The Backyard Foundry And Forced Air Burners

Furnace burners potentially create more than enough problems for the hobby metal casting worker, it is not unusual to read about people who are attempting to build a furnace, only to be confronted with problems and frustration with a complex burner?

It is quite simple to construct a crucible furnace, but the stumbling block seems to be: “The burner”. Why?

Problems seem to manifest themselves because:

For some reason, people choose to fabricate complex burners from detailed drawings without the skills, tooling and machining facilities in which the original designer employed during the design & building process.

With the necessary workshop skills coupled with a reasonable selection of equipment & tools, will have a marked effect on how well you, as a hobby foundry worker, will be able to construct the equipment required for the successful melting of metal.

There are no short cuts when it comes to building equipment for your hobby foundry, to cobble something together in a rough fashion is only asking for trouble in the future, it is well to heed the old trade school teacher quote:

“If a job is worth doing, you might as well do it properly in the first place”

He is right, you know.

You can learn how to build an effective simple furnace burner, which is well documented in the hobby foundry ebook “Metal Casting Made Easy” available at our web site. But to explain everything in detail here would take up far too much time & space.

Following is a simplified description:

The burner consists of a long plain black mild steel pipe. The burner end nozzle consists of an inverted cone. There is a mid section where a venturi is installed; the gas jet is located near the venturi.

The simple brass jet protrudes into the forced air stream, which travels through the burner tube. The gas jet orifice is quite large and operates under low pressure; the air delivered by the blower to the burner tube is low pressure, but moves at a high volume.

The burner design is simple, yet effective, but there are some components incorporated in the design that only require basic lathe turning skills. But general workshop knowledge is sufficient to build this item. There’s no rocket science involved.

The blower consists of a second hand household vacuum cleaner (the type that has a second outlet for the hose connection that blows). The vac also has an electronic vari motor speed control, which enables a regulated low-volume airflow to be delivered during the burner start up phase.

This feature is MOST important during the furnace start up.

Does this burner work? You bet it does, the burner is capable of melting a 5 Kg (11lbs) charge of Aluminium from a cold start in less than 40 minutes.

The gas supply is provided from a Liquid Petroleum (LP) cylinder (Propane in the states) It is essential that the gas supply be controlled by an adjustable industrial diaphragm gas regulator gauge suitable for LP gas, there is no other SAFE way to regulate & deliver fuel gas to a furnace burner. A ball valve should be installed in line as an emergency shut off valve.

There’s no reason to build & operate complex burners that require special size jets, and shrouds, which must be operated at a certain gas/air pressure? There is nothing more frustrating than an apparatus that won’t operate as it should; why spend half the day mucking around with something that is an absolute pain to use, when you should be enjoying your metal casting experience!

The people who design & build complex burners for other’s to copy, possess lathes, milling machines and many other expensive machine tools to build the burners, but if you choose to build it even slightly different to the original design specs, there is a good chance the burner just wont work properly!


Post time: 05-13-2017