Monday, February 13, 2012

Marker Lantern Brackets - The Final Product

In our previous post we chronicled one of the last days at Imbleau's Iron Foundry in Renfrew.  Their last pour was on the following Tuesday, February 7th, 2012.

Our post prior to that were a set of instructions for making the green sand mold to pour the corner lantern brackets.  Here's what the casting looked like about an hour after the molten iron had been poured into the mold at Imbleau's.
In case you're having difficulty seeing where the casting is, here's another photo with some added captions.
Here's a photo of another one of the brackets.
The steam is still rising from the green sand and the castings are still very, very hot.  Don't touch!!

Just to recap on the process, we started off with an original casting that we had to duplicate.  The hollows and holes were filled in by Jedi Master Ross producing the following pattern.
We next had to make a sand core to produce the holes and hollows that we had just filled up. So, Jedi Master Ross made a core box so that we could make sand cores.  After a few modifications, we were able to start production of the sand cores.
Which, as you can visualize from the photo below, would nicely create the hollow that we need in the mold.
From there, we went on to make a dozen sand cores for our 12 castings - 6 for the flat lantern brackets and 6 for the corner lantern brackets.
One thing I learned with the first castings that I had done at Alumaloy was to test the sand cores and make sure that they fitted snugly into the green sand mold.
With the sand cores tested, we took our first batch up to Imbleau's for casting.  Here's the pattern ready to go along with the 6 sand cores.
These were cast on Friday, January 27th.  This is what the castings look like.  The sprue, gate, and risers have been knocked off and you can still see the sand cores in the middle of the casting.
It was then that we discovered a challenge facing us.  I had originally though that I could simply soak the casting in water and the sand core would disintegrate.  So much for that idea!  It took 15 minutes to sand-blast the sand core out of each casting.  This is what the lot looks like with the sand cores removed and a bit more of the "flash" knocked off with a chipping hammer.  Each one of those castings is a solid block of iron! 
I was completely surprised that we were able to get things along this far!  I was expecting an unrecognizable  blob of iron. 

Of course, the fun had only just started.  First step was to drill out the holes for the mounting screws.  While most of the 24 holes (6 castings x 4 holes per casting = 24 holes), there were 4 holes that wouldn't centre.  A bit of grinding with a Dremel solved that problem.

Next up was to grind off the flash and the rough spots.  One thing I discovered was that the sand cores were a bit loose in the green sand mold with the result that we had an extra bit of iron in the flash.  Next time, we'll have to make the sand cores so that there is a tighter fit.  Oh well, that's one lesson learned, eh!?

And this is what the final product looks like before Master Painter Charls gave them three coats of paint.

Not bad for a bunch of amateurs, eh!?

Thursday, February 2, 2012

A Day At Imbleau's Foundry - The Last Pour

I took a trip up to Renfrew today to pick up the patterns and castings that I had dropped off last Thursday and to see the pouring for the patterns that I had dropped off on Friday.  Today was going to be a sad day as this was the last day that Imbleau's, after 160 years, would be pouring iron. 

When I arrived, molten iron was running continuously from the foundry into the large crucible.

From there, each worker would place their smaller crucible on the ground.  The foundryman would then tip the large crucible and red-hot molten iron would pour into their crucible. 

A large crucible suspended on a travelling crane was placed near this part of the operation and the workers would empty the molten iron into the larger crucible.  Three workers would then manouver the large crucible into the rows of large sand molds and align the lip of the crucible until it was exactly into the right position to pour the molten iron in the sprue of the sand mold.  The crucible was slowly tipped forward and molten iron poured into the mold. 
While the pouring was going on from the large crucible, other workers would get their hand-held crucible charged with molten iron and then walk Popeye-like with the handle of the crucible resting on the top of their leg over to the smaller sand molds and pour the red-hot molten iron into the top of the sprue. 
When the iron appeared at the top of the riser, the mold was full of red-hot molten iron.  The heat from the iron immediately turned the moist sand mold into a bath of steam.  Throughout the foundry, steam was rising up into the air clouding the busy workers with their crucibles full of molten iron.   
Through the rising steam I could barely make out the workers with the large crucible pouring the large sand castings. 
Each worker seemed to automatically know what to do.  There were no orders being shouted out by the foremen.  They all worked in unison.  When the large crucible was moved over to the furnace, a semi-circle of workers would form.  As their small crucible was filled, they would move to the other side of the circle and pour it into the large crucible, taking their place at the end of the line once again. 
When the large crucible was filled, three workers would move it away from the furnace and the other workers would then get their smaller crucibles filled with molten iron.  One worker would go off into the south-eastern corner of the building; another worker would go off into the north-western part, each one followed by another worker who prepared the sand molds for pouring - lift the weight off of the molds that had been poured, shove a flask over the mold, then place the weight on top of the mold.  Right behind him was the worker with the molten iron. 
As the pour was coming to an end, the workers not pouring molten iron would up-end the sand molds to expose the iron castings.  This would allow them to cool off faster.  The molds were up-ended into rows where the green sand would be reconditioned for the next molding session. 
I peered into the steaming cauldron of black sand seeing if I could see my castings.  Aha!!  There at the end of the row was one of my corner brackets. 
Finally, the last of the sand molds was filled with molten iron.  It was now time to pull the plug on the foundry to empty it of the molten and unmelted iron that was mixed in with the red-hot and unburnt coke.  The wire rope was pulled, the furnace doors opened at the bottom and a large roar of flame shot up to the ceiling as the whole contents of the furnace dropped to the ground. 
Anyone standing in front of that inferno would have been cooked to a crisp. The flame settled down and one of the workers hosed a steady flow of water onto the fiery mass. 
Hard to understand the significance of that fiery flame as the contents of the furnace dropped to the ground.  It signalled the end of an era that had lasted for more than 160 years.