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Techtchr
03-25-2008, 09:10 PM
I'm almost to the point where I need to invest in equipment to make some silver castings...and possibly other presious metals.

Can anyone suggest equipment they own/have used that will do a good job casting small sterling parts. They are musical instrument parts. Most will be fairly small in size. Most of the parts would fit within a cubic inch volume. Quantity will be low but quality needs to be excellent as the finishing process will require machining. A vod in the casting would ruin the part...of course. My budget is in the 1000-2000 range. Am I dreaming?

Matt

loose nut
03-25-2008, 09:20 PM
Do a search for 'lost wax or investment casting", you will find sites for art metal casting and suppliers that will get you what you need.

Rich Carlstedt
03-25-2008, 09:56 PM
Silver is the neatest stuff to cast.
It is very fluid and takes details beyound other metals IMHO.
Rich

get the book.

The Complete Metalsmith
by Tim McCreight
Davis Publications in MA.

It will put you miles ahead

snowman
03-25-2008, 10:06 PM
Not at all, I could be set up for casting silver with a couple hundred dollars. The most important thing is that you deair your investment. Got a vac pump?

Spin casting is nothing new, nor expensive to set up.

Forrest Addy
03-25-2008, 10:16 PM
All my investment castings of silver and gold were 600 lb or less so I could muscle the criucible shank single handed. More than that, I would have had to buy $$$ a crane.

PTSideshow
03-25-2008, 10:21 PM
Silver is the neatest stuff to cast.
It is very fluid and takes details beyound other metals IMHO.
Rich

get the book.

The Complete Metalsmith
by Tim McCreight
Davis Publications in MA.

It will put you miles ahead

I will only add that you get the pro edition has it has the most complete info in all of the editions, student,shop, pro and pro deluxe comes with a cd of the book and a couple of jewelry design books only on cd.
Tim also has a pretty good one on castings with info all types of molds etc.
The casting book is called
Practical casting
ISBN#0-9615984-5-x
Brynmorgen press
spiral bound
Amazon had The Complete Metalsmith one on sale last week

mwechtal
03-25-2008, 10:44 PM
Oxy-acetylene would do fine for melting. An electric melter would be the ultimate. A vacuum caster can be made with an old automotive AC compressor as the pump. You can make the casting flasks from sections of steel tubing. And as said before, a spin caster is inexpensive and effective. I don't think you'll have any problems putting together a workable setup for $1000. People have even made very intricate jewelry using a steam casting setup, which can be made for almost nothing if you already have the torch. It would be ideal if you could get some lessons from a local rock and mineral club, or a jeweler.

Try Indian Jeweler's Supply, Kingsley North, Rio Grande. Rio Grand would be the best, but the prices are usually the highest. Their web site may be informative though.

Mike

PTSideshow
03-26-2008, 08:20 AM
Came across this site on another forum. It has a lot of great things on it. The Fusion furnace looks interesting. But its the casting and his take on stuff related to home brew casting. Is a little different from the norm. But all makes sense and it is a truly no frills, no mus not much fuss.
http://www.foundry.ray-vin.com/

snowman
03-26-2008, 08:25 AM
Will all of the parts be different, or are you looking at the need to do rubber moulds for the wax as well?

Here are your basic prices for a non DIY, but there is seriously nothing to either machine.

http://www.jemco-usa.com/tools/vacuum%20assist.htm

stuntrunt
03-26-2008, 11:01 AM
For small castings, get an electric melting furnace. They cost about 500 USD.
They do a grateat job keeping oxigen from reaching your silver so you're less likely to get impurities in your casting.
Have a look at https://www.riogrande.com/home/
You(ll have to register, but it's really worth it. They sell everything you're ever likely to need.
I have nothing to do with that company besides being a happy customer.

As for spin casting, I'm sure there is some older dentist on the forum that can tell you all about that. All you need is a small bucket, some plaster and a good piece of string.

G.J.

Stepside
03-26-2008, 11:19 AM
Matt

If you are going to vacuum the investment there are several options. 1) vacuum pump and bell jar. 2) vacuum venturi that runs off compressed air and a bell jar. The second choice is cheapest by far if you have a good supply of compressed air. If you local dentist has a surplus vacuum pump/mixer they are slick. Make sure to buy a high quality bell jar/vacuum chamber. I imploded a cheap one in the classroom. There were plastic fragments stuck in the suspended ceiling. This was a brand new chamber.
I would be tempted to go with the electric melting pot because of noise, safety and equipment required. If you already have the right torch then go for it.

