Re: How to make a fine string has an incredible cutting ability?

THE QUESTION:
How to make a string that can "cut" a hard solid like metal or soft solid like meat easily?

Hello Weddi,

I don't think that I can give you a perfect solution to your problem. Let's look at what is needed to cut metal:

There are three main requirements for a tool able to cut metal:
1. The cutting surface must be harder than the material to cut;
2. The cutting edge of the tool must be sharp and contact the metal at the correct angle; and
3. The contact, or cutting force must great enough to penetrate the hard surface of the metal.

The problem is that the "fine string" that you are requesting would not be able to support the high contact force needed. Even if a high- strength, small diameter steel cable was used, it would quickly break as it bent around the metal surface. This metal cable itself would need to be made from a relatively soft metal. This is because a metal hard enough to cut other metals would be very brittle and would quickly break even faster.

This “soft” metal cable would need to be imbedded with tiny, very hard cutting particles. These particles need to be very small so that 1), the string could make a narrow cut (and not have to remove as much material as a wide cut) and 2), the force to pull through the material would be minimized.

Even if a string cutter was made as described, it would be very inefficient and slow cutting through most metals. You actually can buy thin, round saw cables, similar to this, but they must be held straight by being stretched between the ends of a hand saw (like a hack-saw holder).

If you tried to slice a soft material like meat, this type of blade would immediately clog up and become very inefficient. A cutter for ‘meat’ is either sharp, like a knifes edge, or uses large cutting teeth (like a butcher’s saw). This keeps the cutter from immediately clogging and lets it cut efficiently.

Getting back to metal, if you look at the types of machinery used to quickly cut metal, all will use the “three main requirements” that I described above. The fastest metal cutter that I can think of is a cut- off saw. The ‘cutter’ for this is a thin disk, (about 1/8” thick) and up to two feet in diameter. The disk is made of a strong binder material that contains bits of very hard cutting particles. A powerful motor spins this disk at a very high speed, and the mechanical mechanism permits a high contact force to be created between the disk and the metal. This combination will let the saw move quickly through thick, even hard metals. I’m afraid that any type of hand-held “string” saw would fall far behind the cut-off saw for all of the reasons above!

I hope that this helps.

Regards,
Jay Shapiro