ANOTHER Backyard Foundry setup described in pictures

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Posted by roberto on April 22, 1999 at 07:53:20:

Topic: backyard foundry

Posted by roberto on August 23, 1997 at 19:41:49:

I just ran across some very interesting reading at a site called, "Backyard Foundry",

Very interesting page on an inexpensive way to do some casting.

Sorry if this is old news to some of those here, it's the first time I've read it.

http://reality.sgi.com/kurts_engr/foundry.page.html

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I have also heard that you could simply line a metal trash can with kiln wool. I am wondering if the burner has to be forced air or if a venturi would work. Anyone ever done that?

Cynthi, TX

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Cynthia,

I don't know about the use of a trash can (I would think that it might heat up a lot) but I use 1/2" welded wire screen as a frame, over the wool, and it lasts for 30-40++ firings before burning to a point that it needs replacing. Actually the top around the exhasut hole and the top edges of the body ring are the places that tend to burn the fastest. I fashion horseshoe wires with an inch long piece of "ceramic kiln heating element

wire holder ceramic tubes" (about 1/3" diamater 6"long rods with a hole through the center that I score and break into 3/4 - 1" long pieces and slip a 6-8" piece of nichrome wire through the hole and form a horseshoe/staple deal). These wire/tube staples are pushed through the wool to the outside and bent over the wire. I used high temp wool on the inside and lower temp on the outside (2 thicknesses of wool).

I used a forced air (squirrel cage with an air control flap over the air inlet) into a 2" black pipe burner (about 3" long) with a 1/2" closed off pipe with a 3/32" hole for a gas nozzel stuck into the side of the pipe.

Currently the fan blows directly into the end of the pipe, but the next time I have to rebuild the burner, I will have the fan going into the side of the pipe or use a 90 deg elbow on the inlet side (this to get better mixing). The venturi would probably work for the shell kiln, but I really do not think it would be very good for the melting furnace.

This is my 2 cents worth. Good luck John

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I don't know anything about making a forced air burner. Any books that describe how to make one (though I'd rather make something else)? Who is a good supplier for one that would work on a small crucible furnace?

This is something else for my list of rare and hard to find items.

Cynthia

TX

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I made a burner something like this for a melting furnace and had a problem with it. The flame doesn't have a well defined position. The first time I fired it up, the pipe leading to the furnace got hot and started glowing. I had to watch it like a hawk and regulate the air to keep the flame inside the furnace (not climbing back up the mixing pipe!).

There is an excellent way to avoid this problem called a flame holder. You make it by putting a "target" like shape in the end of your burner tube. For instance, if you have 2" diameter 1/8" wall pipe for your burner, make the target by welding in rings of smaller and smaller pipe concentric with the original tube. Pipe, air gap, pipe, air gap, etc. so that you have a 1/8" ring of metal, 1/8"ring of air, 1/8" ring of metal, etc. Finish it off with a solid 1/2" plug. Use 1/8" rod as spacers for the rings and weld them in place.

The idea behind a flame holder is to introduce turbulence in the

air/fuel flow at a specific place. That is where the flame stays. A flame holder has the fringe benefits of making your burner light easily and stay lit. It also makes the flame a lot quieter.

Steven O. Smith

steve@cc.com

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I have the Graingers catalog and see the blower you mentioned. I am wondering how to connect the gas to it. Is that the 90 elbow you mentioned? Is there any safty shutoff equiptment that I might also install on it?

Cynthia

TX

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Ah yes.... the gas. we took a piece (8") of black steel pipe, welded the end shut (cut sections out and bent the remaining sections into a sort of bullet nose shape and welded it up tight). Drilled a 1/8th" hole in the side of teh pipe neat the end. On the other end we threaded a compressed air fitting to the pipe. I have all of my propane lines with compressed air fittings, my burnout tourch, melting furnace, shell firing furnace etc. and they have worked very well. I set up a smallish needle valve and a 1/2" ball valve on the end of the gas line before the coupling fitting. So from the nozzel back towards the gas supply it would look like: 1/2" gas nozzel, male gas fitting (this is a complete unit) then the next item in

line is the female gas fitting, at least 6 feet of hose (to enable gas adjustment while not next to the furnace), needle valve, ball valve and a male fitting on the end ((this is a complete unit)) (to go into the female fittings on the supply line). Got it so far????

Drill a hole in the side of the 2" burner pipe about 8-10" down from the elbow and insert the 1/2" gas nozzel into this hole. The blower is on the very end of the 2" pipe on the 90 deg. elbow. I run these at about 20 psi gas pressure (I got a variable regulator from my gas supplier, looks like a compressed air pressure regulator).

The needle valve is for fine adjustment of the burner so you can actually turn the burner on and off with the ball valve, leaving the finely set needle valve where it works best. This makes it very easy to turn the burner on and off, as it is relitively "permanently" adjusted.

I do not use any flame sensers (optical/electrical switch that turns off the gas if for some reason the flame goes out or you loose power) so someone is always present when we are firing and/or melting. These burners are a bit difficult to lite, so either use a piece of lit, crumpled paper tossed into the furnace then turn on the gas then the air or a ***very*** long match. I have been told that if you make a couple of circles of wire

that fit inside one another and weld them on a cross frame and insert this into the outlet end of the burner, it will be easier to lite, but I just use the paper (or the burnout torch, which is about 4 feet long and reaches into the furnace easily).

If you have other questions, please feel free to ask.

Best,

John

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I guess I had better make a couple of these and give them a try. Keep hearing of their advantages..... Thanks!

