Hey Dave, Nice videos! Glad to see other foundrymen on the site! Some humble advice for your burner… If you ignite the oil in the furnace and combine it with the vacuum inlet you'll get better and cleaner combustion. The furnace will also run much hotter. For anything with a melting point below cast iron you probably don't need any diesel. Here's a section of a video with my setup… hope I've done this right.

Thanks Dave… videos aren't really my thing, was actually for a FEA conference I presented at.

There's quite a step in heating requirements for cast iron compared to zink and the brasses, but with diesel added you shouldn't have any issues. Please keep us updated!

following with interest……

is gas, ie propane hotter than D fuel or not…..certainly cleaner to use…..

I want to cast bronze items…..getting close to serious about this…..

we do have a place near but they only work during the tourist season…..they manufacture small castings to go with/ display their custom glass works of art……..

Propane, Butane and Methane all burn at a little under 2000°C. It's quite easy to get the flame up to temperature because the burner only has to mix gases in the correct proportion.

Too much air cools the flame, too little air and fuel is unburnt.

Diesel burns at between 1000 to 1400°C, so cooler than gases. As Bronze melts at 950°C, it can be seen Diesel won't work unless the burner is carefully adjusted to maximise flame temperature. Harder to do than with gases because liquid diesel has to be mixed efficiently with air before ignition, typically as an atomised spray or by vaporising it. Oil burners are more complicated to make and control.

Coke burns at about 1100°C but the temperature can be driven up to about 2000°C by blowing air through it. For foundry work, Coke has the advantage of storing heat in the solid, which means the temperature is less likely to drop when cold metal is added, or when extra latent heat is needed to convert from solid to liquid form.

They will all work, but I think Coke is easiest, gas a bit harder, and Diesel on the awkward side.

I'd steer clear of petrol: it has all the disadvantages of diesel plus spillages carry high risk of flash fires and explosions. Nasty stuff!

Dave

Dave you need to be careful interpreting information from the internet. Flame temperatures vary depending for what application the specific tests were done. Adiabatic flame temperatures of diesel can exceed 2300DegC if you run slightly lean. These tests were specific to diesel burners used in large industrial smelting furnaces. Diesel will most certainly melt bronze, in fact it melts pig iron, cast iron and I have even melted BMS in my furnace.

My burner is incredibly simple, with no nozzle and the diesel is fed by gravity. i.e. no compressed air. The fuel air mixture is easy to get right with a simple gate valve. I have melted using propane, waste oil, diesel and a few other fuels. You would be hard pressed to melt cast iron in a gas furnace without freezing the valve (depending on the ambient temp).

We need to be careful not to steer people in the wrong direction based on internet searches, especially when it comes to foundry work which is inherently very practical. The heat and mass transfer also requires an in depth understanding of the governing equations and not only the flame temperatures…

I have been casting gray iron since 2012, and have tried a variety of fuels and burner types.

I use a siphon nozzle burner with diesel, but am converting to a similar pressure nozzle with gear pump to avoid having to have an air compressor for atomization air.

Cast iron can be melted with propane if you have a sufficiently large tank, or you carefully warm (without overheating) the tank as the gas is being used. The vapor pressure inside of a 20 lb propane take will drop too much as the tank cools, and so it is difficult to maintain enough pressure to melt iron (without tank heating).

I use diesel exclusively since it does not contain heavy metals, and it lights easily with a siphon or pressure nozzle type burner, without using propane.

I have started and run my siphon nozzle burner on diesel at 30 F.

Most I know mix at least 20-30% diesel with their waste oil to assist in starting and operating the burner.

The red hot burner tube type burners don't last long. A siphon and pressure nozzle burner tube run cool to the touch if operated correctly.

It is easy to melt cast iron, brass, bronze, or aluminum using diesel.

Generally a #10 crucible full of iron requires about 1 hour to bring up to pour temperature, which is extimated to be about 2,500 F.

