Has anyone try to put s/s self tapping screws into fiberglass and have
the screw break.. :-( Can a put liquid soap or grease/oil on the screw
before screwing it in to the fiberglass??



Any ideas??


Hanz

"Hanz" wrote in message
. ..
Has anyone try to put s/s self tapping screws into fiberglass and have the
screw break.. :-( Can a put liquid soap or grease/oil on the screw
before screwing it in to the fiberglass??



Any ideas??


Hanz


It's largely a bad idea. The threads on self-tapping screws are very course
and highly-pitched. They offer very little "bite" into the fiberglass, and
are quite destructive to it, causing it to crack and delaminate. Regular
machine screws with their finer threads will do a much better job -- but you
should never rely upon the thread contact between the fiberglass and the
fastener for a secure fastening. Always back up the screw with a nut and
washer -- the larger the better, to distribute the load. And ideally there
should be very little, if any, direct contact between the threads and the
glass -- but I have good success with drilling a hole that the threads can
*just* catch.

I have filed a tooth on a regular screw and used it to tap threads in
f/g. Half a turn in, a turn out, etc.

It ain't the best but for non critical loads it works. Be careful
with the hole size vs the screw size vs f/g thickness. Go slow and
easy.

Terry K

Hanz wrote:

Has anyone try to put s/s self tapping screws into fiberglass and have
the screw break.. :-( Can a put liquid soap or grease/oil on the
screw
before screwing it in to the fiberglass??

Use the correct size tap drill and you will have no problems.

Do it all the time.

Lew

On May 16, 4:59 am, Hanz wrote:
Has anyone try to put s/s self tapping screws into fiberglass and have
the screw break.. :-( Can a put liquid soap or grease/oil on the screw
before screwing it in to the fiberglass??

Any ideas??

Hanz

I found stainless self-drilling sheet metal screws in New Zealand and
they hold reasonably well on good quality glass. I keep them on hand
for emergency clamping duty but can't imagine the application where I
would install something with them. Wax and bar soap can be used as
lubricants. Pilot holes are a good idea too and allow the use of
regular old machine screws... If you wax the screw and bed it in
epoxy you can get a reasonably strong connection that can be
disassembled. But, what you really want are bolts.

-- Tom.

Hanz wrote:
Has anyone try to put s/s self tapping screws into fiberglass and have
the screw break.. :-( Can a put liquid soap or grease/oil on the
screw before screwing it in to the fiberglass??



Any ideas??


Hanz

Best to use plugs of the type they sell for fiberboard. The inner end
expands and pulls against the back of the glass sheet.

NEVER, never, never ever use fasteners in FG! They always fail. Fasteners
apply concentrated load to a very small area. The correct method is to bond
into the FG structure either metal or wood to accept the fastener and spread
the load over a wide area.
Steve

"Hanz" wrote in message
. ..
Has anyone try to put s/s self tapping screws into fiberglass and have the
screw break.. :-( Can a put liquid soap or grease/oil on the screw
before screwing it in to the fiberglass??



Any ideas??


Hanz

* Steve Lusardi wrote, On 5/18/2007 7:12 PM:
NEVER, never, never ever use fasteners in FG! They always fail. Fasteners
apply concentrated load to a very small area. The correct method is to bond
into the FG structure either metal or wood to accept the fastener and spread
the load over a wide area.
Steve

NEVER, never, never ever??? I think that would depend on the nature
of the fasteners and the load. The OP never stated the nature of his
problem; I doubt he was attaching chainplates with self tappers.
There's a lot of canvas that is attached through various fasteners.

Steve Lusardi wrote:

NEVER, never, never ever use fasteners in FG! They always fail.

Guess it depends on what you define as F/G and the application.

Have no problem with epoxy and knitted glass; however, all bets are
off with polyester.

Lew