Coffee Can Forge

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unky_gumbi

Joined
Aug 28, 2009
Messages
7,951
I built a coffee can forge a while back to give some home HT a go. Well I am getting things hard enough that they will dull a file, but I did a little testing to night with a small piece of steel. I was checking for hot spots and cold spots.

I have a fairly good swirl going on the flame but the heat seems to concentrate in one area and wont even keep hot steel hot in the front and back corners on the same side that the propane torch enters.
Is there any way to even out the temps without adding a second torch? If a second torch is needed where is the best place to cut the second hole. The first is dead center of the can and at the top so that the flame swirls around the outside and not directed to the floor. My cold spot seems to be larger in the back corner BTW
 
What I do with my full size single burner forge is warm it up really good to around 1800. I make sure the inside is all the same color. I then cut back the flame so I can control the heat using a pyrometer to verify temp. I turn the flame up and down to keep the heat were I want it. If I do not do the preheat I also get the cold spot in the back of the forge.
 
You know I have had it up and running for over an hour and it stays the same way as if I had started 5 minutes ago:confused: I am up loading a little video to photo bucket and will post a link later. It had been running for about 5 minutes at the time I started the camera
 
Perhaps I am misinformed, but I seem to recall reading that a propane torch would not produce sufficient heat for even a two-brick forge and that one would need MAP gas to reach the desired temps. I know propane will get to 2500* at the flame tip, but it seems unlikely there is enough BTUs there to evenly heat even a small open area.
 


It is getting above non magnetic fairly quickly and will melt salt. The plan is to get a mapp gas torch but I had the propane kicking around so I used it to set it up. I still need to coat the wool once I get things set up right. clicking on the picture will bring up the video
 
Running a forge with uncoated ceramic wool is a bad idea. The fibers are very high on "the not good for lungs" list. Also, using coatings will help keep the heat in the forge by reflecting it back. Do yourself a big favor and coat it now. You can always remodel and recoat later if you want to make changes.
Chip Kunkle
 
You shouldnt need to add a second torch to the coffee can. I only had one and it used propane and worked great. The propane torch may not swirl but once its up to heat, it wont matter much. Is it uncoated wool? The wool is for insulation, you need to have some sort of refractory lining, even a light layer, to reflect the heat around the forge.

edit: For a torch tip I used the bernzomatic TS839 and it works great. It works with both propane and MAPP and was enough for my coffee can forge to melt copper and silver and slump gold. Had i left it in long enough, Im sure the gold would have melted as well. Mind you, mine had only refractory, no wool at all.

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You really need to coat the inswool. Not only does the refactory prevent the fibers from floating around, it helps even out the temp on the inside of the forge. It retains the heat. Give that a try and wee what happens. I have never used a coffee can forge so I have no idea if your torch is large enough to do the job. You might want to invest some time in a 3/4 or 1" forced air nozzle. I know that will bring even a larger forge up to HT temps.
 
The only reason that it isn't coated yet is to see if I need the second torch or not, poking a second hole threw once I coat the lining is a pain. This is the second version of this little forge. First time the lining wasn't think enough and it wouldn't come up to heat. I added the second layer of wool and have only fired it twice now, both times yesterday, outdoors and down wind. It definitely gets up to temp now, in spots. In other spots it it still runs cold, move the steel into those areas you can see it darken to a dull orange.

I will give it a coating later today and fire it up after it cures to see if that evens things out a bit
 
Would a small hole in the back of the forge allow the heat to move a little more evenly?

Plus if you want to do something longer than a knife...
 
there is already a 3x2 hole in the back, I use a fire brick to regulate how big the hole is. Closed of cuts the flame, wide open lets too much heat out 1/4-2/3 open seems to work best. I just finished coating the inside with refractory cement, so it will take a couple of days for that to fully cure, then I will fire it up again to see if the heat is more even. If not its a second torch place to what ever end has the larger cold spot, possibly from the opposite side to see id I can gety sort of a spiral effect going in it
 
I did the same as you, got the same results, built this next:
http://www.backyardmetalcasting.com/oliverburner1.html

Never short on BTUs now. Not really hard to build I think you could build it in a afternoon, got the regulator at a propane place just north of Polo Park, I think it is on St James St.
If you want you come by and have a look at mine.
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I have a little one to put in front for heat treating, this gives me a more even slower heat and better control over the holding temp.
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Cheers Ron.
 
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Ron how is the ventri type burner on fuel? I was working on a blower type burner, but put it aside just because my welding abilities aren't up to snuff:o and not having a welder makes it hard to practice. This on looks interesting and may be the way to go for me with my larger forge.
 
OK so I got it up and running again today, with the coating on it and that solved most of the cold spot issues. It is too small to HT anything of size really so it was more of a something to do project. I was checking the hot and cold spots on it with a piece of 1/8" stainless rod from a bicycle fender. I was using that be cause it heats and cools quickly enough for me to judge the hot and cold spots. When I was satisfied it was as good as it was going to get I decided to hammer on the piece of rod to see how easy it would be to shape things with a hammer. I know what I was working with isn't even close to what I would use to make a knife but I did come up with a small knife shaped object, it is more less straight and did what I wanted to do. Any how for your amusement here it is.

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Now to get back to work on my full sized forge.
 
Great knife, as you go along turn it on end and hammer it so the spine stays flat and straight.
This burner will use more fuel than a blower, but no all that much, a 20lb tank lasts me a long time really, maybe 2 in a summer. Once the forge is hot I turn it as low as possible and it still cooks.
This burner is great because you can build it with a drill and a hack saw and a few bucks of pipe, course a drill press is better. You can buy welding tips to make the jet, if you do not have a small drill. You will need a regulator though, dont' know if you need one for the blower.
I have a cheapo welder if you want to borrow it.
Cheers Ron.
 
That little butter knife like thing is a joke:D I was just poking around with a piece i 1/8 rod trying to find the cold spots in the coffee can forge I did something similar yesterday to with a piece of 3/16 rod even gave it a rough edge and cord wrapped the tang just for fun. to give you an idea of the size of these things here is the one from yesterday
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it didn't take much grinding to smooth it out but it is far from a real knife, just something to throw at the garage. I don't even thing the rod stock can be hardened.

I was going to use the burner design that you had linked to but it turns out that the guy I got to do the blower burner finished it up the other day, I just need to get the regulator and my tank filled to try it out, then line the big forge and try the whole works out.

Now I just need to get the steel to make the base for my band saw and I can start making that.
 
Sounds like you are good to go. I like making little knives, very handy once you have a few laying around.
Fastenall has about the best price for 01 rods, a few at Lukes, sometimes they have W1 if you want that.
Cheers Ron.
 
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