ranger58sb
Guru
- Joined
- Aug 21, 2013
- Messages
- 7,292
- Location
- Annapolis
- Vessel Name
- Ranger
- Vessel Make
- 58' Sedan Bridge
Decided I should replace some screws that have slightly buggered-up Phillips heads... while doing routine maintenance on the head (replacing the joker valve).
Turns out the existing/original screws have high/low alternating threads... so eventually I learned they're 18-8 series #8 self-tapping high/low thread screws with a blunt tip.
WHY???
And why would a manufacturer not use some standard off-the-shelf screws?
What benefit do high/low alternating threads provide? If any...
Is there some sort of starting procedure so the replacement screws thread into the existing holes the same as the originals? Or does it matter? And if it doesn't matter, why have high/low threads in the first place?
When I replaced this joker valve in the past, I noted the screws actually could be replaced then... but had to get on with the project at the time, so I just logged the screws for replacement "next time" (which would be now). I didn't do anything special to start the original screws then, not noticing the thread difference at the time...
-Chris
Turns out the existing/original screws have high/low alternating threads... so eventually I learned they're 18-8 series #8 self-tapping high/low thread screws with a blunt tip.
WHY???
And why would a manufacturer not use some standard off-the-shelf screws?
What benefit do high/low alternating threads provide? If any...
Is there some sort of starting procedure so the replacement screws thread into the existing holes the same as the originals? Or does it matter? And if it doesn't matter, why have high/low threads in the first place?
When I replaced this joker valve in the past, I noted the screws actually could be replaced then... but had to get on with the project at the time, so I just logged the screws for replacement "next time" (which would be now). I didn't do anything special to start the original screws then, not noticing the thread difference at the time...
-Chris