July 2, 2010

Setback for the cannon project

The attempt to pour the light three last Wednesday did not succeed.

We started heating the furnace on Tuesday morning and buried the mold next to the furnace late Tuesday afternoon. We kept the heat low to bring up the temperature slowly until about midnight. At that point, we ramped up the heat until it was going strong on Wednesday morning.

Because the quantity of bronze was so much greater than in previous pours, we did not know exactly when to expect the charge to melt. By mid-afternoon, it was taking longer than anticipated, so we increased the airflow through the furnace using a fan.

To all appearances, it was burning well, and by about 4:30, the bronze appeared to be liquid. The crew then punched the plug out of the taphole. Aside from a few dribbles, nothing happened. Repeated tries were made from both the outside of the taphole and probing at the opening from inside, to no avail. A few minutes later, the skies opened up and it poured rain. We were all a pretty dejected and sad-looking crew.

We will not know what caused the failure until we partially disassemble the furnace. We need to do so to remove the 550+ pounds of bronze inside, and it will allow us to closely examine the masonry and metal.

In the meantime, our best guess is that, though undetected, there was a lump of unmelted bronze that was swept almost immediately into a blocking position. We are taking a few days to recuperate and grieve. We’ll post more when we have it.