luck with the pour. I’ll watch/read when I can.
Chris
Chris,
We are extremely grateful to the Newport News Shipbuilding folks. They are experts in all the ins and outs of modern foundry work, and we are delighted they are intrigued by the project, interested in learning about the historical information we have gathered, and willing to blend their knowledge and skills with the project’s historical technology. We all will come out of this next pour with a much more thorough understanding of the processes. You are right: great neighbors!
We have been taking a ton of photos of the processes. I’ll see if we can do a better job of posting more of them right after the pour. I also have asked if we can have a webcam out there. We have electricity, but probably not the connectivity required. They are checking.
Thanks for the good wishes and interest. Keep your fingers crossed for us!