binding ripped / pulled out of ski.. help

[johnmtl11]

For the Blizzards, hard to tell after the fact, but curious if they used an ab tap after drilling the holes. Cutting through the top sheet and titanal layers with a tap instead of using the screw threads should help prevent delamination.

Don't think the Armadas have metal so wouldn't apply to original poster.

[galibier_numero_un]

Good on them, and good for you!

When in doubt, start with a 3.5 - if there's a bunch of metal shavings, bump it up. You can't make a hole smaller.

+1

If these skis were being repaired and skied again, my only concern would be that you let the core dry before plugging the holes (or remounting using the same holes). I've seen a mildewed core and it's not a pretty site. A remount (even in the same spot - using either helicoils or inserts) is better than new as long as the core is dried out.

... Thom

[DropCliffsNotBombs]

That's why I helicoil my soft light skis at the rear 2 screw as soon as I mount them.

Heli-coil right away? Why? Heli-coils are not stronger. They are meant to repair stripped screw holes. Inserts are indeed a stronger method though.

[GeezerSteve]

Heli-coils are not stronger. They are meant to repair stripped screw holes. Inserts are indeed a stronger method though.

I must disagree. I've done informal pullout tests with several different ski cores and it's pretty obvious that a properly installed ski helicoil like these result in a considerably stronger connection than a properly installed screw or BF-type insert. The reason for this is obvious to me: The cross section of a ski helicoil/core interface is much larger than screw/core or insert/core cross section. As I have noted in previous threads, that the BF-style inserts use a machine screw thread (smaller cross section than ideal) bothered me, but they seem to hold up okay if they are installed with due care. Also note that per my informal pullout tests the pound-in nylon inserts that expand upon screwing seem at least as strong as a properly installed screw, maybe a bit stronger. But, as I say above, my informal testing leads me to conclude that the ski helicoil is the most bomber connection. I use ski helicoils for all of my touring skis, not only for the additional pullout strength, but also to enable field repairs.

[meter-man]

For the Blizzards, hard to tell after the fact, but curious if they used an ab tap after drilling the holes. Cutting through the top sheet and titanal layers with a tap instead of using the screw threads should help prevent delamination.

Don't think the Armadas have metal so wouldn't apply to original poster.

So, I brought the skis to my local shop last night, who have served me wonderfully in the past. (Including catching a figure-8 mount job done by a "reputable" shop in Truckee.) I did not buy the Blizzards or the Sally binders there, but they did mount them up for me. Before I could even begin telling the master tech my story, she (Yes, SHE) said, "another Blizzard eh?" Apparently, it has been a rather frequent problem with the flipcore series, as noted by the other posters (see prior page for link to Epic Ski thread). This was the fourth flipcore ski she has seen this year with the same pullout at the heel, although this was the first 13/14 Cochise she'd seen. She said she would try to warranty them, but couldn't promise what would happen given the vintage and this was the second mount. But to answer your query, yes, they tapped (shop policy).

She called me at 9:18 am this morning (not even 13 hours after first speaking with her) saying that Blizzard approved the RA number. I will either be getting this year's Cochise new (if in stock, and turn around has been less than two weeks) or a credit for next years when more get pressed. I remain a VERY satisfied Blizzard customer, and perhaps an even happier customer of my local shop. I mean, that is some amazing responsiveness and follow-through. It's a secret shop though, so I am worried everyone in Northern California will start going there, so I'm not going to tell you its name. I'll leave it to you to guess. Anyway, I'm stoked that this worked out so well.

I must disagree. I've done informal pullout tests with several different ski cores and it's pretty obvious that a properly installed ski helicoil like these result in a considerably stronger connection than a properly installed screw or BF-type insert. The reason for this is obvious to me: The cross section of a ski helicoil/core interface is much larger than screw/core or insert/core cross section. As I have noted in previous threads, that the BF-style inserts use a machine screw thread (smaller cross section than ideal) bothered me, but they seem to hold up okay if they are installed with due care. Also note that per my informal pullout tests the pound-in nylon inserts that expand upon screwing seem at least as strong as a properly installed screw, maybe a bit stronger. But, as I say above, my informal testing leads me to conclude that the ski helicoil is the most bomber connection. I use ski helicoils for all of my touring skis, not only for the additional pullout strength, but also to enable field repairs.

This is super interesting. I've come across your comments on this question in other threads before, and thanks for sharing the beta. One follow-up question -- how does using a helicoil enable field repairs on your touring skis? I've used inserts, but am unfamiliar with how helicoils are superior or different in this regard. Can you elaborate?

