Today my good friend Ian fired his Cupola up for the first time. On an off he has spent the last 6 months building and putting this show together which is based on the Steve Chastain design . Ernie, who lives in Moe around 3 hours drive from us currently runs a 9" cupola in his own foundry arrived around mid-day to offer advice and assist.
This is a 7" Cupola making it a rather comfortable size for a 2 man operation. By our calculations it should be capable of delivering around 250 Kg of molten iron per hour.
We learnt alot from this first trial run. Next time our initial start will involve the use of a separate blower up the tap hole to create a draft throughout the length of the Cupola. We found blowing through the Tyrenes wasn't allowing the bed area in the base to burn so it remained cold for sometime. In the end we added some diesel to get things moving. Everything ran well once the coke began to burn and we had a nice flame extending 30cm out the top, the Coke bed was around 50cm deep.
The back pressure on the Manometer looked good before the 3 iron charges were added and intermittently layered with coke. We soon found the blower was undersized and wasn't doing the job.
Unfortunately we didn't get any molten iron to pour and has appeared to freeze just below the melt zone.
This will be cleared and any repairs made ready for the next run. The new fan is a 700mm diameter 3000rpm 5hp high pressure unit probably capable of blowing all the coke out of the top at full blast. The same mistakes won't be made next time around and we will definitely reshape some iron.
Before we started
Ian adding the charge while Ernie looks on
Preheating the pouring crucible.
Our second run with the Cupola can only be described as an outstanding success. Everything went exactly as planned. When the bot was knocked out for the first pour we didn't know what to expect, what we saw was a stream of red hot iron flowing hard and fast with the consistency of water filling our crucible to around 3/4 full. There is no time to enjoy the fruits of your labour and the fact that there is iron at 1450 deg C staring at you needs to be dealt with very quickly and readied for the next pour. The second and third trial runs were just as successful. I was very surprised at how clean the iron was when poured, I did have concerns about slag and skimming but this turned out to be a non event.
The wedge test showed no white at the tip but a lovely grey colour consistently throughout the sample.
From analysing our first unsuccessful run we determined it wasn't the fact that the blower was to small but rather our cast iron charge pieces were to large which choked the flue off. We will return to the smaller blower again next time.
Our set-up entailed a hot bed of coke at around 500mm deep.
Our charge rates were. - 3kg iron, 1/2kg of coke, (ratio 1:7) 1/8kg of lime.
We will bump the charge ratio up to 1:9 next time around.
Tap out rate around every 8 minutes.
The first tap.
First pour. Ian and myself doing the reshaping bit.
The fruits of our labour. The loco driver wheel was perfect. The finish was smooth with no imperfections. The iron, when filed, could only be described as like cutting through butter. Beginners luck???
A set of air cylinders, unfortunately they were a short pour but the finish is magnificent.
I've been alittle busy myself lately. My sand preparation and moulding shop is nearing completion.
This will mean I can move all my moulding gear out of my workshop and into a purpose built structure away from the house. The next step will be an enclosed shelter extending out from the side of the shop where all the furnaces will be housed. A hole will be cut in the brick wall to allow the moulds to be transferred via a small conveyor.
I've just finished the roof frames and facia's off, the only thing left is sheet the roof, fit the guttering and paint.
I've fitted three RHS beams and tied them back into the brick columns. This will allow me to fit a small overhead monorail with a chain block for lifting the larger loco number plate moulds.