Circle Cutting

[Robert Cohen]

For the last six months (until this week) I have had great success cutting circles with a Fletcher Circle Cutter and following the cutting method used by Patty Gray.
This week, for some reason, every circle I cut has split! : I am using the same circle cutter, following the same cutting methods and using the same type of glass (BE fusible and Spectrum SG Baroque) that I previously used. Does ANYBODY have any idea what may cause my problem. This is driving me nuts and any help or suggestions will really be appreciated. Thanks.

Bob

[The Hobbyist]

Is it getting dull?

Jim

[Robert Cohen]

Jim. Thanks for your comment. When the problem started I put a new blade on the cutter so I don't think this is the problem. I also changed to a new pair of running pliers. Nothing seems to work.

[Stuart Clayman]

Is your cutting surface different?

[PaulS]

Jim. Thanks for your comment. When the problem started I put a new blade on the cutter so I don't think this is the problem. I also changed to a new pair of running pliers. Nothing seems to work.

Robert, is the included angle of the new wheel the same as that of the original?

There are different included angle(d) wheels for different hardness of glass; as in the Bohle cutters -are there different wheels available for your type of cutter?

[Robert Cohen]

Stuart & Paul.
The cutting surface is the same ... carpet on top of a work bench and as far as I know the Fletcher circle cutter has only one size and angle cutting head.
I am thirty miles south of Tucson AZ where the temperature range at this time of year is normally in the low to mid 70's as a high and mid 40's - low 50's as a low. Recently we had a cold wave where the temperature dropped to the mid 30's to low 40's and the highs were in the 60's. Do you think colder weather has anything to do with my problem?

Bob

[Tony Serviente]

I don't think cold has anything to do with it. I used to store my glass in sub zero temps, haul it in, throw it on the bench, and it cut the same as the room temp stuff. I think the work surface theory is the best one. Did something get under the carpet to add a little hump? Or maybe the cold made your whole bench top warp a little, with the decrease in humidity,that is assuming your bench is made or wood. Double check for flatness.

[Brock]

I don't think cold has anything to do with it. I used to store my glass in sub zero temps, haul it in, throw it on the bench, and it cut the same as the room temp stuff. I think the work surface theory is the best one. Did something get under the carpet to add a little hump? Or maybe the cold made your whole bench top warp a little, with the decrease in humidity,that is assuming your bench is made or wood. Double check for flatness.

I don't know Tony, I didn't use to believe it, but after our frigid sojourn at Urban Glass I changed my mind. It happened to us at Eugene Glass School also. Sheets fresh out of the case, stored in a basically unheated environment ran haphazardly, but if left on the tables for a short while under the powerful overhead propane heaters, they cut perfectly. Brock

[Tony Serviente]

You have inspired me to do yet another test Brock. We have single digits in the forecast for the next few mornings, and I am going to put a couple of sheets outside while their identical twins bask in the comfort of my studio, then do identical cuts and see what happens. Stuff I worked with years ago was Scott glass, which is no longer around, and if I recall, some Spectrum. This will be an apples to apples. Will post results.

[Brock]

You have inspired me to do yet another test Brock. We have single digits in the forecast for the next few mornings, and I am going to put a couple of sheets outside while their identical twins bask in the comfort of my studio, then do identical cuts and see what happens. Stuff I worked with years ago was Scott glass, which is no longer around, and if I recall, some Spectrum. This will be an apples to apples. Will post results.

Great! Everything I have heard has been anecdotal. It will be good to have some level of objectivity. Actually, several of us around the continet should do this. Marty and Bob L. are obvious climatic choices, but anywhere cold will do. Brock

[Bob]

Brock,

In order to properly design the experimental technique it is necessary to limit the number of variables so that the only change is tempeature. The best way to conduct this experiment is to send me complete with a few sheets of glass and my trusty schilberschnitt circle cutter to various warm and cold locations throughout the world. I can see this as an important project that demands investigation. Unfortunately I can not fund this project and support my wife and 25 bedraggled children on my artist's salary. I have set up an account in a neutral country that I believe should be one of the test sites.... Nigeria.

Cheers,

Bob

[dee]

You have inspired me to do yet another test Brock. We have single digits in the forecast for the next few mornings, and I am going to put a couple of sheets outside while their identical twins bask in the comfort of my studio, then do identical cuts and see what happens. Stuff I worked with years ago was Scott glass, which is no longer around, and if I recall, some Spectrum. This will be an apples to apples. Will post results.