Pete

alanganes
03-26-2008, 01:04 PM
This is the sort of stuff that folks who make jewelry do all the time. The Tim McCreight books already suggested are excellent. If you have not found this already, make sure to take a look here:

http://www.ganoksin.com/

This is a knowledge depository for jeweler types, from big-time pros to beginner hobbiests, and is a nearly unbelievable wealth of information. They maintain a listserver called "orchid forums" that you can subscribe to for free. You can search the archives from the webpage, and if you join and ask a question there, you will find a bunch of very helpful replies with enough information to keep you busy for a very long time. Unlike some on-line forums in the cyberworld, folks there are very tolerant and helpful to beginners, hobbiests and noobs.

-AL

Techtchr
03-26-2008, 08:37 PM
Thank You for the links and book recommendations. To answer a few of the question people have raised...and some they have not. This project is for one of my hobbies/loves, not for school this time. I visited a flute maker over my last vacation from school and spent a week learning about the mechanics and Art of flute head joint making. One thing we did not get into was casting parts. I know there are a few instrument repairman on this site, but for the rest of you who might be mildly interested I will explain what I am doing. One of the crucial parts of a flute headjoint (part you blow into) is the riser. It is about the overall size of a large mans ring. They are cast out of any number of precious metals. Once the headjoint is assembled the hole that is formed by the lip plate and riser is carefully scraped to certain dimensions and shapes. Changing the dimensions and shape of the riser changes the sound you hear and the way the flute feels to the player. I have all of the equipment to start making my own head joints, except the equipment to cast risers...and eventually other key parts. I will be starting by casting some risers...probably a dozen or so. Then I will move to other pieces and parts. I won't be making hundreds of anything.

My wife (also a flute player) loves the head joint I made at the flute maker's shop. I happen to like it too, so I want to make one for her. I also have a local player that wants me to make him one. Hopefully there will be others down the line.

With all of that said, can someone give me a testimonial to a particular brand of vacuum casting equipment that they have actually used/purchased? Yes, I know there are ways to do this on a shoe string, and I might if I can't swing the costs of commercial equipment. Seems kinda odd that I'm essentially saying I don't really want to build it myself I never say that :)

Your Old Dog
03-26-2008, 09:37 PM
I did some centrifugal casting with lost wax process over 20 years ago. You need the spin caster, oxy/acet torches, kiln to melt the was out. I wouldn't bother with the expensive of a vacuum system unless you can make it yourself. Vacuum will casting will show faint finger prints left on the wax in the casting. If you plan on further finishing such as buffing and such it just won't be necessary. If you have faint crack in the was it will telegraph through in the vacuum casting but not necessarily in centrifugal.
the advantage of Vacuum over centrifugal is size of cast parts. As long as the flask that's been dewaxed will fit under your bell you're in business.


If you are like many of us, you have the torches and machinery to work up a vacuum pump.
All you might need would be the kiln, and some flask and a pump

snowman
03-26-2008, 09:49 PM
Keep an eye on craigslist for a small pottery kiln, it's all you need, but you'll have to put some type of temp control on it. I could put one of these together (kiln) for under 50 bucks. If you can get a book called "the kiln book" by Olsen, it has a section on making electric kilns. All you need is a box of firebrick, a heating element and some type of thermostat. You can do your calcs to decide element size then order it from Eureka Elements.

No real way around the torch.

You could do a spin caster like the one in the link I sent with a shaft and a long bungee cord to provide the "spin". Just make sure it's balanced, which you have to do either way. An old washing machine drum, cut down, will contain any "oh crap" 's that you might experience.

The investment you need to buy. We just had a topic a few weeks ago about making machinable wax.

The only other thing you need is to have something to deair in, which if the parts you are doing are small, you could probably get away with a pyrex bowl. If you know a scientific glassblower, you could get any old piece of tube to do your deairing in. I've personally got a 9" piece of boro I'm saving for a casting bench some day. Even a graduated beaker would work with a little RTV to shape where the spout is...but heck, you've got a torch and a kiln (annealing oven), heat the glass up slow with the torch, anneal it back down and bend that lip back into shape with a piece of pencil lead.

There really isn't much to that goes in to the equipment.

If you are good with mold cutting, you can always carve cuttlefish bones and start REALLY cheap.

With any investment casting, you are going to have to spend time sanding, filing and finishing the casting.

mwechtal
03-26-2008, 11:04 PM
I almost forgot. You don't need a lot of vacuum to cast. The vacuum pump is really overkill. A friend of mine built a caster with just a vacuum cleaner, a silicone gasket, and some PVC fittings.

Mike

Stepside
03-27-2008, 12:00 PM
A vacuum jar for de-airing the investment is the most dangerous piece of the puzzel. Don't even consider a pyrex bowl or even worse a modified chemistry flask. If the price of a commercial labroatory bell jar is out of the question then use a vibratory sander on the bottom of the work table to shake/vibrate the air bubbles out.

