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Just finished a pour.

Posted: Tue Mar 26, 2019 7:16 am
by caedmon
Taking a new mold for a test run.
stars.jpg
stars.jpg (193.15 KiB) Viewed 19949 times

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 7:26 am
by theowl
Awesome

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 9:48 am
by Iodo
Nice work, love it :P

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 10:33 am
by Elleth
Oh my word - those came out incredibly!

I thought your design was amazing as a drawing - they're spectacular in real life! :mrgreen:

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 4:56 pm
by Harper
Very nice!

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 6:15 pm
by caedmon
Elleth wrote:Oh my word - those came out incredibly!

I thought your design was amazing as a drawing - they're spectacular in real life! :mrgreen:
I didn't say this last night, as I was tired and not thinking.

The model for this was a collaboration, Elleth did the 3d model and print for me. And I am very happy with it.

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 6:43 pm
by Taurinor
Those look amazing! What type of mold did you use?

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 9:53 pm
by Udwin
Wow is right - those look spectacular! Great job Elleth and Caedmon. I would also like to know more about the casting/molding process. And how big are they??

Re: Just finished a pour.

Posted: Tue Mar 26, 2019 10:23 pm
by Elleth
Oh, the work of it was all caedmon - I just did some extrusions of the vector work he did.

I was gonna ask about the size to: I remember once upon a time when I sent the model, caedmon you said they might be a little big?
Shapeways has long since totally botched their creation UI, but I think I can still find the re-scale option to get you another if you think that would work better. I'd just need to know the longest dimension.

Re: Just finished a pour.

Posted: Wed Mar 27, 2019 4:07 pm
by caedmon
The brooch as shown is 3 inches to the tip of the star's rays which is what I asked for, but feels large when you have it in hand. This is smaller than a large penannular, but is so bulky that it feels quite big.

I'm not certain what size would be better. Tinkering with the unknowns is the hardest part.

I asked for Elleth's help because I was using TinkerCad which wasn't up for the job. Since getting the model I've gotten a new computer and have moved to Autodesk Fusion 360, which is much more powerful; allowing for things like chamfers, fillets, draft, and lofting. (ways to add rounded edges & angles, better for mold release)

Re: Just finished a pour.

Posted: Wed Mar 27, 2019 4:07 pm
by caedmon
For molds I take a few paths.

Most of my casting right now is pewter, because I don't need a complex furnace for it. Most people think of Pewter as a lead/tin alloy, but it's any mostly tin alloy. I tend to use britania metal, a tin/antimony/copper alloy at a 92%/7.5%/.5% ratio.

For situations where I need to demonstrate historic technique, I have a 100lb soapstone boulder that I have been chopping up for a few years. Soapstone has excellent heat resistance, and I have done upwards of a hundred casts from a mold without substantial degradation. Soapstone molds are carved in reverse and it's very easy to mess up details, especially when attempting lettering.

For most other situations, I use high temperature rubber molds (Smooth-on Moldmax 60). In these cases I make a model first. I have usually made them out of wax (I've also used copper and antler), but recently have started using 3d prints which have allowed me to get much greater precision. The mold material is mixed and poured into place.

When I have done silver or bronze, I do an investment mold. Here you make a wax model, coat it in a ceramic slurry, and then melt the wax out/fire the ceramic. The metal is melted in a furnace, and the investment mold is also heated so it doesn't break when the 2000+ (farenheigt) degree metal is poured in.