Easy Homemade Dual Fuel Furnace

[SciFiJim]

This is not my work, but one I found that I will be working on building this winter. I thought others might be interested as well.

http://www.instructables.com/id/Easy-Dual-Fuel-Furnace-Burner/

I have wanted to try my had as casting aluminum as well. Who knows, it it gets hot enough, I may try my hand at casting iron as well. I knew there was a reason to save the steel WWs.

[nanuk]

I read that Instructible

I thought his comment about melting Cast Iron was a little premature. I doublt will ever be able to melt Cast with propane... but you can always try

here is the site I always refer to when I think about doing this myself.

no one around here does much of this. I had thought about it, as there is ample aluminum car rims to melt down.



BACK YARD METAL CASTING! (http://www.backyardmetalcasting.com/index.html)

[EMC45]

Both of the sites mentioned are great.

[SSGOldfart]

:groner::groner:Hummm lots ofgood info to take in on those sites why couldn't I have found this back when I had two hands to work with????????????????????????????????????????

[scrapcan]

do a search for Ron Reil, he has a great burner website. mostly geared toward forge, but are applicable to furnaces also.

http://ronreil.abana.org/Forge1.shtml

[Buckshot]

..............I've got a book on building a coupla furnace for melting cast iron. You may melt continuously, but the max individual pour for the design is 120 lbs. Tapping off 120 pounds of (luminescent white) 3000º molten cast iron would be way cool, but not in my suburban back yard:bigsmyl2:

...............Buckshot

[nanuk]

buckshot: for cast iron, don't you need coke?

I didn't think anything else burned hot enough.

[Bert2368]

Charcoal will do-

[andremajic]

I found a great source for high carbon steel. Go to a local shop that rebuilds electrical motors. They use an arbor press to remove the old bearings, some of which are HUGE. They can be had for free, as they won't re-use them. Cut in half, using an abrasive disk or drill out the rivets in the races to free the ball bearings.

Here's the specs for bearing steel: http://www.suppliersonline.com/propertypages/52100.asp

[Buckshot]

buckshot: for cast iron, don't you need coke?

I didn't think anything else burned hot enough.

............Yup, ya use coke. The coupla furnace is forced draft up the coupla. In that is alternating batches of cast iron and coke. As mentioned it may be run coninuously, simply adding more layers of cast iron and coke.

..............Buckshot

[nanuk]

i learned about some of that from my old neighbour

he is a welder/machinist who worked at our local foundry

he has told me some stories, and ideas.

They used to cast large stuff, but are famous for "Crow Foot Land Packers"

[andremajic]

Used motor oil burns pretty clean and hot once you got the right mix of air/fuel.
I built one last week and it works awesome. Any of the concrete that you don't PACK in will become seperated and pop off inside the furnace. (Sounds like a 22 pop)
You also need to wait a full week for it to cure and light a small fire inside and let that burn out until there's nothing left, then come back the next day and do the same thing. Don't rush drying it out, or you will have steam build up inside your wet concrete. After the 2nd firing, you can introduce your "other" fuel and let it rip.

Here's the info I used to build mine and it's got info on the correct mix of refractory concrete. http://www.backyardmetalcasting.com/refractories.html
The burner design I'm using is pretty much the same as the one in the instructables info, but the pipe cools so fast with air running down it, I have to actually stick it further inside the chamber so I will get hot enough to ignite. I didn't use a propane fitting one mine, just gravity-fed oil and air. I just couldn't justify 40+ dollars a bottle and all the expensive propane fittings.

The fuel container is an old coleman 5 gallon water cooler with the tap switched out with a brass cutoff valve. The body of the furnace is refractory concrete packed inside an old metal container, with an 8x12" piece of chimney flue. The burner is a piece of water pipe with an 1/8" bendable copper tubing brazed in and centered inside the "air pipe".

I went through about 1/2 the tank in about 5-6 hours of use. The auto shops around here get a gleeful look on their faces when you ask if they can spare some used oil. They can't wait to get rid of it. :D

I was able to melt thick tool steel to an Orange hot and bang it into shape on my makeshift anvil. (8x6x12 steel plate)
I haven't used propane to pre-heat the tip of the burner, just a couple handfuls of barbeque charcoal.

Go to any appliance repair place and ask for a squirrel cage blower motor. They're used inside range hoods, stoves, ovens, dishwashers, etc and shouldn't cost more than 10 bucks used.

All the info you'll ever need will be on the website I just pasted.

As you can see from my pic, it is very clean burning with no smoke. It's because it burns so hot that there isn't anything left unburned. I believe if you are used to using oxyacetylene torches, this would be a "neutral" flame.

After some experimenting this furnace is easier to use when tilted on its side with a firebrick over the opening to retain heat. Then you just insert your bar stock throught the gap and let it heat.

Andy

http://castboolits.gunloads.com/imagehosting/44874efbc6819e685.jpg

[andremajic]

If you look at my thread in the special projects section for "slow rust bluing" the knife was made using this furnace. Since then I have made some chisel blanks, a couple more knife blanks, and some flattened bearing races for future projects.

Once the metal has been hardened and tempered, It's harder than a file, so make sure you do any shaping work on it in the annealed state.

Have fun!

Andy.

[Just Duke]

Used motor oil burns pretty clean and hot once you got the right mix of air/fuel.
I built one last week and it works awesome. Any of the concrete that you don't PACK in will become seperated and pop off inside the furnace. (Sounds like a 22 pop)
You also need to wait a full week for it to cure and light a small fire inside and let that burn out until there's nothing left, then come back the next day and do the same thing. Don't rush drying it out, or you will have steam build up inside your wet concrete. After the 2nd firing, you can introduce your "other" fuel and let it rip.

Here's the info I used to build mine and it's got info on the correct mix of refractory concrete. http://www.backyardmetalcasting.com/refractories.html
The burner design I'm using is pretty much the same as the one in the instructables info, but the pipe cools so fast with air running down it, I have to actually stick it further inside the chamber so I will get hot enough to ignite. I didn't use a propane fitting one mine, just gravity-fed oil and air. I just couldn't justify 40+ dollars a bottle and all the expensive propane fittings.

The fuel container is an old coleman 5 gallon water cooler with the tap switched out with a brass cutoff valve. The body of the furnace is refractory concrete packed inside an old metal container, with an 8x12" piece of chimney flue. The burner is a piece of water pipe with an 1/8" bendable copper tubing brazed in and centered inside the "air pipe".

I went through about 1/2 the tank in about 5-6 hours of use. The auto shops around here get a gleeful look on their faces when you ask if they can spare some used oil. They can't wait to get rid of it. :D

I was able to melt thick tool steel to an Orange hot and bang it into shape on my makeshift anvil. (8x6x12 steel plate)
I haven't used propane to pre-heat the tip of the burner, just a couple handfuls of barbeque charcoal.

Go to any appliance repair place and ask for a squirrel cage blower motor. They're used inside range hoods, stoves, ovens, dishwashers, etc and shouldn't cost more than 10 bucks used.

All the info you'll ever need will be on the website I just pasted.

As you can see from my pic, it is very clean burning with no smoke. It's because it burns so hot that there isn't anything left unburned. I believe if you are used to using oxyacetylene torches, this would be a "neutral" flame.

After some experimenting this furnace is easier to use when tilted on its side with a firebrick over the opening to retain heat. Then you just insert your bar stock throught the gap and let it heat.

Andy

http://castboolits.gunloads.com/imagehosting/44874efbc6819e685.jpg



Well done! [smilie=w: I'll give you a jingle.