The machinable wax and the wax for lost wax are a bit different. I discussed this with Freeman Supply as to the toxic issues of burning out their wax. That isn't a problem, it is a vegetable based wax. I would be more concerned with the expansion rate as compared with Jewelers wax.

The most common problem I have had with the whole process is getting in a hurry to cast and not allowing enough time for a complete burn-out. You might want to do your burn out away from your smoke detector -- or you could tell the little woman you were running a test pattern on the detectors.

We will need pictures of the finished parts.

Pete

mwechtal
03-27-2008, 12:51 PM
OK, one more "I just remembered". Rio Grande now sells a relatively new sterling alloy with Germanium used to replace some or all of the copper. The copper in Sterling is what causes the tarnish, and removing it gives you a silver that is supposed to be easier to solder, and tarnishes much less. I haven't used it, but if I was doing any more silver work I would certainly try it.

Mike

OldDentist
03-28-2008, 09:53 PM
Sorry for the late reply. I've been lurking at this site for a while and finally had something I could add. Took a while to become a member. I'm a retired dental educator, taught restorative dentistry for more than 30 years, and have made many gold castings and have dabbled in jewelery making in silver and gold for a long time. As far as the flute parts Techtchr wants to make I would advise making them in machinable wax which is available at modest cost in a variety of shapes and sizes and then have someone else cast the parts. Every large city has at least one professional jewelery casting firm that could do it at modest cost or any dental laboratory should be able to do the same. The jewelery makers have more experience with the properties of sterling silver. The process of investment casting is not difficult but there is the initial equipment cost and learning curve to be overcome.
If I were looking for the necessary equipment I think an add in the local dental journal might bring results. One only needs a gas/compressed air torch to melt silver, an oxyacetylene torch is much too hot and will probably result in inferior castings. If can answer any more questions please email me.

Techtchr
03-29-2008, 12:16 AM
OldDentist,

I've already started looking into having a local professional jewler do the casting. There is a fairly local one to me with a cnc seteup for making wax models, and he casts his own products. I'd still like to do it myself.

My shop is pretty complete with machine tools. I have a home built cnc machine that I could make injection molds on ( done it before). I have a home made injection molder that I could use as a wax injector. I could cnc the wax directly as well. I also have the torch for melting the silver, and access to a centerfugal casting machine...at least until I buy my own or do the vacuum casting method. So it looks like I need the following to begin and do it "right": a bit more knowledge, investment, wax, burnout oven (we just bought a new range and i saved the old one so i thought I'd try that...the old one), casting silver, rubber mixing bowls, flasks, vacuum pump and bell jar and some chemicals for treating the surface of the wax to elliminate bubbles.
Thanks all!
Matt

Matt

OldDentist
03-29-2008, 06:19 PM
Techtchr,
I have a few more suggestions.
A normal oven will not work well for what you need to do. In addition to melting the wax it is necessary to bring the temperature high enough to burn out residual carbon remaining from the wax. Typically, the mold is brought to about 1300 F, heat soaked for awhile, and then the temperature reduced to 700 - 900 F for casting silver.
It is not necessary to use a vacuum system for investing, it can be done by hand by coating the pattern with investment using a soft brush to carry the investment to the surface of the pattern while it is placed on a vibrating surface and then enclosing it in a casting ring and filling that with the material. Vacuum makes it less likely that you will have bubbles of metal on the surface of your casting. While I was a student I invested many dental castings in this manner on my kitchen table with no problems. For treating the surface you need a method of reducing surface tension. There are debubblizers you can buy from jewelery supply houses or dental suppliers. I suspect that a diluted liquid dish detergent would do the same.
Steam can be used to produce the pressure necessary to force the molten metal into the mold. One needs to form a shallow depression in the ring holding the pattern and use small diameter sprues. After burnout, the metal is melted in this depression and then and then steam used to finish the process. You can make a hand device using a jar lid with an attached handle made from a large dowel which is then filled with packed wet newspaper. This is then brought down quickly over the ring to form steam and seal the opening. More spectacular to an observer is to use a large potato with a cut flat surface instead.
if you are injecting wax into a mold you need to compensate for shrinkage since most waxes shrink 5-10% when cooling from liquid to solid.
For your first attempts you might use sterling silverware purchased at a garage sale. It's the same material you can buy for casting.

Evan
03-29-2008, 07:38 PM
Matt,

In case you are not aware, you can buy what is called "silver grain". It is small beads of silver that are from the spills etc from the foundry and is sold below the market price for bars. It is available in 925 sterling and 999 fine silver. It's ideal for casting.