Prevent Problems by Using These
Glass Cutting Techniques

These glass cutting techniques should help you have success at cutting glass. Sometimes it's just one little thing that can make a world of difference.

Impossible Cuts

There are some shapes that just don't work in glass. Glass likes to break in a straight or curved line. If the piece you're trying to cut doesn't fit into one of those categories, the glass will take the path of least resistance and break where you don't want it to break.

In the following picture, you will see Impossible Cuts and the modifications that will make them work. There are a lot of variations of the shapes shown. For instance, the L shape could also include a V shape since the intersection of the two legs of the L form a V. The half moon shape won't work because of the very narrow tips. Once it's widened out there is less danger of the tips breaking off. That shape could include any shape that has a very narrow tip.

Cutting a Piece That Has a Point

These glass cutting techniques are for cutting a piece with a point. When you cut a piece that has a point, such as a triangle, always start cutting at the narrowest end and run your cutter to the widest end. Break the glass out from the edge you finish cutting on (the widest end). That way, you have a much better chance of keeping the point. It's not so important if you are working with lead came, but it is very important to keep the point if you are using copper foil. With lead came a missing point won't be seen under the lead. Actually, missing points make it easier to lead up a pointed piece. With copper foil, you will have a hole in your panel where the point is missing. So, to recap, always cut from narrowest end to widest end..

Make the Most Difficult Cut First

When you're cutting glass, your tendency will be to do all of the easy cuts, on each individual piece, first and leave the most difficult cut for last. Don't Do It!

On this piece, the most difficult cut is the semicircle. The space above the word "Cut #1" is too narrow for the semi circle to come out without the glass breaking somewhere. You need the extra glass on the other side of the semicircle to prevent that from happening.

If you made cuts #2 and #3 first, here's what would happen:

Not good!

So, to continue, score and remove the semicircle first:

Then make cut #2:

Followed by cut #3:

Cutting Out a Semicircle

Use these glass cutting techniques if you have to cut and remove a semicircle or any other shape that has a tendency to break when you're trying to cut it. I personally would use running pliers to remove any but the tiniest semicircle and most other shapes. There's not much that you can't do with running pliers. You can see how to use running pliers at: Running the Score
You can watch a video about using running pliers at: Running Pliers

If you don't have running pliers, and I would advise getting some ASAP, here's another way to cut and remove a semicircle.

Trace your semicircle on the glass, then draw a series of smaller semicircles within it.

Start cutting and removing each semicircle. Use your breaking pliers to remove them. Garb the glass at one end of the score, with the end of the pliers placed next to the score line, and give it a good wiggle. Repeat this at the other end of the score and wiggle it again. You should hear a click when the score starts to run. Some glass won't give the clicking sound, but you should be able to see the score running. Once you hear the click or see the run from both ends, grab the semicircle in the middle, next to the score line and wiggle some more. Go around the score line doing the same until the glass lets loose and comes out. Repeat this with each semicircle until all of the pieces are out. Sometimes the glass will come out in pieces instead of a full semicircle. Don't worry, that's something that occasionally happens.

Here's the final result:

If you're having trouble with your glass cutting techniques and are having problems with any particular shape breaking over and over again, try a different approach at cutting it out. Let the examples above be your guide. Sometimes it helps to practice cutting it out of window glass until you have the sequence right. There's no sense wasting expensive stained glass when you're practicing. Get it right first, then cut it out of stained glass.

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