Great! Everything I have heard has been anecdotal. It will be good to have some level of objectivity. Actually, several of us around the continet should do this. Marty and Bob L. are obvious climatic choices, but anywhere cold will do. Brock

i have noticed the difference in cutting thick particularly, even here in the "southeast" we get lows in the 20's and 30's, sometimes lower, if i pull a sheet straight out of the case and it's cold, it is more likely to break where IT feels like at that moment than along the score whereas if i warm it in some fashion it breaks along the score - if i have the kiln running i will use that to warm the sheet or my radiant heater, whichever is providing heat to the studio at that point - this is be glass btw...
D

[charlie]

You have inspired me to do yet another test Brock. We have single digits in the forecast for the next few mornings, and I am going to put a couple of sheets outside while their identical twins bask in the comfort of my studio, then do identical cuts and see what happens. Stuff I worked with years ago was Scott glass, which is no longer around, and if I recall, some Spectrum. This will be an apples to apples. Will post results.

you need to do the tests with pieces of the same sheet, as different sheets will probably have different cutting characteristics unless they came off the line pretty closely together.

[Marty]

Great! Everything I have heard has been anecdotal. It will be good to have some level of objectivity. Actually, several of us around the continet should do this. Marty and Bob L. are obvious climatic choices, but anywhere cold will do. Brock

I hope you meant the other Marty- I ain't goin' outside to cut no glass!

the original Marty

[Brock]

Great! Everything I have heard has been anecdotal. It will be good to have some level of objectivity. Actually, several of us around the continet should do this. Marty and Bob L. are obvious climatic choices, but anywhere cold will do. Brock

I hope you meant the other Marty- I ain't goin' outside to cut no glass!

the original Marty

I meant you! Just leave some glass out overnight, and cut it inside the next day. Brock

[Tony Smith]

I'm in. I need to cut some squares for the maglesses, so I'll be doing a bunch of cutting this afternoon. It's 20° in the garage where my glass is stored. I'll cut the sheet in half and bring half of it into the studio where it is about 65° and let it warm up while I cut the other half sheet into little squares in the garage.

When I was cutting in the garage the other day, I noticed that I couldn't run a straight score without a lot of effort. Usually, I can snap the Spectrum without any effort. I had to use running pliers to get a straight run.

I'll provide an update later this evening.

Tony

[Barbara Muth]

Brock,

In order to properly design the experimental technique it is necessary to limit the number of variables so that the only change is tempeature. The best way to conduct this experiment is to send me complete with a few sheets of glass and my trusty schilberschnitt circle cutter to various warm and cold locations throughout the world. I can see this as an important project that demands investigation. Unfortunately I can not fund this project and support my wife and 25 bedraggled children on my artist's salary. I have set up an account in a neutral country that I believe should be one of the test sites.... Nigeria.

Cheers,

Bob

ROFLMAO!

You are too funny Bob!

Barbara

[Bert Weiss]

As I have posted before, my experience matches Tony Serviente's. I can cut subfrozen glass. Unless it is so cold that glass cleaner freezes on it. The glass does have to be clean. I am, unlike Brock, cutting float.

I once spoke with Don Abel from Morton, who is a glass cutting "expert". He told me that there is a theory that glass is difficult to cut during quickly falling barometric pressure. Low pressure is not the culprit, falling pressure is.

Another experience I have had is putting a large sheet on a bench and having the cut run off. I discovered that the bench was very slightly bowed down. This created enough tension pressure to ruin the cut.


Some days you cut the glass. Some days the glass cuts you.

[Tony Smith]

Other than my hands being so cold that I couldn't feel my fingers, there wasn't a noticeable difference between cutting System 96 cold or cutting at room temperature. It was 17° in the garage and about 64° in the studio. I used the same Boehle dry cutter cold and warm, the same sheet of glass and the only runout I had was warm and was due to the way I made that particular score. Total cuts wer about 20 cold and 14 warm.

Not statistically significant, but a good first order test nonetheless.

Tony

some days you cut the glass, and some days your fingers are so cold that the blood won't run out....

[Tony Serviente]

I've been pondering this, and I could tighten it up quite a bit. I'll use a sheet of float cut in half. Float for it's uniformity of internal stress, the same sheet so I know it is from an identical run. Next would be the cutting itself-The outside sheet would have to be cut outside to maximize the differential, or else it may warm sufficiently to minimize any possible effects. The inside sheet should be as warm as is possible to handle, for the previous reason. The cutter wheels should be out of the box, as the possibility exists that with the first cut, the wheel is damaged or dulls sufficiently to give a poor cut on the second sheet, negating the results. The person cutting must not know which sheet is which, as it may cause them to skew the result to accomodate their favorite. This means isolating them so they are unaware of their surroundings to the extent that they cannot perceive the difference between inside and outside. For the purpose of my experiment, I could either consider neurosurgery, a costly and perhaps irreversible solution that may have negative ethical implications, or get them drunk. A sufficiently advanced state of inebriation may cause the necessary spatial and thermal disorientation, but will most likely render them unable to hold a glass cutter. Besides that, what about the controls, and the number of samples, and the statistical analysis! The more I think about this, the more I realize this is the tip of the iceberg. I think I smell an NSF grant in this...