THE VALLEY TRIP
The trip down to the Valley took around 4 hrs. Leaving home at 4.00am we arrived at Ernie Henne's home at around 8.00am. Ernie was going to guide us another hour out to the small town of Longford to pick up 2 tonne coke for the Cupola.
Before doing so Ernie had a treat set up for us, a pour of cast iron. Four number plate moulds had been pre-rammed ready for the pour.
Ernie gave us the flash tour of his set-up. It was roomier than my own set-up and well layed out. The thing that caught my eye was the functional and simplistic gear used in his operation.
The inside layout. On the left is the lower half of his 9" Cupola, this is set-up outside when required.
At the rear in the middle is a very simple and effective Muller. To the right is the ramming bench and in the foreground are the four rammed up moulds.
This is the outside layout where the furnaces are operated. In the foreground is the #12 crucible trolley. In the rear are the small and large furnaces. The bottle next to the door is full of used hydraulic fluid for the burner. The bottle at the rear corner is gas for furnace pre-heat. The chimney fitted in the top of the shelter is for the Cupola.
This is the large furnace which could fit up to a #20 crucible. The furnace lining is around 2" thick of the low temperature Kaowool. The lining has a green tinge from the high temp zirconia ridgidizer that has been applied, this makes the inside surface hard with all fibres well contained.
The lid lifter mechanism is a simple over centre arrangement the locks the lid in the up position so it can be rotated easily out of the way.
The burner is made from a section of a car exhaust pipe, the hose going into the bottom is for the used hydraulic oil, the hose in the top is the gas line. There are no nozzles just a 1/4" copper tube brazed into the exhaust pipe, there is a needle valve (not well shown) that controls the flow of oil into the burner. The oil bottle is pressurized to 100psi with air to force the oil up to the needle valve.
The fuel bottles, the right bottle contains the pressurized oil. Note the yellow air hose attached to the welded fitting to pressurize and force the oil up the internal dropper tube out to the burner. The left bottle is gas, note no pressure regulators.
The blower is an old vacuum cleaner, the oil control needle valve can be seen better in this view. The start up procedure is straight forward and simple. Start the gas and blower and ignite with a match, run for 90 seconds and crack the needle valve to introduce the oil, turn off the gas and your away. I was amazed at how quiet the oil burn was compared to the gas and even more amazed at the fact there was no smoke, just an enormous heat haze. To the left on the ground is a home made 'R' type thermocouple
Ernie doing a quick temp check after 10 minutes of running. The readout shows 1470 Deg C. (2650 Deg F) The temp was literally climbing faster than I could count. We had molten iron in 20 minutes.
Ernie says he has destroyed to many tongs adding more iron to the charge. He now ties the iron with copper armature wire and drops it in through the exhaust hole and onto the slag floating on top of the melt. The wire melts immediately and the process is repeated. The new charge is pushed into the melt with a length of reinforcing bar.
Just before the wedge test and final pouring the slag is scraped off and removed. This was a very hot job, even before touching the melt the scraping tool glowed red and had to be constantly plunged into a bucket of water to cool things off before re-use.
The wedge is poured to look at the formation of carbides (white tip).
As you can see there is a small white tip on the ends. As this pour was for some number plates the addition of Ferro-silicon was not warranted. If this pour was for a machined item an inoculation of Ferro-silicon would be required before pouring.
Before removing the crucible a small amount of phosphorous, about the size of a thumb nail is added. This can be seen attached to the copper wire before adding to the melt. The purpose of phosphorous is to improve the fluidity of the iron particularly when pouring thin sections like the 3mm (1/8") number plates this melt was for. This element like the Ferro-silicon can be purchased from any foundry suppliers.
The #12 crucible is removed from the furnace with a set of tongs and put down ready for pickup with the poring trolley. The final furnace temp just before pouring was over 1600 Deg C (2880 Deg C).
The pour. No fuss and straight forward, the crucible trolley makes this so easy and keeps you at arms length of any spills
Many thanks to Ernie Heene for his hospitality allowing myself and Ian to bombard him with an endless stream of questions about his methodologies. A few hours was certainly not enough time spend and we didn't even touch on his many specialist sand recipes for different metals nor the fact that he alloys all his own bronzes from bare copper. Another trip will be required in the very near future.
MULLERS
One of the pieces of gear that really took my interest was the simplicity of the Muller arrangement. They are made entirely from bits 'n' pieces scrounged from local the scrap yards and in my opinion are so simple they could be knocked up over a weekend.
Here are three views of Ernie's Muller. It must be noted that the bowl rotates in a clockwise direction. The left photo shows the arrangement of the ploughs. The ploughs are mounted off an angle iron section that bridges the bowl. The middle photo shows the Muller wheel, it's arm is pivoted form the angle iron bridge and currently latched in the up position. To drop it onto the sand the handle is pushed down and unlatched allowing the wheel to be dropped. To apply more pressure to the sand the handle is pushed up forcing the wheel down harder. To apply less pressure the handle is pushed down allowing the sand to be fluffed. The right photo shows the drive arrangement which is self explanatory, the 'gearbox' was salvaged as scrap from an old wringer style washing machine and is driven by a 1/2 horse single phase motor.
The bowl is made up of a round aluminium base around 1200mm (4 ft) diameter which was cast. The sides are galvanized sheet which is screwed to the edge of the base.
This Muller was built by Norm who lives out at Longford. It is based on Ernie's design but with a few small changes. The bowl is an old tractor tyre rim and is supported on 4 rollers as shown and rotates in an anti- clockwise direction. The right angle drive is an old differential and the speed is broken down with pulleys back to a 3/4 HP single phase motor. Note the sauce bottle sand scope for removing the mulled sand. I would think a door fitted to the side of the rim that would allow the sand to be pushed out into a bucket would be a good addition.
The tractor shown was originally made in America and restored by Norm from a very dilapidated state. He has restored around 50 vintage tractors. All replacement castings required for these restorations were produced from his 10" Cupola.
What we came for, 2 tonne of coke. This filled the back of the ute and a tandem trailer. It was a very slow trip home and a very hot smoking clutch.
TO BE CONTINUED WITH SOME UNIQUE HIGH TEMPERATURE GAS FURNACE DESIGNS