I have the running pliers (I occasionally do foiled and leaded glass
work). For a straight cut, of say 2" or greater, I still find using
just my fingers or snapping the glass over a straight edge easier.
The ball end glass cutters are very common, but there are lots of
choices and many of which don't have the ball. The ball is an attempt
to make the tool one size fits all - a multipurpose tool. For cutting
small curves, the ball end can be useful for tapping to propagate the
crack. That shouldn't be done on mirrors as it could damage the
If you've ever been in a commercial glass shop, you'll see that the
guys have a carpet covered table and snap the glass over the edge.
It's way faster and less likely to have the glass break due to an
imperfection that you'd never see. The microscopic imperfections are
the weak points in the glass. Tempering is just a way to let the
molten glass fill in those surface imperfections - that's where all of
the increased strength comes from. It's not special glass.
Whether the glass is thick or thin, the same uniform score is
sufficient. If you've ever seen the 1" thick glass used in some church
windows, that's how it's cut. They score it, pick it up with a hand on
either side of the score line and drop/push it down over a hard plastic
edge. It breaks just about as easily as the standard float glass you
have in your window.
To propagate the break along a score line glass artists (like myself -
I do stained and leaded glass work) use running pliers, which are
basically pliers with a curved mouth or ridge in the middle of one jaw.
Gentle pressure is all that is necessary.
Another technique is to put a wood dowel under the score line and snap
the glass over that. There are many techniques for glass, and everyone
will swear that their system is the best. Basically it boils down to
trying different techniques until you find something that works for you
and gives you good, repeatable results. That's when most people stop
trying different techniques because they've found the "perfect"
I'm surprised you didn't mention, the glass has to be clean and you
lub the cutter with mineral oil. ;-)
I like the pistol grip cutters with the resivoir in the handle.
I am not an artist yet but I do stained glass too.
I cut on heavy cardboard, over a very flat counter top.
sections 3,4,5 of <http://www.warner-criv.com/techtips/tools.aspx
I used a lighter fluid (heptane) & WD-40 combo for lube..
I used a level on "spongy fabric" as a straightedge after measuring offset
of spinning wheel center to edge. The ~1" thickness of the level guided
the 1-3/8" high flat edge of the cutter along perfectly perpendicular. I
would recommend this orientation. Held it at 90 degrees and pulled toward
me. The balled handle had a flat. Started 1/8" in from edge, and finished
pulling through, which did leave a 1.5mm chip, which will be hidden.
Looked with magnifying glass and couldn't see the score line after one score
(I thought of lifing 15 lbs. off ground)
Used a plywood sandwich on TS edge, and gloved hand in center of waste about
3" away (at end) and it snapped apart perfectly.
You should always start and finish the cut right to the edge. Just let
off on the pressure a little so you don't blast a crater. The cutting
wheel is round so the cutting force isn't affected by an angle (math
freaks, yes, thanks, I know about vectors) - no need to hold the cutter
at an unnatural angle like 90 degrees. Lean it back some so it's
comfortable then push or pull as is your preference. There was no
need to make the plywood sandwich, it would have broken cleanly without
it on the edge of the table.
Glad to see you had success on your first outing. Keep going.
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