new toy

Home enthusiasts discuss their Foundry & Casting work.

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todd goff
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new toy

Post by todd goff » Mon Jan 11, 2010 8:15 pm

Well, I picked up another furnace today and I am finding myself asking why did I do that? I have been wanting to find a smaller one and it just so happened that this one showed up. It is a fuel oil fired furnace and it holds a # 50 crucible. They were using an air compressor to feed the air to it but I have a 1/2 hp blower that I picked up for another furnace a while back that I think is too small for it but I do think that this will work for this furnace. The problem is that the lining has seen better days and I think that it is going to take some work but I never like to write anything off (just call me a collector of junk I guess). Anyway, I really do think that this furnace will be far more useful than the other ones in the shop, I mean come on who is really going to use a #100 furnace or a # 150 tilt on a regular basis. I still haven't ruled out using the #300 dip out but I really and do mean really need to get a lot more sand mixed up and better save my money as the tank that feeds it probably holds about 300 gallons (well between 2 furnaces anyway). I have heard that some of the foundry supply houses actually offer a steel liner that you put in the furnace that allows you to reline them with the plastic refractory and was wondering if this is so? I really need several of them like right now, you know? :?:

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steamin10
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Post by steamin10 » Tue Jan 12, 2010 1:43 am

In one way, listen to the salesman and he will solve all your problems. (watch your wallet.) I dont believe a steel liner is a good idea, you would have to show me its worth the expense over ram or castable material.

To get started you may want to skin the lining if it is that erroded, and add some ram-up plastic brick, or castable to the shell to hold down the heat loss and protect the shell. Make a layer of 2" chicken wire doubled around in the skin you pour to hold it together if it cracks up, (it will). The fine wire will bend and not stress the shell you pour like say highway wire, which is strong enough to move and unsettle your thin shell.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

Harold_V
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Post by Harold_V » Tue Jan 12, 2010 3:09 am

steamin10 wrote:I dont believe a steel liner is a good idea, you would have to show me its worth the expense over ram or castable material.
I got the impression that the steel liner was a form so one could ram or install the castable refractory. It might be a good idea for Todd to clear the air on that one.

Harold

todd goff
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Post by todd goff » Wed Jan 13, 2010 7:42 am

Supposedly the liner is so that you can ram the plastic in the lining of the furnace. I wasn't aware that these liners even existed for relining furnaces like this, but the other day someone informed me otherwise.

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Post by Harold_V » Wed Jan 13, 2010 4:48 pm

I used a similar system when I built a tilting reverberatory furnace, although I cast mine instead of ramming. Making a form that is removable makes it a lot easier for future repairs. They are a very good idea.

Harold

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steamin10
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Post by steamin10 » Wed Jan 13, 2010 6:26 pm

I was not aware that this is a form for the sizing and finsh for a furnace refractory. In my experience a tape measure and some simple tools are that is needed for making a new lining in a furnace. Worth the expense?
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

todd goff
Posts: 128
Joined: Fri Jun 12, 2009 12:59 pm
Location: South Carolina

Post by todd goff » Wed Jan 13, 2010 9:03 pm

It probably isn't worth the expense. I talked to a friend of mine today that runs a foundry and he said that he builds his forms out of wood and then fires the furnace up to burn the wood that he used for the forms and also dry the lining at the same time. I took a blower off of a larger furnace that I was going to use but figured that it was too small and would do better on the smaller furnace. I went to Lowes and found a floor flange (2") that I could use to mount to the blower and then screw an air pipe into it to mount it on the furnace so I am looking good on that end of it. The next order of business is a small jib crane to lift the lid off of the furnace, plumb the fuel lines in (gotta get a pump) and look over the crucible lifting shank real good and make the necessary repairs. I have 4 crucibles with it but I think that only 2 of them may be salvageable. I think that a #50 may be my best bet as it isn't too big or too small. The lining does concern me immensely but I do not think that all is lost. It is my way of thinking that maybe I can patch the lining with plastic and then dry it out and be good to go but I really don't know if this will work or not. Which is better in a furnace anyway, fuel oil fired or propane? Anyone have any ideas on pros and cons?

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Post by Harold_V » Thu Jan 14, 2010 12:12 am

todd goff wrote:It probably isn't worth the expense. I talked to a friend of mine today that runs a foundry and he said that he builds his forms out of wood and then fires the furnace up to burn the wood that he used for the forms and also dry the lining at the same time.
I made mention of a tilting reverb I built. I used a removable steel (galvanized) steel form for the outer layer of insulating refractory, then a turned insert made of wood for the chamber. I wanted to be able to remove the form, so I worked accordingly.

Unfortunately, I was not aware that finishing the form in shellac would serve to fuse the castable to the form. No amount of coaxing would remove the form after the chamber was poured, including applying enough air pressure inside the furnace to blow out the form. Instead, it collapsed the base of the lining, which had to be re-poured. I ended up burning out the form, much to my chagrin.

