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mikem
09-22-2002, 12:16 AM
Have been building a Gingery "Little Bertha" melting furnace on and off over the years but today I found a 110V ceramics kiln at an auction for $45.

Has anyone had any experience using these to melt aluminum? It draws 15 amps and has a maximum temp of 2300 degrees F. It's a cute little thing with stainless steel sides.

Should I try to melt with it or continue to work on my Little Bertha? Thanks--Mike.

Samuel
09-22-2002, 01:55 AM
have you seen the http://www.backyardmetalcasting.com? although I built my gas melting setup before I got one of these computer things, this sight would have really helped. but for 45$ I would get the kiln, you can do all kinds of things with electric that are more difficult with gas (exact temp. controll over long periods of time) anyhow I hope this is helpfull. Samuel

Rob Frink
09-22-2002, 09:17 AM
Mike

If the kiln will go up to 2300f, then you will certainly have no problems. I typically pour alumininum at about 1400F and bronze at about 2000F.

http://www.beaumontmetalworks.com/frink/pour.jpg

I think the kiln is a good way to go for the $$

Rob

mikem
09-22-2002, 09:53 PM
Samuel--thanks for the tip. Looks like this site will be a good resource.

Rob--Great picture. How did you do that? What are you casting there and what metal? Thanks to all for great advice. Thanks--Mike.

Thrud
09-22-2002, 11:04 PM
Why, he is making cast marijuana joints - those are the best kind! http://bbs.homeshopmachinist.net//biggrin.gif

Rob you are a braver man than me - I would never do that near anything flammable - like my legs.

mikem
09-22-2002, 11:54 PM
Hi Thrud:
It looks from the picture that he is 3-4 feet from the pour. Do you think that is too close and if so how do you pour more remotely? Thanks--Mike.

Rob Frink
09-23-2002, 10:54 AM
Mike,
The photo is a bronze pour. It is a #8 crucuble that has about 24lbs of bronze in it. I can't remember what I making here...but from the flask shapes...I think these were probably silicon bronze garden bells. The tall flasks have the bell and the smaller flat flasks have the clapper and hardware....I think.

Trud, yep! a 24 lb crucible full of molten bronze is something to behold. The radiant heat is unbelievable. I recommend that you play with aluminum first before using bronze... Iron is even more spectacular.

Go through your learning curve and mistakes with aluminum...where the hazards are much lower.

-Rob

mikem
09-23-2002, 12:46 PM
Hi Rob:
Thanks for the info. How far are you standing from the mold in the picture? Is the crucible handle made for one or two men? Is it made of anything special? How do you gauge the temp? Thanks--Mike.

Rob Frink
09-23-2002, 01:58 PM
Mike,

I guess I'm a few feet away or so...The pouring shank is about 4 ft long and you can see my right hand in the photo with a welding glove on it, my left hand is holding the end of the shank.

This shank is a one man shank since the crucible is small. Aluminum is 1/3 the weight of bronze and iron...so this would only be 8# of aluminum.

I probably made it from from some CRS laying around. It is just for pouring...I have a set of tongs for removing the crucible from the furnace and placing it in the shank.

I use a hand held lance pyrometer. You just poke the probe into the molten metal and read the temp....very important tool if you plan to do much casting.

Rob

Crazy Ed
09-23-2002, 06:55 PM
Mikem

If you go anywhere near the 2300F limit, the elements burn up fast. If you can stay down at or below 2000F for most things, the elements will last about ten times as long. FYI from an old ceramics messer around with'r. I did HI fire, 2300F and had to replace elements much faster. The lower temps don't 'eat up' the elements as fast. Brass at 2000f should last quite a long time, but anything over that..and kiss the elements good bye.

I bet your kiln has a 'cone' controlled electric kill switch. It looks like something sticking in from the wall slightly and has a hinged weight that trips a switch on the outside. Learn how to use it, go to a ceramics store and ask questions.

