Well...what a week! I've been trying to get around to this tutorial for days but as usual work and life got on top of me! January is supposed to be a slow month but the opposite has proven to be the case this year. Let hope things get back to normal soon! I'm working on a great new range of dichroic glass jewellery, I'll have pics next time!
Anywho.. First things first!
Glass donuts are easy to do but ...as with so many things in life, you need the right equiptment!
For my version you will need-
A drill press....you can buy a reasonable for £30/$60, nothing flash!
Diamond core drill...2 sizes, one around 35mm and another roughly a half to a third the size, around 14mm
This method is great for using up all your scrap/mis-shapes and the great thing is that it's a great way of recycling because not only can you make dichroic cabs whilst you're making the donuts but the scrap you make can be used again to make more donuts.
Firstly you need to fire a slab from which you cut the donuts. I use hot damz and arrange them in a square. If you're not familiar with them, they're kiln furniture you can use to build dams to control the thickness of pieces as they fire.
Fill the square with scrap but don't over fill. You want the fully fused slab to be around 1/4 inch thick, any thicker and the fired donut will lose it's shape. If you're using dichroic glass scrap try and keep the dichroic layers all facing the same way to avoid them 'repelling' each other as they fire. A good tip is to use either clear or transluscent glass along side the other scrap, it give the finished piece real depth! You can simply use layer dichroic glass if you wish...4 layers of 2mm is about the thickness you should fire.
Fully fuse your scrap slab and don't try and skip the annealing stage. the slab will be subject to heat later on in the manufacture so you want the slab to be as stable as possible.
Arrange your drill press on a level surface and make sure the surrounding area is covered to protect it from water splashes.
Set up the drill with the larger of your diamond core drill bits.
These are usually used by plumbers to cut through marble or granite worksurfaces so work well with glass.
You're best to put something over the base of the drill to drill onto, and old towel or piece of carpet works well. Also, have to hand a water bottle in order to cool the drill bit as it's working through the glass. Wearing both your protective gloves and glasses drill the glass with the core bit, making sure the drill is set to a fairly high speed other wise you'll simply blunt the dimond coating. Keeping the drill bit cool as you work with the water and don't try and 'force' the drill otherwise you'll leave the cut glass uneven. You should be able to quite easily cut a circle through the glass. It doesn't if the cut piece is even...a minute or two with the grinder should see to that.
Next step is to fit the smaller sized bit. Work out where the centre on the cut glass circle is and line it up with the centre of the bit. Cut through the glass making sure your wearing the gloves. At the this stage you need to work slowly! If you try and rush things now it'll simply crack the donut and you'll be swearing like a marine.
Carefully wash your cut glass and fully fuse! When you fuse ground glass, drilled glass etc slowly ramp the kiln up to full temp to remove the marks left by the diamond coating.
Here's one I made by simply stacking 4 layers of glass....rembember, the thicker you make the initial slab the less control you'll have over the finished piece.
Hope that clears up a few queries...leave a comment if you have any questions etc..i'll try and answer ASAP
It's late...so i'm going to bed. Forgive the grammar if it's bad, my tired eyes can't cope!