If I can find the time, I'll eventually transfer the information from my old computer to the one I'm using now. In it I have several pictures of the furnace in various stages of construction, including shots of the forms. I'll try to get them posted.
The next order of business is a small jib crane to lift the lid off of the furnace,
It might pay you to explore the design of the McEnglevan furnaces for an idea in handling the lid. While I didn't copy their design, it gave me an idea that worked very well for the lid of the furnace I made that used a #8 crucible. A steel ball lifted the lid with a lever, which was removable, and then permitted swiveling the lid to the side. You could open or close the furnace in just a couple seconds, and you didn't have to find a place to store the lid, which remained on the pivot pin, but completely out of the way.
Which is better in a furnace anyway, fuel oil fired or propane? Anyone have any ideas on pros and cons?
I'm of the opinion you would be better served with oil. It's safer, and yields far more btu's, gallon/gallon. Cost could prove to be a disadvantage with propane, too, depending on what you pay in your area. One more thing to keep in mind, you may have success firing your furnace with waste oil. There are some doing that now, melting for almost free.

I always used natural gas, but I no longer have it at my disposal. I plan to melt with oil, for my non-ferrous furnace. I will use an induction furnace for ferrous alloys.

Harold

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steamin10
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Post by steamin10 » Thu Jan 14, 2010 6:12 pm

Ok. My .02 here. Fuel is the conveinience that maters by choice, from charcoal, ( a pain really ) to fuel oil, (better temp gain for time of firing) to using Natural gas or propane. Propane allows you to turn up the pressure and dump more BTU's into the frunace with an air adjustment. Natural gas is regulated to the house, and cannot be changed in any significant way.

Given that, I want to know how to build a gun burner for waste oil. I have several mecahnical shops that give away their drain oil, so it -could- be a low cost fuel. This would allow me to convert or build a hearth furnace for aluminum pigging and salvage. I want to be able to charge whole heads and engine blocks, or a pair of automotive wheels and save the time, and somewhat dangerous effort of breaking this stuff small enough for charging into the smallish furnaces I have. The only two waste burners I saw were not fully available for examination. The cost of the basic burner is over 1K and that makes it unavailable to me for hobby use. So does anybody have plans or sketches of one of these ? How about Mother Earth info, anybody?
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

4-6-4
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Furnace Lineing.

Post by 4-6-4 » Fri Jan 15, 2010 8:39 am

Dear Todd. The steel liner you are talking about is probably to be used when ramming up a replacement lining on an electric induction furnace. So its of no use to you. I now speak from personal experience. My furnace was made from a drum slightly smaller than a 44 Gallon drum. I lined it with stuff called Caowool. This is NASSA space age stuff. It comes in a blanket about an inch thick you wind two thicknesses around the inside of the drum. There is also stuff that you can paint on the caowool so that it goes hard after being heated. The base is refractory and the crucible sit on a disc of refractory to keep it up out of the inevitable spillage when topping up the crucible during firing. I melted Gun metal Silicon Bronze and aluminum. The aluminum Crucible was about a foot high and nine inched across the top. It was the maximum I could handle on my own. My furnace was LPG gas fired with a vacuum cleaner to supply the puff. But you can get normally aspirated gas torched that do not need puff. You put the torch in at an angle so the heat swirls around the crucible. My lid was the end of the drum I had cut off the drum and it was packed with caowool I could lift it off with heat proof gloves. There was a four inch piece of pipe in the center of the lid to allow to allow the heat to escape and to allow inspection of the progress of the melt. With the caowool lining the paint on the outside of the drum remained in place except where the flame actually touched it.
The fire brick or refractory lined furnaces are pretty much a dead loss unless you enjoy watching it heat up. I was more concerned with turning out castings.
What equipment do you have to process the sand. This I found was the most onerous job in my foundry. Do you use metal or wooden or metal molding boxes. I spent 13 years as a student at a local tech failing each year so I could continue to make patterns and use their foundry to make cast iron. I also worked in the Foundry and pattern shop full time for a while. So I do have a bit of an idea of what the story is.
All the best 4-6-4

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steamin10
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Post by steamin10 » Fri Jan 15, 2010 7:38 pm

I have a hearth brick built furnace, that is built with 1 Inch bricks standing on end, radiating from the center. It is backfilled with a sand, clay, exploded Mica mix between and behind this brickwork. A 20 minute preheat on low pretty much does it, and then high fire, and commit the vessel to the bottom block. I stayed away from the rockwool, only because I was told it was brittle in a furnace, and could cast particles and shards of the base material, if it were not coated. I was told the light weight bricks for ceramic Kilns were better to use, c/o the basic material could be cut and shaped to the inside curve of the furnace, was more stable if bumped, and did not cast any particles like the softer roll stuff.

If I had my turn to do it again, I will use the light weight material, with maybe a brick target wall for the burner.

I dunno, I think what works for you , is what you wind up with.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

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JHenriksen
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Post by JHenriksen » Wed Jan 20, 2010 8:50 am

Steamin10, a good start for a waste oil burner is an old fuel oil furnace that has a 'Beckett' burner in it
The waste oil furnace we set up in Franklin Park has one. The mods involve removing the integrated oil pump and adding a heater block for the incoming oil. The oil is heated to about 150 degrees f before injection.
I set up a small gear pump with a check valve and pressure relief valve at the tank then feed the oil through a ph8 a car oil filter before the burner.
Compressed air is injected into the nozzle at 15 psi behind the oil injector to atomize the oil. Oil is regulated to 4 psi through a .875 orfice. (thats .875 gpm) about .020 inch.
a few more details there i'd be glad to share with you. or come have a look sometime when i'm cleaning out this unit.

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