A few "simple" questions from a complete amateur

Hey Guys,
I recently got into casting and am really facscinated by it, but I might need some expert advice.

I have a "schematic" of my furnace attached (I'll currently need to remake it completly, so no pictures) and also a picture of my crucible. It is a rather cheap ceramic (5cm out diameter) from E-bay designed for copper, for which it worked rather well.










As blower I use a simple Hairdryer and the lining is a mixture of -1 Part Sawdust, -1,5 Parts Sand/old lining and 1 Part clay rich earth, all assembled in an old metal garbage can.
I used charcoal for my first few tries with aluminium and old 30-06 Winchester casings and it worked well enough for making my beloved a ring, at least after I made a lid from a bolt, nut and washer.

With everything going well, I decided to use proper black coal, simply to cut my expenses in half. I mean, how much hotter can it possibly burn?
As it turns out it gets hot enough to melt parts of my crucible lid .
Not only that, but because the coal pieces are a lot smaller my crucible sinks to the bottom and becomes lost until it cooled down completely and I can tip everything out.
As a measure against that I tried to use a 15mm steel rod in the middle of the coal as a rest for the crucible. Again, I didn't expect it to get hot enough to melt the bloody steel rod .
For your amusement there is a picture the rod's remains:



That brings me to my questions:
1. How can I keep my crucible from disappearing through the coal?
2. Do you have any recommendations for a replacement crucible preferable with lid, I don't want pieces of coal clogging everything up, again and preferably rated for steel, I might as well use those ridiculous temperatures I get
3. Do any of you guys have any Idea why ma beloved got a rash from the ring made of old casings? Could it have something to do with the fact that there was some weird residue when it got molten? Yellow-ish and looked somewhat like cotton candy?

If you have any questions, comments or want to tell me how stupid I am, feel free to do so,

Best Wishes,
Glod

PS: English isn't my first language, so please excuse my imperfect writing, I hope it is at least somewhat intelligible

 

For the purposes of this discussion oxidizing pretty much means burning. Thats where your steel rod went. It may have melted to an extent since you were probably hot enough, but it mostly burnedup. Thats also what has punished your crucible so badly.
Jeff and I are pretty much kin when it comes to over blowing solid fuel. Finding the balance of volume and pressure (both lower than you think) is the big secret. Coal and charcoal behave a bit differently, but the same rules mostly apply. Both are extremely hot and will wreck your stuff until you get the air figured out.
As to the rash, some folks are sensitive to copper based stuff, plus bullet brass may have other undesirable stuff in it.

Welcome Glod.

Pete

 

Welcome aboard. What happened to that poor crucible? If you REALLY want to save your piece and be able to wear it without the rash issues, try painting the inside of it with clear nail polish. Also, if the inside is rough, it will also harbor bacteria and that can cause a skin reaction too. There is a special lacquer that made specifically for this purpose and we can't remember the name of it at the moment. It lasts longer than the nail polish. Try the clear nail polish and just don't wear the ring full time.

 

Thank you all for the kind welcome,
Sadly liquid fuel isn't an option, technically I am not even allowed to wash my Bike at home, stupid environmental protection laws. Clean drinking water? Who needs that?

I'll dig up my soldering iron and see if I can't make some better regulation for the dryer, somehow I didn't think of that. Until now I was thinking how I can get more pressure out of it, but too much heat isn't really my problem at the moment. That should also mean that the coal won't burn away so fast and I have actually time to see that the crucible doesn't sink to the bottom.
Thankfully I won't run out of materials for a furnace anytime soon, so I can spend some time experimenting.

To be fair, there is a chance that crucible was a bit dodgy from the start. After my first attempt at getting aluminium molten there was already some sand burned in on the outside and it got some hairline fractures quickly. I can't even find the seller any more, completely coincidental I am sure .

I would have chucked it back in as soon as she told me, but my beloved doesn't want to give it up, kinda sweet of her. At least after some nail polish it isn't that bad anymore. The inside and everything was pretty good and I am pretty happy with it. Except for the fact that it isn't entirely round any more, did you know that using a power drill with a steel drill to clean up the inside will deform your ring? Well, I do now

 

Guten tag Glod. Germany does have some pretty strict and strange rules. I lived there for over 5 years. Do I miss it! Have a schnitzel and a bitburger bier for me will ya?

I had a propane grill when I lived there. Can you find an old gas grill to use as your trojan horse? You aren't melting THAT much metal and we won't tell anyone. Even a propane torch with a small gas bottle pointed into a metal coffee can would work for small amounts of metal. If your pours will be small, an electric kiln would be the way to go. Do you like the jewelry side of this? Proper jewelry investment isn't expensive and wax is cheap. The only thing missing is the furnace and some learned skills to carve the wax. Keep working at it. Casting metal is a hoot.
That's sweet of her to cherish it. My schatzi is like that too.
Tchuss!

 

You can limit the air flow by partially covering the intake to your hair dryer with a piece of cardboard. Suction will hold it on. You may burn out the heating element if you don't have it on no heat setting.