Another keg furnace

It has been several months and a major cleaning since I have had a chance to do anything on the furnace.
I was out at the shop yesterday and built 2 more OXB boxes for storage. I now have 6 and plan on building another 6 to help with organization. Anyway I ran out of material and had a chance to start thinking about the furnace again.
I like the way Melterskelter did his fuel system so I have decided to build similar. The Rube Goldberg machine is out and a 12 VDC fuel pump is in. It will be supplying the fuel for the siphon nozzle.
I misplaced the sd card with more pictures but here is 1 I had in file.



The tank is a 20 gallon air tank, The pump is a low pressure fuel pump 8 to 10 Lb.
I plan on sucking the fuel from the last couple of inches off the bottom of the tank with a 1/4 inch copper line. This line will run through a cord grip used for centering the copper tubing while holding it securely in the L It will then pass through the top of the T on the tank and go inside the tank unbroken to just above the bottom of the tank.
This will go through the pump where it will be pushed from this point forward through the filter, a 1/4 turn ball valve then to a needle valve before going to the siphon nozzle.
The other side of the T will go to a hose barb concerting a clear poly tubing that then attaches to another hose barb and T on the bottom of the tank. This will be used as a fuel indicator running up the side of the tank. The other side of the T below the tank will go to a valve and be used as a sump drain.
It is not a lot at this time but is at least a step in the right direction. I hope to have this part finished in the next couple of days.
I still have quite a bit to do as far as building tools, boxes and casting related items and I will have to pick up a bag of refractory before i do any melting. I don’t have a pith cast and have a bit of work to do on the lower section of the furnace.
Now that things are coming together in the shop. I hope to have the time, energy and room to work on things before spring is here. Then i will be modifying an old shed to give the furnace a real foundry home.
Joe

 

Joe,

Due to coincidental circumstances I had to run my furnace using a couple of high-temperature firebricks turned so they were sitting on the 2” side in lieu of a formal plinth. They worked just fine. I have a plinth cast and will use it, but I doubt it offers much actual advantage over the bricks. I think it would be slightly better if I were to break the brick so they were only 3/4 length (but that is splitting bricks)

Denis

Edit: Those bricks were the heavy non-insulating type.

 

Thanks for the information on the bricks. I will have to buy some refractory soon to modify the burner hole. The one I could not spell on a bet, tyner tunre tyiner, tiner, hat thing the flame enters hole.
I would like to make a reverberatory furnace burner some time in the near future.
It will be used on natural gas just to see how well it works.
Joe

 

I want to start in the hobby and recently joined the forum to read and learn. This is the first building-from-scratch thread I've started on (I already had the idea that a keg might be a good starting point, so it was an attractive thread title) and dang! I'm glad I did, as I will now take a detour and read the linked book. Thank you.

(Also, the advice from an earlier post to start a design with the crucible, then the burner, and the furnace last sounds like excellent advice. In my engineering career I know to start with the requirements and work backwards to a design, but I keep forgetting to do that in other areas.)

 

Welcome to the forum Joe
A lot of furnaces are built from kegs. They are solid , stainless steel that looks nice and does not corrode although mild steel is a lot easier to work with and of a size that works well for many.
I started this build year ago this month. I should have had it finished long ago but ran into life complications. Most of which was a shop that needed attention more than a new furnace for a foundry. I am happy to say that after month of cleaning that project is now 80% complete.
There are many things to be completed before I have what can be called a foundry. Right now I could do small melts with my heat treat oven but that would be working ill equipped = dangerous.
I will do a lot more cleaning and some repairs in preparation before a dedicated 10 foot X 24 foot shed is ready to be used. The goal is by the 4th of July of this year.
Most people on the forum just use an existing space with a lot of them working totally outside.
A foundry can be very simple or as complex as a person wants or needs. If I was to do it again. I probably would not have chosen a keg just because I would have liked a bit wider chamber. A keg will hold a number 10 crucible. Looking back if I was to have 1 furnace. I would have probably started with a 35 gallon drum or similar with a diameter of 20 inches. That ship has sailed and honestly the smaller furnace will be the best fit for now. I have learned a lot on this build so hopefully if a larger one is needed. The second larger furnace will be much faster and easier.
Before you start ask yourself what size furnace do you want? How much metal are you planing on melting and what type of metal? What fuel source are you going to use?
Most on the forum cast in aluminum, brass / bronze or cast iron requiring the highest temperature.
There are many on the forum with vast knowledge, willing to help you through every step of the way. A lot of people are very successful with very basic setups Others have more elaborate ones.
It all depends on what you want to do. Have fun!
Joe

 

Not to hijack this thread, but here is a furnace build that I ran across after I built my furnace, and I considered my design as breaking new ground, but upon looking at what others have done in the past, it appears that I only discovered what many have known for years, ie: use a thin high density hot face (I recommend it being rated at 3,000F minimum).
http://forums.thehomefoundry.org/in...lting-furnace-build-thread-highlight-reel.18/

A good grade of hot face and an overall furnace mass that is kept as low as possible will greatly improve furnace performance.
Melterskelter is trying a coated ceramic blanket design, and I wish him the best of luck with that, but the tried and proven design is the high density thin hot face.

Just my 2 cents on someone starting out and looking at furnace designs.
I also agree hardily that starting with a crucible size and working outward is a great idea.

.

 

Thanks. As to what I plan to cast, I don't really know yet, as I don't... Wait, just read my introduction post in that subforum. The short version is I have interest in starting but a lack of projects to start on. I expect to do alumin(i)um, copper, brass/bronze, silver, and/or experiment with alloys. The only two projects I already have in mind are one in silver and one in aluminum brass (which I've read about but never seen, so now I just have to make some!). A small setup will be fine to start with.

Along with "First, pick a crucible" and "Here's a good book to read", the best thing I've seen is how the guideline on how big the furnace should be based on the need for space around the crucible. But I'm sure that's also in the book. I've got to read the book.

In the past I've done some silversmithing, including plenty of soldering, which is generally done on a platform of soft firebrick. That stuff is a terrific insulator and I've had it bright red hot with no damage, so I had thought to use it as the inside surface of my furnace, but I've now read advice to the contrary. That's the sort of thing I expected to get by reading a bunch of stuff on the forum, and why I have to read the book.

I got far enough from the beginning of this thread to read of your simultaneous flu and tooth pulling. Yuck!

 

I'll just throw in that a 30 gallon steel drum can also provide the sheet metal to make a decent-sized furnace. I cut mine in height to suit my needs, but am very pleased with the overall size, shape and workability of the materials. So far the Satanite hot face over 2600 degree wool on the vertical walls has been fine. I found the floor needs protection from spilled metal and so now has a thin (1/2") layer of dense castable over the combination of 2" of wool originally laid down around the edges of the floor and the IFB that sits where the crucible resides. That floor looks like it is holding up well. The lid lining is "in process." Applying 1/8" Satanite to unrigidized and "untoasted" wool resulted in flaking after a couple of firings for iron. It looks like first toasting the wool to toughen it may result in better durability of the lid. It is too early to tell if that will hold for the long term. OldIronFarmer and others have built very nice and quite low mass lids with IFB laid up in a dome shape.

Welcome aboard!

Denis

 

I think Denis is right about a 30gal drum being just about the perfect size for most of us. I used an air tank and it was just wide enough. I would have liked another inch in diameter...

 

I cut mine down in height about 6 inches or so and made the cuts (with an angle grinder) and resulting welds so that the lid utilized a section one of top rib of the two "ribs" in the side wall of the barrel to make a weather flange to make the top of the furnace shed water properly where the lid meets the main body of the furnace. So I actually cut out a circumferential band of metal 6" wide between the top of the barrel and the upper rib and then welded the remaining two pieces circumferentially. Then I made a circumferential cut right in the middle of the upper rib. By then inverting the bottom 2/3 of the barrel, the body of the furnace made use of the rolled rim of the bottom section of the barrel to form the upper lip of the body. I just cut out what was the bottom of the barrel leaving the rolled rim intact and it now formed the reinforced upper rim of the body of the furnace. I think maybe I should draw this out---tomorrow. getting late.

I am quite happy with how that furnace is working out overall. I am redoing the wool lining of the lid so that it will be protected by a longer tube of castable at the chimney. Having the EDGE of the wool exposed to hot gas there resulted in some breakdown of the wool. I am pretty sure if the edge of the wool can hide behind a castable "chimney liner" all will be well. Otherwise that single coat of Satanite on the 2600 degree wool did fine over 5 heats and looked like it would continue to do well. only one way to find out.

