This is a brief outline of my lost wax casting technique. There are several ways to cast, this is just the way I do it as a one woman show!
You can view a lot of my finished work at http://bcyrjewelry.etsy.com
To see more tips, techniques and musings check out my blog - http://bcyrjewelry.blogspot.com
I use all sorts of random tools for my wax working. Most importantly, my fingers, and a tiny needle in the end of a pencil! I also made a little denatured alcohol lamp out of a baby food jar. The wax I use most of the time is a soft brown wax. Its my favorite.
You can view a lot of my finished work at http://bcyrjewelry.etsy.com
To see more tips, techniques and musings check out my blog - http://bcyrjewelry.blogspot.com
I use all sorts of random tools for my wax working. Most importantly, my fingers, and a tiny needle in the end of a pencil! I also made a little denatured alcohol lamp out of a baby food jar. The wax I use most of the time is a soft brown wax. Its my favorite.
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http://www.instructables.com/id/Lost-Wax-time-lapse-silver-casting/
If I wanted to cast multiple copies of an item can I use silicone rubber moulds to cast multiple wax masters?
I've tried pouring carving wax (not decent jewellers wax though) into a mould and it was far too thick.
Each metal has a conversion factor - the "specific gravity".
I use this chart on the H&S site since there is where I buy my metal.
Standard nickel white gold in 14k is 12.7. Which is different than 18k or palladium white gold.
https://beta.hooverandstrong.com/casting-grain-specifications
There is also a phone app I have that does conversions called iMakeJewelry.
Multiplying the wax weight by the specific gravity will give you the metal needed for the piece. Then you need to add extra for a button. My buttons for gold tend to be a lot smaller than sterling - especially with vacuum casting - generally around 4 - 6dwt depending on the size of the piece.
Hope that helps!! Let me know if you have any other questions!
Guess I don't know how to get my info to ya......Any suggestions?
Don
Don
Thanks for any advice you can offer!
It really depends on the metal that you're using as well as what areas might be thin, so it is a little hard to just give a simple answer. I personally wouldn't go below 18g (1mm) for sterling, although some areas could be thinner. My rings are usually between 1.5 - 2mm. If there are some thicker areas and some thinner areas, you can make sure to sprue appropriately to make sure the metal casts all the way. so if you have a thicker band and some small thinner details on top, that would cast fine as opposed to a thin band and even thinner details.
No, there is no hole in the mold. Some people use a wax web around the inside of the flask - so when the wax burns out there is a web of holes that allows the vacuum to pull better. i think that may be useful for larger flasks... i use pretty small flasks and the wax webs just weren't worth it for me. The vacuum just creates suction and slight porousness of the investment is enough. I'm always kind of amazed that it works!
If the investment didn't set up properly or there was not enough investment between the negative space of whatever you're casting and the top, the vacuum can pull a chunk off the mold. It is important to leave about 1/8" at the top of the flask, allows for better pull.
hope that helps?
I are beez confuzzled, you make the mold using wax positive and some kind of plaster (investment?). I understand you suck the air out of the plaster while it is wet, then bake out the "wax" , but how does one get a vacuum to stay that way when you pour in molten silver? or does one do it real fast and then bell jar it and suck air? The mold being so hot the metal does not solidify while you pour, ALLOWING the bell jar to be used with vacuum, after the monolithis pour, (no dribs and drabs)?
sorry if I am too dense for this. I want to cast a few simple shapes out of silver soon and this looks cool. May I also ask does "investment" material have less of a "shrinkage", Or none perhaps when compared to plaster of paris?
I think I need a primer on this !
The vacuum for the casting part does not actually use the bell jar. The vacuum has a toggle switch that changes where the vacuum pump pulls from - for investing it is through the bell jar and for casting it is through the table. If you look at the image #15 - right above my hand you can see the hole in the rubber mat and table. The vacuum creates suction through the investment and pulls the metal in to the fine details once the pump is turned on (it is actually turned in before the metal is poured b/c yes, the metal cools extremely quickly)
There is a tiny bit of shrinkage, though not very much.
Is the vacuum system good for casting liquid resin and epoxy goops as well? I know all the non understanding on my part is due to total lack of knowlege.But I would like to make a few item and any info I read first will help in the end.
thanks
I would definitely not use a regular oven for a couple reasons - one is that I usually burn out up to 1300 degrees. For the investment I use, the kiln needs to get much hotter than 500 - sometimes it only goes up to 1150 if I'm casting stones in place.
There might be types of investment that are formulated to cure properly at lower temperatures? I've never looked in to it.
The other thing is that the wax fumes are pretty toxic and I wouldn't want the wax burning out in an oven that was in a house or would be used for food.
You can use any kind of wax and even burn out natural materials and some plastics. (again, that can be pretty toxic too) I have friends who experiment with all kinds of things - some work and some don't.
hope that helps!?
Chris: cc_tazman11@yahoo.com Owner Mad Scientist's Laboratories & Cavender & Kin Jewelers
OOps! also if you want to reproduce almost anything plastic in metal IE: tin or plastic soldiers, you can sprue them up and gate them for better flow but you will need a high temp burnout!
Bravo!!
It seems that those Tables are kinda expensive? Do you really need one like this or can you use an vacuum former used for plastic or a bell jar? also where did you get yours?
thanks :)
How do you create a seal between the vacuum table/machine and the flask during casting? Looks like maybe a special gasket of some kind, is that right? It looks like there are rings burnt in the surface from previous castings, implying that it might be something that wears out with repeated use and gets replaced. If so, can the gasket be purchased separate from the device?
I have a vacuum setup for resin casting, and it would be super simple to DIY a benchtop unit like that for use with the same pump, if I could figure out or source a seal that could take that kind of heat.
We used a vibrating table and centrifugal caster. I ended up with a few bubbles in between the stems, but they looked like puffballs. :-)
-m
unfortunately, I have no tip on having the investment go in to the table/hoses etc... and am quite fearful of that happening! well, more terrified of having the metal go straight through... the only time i had the top of the investment come off was a HUGE wax that i knew was risky and only had about 1/4" of investment above the wax. I would say just make sure that there is plenty of investment above the piece. I normally have between 1/2 and 3/4" above the wax - particularly if the wax is large and creates a large open area.