With a sharp thread profile like a wood or sheet metal screw and especially a
self cutting thread into plastic there's a simple trick to make the threads
last a long time with repeated use.
While applying gentle pressure, or just the weight of the screwdriver, first
turn the screw slowly *backwards* until you can feel and/or hear the screw drop
into the thread start. Then you can drive the screw home into the original
threads that were cut or formed.
On Saturday, July 25, 2020, 12:44:33 PM MDT, Chris Albertson
<albertson.ch...@gmail.com> wrote:
I watches a Youtube video where sme one tried different methods with
threads and then put in an M5 screw and then pulled the screw head in a
test cell until the it failed and measured the pullout force. If you do
it right one is about as good as the other as it was never the threads that
fails but the plastic around the joint. So as bad as screwing a screw
directly into plastic with no nut sounds, it works. The difference is how
many times you can remove and replace the screw. Plastic threads simply
wear out from repeated assembly and disassembly and become loose.
Nuts are good only because you likey already have a nut but the "class"
solution is the brass insert that is place with a solder iron. They look
the best. Some people use helicoils. But plastic treadswork well if you
are any going to assemble the screw a dozen times of so, Just don't bother
with nuts of any type and you get the same strength.
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