The Trouble With Plastic

I spend a lot of time dissecting all sorts of mechanisms for one reason or another. It's been both a blessing and a curse at times. I enjoy "seeing" how things work. How they function,  how they are assembled, and inevitably, how they come apart. Hopefully, I pay close enough attention at disassembly, to remember how the blessed thing goes back together. That, is the reason for this entry.

A very large majority of our everyday possessions are constructed of some type of thermo-plastic. In fact, more and more items that once were solely made from metals, are now produced out of reinforced plastic, or composite materials.

One of the most important factors to remember when reassembling a device after you have successfully repaired it, (we will assume you are successful, otherwise the item might become fodder for the trash heap), is the proper reinsertion and tightening of the self-tapping fasteners.

When the item of interest is taken apart, the fasteners are usually metal screws with aggressive threading, that when originally assembled at the factory, cut spiral threads into the undersized hole in the mating component. When reassembling the device (properly), it is very important to "feel" for those precut threads to be sure the screw does not cut new threads, thereby weakening the fastener's hole.

To be sure I return the screw/s into the original threads, I simply start the screw into the hole and carefully rotate it in reverse (left-hand direction) with VERY little downward pressure. As the screw turns around counter-clockwise, I feel for the exact point in the rotation where the screw drops slightly into the original precut thread. Then, I simply reverse direction slowly and the screw should go into the threaded hole with very little effort, and tighten without threat of stripping the plastic receiving hole.

Sounds pretty trivial I guess, but if you plan on reassembling something for future use, and the screws do not tighten properly, that will prove to be a difficult problem to solve in a "professional" manner. I guess the duct tape, and hot glue gun people would not be phased by such a development. I however, tend to want to return the item in as close to factory specifications as I possibly can.

There you have it, turn left, feel for the drop, before you turn right to tighten. It will make a much better job of your fix-it attempt.


Thanks for taking the time to peruse this entry.  I hope it may help in some small way.

Gaff