Casting confusion

[jpo31]

Hi! I am hoping to get some advice re casting. I don't understand the process fully, so I am a little confused.
I had made a wax ring in size N. I took it to a caster and he cast it into silver and I was happy with it. So I asked for 30 of the ring to be made which he did. I then asked about different sizes. So he made me wax models in 1x K and 1x Q as a favour but has said that I will need to make the model myself each time I want the different sizes cast. I asked if I can just get multiples cast from one wax model but he said no as there will be shrinkage. But then he had already cast 30x for the original N?! Can anyone tell me if this is right? I find it hard to believe that you have to make a wax model for every ring.

[ps_bond]

The casting process reproduces what you provide and nothing else - each different size might as well be a different design. If you want different sizes you'll need to either provide different size models to cast from or cast one size and resize as needed (or use a separate shank & head, perhaps). Depends on the design which is most appropriate.

If your caster is making additional wax models for you, is he resizing the original design and making moulds from that, perhaps?

[jpo31]

Thanks for your reply. Yes, he had made two resized models of the original design. However I understand he is saying he can only make 1x ring from each model. I am looking to get around 50x in the various sizes he made. I guess my question is, how is this done? It will be very time consuming to make 50 wax models of the same size ring!

[josef1]

the fisrt one is cast and polished then a mould is made from this its called a master and copys can be made from that by injecting wax into it but they will be smaller than the master as you have 2 lots of shrinkage to contend with.The master has to be sized to allow for the shrinkage of the full process. sometimes a sizing part will be built into the ring so you only need a few moulds as you can size the ring up and down a few sizes, depending on the design. Also you can size the injected wax model a certain amount

[jpo31]

the fisrt one is cast and polished then a mould is made from this its called a master and copys can be made from that by injecting wax into it but they will be smaller than the master as you have 2 lots of shrinkage to contend with.The master has to be sized to allow for the shrinkage of the full process. sometimes a sizing part will be built into the ring so you only need a few moulds as you can size the ring up and down a few sizes, depending on the design. Also you can size the injected wax model a certain amount

OK, Thank you! I think I've got it. So essentially if I make a mould slightly bigger than the size required, the master will be the right size. And from that master, he will be able to make multiple copies of the ring. It will not keep shrinking?

[josef1]

Yes from the mould of the master, but the copies will all be the same size this shrinks again because your making a wax copy for the second time. most of the shrinkage is in the wax injection.