Donkey I'm not sure about placing this on this part of forum,so please move it if necessary. Been jumping around the forum and talked about the possibility of melting aluminum.After asking Peter about temps at the top of insulated riser tube,it seems like it could be done. Of course there are some questions(go figure LOL!) If a core similar to the Peterberg dragon type was used below a chamber similar to the institutional cooker design insulated like the riser with a lid to contain the heat. It seems to me it could certainly melt aluminum. Suggestions?? Presently I'm using a waste oil burner in a homemade foundry furnace. It requires a preheat with Propane and a blower to melt. Being frugal(read cheap)it seems like using a rocket stove for melting would cost less and be greener.A further idea will be to used pressed oak saw dust and news paper for the fuel would be even greener if it could produce enough BTU's. Suggestions?? Currently I have a rocket stove built of a section of a 30 gallon water heater. It has a 4.5"feed tube,3"X6"X18"fire box,6" dia.X24"insulated riser and 4"dia. exhaust pipe.The fire is smokeless in less than 10 minutes and it's heating my garage/shop.Originally was going to convert it for metal melting but have decided better to leave it alone and build another for melting metal(plus building and firing these is great fun). Please offer any and all suggestions you have.... Thanks in advance. Don
Heh.. I've got a WVO foundry as well and I love the thing.. I know, they're smelly, dirty, tend to splatter hot oil around. etc.. I fire mine with wood to get it started..
The issue with the rocket stove is going to be it's consistency. The place where it's hot enough to CONSISTENTLY melt the metal is down inside the heat riser, about a third from the bottom. 'Course, taking heat from that place is exactly NOT what to do in a rocket stove, it will reduce efficiency of burn by a LOT. It is possible to create thermal runaway.. I've seen the tops of barrels turn cherry red, I've seen 1/4 inch plate steel writhe around, etc.. I just don't see these things happen on a consistent, every time you run the machine kind of basis. Not yet, though perhaps through Peterberg's new additions, it may be possible to do what you are thinking.
You'll need to make a stove gets immediately into thermal runaway mode and stays there for the duration. It maybe doable. It's a tall order.
Thanks for the quick response guys. Guess I'll need to research the "thermal path",'cause I'm ignorant about it(and a lot more!!). Glad to hear about your foundry Donkey. If you're interested I think my web site is still up but probably not much longer(tired of paying for it I guess).Anyway give it a look,it was a vain attempt to cover the costs of my hobby and just covered the cost of keeping it up so will cease to exist when current funding run out. www.blindpigetc.com Again thanks for the suggestions.... Don
Post by matthewwalker on Mar 26, 2013 9:42:30 GMT -8
Love the bookends! I'm not sure if this would work, since I know nothing about metal foundry, but...
My outdoor cookers are basically standard rocket mass heaters, either vertically fed or horizontally. On top of the barrel I have a hole above the riser, with an adjustable baffle. I have built small insulated masonry ovens on top of this configuration. Upon burning out the form for the oven, I will often "fire" the oven by continuing to feed the "top fire", which is coming out of the hole on flashover, with more small wood. By doing this, I've achieved some seriously hot fires up there on top of the barrel, in an insulated masonry chamber. It completely disappeared a beer can in a matter of three seconds or so. Maybe that will give you some ideas. Here's a photo of the "oven" to help you visualize.
MW, thanks for your info. Do you think if the oven on top was an enclosed insulated cylinder with an insulated lid that the temps would climb without the added wood? I realize I'm asking for an estimate on your part but think the estimate(guess) will be enough encouragement for me.... Thanks also for the bookend compliment,there's a lamp with a couple of those little guys on it as well now. If you've melted aluminum cans in your oven can some casting be far behind? Again thanks, Don
Post by matthewwalker on Mar 27, 2013 9:37:34 GMT -8
Well, I do think you could most likely heat that insulated chamber to aluminum casting temps without the top burn. As the fellows were discussing in another thread, on flashover there is a column of flame shooting a couple feet out of the top of the barrel. By putting it up there, and retaining the outer barrel as the flue path back down, I think you'd have a good shot at getting it to work.