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Terrible Night Of Glass Cutting

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#1 Michael


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Posted 14 September 2016 - 08:45 PM

I guess it was just one of those nights, I broke quite a few pieces tonight. I am still learning so any suggestions is appreciated. The first couple I broke were to 1x10 strip in a row and it ran off right as it got to second piece. Should I not try to go 20 inches with one cut. The happen twice but the other set wasn't that long. So I went to get the giant piece 32x32 to cut a twelve inch strip off of it to make up for the glass that broke. I scored it and slide it to the edge of table to break off and it splits off near the middle leaving me holding a piece in each hand.....urggggggggg. Quit for the night and hope it will be better tomorrow.

#2 Tod Beall

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Posted 15 September 2016 - 08:04 AM

We all have those nights; have faith that you'll do better next time. ;- )


A 20" strip 1" wide can be difficult to break, especially if the rest of the sheet is comparatively wide. It's generally easier to divide long pieces in half - more or less. That's not always practical, of course. This is a time for good running pliers and a gentle touch.


My suspicions are: you're pressing too hard on the cutter and/or you're not running the wheel properly along the straight-edge. I mean that it's not rolling parallel to the guide, that it may be slightly cocked.


When breaking that 12" piece off the 32" square, you might consider beginning the run at each end with running pliers before you bring it to the edge to snap.


Be careful, too. And remember to have fun!

#3 Mt_Top



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Posted 15 September 2016 - 08:44 AM

Some glass cuts like butter, other glass cuts like a bag of rocks.  Tod's tip on using running pliers from both ends is great.  Often doing that, both ends can be wiggled up/down a little, but the middle is still solid. At that point using grozing pliers on the middle piece (starting from both ends, working towards the center) can work for narrow strips of glass.  Another thing to try is putting a ruler or yard stick under the glass, lining up the rulers edge with the score line, then gently press down on both sides of the score line to finish the break.  Sometimes snapping a thin piece along the table edge uses more force than necessary. 

#4 stargazer99


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Posted 15 September 2016 - 10:39 AM

I like to do a little light tapping on the underside of the score first.

#5 GlassVaMts



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Posted 18 September 2016 - 05:23 PM

Good advice from all so far. Are you using a running plier to cut the strips? Do you adjust the screw on the pliers for the glass thickness? Many people DON'T do this! Did your score look and feel ok - or was it not quite normal?

#6 collswill



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Posted 21 November 2016 - 03:59 PM


I am a professional stained glass maker and material supplier.Originally I also have worked for a major flat glass company. I have over 40 years experience so I hope I can help. Glass cutting is a recognized profession and it can take many years to learn to cut properly. Never press to hard. Always try to find the minimal amount of pressure to cut the glass. Having cut glass every day for many years I can see, hear and feel whether I have cut the glass correctly. This will only come with experience. Having taught glass classes the most common fault is the failure to hold the glass cutter at 90 degrees to the glass. sloping the cutter towards or away from you is not a problem but the instant the cutter is not held perpendicular to the glass results in a poor cut.Most people will hold the cutter upright but not realize that it is not completely upright, Their technique and grip can be wrong. The correct way to hold a glass cutter is between the first and second fingers but most people hold a cutter like a pen. Usually the most comfortable way is the best. Never press to hard. If the cutter is in the correct alignment pressure doesnt become an issue

Also certain glasses are harder than others. Reds and particularly vivid yellows are harder. Remember that coloured glass will not cut like clear float glass. Clear float can be cut and run with the fingers. It has been manufactured and annealed to make it that way. Coloured glass contains many imperfections and needs to be broken over an edge to ensure a proper break. Even an excellent cut on coloured glass will not always break properly when being broken with cut runners.

I hope this helps. If you have trouble cutting ask someone to watch you and see if you are holding the cutter in a perfect upright position as it is not always obvious to the user

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