[GeezerSteve]

One follow-up question -- how does using a helicoil enable field repairs on your touring skis? I've used inserts, but am unfamiliar with how helicoils are superior or different in this regard. Can you elaborate?

Helicoil is Al alloy so helicoil/screw interface is metal-on-metal and can be cycled many times without any significant weakening of the connection. Also, I've never needed heat to break a screw free from a ski helicoil.

I'm not suggesting that helicoils "are superior" other than my observation that my informal tests indicate that, if properly installed, they result in greater pullout strength (as a result of the larger purchase cross section). But they are not a substitute for BF-type inserts for multiple binding applications because helicoils do not have a closed bottom. The connection need only be strong enough, and it seems that properly installed BF-style inserts usually meet that standard.

[DropCliffsNotBombs]

I must disagree. I've done informal pullout tests with several different ski cores and it's pretty obvious that a properly installed ski helicoil like these result in a considerably stronger connection than a properly installed screw or BF-type insert. The reason for this is obvious to me: The cross section of a ski helicoil/core interface is much larger than screw/core or insert/core cross section. As I have noted in previous threads, that the BF-style inserts use a machine screw thread (smaller cross section than ideal) bothered me, but they seem to hold up okay if they are installed with due care. Also note that per my informal pullout tests the pound-in nylon inserts that expand upon screwing seem at least as strong as a properly installed screw, maybe a bit stronger. But, as I say above, my informal testing leads me to conclude that the ski helicoil is the most bomber connection. I use ski helicoils for all of my touring skis, not only for the additional pullout strength, but also to enable field repairs.

I have done formal testing of different binding screw configurations myself on a tensile-testing machine. The results were quantified by a computer program which produced a graph following the tension arc right up until pullout.
You are right, the nylon pound-in "heli-coils" are slightly stronger than a regular screw. The brass pound-in "heli-coils" are actually considerably weaker than a regular screw. And the BF inserts were by FAR the strongest method that I tested (more than 4x stronger than a regular screw!).
I didn't get a chance to test a true heli-coil like you are referring to but I would imagine that it would be at least as strong as a BF insert. If not, possibly stronger.

The reason I wouldn't immediately go to heli-coils for durability is because that is a HUGE hole in the core. And if that hole fails, there's no repairing it since they require that you drill the largest hole possible to hold a binding screw.
If you blow a regular screw hole, you can repair it with an insert.
If you blow an insert hole, you can repair it with a heli-coil.
If you blow a heli-coil, your skis are done (unless you remount way forward or way back).

[GeezerSteve]

I didn't get a chance to test a true heli-coil like you are referring to but I would imagine that it would be at least as strong as a BF insert. If not, possibly stronger.

Way stronger per my observations because the purchase cross section is much bigger than with a BF-type insert machine screw.

The reason I wouldn't immediately go to heli-coils for durability is because if that hole fails. . . .

I've never seen nor heard of a properly installed ski helicoil failing. I think the only way a properly installed ski helicoil could fail would involve a ski core turned to mush, in which case the ski needs to be tossed anyway.

I will also note that two times during my informal pullout tests, the failure happened when the head of the screw popped off, i.e., the screw was the weak link in the chain.

I agree re pound-in non-expanding brass inserts.

[AlpiNord]

At the risk of shooting my foot off as a supplier of heli coils, nylon and brass tap-ins and Binding Freedom inserts, does the heli coil have to be compatible with alpine screws?

The BF inserts are pretty bomber (and use smaller holes as noted above) even if the heli coils are stronger, but one of the advantages is the M5 x 0.8 screw is far more universal than 5.5mm alpine 12 AB screws. So what about an M5 heli coil that matched the BF pozi screws or all of the other M5 screws out there? Our costs of the heli coils and tools keep going up and I'll bet common heli coils could be had more economically.

[GeezerSteve]

one of the advantages is the M5 x 0.8 screw is far more universal than 5.5mm alpine 12 AB screws.

FWIW, #12 sheet metal screws -- which are as universal as it gets -- work fine in ski helicoils (although it'd be nice to have Grade 5 or stronger). As you know, unlike the BF/M5 machine screw connection, there's a bit of slop with the AB (or #12) in a ski helicoil, which can be good if the holes are not perfectly drilled. Don't get me wrong. I'm not knocking BF inserts, which I've used with success, but a machine screw thread in a wood core makes me nervous compared to the larger purchase cross section of a ski helicoil. As I said above, my informal pullout tests indicate that the latter makes for a considerably stronger. IMO, the ideal would be a closed-bottom insert with a coarse wood screw type exterior thread similar to a ski helicoil thread, and paired with a tap for the ski. But I acknowledge that BF inserts are working for almost everyone who uses them, i.e., they result in a connection that is strong enough.