Denis

 

I had a chance to make it out to the shop for a few hour. I worked a bit with the furnace and some part fitting for the fuel system.
I have been undecided on weather to use a boat hoist or some kind of counter weight setup.
Practicality and the boat hoist won. The hoist only has to lift the weight of the barrel and lid so I decided against the added complication of a counter weight. With the boat hoist I will be behind a heat shield so a fast open and close wont be as important as if I was directly exposed to the radiant heat.
This project is way overdue for completion but it would seem that life gets in the way every time. What I did accomplish was to mount the hoist, pulley, pulley stand and run the cable.
Everything is coming together but I did run across a rather big mistake. The barrel clamps are to far apart and will have to be modified to work properly.
The 3 pieces of the furnace fit very nicely together and after the strap clamps are modified. Should lift smoothly. I still will need to make the lid swivel and locking assembly along with some metal and refractory work around the outside of the keg where the burner will attach and a small patch or two. Then the furnace portion will be ready to use.
The fuel system is coming along. I have mostly been mixing and matching parts and have it down to needing very little. I will have to buy a few fittings but I am still slowly finding parts and pieces. Cost on the fuel system will be almost nothing.
The burner is finished other than hooking it up. Right now it is a siphon nozzle in a 2 inch water pipe. This pipe matches the blower nicely but I might go with a bit different configuration to help with the parts layout. With this being a 3 piece furnace. The bottom will be bolted fast to a ridged stand. This will give me some options as to how I want the burner and blower mounted.
The pictures are not good but they do show some detail.
Joe

 

Two Steps forward and one back. I made it out to the shop today and worked a bit on the furnace. I was able to finish the clamps and slide to lift the barrel and top along with making 3 small brackets to hold the bottom section in place. This was the 2 steps forward. The one back was that I realized that the diagonal brace holding back, slide assembly will impede the lid opening, bummer.
Now there are several things I could do and this is where I would like any thoughts or suggestions.
As it stands now the brace that is the problem is made of very thin angle from a Chinese packing crate approximately 1.25 x 1.25 inch around .08 thick. I could remove this brace and replace it with something like .250 plate that would extend only a few inches from the bottom on that side or ? The other side had the same type of brace but I had to set the furnace off center on the platform to fit the burner so I replaced it with a 1 X .312 bar to allow the clamp to clear properly. This brace alone would be strong enough considering how ridged the rest of the structure is but for the sake of safety and long life I would like to do a bit better than one brace on only one side. The hoist will only be lifting the top and barrel or around 50 - 60 Lb.
I am wondering if I need to open the lid under normal circumstances. I could just lift the lid off and place it to a side if I would need to. Right now the vent hole is 4 inches. I could get tools in and out of it or I could cut it a bit bigger. The vent hole is another minor step back in that the lid is made of wool, insulated fire brick and dense refractory. The hole where it goes through the stainless, fire brick cracked all the way around and is separating from the material above the stainless on the lid. It would not to be to difficult if I wanted to cut this whole a bit larger. It would also be a good way to repair the crack. As of now the obvious way to repair this crack would be to chisel or grind it out and fill it with mortar. No mater what I do. I will have to line the vent hole with a coating of mortar reducing the whole to as small as possibly 3.6 inches. I could bore the whole out to say 5 inches to allow for more tool room.
This is where I am at. What do you guys think and how would you proceed?
Joe

 

I took a half dozen pictures with my wife’s phone but the 2 were the only ones that turned out. I hope the description is enough. I will try to make it out to the shop in a couple of days and take a few more and see about a bit more rework.
Although I don’t drink over a 6 pack a year tonight might not have been a bad night to have one and call it.

Joe

 

If the tall diagonals are what is obstructing the lid, you can weld a piece of pipe angle iron onto the bottom sides of the frame, and let these new pieces protrude back beyond the back of the frame.
The move the diagonals to the back of the unit, on the outside back.

You already have the winch protruding out the back, so the footprint really won't get any bigger if you move the braces to the back.

.

