weaponizing the string trimmer

August 27, 2005 8:06 PM

Why don't string trimmers use wire instead of plastic? My guess is that with wire in there, it's like a surburban guy in shorts and flipflops walking around the yard waving around a little tablesaw, but is it really that much more dangerous than plastic if it should strike flesh? You're pretty much flayed either way, right? Is it a safety issue or something else?
posted by stupidsexyFlanders to home & garden (11 comments total)

Mass. When a piece of plastic trimmer twine breaks off and goes flying, it loses velocity quickly as it has little mass to push it through the wind resistance. So it doesn't put your neighbor's dog's eye out. A piece of wire flung at the same velocity could do some real damage—like embedding itself in your leg.
posted by bricoleur at 8:24 PM on August 27, 2005

One of the early patents, #5,276,969 has some interesting reading.

Various attempts have been made to overcome the aforesaid hazardous conditions created with rigid type metal cutting blades of the prior art and, in particular, attempts have been made to utilize some type of flexible flail-like member which will have sufficient resiliency so as not to project impacted rocks and other objects at dangerous velocities. Most of these resilient type cutting elements of the prior art suffer a disadvantage in that mere resiliency alone is not sufficient to insure that the dangerous conditions will not be created when rotation is effected at desired cutting speeds. Further, resilient cutting members of the type represented in the prior art have no cut vegetation as well as the metal blades hereinbefore described, and have not enjoyed commercial success for this reason.

Essentially, wires will cut through your shoes or pants and monofilament won't.
posted by smackfu at 8:28 PM on August 27, 2005

The plastic line is tough enough to cut grass but doesn't damage other things too much, and provides a simple way to "renew" the blade.

One of the advantages of a string trimmer is that you can safely let the spinning end come into contact with things like fence posts, edges of buildings, trees, etc. Because the string is just plastic, it deforms and does not damage the object, while still being able to cut grass. So when you trim the edge of your concrete driveway, the plastic string just gets worn down and you bump the tip to release more of it until it gets back to normal length and the tip is cut by the blade in the guard. This is a simple and effective way of renewing the blade.

If the string were made of wire, it would do much more damage to everything it came in contact with, including the things you don't want to damage. It would be more difficult to spool out new wire, and nearly impossible for it to "cut off" when it's at the proper length, as with the plastic line.

The mass argument is also good. At the speeds that thing is spinning (upwards of 10k rpm) the mass has a huge effect, especially when it's several inches from the center of rotation. A wire cutter would require a larger and heaver engine to spin at those speeds, and would be too destructive. The beauty of the device is that the string does degrade and is replenished.
posted by Rhomboid at 8:39 PM on August 27, 2005

One can purchase hard plastic blade thingies that are articulated.

Also, wire might spark on small stones and ignite dry brush.

I wonder, however, if braided metal mesh would work.
posted by mecran01 at 10:36 PM on August 27, 2005

I've had my hand in those plastic string trimmers; they sting a bit but don't break the skin. Wouldn't like to try it with a metal wire.
posted by ikkyu2 at 10:44 PM on August 27, 2005

http://www.acehardware.com/product/index.jsp?productId=1335608

Nylon one, links don't take from me.

I had one of these a few years ago, it works really well. Someone then stole it and the weed wacker from my garage!
posted by lee at 11:02 PM on August 27, 2005

yet, despite all these good arguments, you can actually buy replacement heads that have what look like chainsaw links on 'em. for "heavy brush". they do not, however, come with kevlar pants.
posted by Hackworth at 12:18 AM on August 28, 2005

Hackworth, that's 'cos the nylon monofilament will only cut relatively thin grass or leaft plants. Anything with a woody stem -- something like milkweed, or even thistle -- will survive the regular cutter.

But yeah, ballistic nylon trousers, steel-toed boots and a full face guard would be a good idea using one of these blades.
posted by scruss at 3:52 AM on August 28, 2005

there are also "sharp" rolls of nylon cord that have an edge on them that can slowly cut through some of the heavier stuff. And some recommend a well-balanced european scythe for that sort of work. Quieter, anyway.
posted by mecran01 at 6:20 AM on August 28, 2005

This thread is kind of old, but in case you check, I've experimented with various metal wire types and the ALL break quickly! It was a good experiment but I found no use there. I am back to the nylon line.
posted by snsranch at 4:36 PM on August 29, 2005

It's never too late for real life experience, thanks snsranch.
posted by stupidsexyFlanders at 5:34 PM on August 29, 2005