I wonder why no one has been pour-casting cups in metal lately?

I see a lot of beautiful, technically exquisite lathe spun cups being bandied about on this board, yet such cups are prohibitively expensive- not to mention the labor...

It would seem to me that some enterprising metalsmith could do very well by himself, and the magic community, by offering a set of cups using a lost wax casting procedure (or something along those lines- I'm not in that biz!).

Wouldn't these also be much less expensive to produce?

The lost wax process really isn't cheap. It's almost as labor intensive as spinning. I have some cast cups in the museum. Lost wax duplication involves two sets of molds. One is a rubber mold for the wax, the other is the investment mold for the metal. You make your original piece in wood, plaster, plastic or whatever, then you work on the surface to make sure it has the finish you want. You do all of this on the original, to lessen the work you do on the casting. After that, you make a silicone rubber mold of the original. If your original is made of plastic, you have to make sure that it's not something that will react with the silicone RTV.

After you have done that, you carefully cut the mold away from the original, and make sure that you got all of it. When you finally have a successful mold, then you inject it with molten wax and make your wax form. At this point, you check the wax for voids and lumps. You fill the voids and smooth off the lumps. Then you add sprues to the form to allow the molten metal to reach all of the parts of the mold once you start pouring in the molten metal.

Once you have done this, you make the investment casting. You can't reuse this material. You would need to purchase a 100 pound bag of investment, which would cost you about $70 for the grade necessary to do a set of cups. So, you make the molds, one for each cup and one for the cup you mess up, and burn out the wax.

Now, you need either a steam pressure machine or a centrifugal casting machine to get the molten metal down into the mold. Let's assume you have all that. Once the casting is done, you need to grind off the sprues and check the casting to make sure you did it right.

With spinning, you know when the process works and when it doesn't.

To give you an idea of what a single cast cup would cost you, if you purchased it from someone who was in the business, so they already had all of this material, take a look at the price sheet for the Whitechapel Bell Foundry.

The smallest handled bell they make costs £83 in a polished finish. That's roughly $160 US. That's for ONE bell, that's about the size of a cup.

Cast pieces in the metals we normally use for cups generally tend to be a bit thicker than what we are accustomed to. I do have a set of cast cups in silver by Auke van Dokkum. There was nothing saved by casting the cups. What you think you might gain in labor costs, you lose in other labor costs.

The least labor intensive method of all is CNC machining. But even that method involves hand polishing after the cups are turned, unless you want cups with a rough finish.

Thanks for that info, Bill. It looks like you did some homework in this area.

If they were, you'd see a whole load of them for sale

Spinning the cups in India and China seems to be the least expensive option judging by what's on the market right now.

I used to have a friend who ran a bronze foundry here in Houston. I actually got to see them unveil the statue of Sam Houston that is on the Sam Houston State University campus in Huntsville, TX.

There is a way that you can cast directly into a Silicone RTV mold, but the molds don't last very long. It requires a special compound.

The heat of the metal destroys the mold really fast.
I have done some casting for movie props ....even resin in those molds will wear them out but it works for a short run of product.
Mobius

On 2007-03-15 14:16, Richard Evans wrote:

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If they were, you'd see a whole load of them for sale

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Oh, you never know... sometimes an obvious idea is overlooked. I just thought I'd bring it to everyone's attention- seeing how everyone who is in the biz is always bemoaning the costs and labor of lathe spun cups!

And even given Bill Palmer's breakdown, if you could produce a good enough cup the cost would only be as much, maybe higher, than a really high end cup that is currently available. Perhaps it would not be "profitable", and you wouldn't be able to produce a huge quantity of cups for sale (though it's not like the market for good cups costing hundreds of dollars is booming anyhow...). There are other concerns besides profit. Prestige? The joy of using a set made by one's own hands?

Anyhow, it was just a thought borne of my desire to find a way to avoid shelling out the price of admission to the high end cup market because, well...in a word- I'm poor!

Gaddy - I absolutely agree with your sentiments about making cast cups in terms of the aesthetic value, the value of having something different (or beautiful) - and especially the joy of making something with one's own hands. I also agree that all ideas are worth airing.

If sales for high priced cups were not booming, Auke van Dokkum wouldn't be making them. Even at the prices he charges, he isn't making much money. There is at least one person on the forum who has cast some cups in aluminum.

When you say "The joy of using a set made by one's own hands?" you aren't taking into consideration the two most important parts of this. One is the cost of the tools necessary to make the cups. The other is the learning curve.

If you make the wax models yourself, it's still going to cost you a bump to get a cup cast.

There is nothing cheap about casting. Tool up, buy the metal and propane - then come back and tell those of us who know what is involved how cheap it is. I'm set up to do casting and would not consider casting cups. There are reasons beyond what Bill has mentioned above. The cups are not done and ready to use after the casting process. There is still lots of skilled labor finishing such castings. The resulting cups still can be rather clunky and difficult to use effectively in a routine.

Gaddy, you say that you are poor. Do you have a marketable skill like brick laying? I need a block wall laid and am willing to swap cups for the completed wall - I'll even buy the blocks and mortar. You could have "free" cups! People with marketable skills are never "poor" - perhaps cash strapped at the moment; but not poor.

Or you might consider saving up for a better set of cups. Put some money away after each show you do and after a while, you'll have the cash you require.
Jim

Bingo! I've swapped shows for dental work. I taught guitar lessons for medical treatment. I've taught magic for auto repair.

Bartering is an established method of payment.

I bartered photos services for a new car.

I bartered a magic show for photo services!

I am currently learning how to cast metal. My ultimate goal is to cast a flute (music!) with sterling silver which has nothing to do with magic. But because I am a hobby magician also working on cups & balls performance, I am planning to cast some nice cups too (brass, silver). The process will be almost if not completely identical. If you are interested in following my journey, please feel free to visit: https://www.spirit-flute.com/silver-flute-blog

If you are experienced in this or even have done it, I would love to exchange.

There are always stadium cups, if one is poor. Some of the metal cups made in India have a low price point.