Binding mounting myths:

[DropCliffsNotBombs]

OK here are some recurring mistruths that seem to keep coming up on this forum.

- Binding screw threads alone are not enough to hold the screw in. You MUST also add epoxy(or whatever else) in order to keep them secure. <binding glue is meant to lubricate the screw, keep out moisture, and dampen vibration, NOT to hold the screws in!>
- Epoxy, steel wool, broken toothpics, and wood chips are a good way to fix stripped screw holes. <"ghetto-fixes" sometimes do work, but...>
- Heli-coils are somehow stronger than mounting as normal. <never, ever>
- Installing inserts is a convenient way use one pair of bindings on several different pairs of skis. <what a PITA this idea really turns out to be>
- JB weld is somehow applicable for ski repair. <it doesn't flex- skis do!>
- Tapping all screw holes is a good idea. <ski taps are made to fit only 4.1 holes in metal laminates>

[stuckathuntermtn]

Are you saying you DO or DON'T think you need epoxy?

[DropCliffsNotBombs]

Epoxy is required for making and repairing skis. Not for mounting them (DPS excluded).

[gregL]

The vast majority of the time, binding screw threads are enough to hold the screws in. God knows I never used epoxy when I worked as a ski tech. However, if you want to add some strength to the mount as well as waterproof it, it makes sense to use epoxy which happens to be the adhesive they use to hold the ski together.

A #12 AB tap is made to match the profile of a typical 5.5mm ski binding screw, not to match any particular hole size. It works fine in a 3.6, 9/64, 5/32, or 4.1 hole and if used properly cuts cleaner threads more quickly than just running screws in.

Assuming the goal is to achieve the strongest possible mount, I'd use both all the time.

[DropCliffsNotBombs]

The vast majority of the time, binding screw threads are enough to hold the screws in. God knows I never used epoxy when I worked as a ski tech. However, if you want to add some strength to the mount as well as waterproof it, it makes sense to use epoxy which happens to be the adhesive they use to hold the ski together.

A #12 AB tap is made to match the profile of a typical 5.5mm ski binding screw, not to match any particular hole size. It works fine in a 3.6, 9/64, 5/32, or 4.1 hole and if used properly cuts cleaner threads more quickly than just running screws in.

All alpine binding screws measure 4.1mm (measuring the solid post inside the treads). Using a ski tap in 3.5mm holes will work if you force it, but it will buckle the topsheet up slightly before engaging. On another note, why would you want to make a 3.5mm hole into a tapped 4.1mm if the manufacturer suggests using a 3.5mm pilot hole?
I had a buddy mistakenly use a 4.1 bit on his ObSeths and all the screws ended up as "spinners" when tightened under normal torque specs.

[gregL]

I use a Wintersteiger 3.6mm bit and tap all the time and have not experienced a problem with the topsheet pulling up (I also countersink with a 45 degree bit after drilling/before tapping). Manufacturers suggest 3.5mm/3.6mm for non-metallic topsheets assuming people will not tap, giving extra allowance for grinding away with screws before they catch. I'd prefer to cut it cleanly to 4.1mm before the screws go in.

Binding screws are typically spec'd as 5.5mm, that is the nominal outside dimension (actually something like 5.43) but the shaft dimension, as you say, is 4.1

[DropCliffsNotBombs]

Larger pilot holes hold the screw threads less tightly (physics). Why would you choose to make a less secure pilot hole if you didn't HAVE to?

[gregL]

It's going to be 4.1mm eventually anyway. I'd rather it fit perfectly before I screw the binding on than grind it down/displace fiberglass with the screw itself. YMMV.

[DropCliffsNotBombs]

You just proved my point. A 4.1 pilot hole will hold a binding just fine if a threaded metal layer is present. The whole reason to go with a smaller pilot hole (than the screw itself) is because more "bite" is needed in skis without the threaded metal layer.

[gregL]

The smaller pilot hole turns into a 4.1 hole as soon as the screws go in, but tighter fit doesn't necessarily = longer relationship IME. Pullout strength has more to do with contact around the threads and the integrity of the deck material. Cleaner cutting and less stress on the fiberglass seem to be the way to go for me, but go ahead and forgo the tap on your skis.

[old goat]

You just proved my point. A 4.1 pilot hole will hold a binding just fine if a threaded metal layer is present. The whole reason to go with a smaller pilot hole (than the screw itself) is because more "bite" is needed in skis without the threaded metal layer.

And because wood--at least the relatively soft woods used in skis--compresses. Metal doesn't.

[XXX-er]

OK here are some recurring mistruths that seem to keep coming up on this forum.

