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!?

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