Melting Bullseye to a pre-determined size - No mould method?

[Barnacle Bay]

Hi Folks,

I am wondering if there is a method or rule of thumb when melting bullseye to finish up at a predetermined finished size in a kiln, i.e want a finshed pendant to end up at a specific size like 25mm x 25mm, without using a mould, which will fit into a pre-made bezel/cab setting?

I am asuming it will depend on the thickness of the glass and size cut, but I am also wondering if there is a expected expansion formula to the pre-cut size?  

Thank you in advance.

Lou

[Hamilton Taylor]

A chunk of glass in the kiln, taken to full fuse, will form a puddle about 6mm thick. This is due to the surface tension of the molten glass.
If you want a specific design, arrange your glass so that it is consistently 6mm thick, and it should fuse 'in place', changing little as it fuses.
Unfortunately, absolute accuracy is not guaranteed, so a little coldworking is often necessary if you want to fit a pre-made bezel.

There is no expansion to take into account - you end up with the same volume after fusing as you had before.

Sean

[Barnacle Bay]

Thank you ever so much for that Sean, but could you explain coldworking  - is it allowing the kiln to cool inbetween the fusing/heating process?

[Hamilton Taylor]

Sadly not! It's using grindy-things such as diamond pads and dremels to shape, clean and polish glass.

Download an overview here

Sean

[Nicknack]

Cold working is grinding, smoothing and polishing the cold piece after it's come out of the kiln.  A bit like lapidary (stone polishing).  if you follow Sean's instructions you shouldn't have to do much, and probably wouldn't need to polish the bits that would be covered by the bezel.

Nick

[Barnacle Bay]

Sadly not! It's using grindy-things such as diamond pads and dremels to shape, clean and polish glass.

Download an overview here

Sean

SUPERB replys - thank you again    I do have Dremels & Grindy things thanks to hubbys vast emporium of gadgets!

Oh No - Link not working Sean  

[Zeldazog]

Modified Sean's link, it should work now.

[Barnacle Bay]

Modified Sean's link, it should work now.

Yes it does thank you for fixing it 

[Flyingcheesetoastie]

  Just stealing that link for future student handouts....

[Barnacle Bay]

Just stealing that link for future student handouts....

Good bit of info - I just need to find out about fine grade kit for our tumbler that has been sitting idle in the garage - I feel it may now come in use 

[Hamilton Taylor]

Oops, sorry about the link, I was in a rush...