Insert failures?

[GeezerSteve]

I have never once heard of an insert pulling out of a ski.

Now you have. FWIW, in one of the prior threads, Jon said that the ideal would be a knife thread or wood screw thread. Anyway, while I am convinced that a wood screw thread profile would be better I also acknowledge that the vast majority of BF and QK inserts are staying put. IMO the key is to have the insert surrounded by a female thread in a wood/resin plug, for which a machine screw thread seems like a reasonable connection. That requires saturating the wood core in epoxy resin. 30 years ago when I mounted hundreds of Nordic skis the old timers turned the ski upside down while the epoxy/glue set; the idea was for gravity to pull the epoxy down to create the wood/resin plug just underneath the top sheet, rather than to let the epoxy perc into the core. (Okay, yeah, XC skis usually don't have top sheets like alpine skis, but you get the idea.) The old timers on here who have mountain Hexcels will remember doing a similar process. I've done my BF inserts the same way, turning them upside down, but with a HPDE plate clamped to it to avoid leakage.

[auvgeek]

I don't think that's waht adrenalated meant when he said he's never heard of an insert pulling out of a ski. I've heard of people "unscrewing" their inserts (ala that thread) if they've used too much loctite and/or not enough epoxy or just because it happened, but I've never heard of a pullout in the field (like you sometimes hear about with binding screws, particularly those with a narrow mount pattern FKS and Dynafit.<-- may or may not be an urban myth.)

[adrenalated]

Oh yeah, I've had inserts unscrew from the ski when you remove bindings, and have seen that thread before. As auvgeek said, that's not what I'm talking about. I'm talking about bindings ripping straight out of the ski while skiing, which was a huge problem with BD O1 tele bindings and I've had a variety of friends do to traditional mounts with a variety of bindings over the years. I've never heard of an insert doing that.

Changing the thread type wouldn't fix the inserts unscrewing problem, except for going to a left hand thread (which countless people would undoubtedly fuck up). It would only make the pullout strength higher, which AFAIK is a problem that does not exist.

[GeezerSteve]

Right, there is a distinction between pullouts and screwouts.

I wouldn't even think about installing BF or QK inserts for O1s, which have roughly the same cross section as binding screw, so if a binding screw can pullout then a BF/QK insert can pull out. IME the best way to deal with O1s is to not use them or to mount them with helicoils (much bigger cross section, coarse wood screw bite).

[adrenalated]

Definitely the best way to deal with O1s is to not use them. That binding failed at life in so many ways.

[GeezerSteve]

I hear ya. All telemark bindings rear screws are to some extent akin a to a claw hammer prying a nail with each turn. O1s were the worst.

[Alpinord]

Yep, have a tap custom made. It's an expensive solution to a problem that does not exist. I have never once heard of an insert pulling out of a ski.

...or go for the gold with a machine screw in an insert in a heli-coil (with customized, standard tap):

[Dromond]

I had one come loose and I had to re-epoxy it. Other than that they have been fine. They are a pain to install and sort of a pain to swap, but can add a little versatility to your bindings. They work best if you swap only occasionally...

[altis]

Timely:
http://www.earnyourturns.com/23865/t...-ski-bindings/

[toast2266]

...or go for the gold with a machine screw in an insert in a heli-coil (with customized, standard tap):

That looks sketchy. I think it really needs a machine screw into an insert into a heli-coil into a T-nut

[Alpinord]

That looks sketchy. I think it really needs a machine screw into an insert into a heli-coil into a T-nut

...or a thru bolt with a lock nut on the bottom.

[coldfeet]

...or a thru bolt with a lock nut on the bottom.

Not complete without a lock washer under that machine screw to keep it from backing out.

[GeezerSteve]

this thread is getting silly

[skimaxpower]

...or go for the gold with a machine screw in an insert in a heli-coil (with customized, standard tap)

That looks sketchy. I think it really needs a machine screw into an insert into a heli-coil into a T-nut

Not complete without a lock washer under that machine screw to keep it from backing out.

This sounds like a great solution for my ultralight rando rig. What kind of locktite should I use with titanium machine screws I'll be using?

[snoboy]

I have had a few spinners, no pull outs. My plan is to cut a vertical groove in the threads from now on. I think that will stop the spinners, and allow easier install as it should prevent the hydraulic lock you get if too much epoxy.

[GeezerSteve]

My plan is to cut a vertical groove in the threads from now on.

Good idea. As mentioned in the other thread, I bead blast the outer threads.

[wren]

I've used quiver killers on 5 pairs of skis, and have mounted 2 sets of holes twice (one dukes+FKS, the other radical FT + FKS). So I've done 7 sets of inserts on my own skis, and helped buddies out do another 3 pairs (at least). Never had an issue with a spinner or one backing out. I use a drill press to both drill and tap the skis, and used marine grade epoxy with the inserts. Only issues I've had is with screws loosening on the dukes and dynafits without using loctite. I no longer make that mistake and I've been trouble free. I ripped the toe blocks off my Sally Quest 14s when riding a pair with the FKS and there was zero issue with the toe pieces, despite a pretty large of force being exerted on them. As far as I'm concerned they've been perfect for me. Certainly won't hesitate to using them again.

[1000-oaks]

I'm not clear why the inserts have a machine thread on the outer.

I'll wager inserts are cut from all-threaded rod, which transfers half of the machine work to a big company that specializes in that operation at the lowest possible cost. That's also why the exterior threads are rolled (stronger and no wasted material), instead of cut.

[xtrmjoe]

Ive done one set of inserts with not issues as of yet. Again clean them and use a good epoxy. I think I still prefer the sollyfit plates though especially for dynafits in carbon skis which have a tendency to pull out at the worst possible time.

[1000-oaks]

These would be a pretty burly mount, if the bottom could be sealed with epoxy.
http://www.ebay.de/itm/RAMPA-Muffe-T...-/370894582019