Smart crucible

Jewelry Discussion
1

i would like to ask if anyone out there has tied to adapt a pyrometer
to a hand held crucible for torch melting?

best regards goo

2

Hi Goo;

i would like to ask if anyone out there has tied to adapt a
pyrometer to a hand held crucible for torch melting?

I can’t imagine how you’d do that. You’d pretty much need to have the
probe right in the metal. Maybe you could get an optical pyrometer,
you know, the kind you aim and read through an eyepiece. Mount it so
your hands would be free and you could hold the crucible under it.
But even this would be unreliable. You’d get reading from the surface
of the metal or the torch, not getting an accurate reading of the
metal temperature. I think, if you need that kind of accuracy, you’re
better off with an electromelt.

David L. Huffman

3

Goo,

I haven’t but my first thought would be a stand holding an optical
pyrometer a couple feet away. Probably not as accurate as an
immersion one but the consumables are lots less. In the distant past
I tried to keep well shielded immersion ones alive in an induction
machine, very expensive proposition, I switched to just eye balling
the temperature.

I’d hate to think of the destruction possible from a moments miss
direction of an oxy torch even on a quartz sheath

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

4 
i would like to ask if anyone out there has tied to adapt a
pyrometer to a hand held crucible for torch melting?

Yes, I have… What you will find is that if the Thermocouple goes
into the top of the crucible, It gets affected by the Torch flame
hitting the thermo-well no matter what the thermo-well is made of.
This gives you faulty readings… You could play around with this
idea and get frustrated… You could drill a hole into the bottom or
side of the crucible and you will end up with the crucible
temperature… Then have all the fun of connecting the wires in a
manner that won’t allow them to break.

What are you going to do when you change Crucibles for different
metals ? If you are not changing crucibles for each of your metal
alloys, your metal will not be the correct Karat and will suffer cross
contamination.

Optical pyrometers won’t help much as the flame from the torch will
give the wrong readings.

If you could heat the crucible from Underneath, then, you could use
a thermocouple in the top…

But… the side effect of this is that you will use a massive amount
of gas/ oxygen and the entire process would be a royal pain. Again,
you would need a different thermo-well and crucible for ea. metal.

With torch melting, you don’t need to read the temp… you need to
pay attention to how the metal melts, when the metal is nearly ready
and anticipate having the flask on the casting vacuum table or
centrifugal machine at the correct time. For Vacuum casting, you want
the metal to have just melted when the flask is put on the Vacuum…
Bring the crucible over with the torch on the metal… sprinkle some
borax to clean the surface… now, the surface should look like a
mirror and it’s ready… Pour it !!!

Daniel Grandi
http://www.racecarjewelry.com