After grinding a piece of glass there are always the rough edges left along the tops of the glass. Ive been grinding those down. I turn the piece of glass to the angle of the roughness & grind to make it smooth. Im doing this with the 3/4 inch standard head. Im wondering if this could be my problem for my copper foil always lifting after sodering?? Im a Newbie~ :) Thnx~ Kim~ :)
It could be causing the problem, but there are other reasons for foil lifting.
First of all, don't worry about those rough edges, they will be covered up with the foil. It always happens when you grind.
When you're ready to foil, wipe the edges of the glass with a paper towel and some alcohol (plain alcohol sold in any pharmacy). It only takes a swipe along each edge to get rid of glass dust, left from grinding, and fingerprints. Foil seems to stick better after the alcohol wipe.
Burnish the foil well. Make sure it's pressed down tightly everywhere. If it's not burnished well, flux will get under the foil and cause it to lift.
When you're soldering, don't stay in one spot too long trying to get the solder just right. You can go back and fix it after the solder has cooled. Staying there too long can cause the foil to lift and can cause the glass to crack.
Finally, don't grind unless you need to adjust the piece of glass. I know a lot of people disagree with this concept, but I started working with glass long before grinders were available and I have never had problems with foil not sticking to the glass.
When I teach a beginner class, the students don't even know a grinder exists. They use a carborundum stone if they need to adjust anything. They learn about grinders in the intermediate class. By then, they are so used to not grinding that they seldom use it.
The only thing I always grind is the edges of glass nuggets/gems/jewels. Those edges are completely smooth and foil won't stick without grinding them first.