The two little blades and the wire thingy that trips them use little pieces of special clay that bends down under the weight when it reaches a certain temp. They are called 'cones' and IF you have a good ceramics supply store, go and get some and have them teach you how to check the 'trip' of the blade that lets the weight fall and cut off the electric. Very handy, all you have to do is find the right 'cone number' and let them do the temp shut off for you. The down side, is that you probably will have to over shoot slightly to get good melting in the middle of the crucible, but that is just a test of patience and trial and error. Once you find the right 'cone #' then the game is easy, all you have to do is listen for the slap of the shutoff weight.

Cones, when bought in boxes of 100 are cheap, don't remember, but I think about ten cents or so each.

Crazy Ed
09-23-2002, 07:00 PM
Oh, Mikem I forgot, there used to be a supplier of elements in I believe in Conn. somewhere that was about 1/2 the cost of my local main ceramics supplier(s). Grab a copy of 'ceramics' from a supplier or go to the local library and look thru the adds. Much cheaper to buy some of the stuff that way.

To my memory, cones were about the same locally as via mail.

Jaymo
09-24-2002, 01:00 AM
Rob
Great picture. What kind of protective gear do you wear. I'm getting into casting as soon as some connective tissue heals. I'm going to start with aluminum and pot metal. I've done a bit of lead casting and love melting and pouring metal. Can't explain it. You either have the metalcasting bug or you don't. You appear to be at least as infected as I. Congratulations on having a very fun affliction. My humble beginnings melting lead on an electric hot plate on the front porch really got me addicted. My wife makes me wear a respirator with cannisters that filter out lead dust and fumes. She says it can adversely affect my reproductive system. Wouldn't want that. But It smells so good when you melt it. Well, maybe good isn't the best descriptive. Anyway, do you use oil bonded sand or do you mix your own? What kind of furnace do you have? Store bought, or hame made? Amazing how fast heat comes through those welding gloves, even with the low melting temp of lead. Thank God for Channellock pliers. What safety gear do you recommend? Welding suit or foundry suit? I thought about welding suit and foundry gloves. Suggestions graciously accepted and greatly appreciated.
I can't explain it. There's just nothing like taking a piece of scrap metal and casting it into something you can use. We are the ultimate recyclers. I have one and a half of those fifty gallon Rubbermaid type tubs filled with aluminum castings. I also hae some big diesel truck pistons, about six pounds each. Can't wait to heal up and go back to the scrap yard to scrounge for more pistons and intake manifolds. Maybe I'll try some local auto/truck machine shops. Seems I should be able to buy lots of pistons cheaply.

Thrud
09-24-2002, 02:09 AM
Jaymo:
Casting lead is dangerous, casting aluminum and the higher melting point metals gets progressively more dangerous. A flame retardant suit, boots, gloves and hood should be used even with Aluminum. Proper gear for handling the crucibles safely is a must - even samll spills can cause severe 3rd. degree burns or loss of limbs. Casting sould also be done in a dry area with at least 4" of dry sand covering the concrete to prevent and explosion from spilled metal hitting the concrete.

Casting should also not be done with out an obverver for emergencies - more for larger pours.

THIS CAN BE EXTREMELY DANGEROUS - MAKE SURE YOU HAVE AND USE ALL SAFETY EQUIPMENT.

It's a great feeling to do your first Zinc, Aluminum, bronze, and then Iron pour and to see the results - but don't think you can get by with crappy safety gear - it is not worth it. The first time I melted Aluminum I was young and stupid - I did not have the wisdom of others to tell me what NOT to do. Luckily the hole in my foot grew back. http://bbs.homeshopmachinist.net//frown.gif

[This message has been edited by Thrud (edited 09-24-2002).]

Rob Frink
09-24-2002, 09:40 AM
Jaymo,

You should stop st your local library and pick up a few books on the topic. It is not something that you learn over night and melt lead is a start. There is no way I can explain enough to you on this board or through email. Like anything, you start small and keep gathering info and skills. Check local art schools and colleges for classes also. Shop ebay for old foundry books...Search online for metal casting forums and for foundry supply companies. There are a few good books by C W Amen.

