Originally Posted by Talyn
Yea. I would think to tap metal.
You mean that the screw size is printed on the binding, not the top sheet of the ski right?
I really hope you dont mean the other way around, unless you just mean depth. =)
Tapping wood is not necessary if you drill a pilot hole the correct size. Your just asking for trouble tapping wood with a tap, IMO. Nothing says the threads have to follow the tap path you made, so you just took out wood that holds the screw in. =)
Plugs and epoxy are what I have on my list at the moment.
Still havn't decided if i want to buy a ski specific drill bit yet. I have plenty at the workshop.
Forget about the wood core, it does not hold the screws. The topsheet does, and that's what benefits from tapping whether or not there is a metal layer. It is *required* for a metal layer to prevent the screw from blistering/puckering the metal layer if you were to just drive it in. But in general, tapping the topsheet improves the mount on any ski because it gives you a lot more control when driving the screw in. Screws crank into a tapped topsheet smoothly, and you can easily tell when you come up to the whoa point (at which point, just give 1/16 to 1/8 of a twist to snug and stop).
It sounds like you haven't mounted before, so here are a couple things to watch out for.
1) if you haven't tapped the topsheet, the topsheet will probably funnel up around the screw, and this can create a blister that keeps the binding from sitting flat on the ski. Rather than cranking the screw down and risking strip-out, use a chisel or countersink to remove the blister. You can pre-empt this problem by countersinking the topsheet a little (some of the stepped bits do this) but be very careful to not remove a lot of material. The topsheet is holding the screws in!
2) Get a true pozi #3 screwdriver to avoid stripping the screw head. Phillips will slip, especially if the hole isn't tapped and you are applying a lot of grunt to the screws.
3) regarding the grunt, make sure the screws are going in absolutely straight. If they are crooked and you try to boss them around, the holes will enlarge and risk strip-out.
4) Don't over tighten. Can't stress this enough. You want the screws snugged down tight with the bindings flat to the ski, but you can strip out a hole all too easy.
5) be sure to use glue in the holes to lube the screws and seal the hole.
BTW, many of these issues are moot if the topsheet has been tapped, so suggestion zero would be to tap the topsheet if you can! #12AB taps are cheap and readily available online.
P.S. If you have a good scanner and a computer that can scale input/output graphics correctly, an easy way to make a template is to scan the bottom of your bindings. Use the boot for rough spacing, remembering to subtract 3-5mm to account for forward pressure (real number depends on the binding model).