well, one of my profs asked for some help with cutting costs on prototyping new equipment bucket/tooth designs for lab tests.... they're normally aluminum too.
soooo i'm building a foundry!
conceptual design is a 16gallon trash can, with 2" of ceramic wool insulation and 1-1.5" of dukast 2800F castable refractory.
I've tracked down an old oil furnace burner, and am intending to use filtered waste oil. Some of these pours are looking to get into the 20-25lb range, so i'm going to need a large bore/height.
The big problem now, is how much room do i leave between the crucible and the walls?
I'm going to have a roughly 10" bore.
Conceptual design... (Sans lid, mechanisms, etc, and with a 1.5" burner tube instead of a 4" like the burner that's coming tomorrow)
frame tacked...
gotta find some cheap wheels too....
MY ultimate goal with this is to cast my own intake manifold for the vintage volvo amazon wagon autocross car.
I've built a few furnaces similar to that which you've described. Best advice I can offer is to make the chamber such that it is a good fit for a given sized crucible, including enough clearance for lifting tongs. If you shoot aimlessly, you may end up with one that isn't a good fit for any particular crucible.
Those I've built were all fired on natural gas, so ignition and combustion wasn't an issue. I expect that you may have some difficulty firing on used oil when the furnace is cold, but it should work well once it has been warmed.
I'd be interested in hearing more about your success as you progress. I no longer have natural gas service, so my next furnace will be oil fired. I, like you, will be breaking new ground.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
My only suggestion would be to start with a steel drum rather than the trash can. I have a similar furnace and it is quite heavy. If you use a steel drum you can weld handles to it that will carry the weight better than the trash can handles. The ceramic wool (e.g. fibrefrax) is a good idea, because the refractory is not a great insulator, and you can loose a lot of heat from the sides. I put it on the outside of the drum and then wrapped an aluminum jacket around the ceramic wool.
thanks for the input guys! My big concern is that the refractory wasn't goign to be thick enough.
as far as crucibles go, since i'm doing aluminum, i'll end up just welding one up of whatever size i require, that shouldn't be a big deal, but i'm figuring about an inch and a half of clearance on each side to get good airflow around it.
first pour will be to pour some good flasks
As far as lifting it off/all, the intention is that it won't come off of the cart, so if it does, i'm screwed. BUT the garbage can is cheap... and there... and there will be a steel hoop welded around the underside of the bottom lip of the trashcan so i can pull it off with a chain hoist if i ever do need to get underneath. (and to support the lid some)
Rockmonton wrote:as far as crucibles go, since i'm doing aluminum, i'll end up just welding one up of whatever size i require,
Don't overlook the strong solvent property of molten aluminum. I'm not a fan of using a metallic vessel in this case, but if that's going to be your choice, investigate refractory washes. You can retard scaling and dissolution of the steel flask by coating.
The addition of iron (from dissolution of the flask by molten aluminum) changes the properties of the chosen feed stock. It isn't in a good direction.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Yes, the steel crucible will corrode fairly quickly,
that being said, i'm not sure what else is out there as far as budget options go... does anyone know?
Could i possibly coat the inside of a steel crucible with refractory? or would that just explode under the heat/temperature?
used up some of the scraps and got some iron casters.
decided to use #9 wire through the garbage can and wool to reinforce the refractory, along with some stucco mesh. The plan has changed to just using one 10" sonotube in the middle, and then from the garbage can, the ceramic wool, a layer of wax paper, stucco mesh held by the #9 wire, then the refractory in/around that, and lastly the sonotube in the middle.
Well , too late. Bigger casters are better. Seldom is the floor clean enough for small wheels to roll freely. But no matter. You did good with adding some small material to carry the 4rth corner of the caster. Honestly, the snails you are welding is as much heat, as it is stop and go technique. You should weld out of the edge of a puddle that will freeze behind you, giving the effect of a row of coins laying over each other. The blobby snail-like or grape looking things, are from cool welds, too fast of movement, or not being able to see the molten metal and guessing at whats going on. If you cant see it, you cant do it. It is the biggest problem I have because of the focal distance I have. Also small box machines are not known for their great power, and have to be rode hard in order to produce good cosmetic welds, that may be weak.
After that seemingly scathing criticism, you are not too far off. I have made worse looking blobs a lot, so just understand we need to practice to improve and noodle around with our equipment to get the best we can. Overall I think not too bad.
As far as iron pots and pipe things for aluminum, do yourself a favor and decide from the get go, to make the best castings you can for all this effort. A bit of iron disoved in aluminum, destroys its properties, very quickly. At some point, you will get aluminum that has so much iron in it, it will be not much more than a peanut butter consistancy, and wont even flow. Trust me, I have already been down that road, with my cast iron dutch oven, and bolts and rivets that disappear from the trash aluminum going into the pot.
There are a lot of threads to this effect, and you should read some of Ammen's writings, geared for the hobby guy on the subject. They are very good. If you are going to do much casting at all, it becomes a long winded learning process. The quality is in the details.
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.
Rockmonton wrote:Could i possibly coat the inside of a steel crucible with refractory? or would that just explode under the heat/temperature?
Harold wrote: investigate refractory washes. You can retard scaling and dissolution of the steel flask by coating.
Note that I did not make reference to a steel melting vessel as a crucible. I think it sends the wrong message, as if, somehow, it's a good idea. It isn't. Note, also, that I suggested a wash will retard the problems. It isn't likely to be a 100% solution.
There are two factions in this matter, those that use steel vessels and see no harm in doing so, with the balance understanding the ramifications and choosing to not use them.
I am a strong believer in not using them and in clear conscience would not make the recommendation to do so. Too much effort is expended in preparing to pour to risk an unnecessary poor quality outcome.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Harold_V wrote:
Note that I did not make reference to a steel melting vessel as a crucible. I think it sends the wrong message, as if, somehow, it's a good idea. It isn't. Note, also, that I suggested a wash will retard the problems. It isn't likely to be a 100% solution.
There are two factions in this matter, those that use steel vessels and see no harm in doing so, with the balance understanding the ramifications and choosing to not use them.
I am a strong believer in not using them and in clear conscience would not make the recommendation to do so. Too much effort is expended in preparing to pour to risk an unnecessary poor quality outcome.
Harold
Hear, hear! Getting and using a proper crucible doesn't have to be a big deal. I have used separate clay graphite crucibles for alum, brass, etc. and they have lasted for many melts and years, and I don't have all that much invested in them. I bought four #10 crucibles on ebay for about $20 each. None has ever failed. Snoop around on ebay and other alternate sources if you don't like the price of a new one, e.g.:
