Five-finger exercise

Cynthia reviews the Bohle Circle Cutter (lens cutter)

>>>>Five-finger exercise

circletraysunJust got out of Kirstie Rea’s class, where we discussed how the medium influences the art, i.e., since glass has transparency, transparency becomes a significant part of the work. It’s one of those “duh” statements that seem obvious on the face of it, but have a much deeper meaning when you think on it awhile.

Nowhere, however, did we discuss how the available tools influence the art, something I experience on a regular basis. Kiln size, the presence (or absence, in my case) of a sandblaster, excitement over a brand new mold…all that stuff can have a strong influence on what’s coming out of your studio.

circlecutterSpeaking of that, I’m afraid my work will take a “turn” because I’ve used my Bullseye class discount (sigh) to pick up a Bohle repetitive circle cutter, AKA lens cutter.

Here’s what it looks like:

I got it for the next step in my Watercolors series of glass panels (one of which, a tryptich, is just to the left in this picture), probably overkill but I get REALLY tired of almost cutting out baby circles and then having to shape them on the bench grinder.

Wasn’t sure it would do any better than the Silberschnitt I already have but I was desperate…and I had a discount card.

I also knew that I needed to practice before turning it loose on the real piece, so I set myself down Thursday night and started cutting scrap. After a few false starts (pre-lubricating the circle and firm, continuous pressure figures heavily in getting something that actually looks like a circle), I was very pleased with my ability to cut circles about the size of a US dollar.

cutcirclesI didn’t have a lot of difficulty with cutting inch-diameter circles, either, and even messed around with half-inch, although those were a lot harder in 3mm glass.

Not a whole lot of chips or dings, and with thin glass, especially irid on black, the cutter worked so well that it was almost (just almost) like popping them out with a hole punch. 3mm takes a lot more concentration; 6mm requires significant tangent cutting, tapping and finally grinding so I didn’t really see the advantage of using the cutter.

Overall, though, not bad. The circles were reproducible, enough so that I can stack up to five at a time through the grinder for smoothing. Zip, zip, zip.

It’s pretty easy to operate the cutter–you just cut a strip of the right size, slide it into the unit, press down the handle and give it a full turn. Then you slide the glass along the cutter’s platform to the next blank space, and repeat.

circlecuttingIt makes a relatively fine score which can be tough to see with transparent glass, so I slip white paper between the glass and the tool’s black stand.

It’s also difficult to exactly line up the cutter head with the right spot to avoid waste, but not that big a deal. I suspect with a little bit of thought I can use the gauge on the tool to increase my accuracy, but the multi-lingual (and not all that well translated) instructions that come with the thing aren’t very forthcoming on how you do that.

circletrayThe hard part, though, isn’t the scoring, it’s the breaking. I’ve got a pair of Silberschnitt breaking pliers that make running light scores much easier than my older duckbeaked ones, and I cut plenty of relief lines into the scored glass. It’s the relief lines that save your bacon–by scoring three or four lines around the circle, from the circle out, tangentially, to the edge of the glass, you give the stress a place to exit before the glass breaks in the wrong place.

In the end (and after the first five or six failures), out of 80 or 90 circles I only broke one.

Of course, all that practice left me with a whole BUNCH of glass circles to deal with. I’ve got an informal class coming here on Saturday to play around with fusing so I thought about saving them for that but, heck, I can always make more. So I’ve started laying them up in a shallow tray.

circletraydoneI think I’m going for a light tack fuse with this one, want to preserve the texture even though that means I wind up with a non-functional piece.

And, naturally, I ran out of circles so in order to finish this I’ll need to cut about twice this many.

Later: Here’s the finished piece. It’s too fragile to give to someone, but the color blends when the sun hits it are kinda spectacular. I’m going to figure out a way to mount it on a white wall so I get nice transmission patterns.

If anyone wants a cutter, Bullseye and sells it for the mid US$300s. There’s what appears to be a far more expensive version available for the glass industry (Sams Glass sells it for (ulp) $1,347 which I hope is a typo). People who use a lot of small circles will definitely appreciate one.

2016-05-15T13:18:21+00:00

2 Comments

  1. Cynthia May 20, 2013 at 8:06 pm - Reply

    I’ve done that several times with the Bohle lens cutter although I’m not sure I could claim to be able to do it every time. It will indeed pop out the circle as you’re finishing the score, as long as the glass is what I call “easy-cutting,” i.e., it’s thin, probably transparent or black, and quite likely iridized.

    I’m not sure what it is about irid, but on irid this thing cuts absolutely straight, perpendicular to the face of the glass and no chipping. You score on the irid side and just lightly press…out it pops.

    3mm French Vanilla? Forget it–you will be making relief cuts. 😉

    In fact, the more I’ve used this thing, the more I actually thing the “-and break” is a liability–it’s very easy to press just a tad too hard while you’re making the score and break out part but not all of the circle. Getting the right amount of pressure takes practice.

  2. Valerie May 20, 2013 at 6:30 am - Reply

    Hi Cynthia; I was glad to see this post (and save it!). I bought this cutter a few years ago, tried it for an hour, and packed it away to collect dust. I was at Bullseye the other day and asked about it. Camille told me that it “scores and runs the circle at the same time when used correctly.”

    I’m going to ask for a demo next time I’m there, but I wondered if you’ve experienced this?

Comments welcome! (thanks)

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