 

You'll want to be able to open the lid during operation whether it's for loading or just to get your initial cumbustion going, and although it's probably not that heavy, it'll be hot-hot, needs a safe place to be set down, and becomes one more thing to think about when things are in motion. Having a built-on setup is helpful so I wouldn't abandon the idea. Pat's suggestion seems like a simple effective solution. Plus it could act like wheelie bars.

Pete

 

Thanks guys especially Pat! That will work well. I think I had my face so far in the problem that I could not see the solution. I don’t know why I did not. Placing the braces on the back will not only solve the problem but I could build them in such a way as to be a cage eventually protecting the motor / blower assembly.
Good eye Petee. You noticed my wheels are a bit forward and close together. It now acts more like a 3 leg stool rather than a 4 point contact. For now it is very stable with the furnace weight forward of the wheels but as I add weight to the back that is surly going to change. The reason the wheels are like that is. It was built from my old work service cart where keeping the wheels close together was an advantage when navigating during repairs in factories where room was limited or damaged parts and materials might be piled. I have looked at that problem several times and had decided to move the wheels back and further apart but had not got around to it yet.
With the new thought on the braces. I will move the wheels out to where I extend the frame of the cart for the base of the brace. I am not concerned with the foot print or weight of this thing.
It is a rather long term project and when it is fired next. It is unlikely it will be moved often.

Joe

 

I made it back out to the shop last night and made some modifications to the furnace carriage.
It is now a stand rather than a carriage. I removed the 2 diagonal sports and extended the frame out the back I am thinking a foot. It is way past my bed time. A somewhat sore back is keeping me up so I don’t remember if it was exactly 1 foot or just close. Anyway when I removed the diagonals I realized that the 2 uprights being made of schedule 40, 1.5 inch pipe would be more than strong enough to do what I want so for now I don’t intend on replacing them. I also removed the wheels and most likely will not be replacing them either. When I put the furnace in to operation in mid summer if all goes as planed it will be under a roof and not moved from its original spot other than possibly being moved a few feet if I decide to build a second larger one. There will be no need for the wheels. They were uncomfortably close together under where the extension was added. Now the rear ground contact point is a 2 inch piece of channel iron that spans the full width of the furnace and is approximately 16 inches back from the original center line of the wheels. This made the stand set a lot more stable.
The things I still have to do to complete the stand is make the lever assembly for lifting the lid. Stiffen the plate the hoist is bolted too. It is 1/8 inch or close but still flexes quite a bit. I plan on welding 2 pieces of angle running approximately 3/4 of the length of the plate, one on each side of the hoist. Then I will need to make the platform for the new extended portion on the rear and any brackets for the burner, blower and controls. Sand blast and paint.
Then it will be on to touching up the burner hole. If I try to spell tawnier I will spell it 6 different ways and they will all be wrong so it is the burner hole. Then finish up a burner. This will finish the furnace. It will then be on to the rest of the foundry. It might be a month or two before all is finished on the furnace only because I will need a bit more refractory. The last time I spent more on shipping than for the refractory. I have since found a supplier 75 - 80 miles away and beings I can do everything that need be other than a couple of small repairs and a few pith. I will wait and pick some up the next time I am down that way.

Joe

 

I made it out to the shop today and although progress is somewhat slow it is moving along again. I have been working on several foundry related projects in the last few weeks but they have been varied and somewhat scattered so it would appear as though little is being done when in actuality they have. It just does not show and will not until things come together.
The days effort was redesigning and building a new tawnier.
Originally the burner was built from a 2 inch water pipe that is 2 and 3/8 inch O.D.
The box I have added has a hole that is 2 inch and I have hope that a 2 inch O.D. tube will work satisfactory. With the 2-3/8 O.D. pipe there was only ½ inch of refractory above.
This looked to be a bit structurally questionable so I would like to use the smaller tube and put another 3/8 of refractory above the tube for a total of 7/8 inch above the burner tube where it enters the keg. I then plan on putting in something either a card board tube or Styrofoam plug that will be later removed as a core to forum the cavity for the burner assembly to pass through. Then flooding the S.S. box part I added with refractory.

What are you thoughts on the add on of the squared S.S. base modification around the burner?

How would I go about curing the newly added part to the tawnier?

Should I stay with the larger water pipe at the cost of structural integrity or should I go with a smaller tube with more refractory on tope where it enters the keg?

Joe