If you use a filler like glass fibers with your epoxy, and then use a
machine screw, it'll be stronger than a wood screw driven into wood. I
wouldn't be surprised if it's stronger even if you use wood flour for the
Speaking of machine screws... Somebody did some experiments with machine
screws driven into wood -- no epoxy -- and found that they held better
than wood screws or sheet metal screws! I've been using machine screws in
the renovation of my little power cruiser (not an Atkin design, Karl
Stambaugh's Redwing 18) when putting screws into plywood, thinking that a
machine screw has full grip right to the tip, while a wood screw doesn't
grip much with it's pointy tip, and I can't use a very long screw into
plywood. I've found them easy to use, and they feel like they're gripping
real good. Now I'm reluctant to use wood screws or sheet metal screws
except in places I'm not worried about strength. <g>
In plywood and Doug fir I don't need to tap the holes, the screw itself
does that just fine. The pilot drill sizes I've been using are 1/8"
(.125") for #8-32 and 5/32" (.156") for #10-24.
On Mon, 11 Jul 2011 09:08:30 -0700, cynon7 wrote:
> I think you mentioned that you would be using epoxy and fiberglass...
> one trick I picked up from the wood/epoxy/fiberglass kayaks I built was
> the "drill-fill-drill" method of fastening: drill an oversized hole,
> fill the hole with a mixture of epoxy thickened with wood flour and
> silica hardener, and then drill into the epoxy resin matrix for the
> screw. It's not as strong as screwing into the wood directly, but
> screwing into thickened epoxy is strong enough to hold trim in place;
> and then the wood is sealed at the threads to prevent water intrusion.
It s a damn poor mind that can think of only one way to spell a
word! (Attributed to Andrew Jackson)