Additional Math Pages & Resources

Wednesday, September 29, 2010

Zip Zap Zip Strap

What do you call these things?

  • Cable Ties

  • Strap Ties

  • Tie Wraps

  • Zip Straps

  • Zip Strips

  • Zip Ties

Here's how patent applications describe them: 

1. A cable tie is moulded in one piece and comprises an elongate flexible strap provided with ratchet serrations on one side and a head at one end of the strap, the head having an aperture provided with a pivoted pawl having teeth which engage the ratchet serrations of the strap when the free end of the strap is passed through the aperture. 

2. A cable tie comprises a head and a strap of plastic material. The head has a transverse aperture formed therethrough and contains a separately formed barb. The barb has a head engaging portion and a strap engaging portion extending at least partly across the head aperture.

Just for simplicity today, let's call them cable ties.

Ties are not just used to fasten cables together. You can attach signs to a fence, hang pipes from the rafters, or  lock the hubcaps to the wheels of your car. Sometimes the police use them as hand cuffs. I'd say these things are nearly as useful as duct tape!

I used some of the giant ones just this morning to repair a torn panel on the seat of my car. Here are 5 of the 6 straps installed under the seat. 

Cable ties come in many sizes - tiny ones just an inch or two long, and giant ones in excess of four feet. Most of them are made of molded nylon (plastic). If you need something to tie things where it's really hot, you might want stainless steel or military-spec ties. Cable ties can also be customized - with colors, special finishes, stripes, your company slogan, etc.

Here are some write-on flag ID ties in assorted colors, from Cable Ties and More Online Store. Just in case you need to buy some today!

Here comes some math!

 Cable ties have ratings which help you to chose which one to buy. Usually you are given the length and tensile strength in pounds. Strangely, the width and thickness are seldom listed.

Tensile strength means the amount of force that an object can withstand before stretching or breaking. (Go here for more info.) Here are two of the ties I used - one straight and the other deformed due to my pulling with all my strength during the installation:

Here's a selection of choices that I found when shopping on the internet:
  • 4 inch 18 pound
  • 8 inch 40 pound
  • 7 inch chrome tie for engine compartments
  • 7 inch 50 pound flag ID head
  • 7 inch 50 pound Tefzel - radiation, acid and heat resistant MilSpec 
  • 8 inch 50 pound releasable
  • 8 inch 100 pound stainless steel
  • 11 inch 50 pound
  • 14 inch 50 pound mounting head #10 hole
  • 14 inch 120 pound
  • 36 inch 175 pound air duct straps
  • 22 inch 250 pound

The ones I used on my car seat are 48 inches long and rated at 250 lbs each. I used 6 cable ties due to the space I needed to span. Does that mean the seat will hold (6 x 250 = 1500)  fifteen hundred pounds? I hope that poor seat never has to find out! But equally I am sure that I won't break through it as I did the skimpy rubber fabric which came from the factory 20+ years ago.

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