[Boatanchors] Re: Fixing cracks in plastic

[J. Forster]

Steve Uhrig wrote:

> [snip]
> To keep the cracks from getting *worse*, drill a tiny hole at the end of
> the crack. Something like maybe the size of a #24 or #22 gauge wire is
> what I use, whatever decimal size that is. I use a bit in a Dremel tool.
> Works on windshields too. I'm usually trying to get someone's plastic
> motorcycle windshield through one more winter by doing this sort of
> thing.

After my post yesterday, I chatted with a pilot friend. He was not really
optimistic about being able to fix the cracks invisibly, especially if they are
fully internal. He did suggest heating to just below the melting point as a
possible remedy also. (Just 'till it softens a bit)  Heating will also relieve
the stress that caused the cracks.

As to drilling crack stop holes, he commented that's it's usually unnecessary
unless more stress is applied. In fact, a small hole could become the focal
point of new cracks if it's drilled in an area of high tensile stress.

The best alternative is not to cause stress concentrations by avoiding lock
washers directly in contact with the plastic, but it's a bit late for that.

Good luck,
-John