MOTHER’s Fluorescent Glass Tube Cutter

By The Mother Earth News Editors
Published on September 1, 1978
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The completed fluorescent glass tube cutter looks something like this.
The completed fluorescent glass tube cutter looks something like this.
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Cut a dowel rod in half and make a groove down the center.
Cut a dowel rod in half and make a groove down the center.
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The cutter in use.
The cutter in use.
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Diagram of the assembled cutter.
Diagram of the assembled cutter.
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Diagram of the wooden handle assembly.
Diagram of the wooden handle assembly.
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Diagram of the steel rod assembly.
Diagram of the steel rod assembly.

The principle of this amazing little glass tube cutter is quite straightforward: A stainless steel wire, which can be heated electrically, encircles the tube. When the current is on, the wire heats and melts into the glass. Then, when the power is turned off, the glowing wire immediately cools, causing the glass to cool unevenly and break apart on the melted “score line”.

You can build your own cutter in about an hour with a drill, some assorted bits, a handsaw, a hammer, a center punch, a tap and die set, a chisel, a hacksaw, a pair of wire cutters, and a screwdriver.

Start by cutting the 1 1/4″ X 7″ wooden dowel exactly in half lengthwise. Then temporarily nail a short scrap of wood to the rounded side of each dowel half and clamp them, one at a time, in a vise so that the flat side of each half faces up.

Now take your handsaw and cut a 1/8″deep lengthwise groove down the center of each half-dowel’s flat side. Then use a wood chisel, carefully, to open one end of each of these grooves into a wider and deeper (5/16″-wide, 3/8″-deep, and 1 1/4″-long) slot.

Next drill four 3/16″ holes through the dowel halves (one hole 1/2″ in from each end of each half). And use a 3/8″ bit to bore two holes (each about 1/4″ deep but not all the way through the wood) into the flat faces of the half-dowels about three inches from their “unslotted” ends and to one side of the center grooves.

Now drill two 5/32″ holes—one 3/16″ from the end and the other 3/8″ from the opposite end—through each of the two 1 1/4″ X 5/16″ X 5/16″ square steel rods. Cut threads into each of these four holes with a 10-32 tap. Then put the square rods—one at a time—into the vise “short-end” (the end with the hole drilled through it 3/16″ back) out and bore a 1/16″ hole lengthwise into each block 3/32″ from the edge, until the drill bit pierces through into the first tapped hole.

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