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I have found lighting with paper to be very dangerous and set up my forge blowers so they can be slide in and out of the burner port. I pull the burner out so only the very end of it is inside the burner port and light it with a propane torch. When the flame is adjusted and the inside of the forge has picked up some heat, I slide the burner head in. This is not only safer, but it also extends the life of the burner heads because you can withdraw them when you shut down. The slide need be no more complicated

that a flat bar welded to the side of the furnace and a hanger on the burner.

Another way to light the forge if you have a fixed burner configuration is to drill a hole 3/8ths or larger at the port and light it with a propane torch through the hole. This small hole is also useful as you adjust the fire.

All of these devices put out volumes of carbon monoxide gases and if they are used inside they must have a hood over them to vent. The hood should be a foot over the top of the unit and exend beyond it. It should also have a straight pipe to the outside with no elbows.

Don Fogg

dfogg@concentric.net

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Hello friends,

You've given me lots of great info on this subject. Thanks to John, Cynthia, Steven. I produced a web site for this type of forge/foundry using a "target" type burner. It's in pdf format. So you need Acrobat to view the file. The question I have is, isn't this what your talking about? I'm a total novice here. If anyone would please take a look at the plans and let me know. The Plan 1 illustration has a "target" type drawing.

David

Graphic Design/Illustration; http://www.flash.net/~dwwilson/

Environmental Links; http://www.flash.net/~dwwilson/environ.html

Forge Plans; http://www.flash.net/~dwwilson/forge/fgpl.html

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David Wilson wrote:

It may be "off the wall", but would it be possible to install a barbeque grill spark ignitor? I've seen these for sale at hardware stores as replacement parts.

David

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It's not off the wall at all, as a matter of fact it's been done many times. You would install it between the flame holder and the 90 degree bend.

Bill

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Another good way to ignite is a spark plug and a flourescent tube ballast(at least 10,000 v). Set it up so it shorts to the opposite side of the burner, right after the mixing chamber.

Also, better than chucking paper in, just wrap some cloth around a piece of metal rod, wrap wire around it and soak with a little paint thinner or kerosene (not gasoline). A very nice little torch that will fit the space between the crucible and furnace wall very nicely. You can even put it in and back away as you ignite then pull it out after ignition. I keep a length of pipe next to the furnace to stick it into after the furnace is lit-it smothers itself and keeps the solvent fresh if you need it again. Pyro's unite!!!!

MP

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I examined the monster burners on my kiln the other day (I don't know why I didn't think of this before...duh). On the burning end of a 3" black pipe is a 4" section about 4" long. One half inch inside from the end is welded a 1/2" ring which chokes the opening down to the 3" pipe size. I am assuming this inner ring does the same thing that Steve is talking about, if so it would be simpler to make. At 500,000 BTU maximum ea. these burners are real quiet. They stay lit *but* there is a pilot burner under each one with a thermocouple safety shutoff. So, I wonder if this single ring would keep the burner going without the pilot burner.

Cynthia

TX

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There is a very useful small paperback called The Backyard Foundry, written by B. Terry Aspin, ISBN 0 85242 603 8. It was originally published in the UK by Argus Publications, since taken over by Nexus Specialist Interests. Their latest catalogue does not list this book, but does have Foundry Work for the Amateur, by the same author. May in fact be the same book, updated. I have no ISBN for this title though. It is also available from

Camden Miniature Steam Services, Rode, Bath BA3 6UB,

priced at GBP 6-65 Roughly half the book deals with patternmaking, slanted mainly towards model engineering projects, and the sandcasting process.

The remainder deals with the how-to side of melting metals, using

solid fuel (coke) fired furnaces, with air blowers. Small designs

for non-ferrous, and a separate chapter on ferrous.

In 91 and 92 the author had a long running series in Model Engineer which considerably expanded on the book. The parts dealing with ferrous foundry work started with Part 10, 6th March 1992, Vol 168 No.3916. Model Engineer is published by Nexus

Special Interest, Nexus House, Boundary Way,

Hemel Hempstead, HP2 7ST, England. They operate

a search and photocopy service on back issues.

Kevin Eva, Northern England, UK

k.eva@msmail.trctho.simis.com

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OK, here's a web site for you

http://www.rockisland.com/~marshall/foundry.html

It has a link to a page on small cupola furnaces. Here's the relevant text:

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We have three cupola furnaces of various sizes, the largest being

10 inch bore. Cupolas are continous melters, with the charges of

metal melted in layers alternating with layers of replacement

fuel, usually coke. There are no expensive crucibles to worry with.

The molten metal is accumulated in the base of the furnace and

tapped into homemade ladles as needed. The 10 inch Marshall furnace is capable of approx. 20 to 25 lbs. of grey iron every 5 minutes or about 40 to 45 lbs. of bronze every 6 minutes. Heats of upwards of two hours are possible, so it is obvious that these furnaces are capable of producing vast amounts of metal for their size and cost.

The 10 inch furnace costs less than $200. US to build and the blast can be provided by a large shop vac. One man can easily operate it alone. If you are interested in building one, there is more information on our foundry page for ordering our book, BUILDING SMALL CUPOLA FURNACES.

And, from the foundry page:

CUPOLA FURNACE BOOK

Our small Cupola Furnaces are our own design and have proved so successful that we have produced a 100 page book with over 50 drawings and sketches showing how anyone can build their own home hobby foundry for casting iron and bronze with this type melter. The book is available direct from us for

$25. plus $3. postage and handling at the following address:

Marshall Machine & Engineering Works Ltd.

P. O. Box 279

Lopez Island, WA 98261 USA


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