Ski Builders Forum

Hi all. Not a builder (yet) but occasional visitor. I could have bumped the ripping inserts thread but decided this was specialized enough... And here is where I thought I'd find people who know, and CARE, enough for my best shot at an answer.

I've built master risers to swap Voiles and Hammerheads between skis. The three pair I've made have three different layups, but except for one pair with t-nuts for the Voile, I've tried for "epoxy inserts." This was inspired by the West System/Gugeon Bros claims of a fortified-epoxy set for hardware being stronger than even epoxied wood. So I mixed Cabosil & Milled fibers into the slow-cure epoxy, coated the screws with (TriFlow or WD40) and unscrewed after set. Now, as I go to attach the bindings, I find these molded threads are failing.

I know one thing I did wrong. Too cold. I waited for the warmth of the day, but it was done in my garage and the QCM interview really drives home the need for temperature. Some were so cold, I saw entrapped air bubbles from stirring.

My longer term plan is to re-do all with t-nuts. But, to get skiing with the mounted shims, I'd like a make-do.

Current plan is to: drill out epoxy, refill with fortified and cure at @ 200deg! Then drill and tap with my Tognar drill and tap.

Q--My big question is, has anyone else successfully done something similar and managed to remove and re-attach screws several times (say, 4) in purely fortified epoxy?

Q-- My smaller question is, shouldn't the wet-set/removed thread be as strong as drill&tap? (assuming THAT works!) Just the temp of cure? I'm now thinking the oil coating contaminates the epoxy, extra vulnerable in the low-volume of the molded threads. Shouldn't epoxy resin be as reuseable as p-tex in a factory riser?

Thanks,
Charley

QCM recommendations are a great resource.
The three things I see from your write-up are:
1. Air bubbles
2. cure temp too cold, and
3. possible contamination from WD-40
Just as a guess, Slow mixing of the epoxy will help eliminate the making of air bubbles. You know of the temp for good cure and try using car wax on the screws as a releasing agent. I just used it for the second time on my pressing layers (HDPE) and it has worked good. The other thing I have read that should work for releasing the screws from the set epoxy is heat applied to the screw. Good luck and keep us posted on the outcome.
ra

you're going to have a hard time doing it in just epoxy. your best chance is to get some real high density filler. cabosil isn't going to be good enough. West system makes a high density filler which should be good enough. Another thing you can try is wrapping the bolt in glass or carbon strands. Wax the bolt (use wax instead of WD-40) wrap a couple of stands around the bolt and stuff it in the hole filled with epoxy. Let it go off and wind out the bolt. Have done both approaches on more highly loaded applications before the problem is if you're not careful it's pretty easy to bugger the threads.

you're going to have a hard time doing it in just epoxy. your best chance is to get some real high density filler. cabosil isn't going to be good enough. West system makes a high density filler which should be good enough. Another thing you can try is wrapping the bolt in glass or carbon strands. Wax the bolt (use wax instead of WD-40) wrap a couple of stands around the bolt and stuff it in the hole filled with epoxy. Let it go off and wind out the bolt. Have done both approaches on more highly loaded applications before the problem is if you're not careful it's pretty easy to bugger the threads.