String (Saw) Theory

There's a limitless number of cutting tools in the world; many are common and well known, while others are far less known even if they're the best tool for the job.

Cable saws have been a thing for as long as I have memories. Some have been decent, and many have been complete garbage. In the 1980s and 90s they were part of the Rambo cool-guy survivalist hardware despite being terrible. More expensive models from major tool manufacturers hold up and perform well. Despite the quality of the products offered, the principle is sound and friction saws have a place, though it's more limited than most sellers would have you believe. While they can cut through something like a tree branch, it's a slow process, but where they really shine is cutting soft materials with bad access... and you don't even need a commercial cable saw to do it.

A couple of weeks ago at work, we had a PVC conduit in the ground that we needed to cut. It had wire in it that we couldn't damage, and the conduit was in a place where we couldn't get a normal saw around it to finish the cut. Fortunately, I had a roll of string in my tool bag. String easily ran where a saw blade couldn't, and it's also sensitive enough that I could feel the wires before I damaged them.

The process for making this cut is fairly straightforward.

1. I used a saw blade to start a groove in the parts of the pipe I could reach. This kept the string cutting right where I wanted it to. This groove isn't necessary, but it makes the process cleaner and more accurate. With or without the groove, the rest of the process remains the same. 
2. Run your string around the material to be cut in a single pass. You want to concentrate all the friction in a single line. 
3. Put one hand on either end of the string and pull back and forth with long, smooth strokes. Slow and smooth is the best technique, as fast jerking strokes will wear out and break your string before you complete the cut.
4. As you cut through the material, work the string so that the cutting portion moves along the desired cut line. This will give you an even cut, which is especially important if you're trying not to damage the interior or contents.

A good cable saw has a place in your tools, but a length of string can do much of the same work for free. Make long, smooth strokes, and you'll cut right to the heart of your task.

Lokidude