A #10 crucible holds a little less than 30 lbs of iron.

Most folks I know run their oil burners at about 2.7 gal/hr, and the combustion air blower is adjusted to accomodate this fuel flow, using either a variable speed blower motor, or a dump damper to get rid of the excess blower air.

My casting videos are on Vimeo.

I will try to post a link here; hopefully it will work.

Good luck with your metal casting. I must say I really enjoy metal casting, and it creates unlimited opportunities as far as the engines you can make.

Hit the "scroll down" or "load more" at the bottom of the Vimeo page to get to my casting videos.

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Hey Noel-

I am trying to get lots of people into making their own iron castings, but so far have only roped one into it, but he is doing it successfully.

The central heating unit is the same configuration that I am going to change to, except mine will not be a packaged unit, but will consist of the same parts mounted separately, to be more modular, and because I don't have a spare central heating unit.

Central heating units use a gear pump with pressure nozzle, generally operating at about 100 psi (that is where I will operate mine on diesel). And the beauty of them is that you don't need an air compressor, which is really what I am after. The siphon nozzle and pressure nozzle operate the same, except one uses compressed air for atomization and the other uses pressure from a gear pump.

I have tried a drip-style burner, an Ursutz which is a precombustion chamber type burner, dual nozzle burner, propane, etc. The siphon or pressure nozzle burner is the most reliable and infinitely controllable/stable burner that I am aware of, and no degredation over the life of the burner (which is infinite). Both of these burner types do need clean fuel that is well filtered, which is why I use diesel. Waste oil can be used, but generally it is thinned with diesel, and it must be filtered clean.

I use about 10 psi pressure on my diesel fuel tank with my siphon nozzle, but when I convert to a pressure nozzle, I will not pressurize my fuel tank.

Pouring iron is not much more difficult than pouring brass/bronze, and easier in many respects since you don't run into the zinc problems that brass has.

Using good heat shields on the skimmer handles and pouring shank is a must with iron, to prevent overheating the gloved hand. And gas welding goggles are required to shield the eyes from the intense IR that comes off the furnace and crucible.

If you want to pour iron, and are not exactly sure how to do that, I can save you a great deal of grief.

It took me six years (on and off) to master the iron process.

I am across the pond, but with the internet, we are all close, and brothers in casting for sure.

There is nothing like pulling fresh iron castings coming out of the sand mold (when all goes well that is).

Note, leave iron castings in the sand overnight to cool, else you will get hard spots in them.

Pat J

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I am still working out the exact details of my new pressure nozzle burner, but this is my progress to date.

The fuel line on the output of the pump is rate for 100 psi continuous, and I think is automotive injector fuel line.

I hope to get this unit operational this year.

Note that my initial rough sketch is not quite complete, so don't use it literally.

Fuel flow will be adjusted using the needle valve to about 2.6 gal/hr, and then the combustion air blower tuned for that fuel flow.  My combustion air blower is a varialbe speed Toro leaf blower running on its lowest speed.

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I'm curious…How quiet can these furnaces be made to run? I would love to try casting, but live in the city with close neighbors who may complain.

The running joke in our house is that anyone who looks over the wall and complains about someone casting metal should rethink their strategy. At least the person casting has a hobby and doesn’t get up to mischief. Seriously though, I live in a city suburb and have asked all my neighbours if the furnace makes a noise and they all said it does not. I have a large box covering the blower (this makes most of the noise) with inverted egg boxes glued to the inside which dampens most of the noise. The furnace itself isn’t too noisy.

Thanks, Luker. Unfortunately, I live in the city proper. Small city lot and exposed to neighbors on all sides, no fences. If I lived in the suburbs I would have much less concern. My next door neighbor has complained about a lot of things, including me parking my car in the *public* street in front on her house. I suspect she would think I *was* up to mischief with a casting furnace. Some people take the hint when being ignored, others unfortunately don't. From the videos I've seen, the burner has a pretty big roar even without the blower. No?