Circle cutting question

[Terry Gallentine]

While I was looking through information regarding circle cutters that on the market, I came across a supply for circle cutting that I didn't know about and I was wondering if anybody had any experience with it. C.R. Laurence sells an aerosol refrigerant for running scores for circles. They suggest cooling the circle just inside of the score. I have tried running the score with a torch just to the outside of the score but didn't have much luck. Does this cooling thing work?

[Valerie Adams]

What kind of glass are you trying to cut?

I work with beginners; folks who've never cut glass before. By the end of a couple hours' of instruction, they're all successfully cutting circles. I've got good tools for them but no magic potions or sprays.

Can you elaborate on what aspect of circle cutting is difficult for you? I'm thinking with some good instruction and lots of practice (float glass is often free at your local window stores), anyone can easily cut circles.

[Bert Weiss]

Terry, cold does the same thing as heat does, relative to running a score. I was taught to tap once in each spot, enough to make the score run. Once it has run 360º around, I get out my propane torch and run it around the score (on the side opposite the score). The tap starts the break. Heat shock finishes the break. It does this in the shortest possible distance, so I get square edges, not flared edges. Cold does the same thing, but I believe freon is both more expensive and more environmentally unfriendly than propane. My everyday glass is 10mm thick, so the flare factor is a much bigger deal than on 3mm glass.

I tried a few times to make heat run the break. That never went well for me.

I make a special tool for the tapping procedure. I take a cheap flat screwdriver, heat it red hot with propane, then let it cool. This makes the steel softer than tool steel. I grind the flat edge with a rocker, so the tool really contacts at a single point.

So, I make the score, flip the glass, then carefully place my tool exactly over the score and strike it with a hammer just enough to start the run. Then I move it to near the end of the run and strike it again, moving it around, striking only once in each spot, until the run is 360º around. Then torch it over the score. When the snap crackle pop is over, the glass is run from top to bottom.

I do this for 6mm and thicker glasses. For 3mm, I find my thumb is sufficient to get the job done. If I lacked strength or control, the tool would work fine. For 3mm non-transparent glasses, Morton makes a tool for running scores.

[Kathy K]

I agree with Valerie. It takes a little instruction and some practice.
When I first started fusing, I had a terrible time figuring out how to cut out circles-fear being a huge part of it. The people at Bullseye showed me about using the grozing pliers to gently pull out and down a little bit to start the run. There is a lot online about how to cut circles. I use a silberschnitt and it works well. Good luck.

[JestersBaubles]

I wrote a blog post recently about how I cut circles. It is a slight variation of the "normal" way. I get perfect circles nearly every time -- if I have to do anything, it's just to groze off a little chip. If you are interested, it is here:

http://jestersbaubles.blogspot.com/2015 ... rcles.html

Dana W.

[JestersBaubles]

Just FYI, this is a "beginner's post" -- if you are not a beginner, please excuse my ignorance and ignore the post/me

Dana W.

[Terry Gallentine]

This is a technique posting area not just a beginner's site. I have been cutting circles for some twenty years now but I hadn't run into the spray cool technique until a few days ago. That being said, I still run into an occasional problem depending on the glass type or the size of the circle. I assumed it might be a valid question since C. R. Laurence sells the stuff to commercial glaziers and shops. Thanks Bert for the informative response.