-Rob

Rotate
09-24-2002, 11:03 AM
There are number of good websites showing you how to build a furnace, make the sand mold, and cast your own aluminum/bronze parts, however none that I've seen really explain the dangers and safety precautions that must be taken. I saw one guy pouring aluminum in his garage with running shoe on! Yes, it can be done, just as you can drive without your seatbelt and ride you're motorcycle without a helmet but it's down right stupid (I don't want a open debate on the merits of motorcycle helmet, I'm just tyring to make a point). Would you ever operate your lathe or milling machine without eye protection?

Molten bronze has enough energy that if you spilt some on your garage floor and the floor wasn't bone dry (unlikely because of soil below), you can have molten bronze splattering around, and should it land on your running shoe, you can kiss you foot goodbye. If you don't believe me, the next time you pour bronze or aluminum, get an old running shoe and see for yourself what it does in under a second when that molten metal hits the shoe.

Albert

docsteve66
09-25-2002, 09:52 PM
Friend had a Pyramid kiln, used for melting Al and Bronze (mainly, asyou shall see). Heleft the kiln on, melted the bricks or what ever in the botttom. The elements sagged and the turns did not short. They had continuity when we investigated.

Some points to remember: When concrete is heated it begins to explode and thing get exciting. Just a wood fire will suffice to get the results. so use the sand covering.

Proper clothing is a good idea, butI have cast a bunch of iron into molds, wearing only long legged trousers, heavy shirt, work shoes gloves etc. Will they provide adequate protection? I doubt it. I have never worn the proper gear so I am not sure it would protect either. I doubt it. Point is I never had a spill, splash nor steam blow back. I am happy to say that I have never tested ANY safety device in real life except a safety belt on top of a water tank and an aircraft crash. Be careful, trust nothing and plan ahead.

be sure you know how to arrange sprues and vents in your molds. Expanding hot air can back up molten metal.

I havenot done this but I should: put a fusable link INSIDE the container in series with the heating elements. The link might be made of iron wire (so it melts before your elements melt the container). The connections dont have to be inside in the high temp. I think I would put the link in the white wire so it has no voltage exposed until the link burns into two pieces. Yep, I know best advice is never fuse the "neutral".

Several sources sell thermocouples for temp measuring. They can be made at home also. Lots of sources for the wireing and you can use a cheap volt meter and chart forreading temps.

Kiln is worth the money for "heat treating", case hardening.

Rob, you have a good looking cope and drag, why the clamps and plates? ever have the sand give way on you? might be a story worth hearing !!! http://bbs.homeshopmachinist.net//smile.gif Admit a mistake and save some one elses skin?
Steve

Thrud
09-26-2002, 01:03 AM
Jaymo,
An addendum to mine and the others comments:

The flasks used to melt metal can and do fail. I have seen this happen 6 times and it ain't pretty. Using faulty or incorrect equipment is a good way to end up totally disabled.

Casting metal is like stopping cannonballs with your gut - it is fun until someone gets hurt.

Rob Frink
09-26-2002, 10:57 AM
Steve,

Those flasks are actually pretty crappy. Steel jobs are terribly expensive and I found that my shop made versions can be made very quickly and to a size that would work for the task at hand. Otherwise I may be forced into shoveling 200lbs of sand for a 1/2lb casting if I didn't have small flask avalable. I also have some shop made snap flasks that I used for some jobs.

Yes, I frequently clamp the cope and drag together to prevent the steam from lifting them apart and causing a shift or spill. The plywood on the sides of the vertical flasks in the photo keep everything together. Similiar to bars, grids or chucks. Note that the pour is in the yard and spills harmlessly puddled up and chilled since the soil permeabilty is similiar to the foundry sand.

Nearly every pour had one mistake or another. It is all part of the learning curve which never ends. Accidents on the otherhand is something that I avoid. Like with anything else I guess, you should know what you are getting into before you get in it. A little common sense goes a long way.



[This message has been edited by Rob Frink (edited 09-26-2002).]