[DropCliffsNotBombs]

Inserts (QK or BF) are my "go-to" method for bomber binding installations rather than heli-coils. For a few reasons:

1. Inserts make smaller holes in the core than heli-coils do.
2. You have more available screw options. You can get them at ANY hardware store. Not the case with ski binding screws.
3. They are a sealed system which protects the core from moisture. Heli-coils are not.
4. You can reinsert the screws and change your bindings around to different skis as much as you want. Not so with heli-coils.
5. Epoxy doesn't touch the screws, which allows them to be removed MUCH easier than trying to get an epoxied screw out of a heli-coil.
6. Pullout strength is just as strong as a heli-coil. Both are overkill, really.

[DropCliffsNotBombs]

I've never seen nor heard of a properly installed ski helicoil failing.

Personally, I have seen good heli-coils rip out of skis before. Often times because the ski broke at the holes, but still, they'll come out.
I have never seen or heard of a properly installed QK or BF insert ripping out though.

[AlpiNord]

Regarding relative coarseness of threads, it's not like the Binding Freedom inserts aren't coarse:

[GeezerSteve]

That pic shows that larger depth and coarser thread of the helicoil, which is more apparent when looking at the tap. Can anybody here think of any other application where a machine screw thread profile is used in wood? There's a reason.

I have never seen or heard of a properly installed QK or BF insert ripping out though.

I have

2. You have more available screw options. You can get them at ANY hardware store. Not the case with ski binding screws.

Nah. As I said above, #12 sheet metal screws work just fine with ski helicoils, and are available in ANY hardware store, but OTOH not all U.S. hardware stores carry a large assortment of 5M machine screws. (Yeah, I know that a 10-32 SAE machine screw will work in a BF insert in a pinch.)

4. You can reinsert the screws and change your bindings around to different skis as much as you want. Not so with heli-coils.

Nah. You can cycle bindings off and on a pair of skis with helicoils an indefinite number of times, just as you can with BF inserts. I've been moving a pair of bindings between two helicoiled skis for 4 seasons, dozens of cycles, no issues.

5. . . .MUCH easier than trying to get an epoxied screw out of a heli-coil.

Nope. AB screw epoxied in helicoil unscrews just as easily as a 5M machine screw with threadlocker. I know cuz I have done both many times, e.g., see above.

6. Pullout strength is just as strong as a heli-coil.

We can agree to disagree on this.

ETA: Again, I have BF inserts in some skis too and they're working fine.

[AlpiNord]

That pic shows that larger depth and coarser thread of the helicoil, which is more apparent when looking at the tap. Can anybody here think of any other application where a machine screw thread profile is used in wood? There's a reason.

I have

Nah. As I said above, #12 sheet metal screws work just fine with ski helicoils, and are available in ANY hardware store, but OTOH not all U.S. hardware stores carry a large assortment of 5M machine screws. (Yeah, I know that a 10-32 SAE machine screw will work in a BF insert in a pinch.)

Nah. You can cycle bindings off and on a pair of skis with helicoils an indefinite number of times, just as you can with BF inserts. I've been moving a pair of bindings between two helicoiled skis for 4 seasons, dozens of cycles, no issues.

Nope. AB screw epoxied in helicoil unscrews just as easily as a 5M machine screw with threadlocker. I know cuz I have done both many times, e.g., see above.

We can agree to disagree on this.

ETA: Again, I have BF inserts in some skis too and they're working fine.

Isn't the outside coarser threading of the inserts the issue and not the inner machine screw threading?

[sb]

They make nu ones every day.

[DropCliffsNotBombs]

Can anybody here think of any other application where a machine screw thread profile is used in wood?

Can anyone here think of any other application where a self-tapping wood screw thread profile is used in metal?

[Jack Burton]

Good info - thanks. Will be asking a reputable shop in Truckee (where i bot the skis) to send my 13/14 Cochise back and see what Blizzard says, not likely what i want hear but gotta try.

[meter-man]

Good info - thanks. Will be asking a reputable shop in Truckee (where i bot the skis) to send my 13/14 Cochise back and see what Blizzard says, not likely what i want hear but gotta try.

Blizzard replaced my 13/14s with a brand new 16/17 pair this spring. Same delam; no problem. See http://www.tetongravity.com/forums/s...78#post4685478

Blizzard is aware of the delam issue, and seems to be good about warrantying. If you have any problem warrantying through your local shop, bring em to an REI. REI SF handled mine even though I did not buy the skis there.

[Jack Burton]

yup Blizzard did replace my 13/14 cochise with snazzy blue/carbon skis. as far as i know there was no back and forth between the shop and blizzard.