In article , news.ind.net.spamtrap1
@yunx.com says...
We use some decent flat head screws on our units and I've run into a strange
problem. When we tighten them into the aluminum housings, they hold a
galvanized plate in place. After about 10 minutes of being on there, they
are almost impossible to get off.

We have turned the highest quality allen keys we can find into pretzels and
have stripped many using impact and a shorter length. Sometimes we have
success by using a chisel to "spin" the flat head loose but that's the
Neanderthal method I'd like to avoid... Even that fails 50% of the time.
We can't use heat because there is a rubber seal in the aluminum very close.

The flat head actually grabs onto the galv. plate so well that our customers
(and us!) have to drill them out 8 out of 10 times we need to remove them...

Anyone know of a super allen key or some other method of removing these that
might work? We know that when we use painted plates, we have less of a
problem and have considered painting the countersink of each flat head hole,
but that's crazy in the big scheme of things...

Thoughts, wisdom and random visits from friends welcome.


I've run into this when installing cap screws into aluminum that's been
anodized after the holes were drilled and tapped. I've always assumed it
was due to the hard anodized surface having a bit of tooth and biting
into the surface of the screw. As you imply, it seems to take a few
minutes for the effect to take place.

The fact that you have less problem with painted material is puzzling.
Could it be that the screw is seizing in the tapped hole, but the paint
is acting as a lubricant making it a bit easier to break it free? Have
you tried never-seez in the tapped hole and under the head? What about
plated fasteners?

I imagine this is a well known phenomenon. Perhaps a call to Allen or
Holokrome would get you an answer.

Ned Simmons