- Binding screw threads alone are not enough to hold the screw in. You MUST also add epoxy(or whatever else) in order to keep them secure. <binding glue is meant to lubricate the screw, keep out moisture, and dampen vibration, NOT to hold the screws in!>
- Epoxy, steel wool, broken toothpics, and wood chips are a good way to fix stripped screw holes. <"ghetto-fixes" sometimes do work, but...>
- Heli-coils are somehow stronger than mounting as normal. <never, ever>

- JB weld is somehow applicable for ski repair. <it doesn't flex- skis do!>
- Tapping all screw holes is a good idea. <ski taps are made to fit only 4.1 holes in metal laminates>

Ok so I just remounted some fr+, one of the holes was a spinner , I wet out chopped fibreglass strands with slowset ,cram the hole , let set and the screw tightens down with as much force as I can put on the screw so what is wrong with that ,since you also say a heli coil isnt any stronger than a regular mount ? FWIW I wouldnt use tooth picks or steel wool or wood chips either

slowset epoxy in and around a screw hole is pretty tough stuff just more holding power and they are not about to come loose ,you wana remove the screw hit it with a soldering iron for 30sec and it releases

IME often ghetto fixes are done by people who can't fix anything ...they shouldnt be allowed to own tools

[ripvanwinter]

OK here are some recurring mistruths that seem to keep coming up on this forum.

- Binding screw threads alone are not enough to hold the screw in. You MUST also add epoxy(or whatever else) in order to keep them secure. <binding glue is meant to lubricate the screw, keep out moisture, and dampen vibration, NOT to hold the screws in!>
- Epoxy, steel wool, broken toothpics, and wood chips are a good way to fix stripped screw holes. <"ghetto-fixes" sometimes do work, but...>
- Heli-coils are somehow stronger than mounting as normal. <never, ever>
- Installing inserts is a convenient way use one pair of bindings on several different pairs of skis. <what a PITA this idea really turns out to be>
- JB weld is somehow applicable for ski repair. <it doesn't flex- skis do!>
- Tapping all screw holes is a good idea. <ski taps are made to fit only 4.1 holes in metal laminates>

Agree with all but two:

1. You seem to feel a need to personally crusade against inserts, which many people here, myself included, really find useful. The hour or so it takes to set up a pair of skis is pretty minimal and is worth the money saved in buying multiple bindings and the PITA of lugging them around if travelling by air.

2. Ghetto fixes are fine in certain situations. I personally wouldn't use toothpicks in my skis, but steel wool or fiberglass fibers when bonded together with a good epoxy can be stronger than many species of wood and have fixed borderline spinners for generations.

Some guys in here mount their skis with CAD assisted router tables and some guys with 12volt cordless drills and paper templates.

[Chowda]

- Heli-coils are somehow stronger than mounting as normal. <never, ever>

Other then the anecdotal binding blowout you mentioned in the other thread (which very easily could have been the result of a soft or water damaged core), what evidence do you have to say this with such absolution?

- JB weld is somehow applicable for ski repair. <it doesn't flex- skis do!>

If you are talking about delam repair then yes. Since this thread is about binding mounting myths, I'm assuming you are referring to filling old holes and remounting with close proximity or overlapping holes. In this case flex isnt a concern, and the ability to machine/tap the epoxy is. JB Weld is a better solution here then say West Systems Marine. I will ignore whether overlapping holes are ok, since its been discussed many times.

- Tapping all screw holes is a good idea. <ski taps are made to fit only 4.1 holes in metal laminates>

I think tapping adds complication, and IMO has no real benefit unless there is metal in the layup. If you do tap it is important to use the tapped threads, and not really pressure the screw to tap new ones. If you've had problems with retention on tapped holes, this is likely why. Tapping holes (and installing helicoils FWIW) takes a bit of skill, and not every asshole whose used a screw driver will get it right, done well it isn't compromising to the mount.



Also, you speak as if there is a right and wrong way. Sticking with industry norms and mfg guidelines will give the most predictable results. But if you are trying to push the limits when mounting, as many here do, there is not a one-off solution for every situation.

[Jethro]

All alpine binding screws measure 4.1mm (measuring the solid post inside the treads). Using a ski tap in 3.5mm holes will work if you force it, but it will buckle the topsheet up slightly before engaging. On another note, why would you want to make a 3.5mm hole into a tapped 4.1mm if the manufacturer suggests using a 3.5mm pilot hole?
I had a buddy mistakenly use a 4.1 bit on his ObSeths and all the screws ended up as "spinners" when tightened under normal torque specs.

If a tap creates a volcano cutting out material, what the hell do you think a binding screw does displacing material in a non metal topsheet ski? I often tap them and fill the hole with epoxy. I like to try one hole untapped to see how that ski reacts to an untapped hole. The epoxy reinforces the crap light wood in the core of todays fat skis. Really, how much holding power do you think you have in Aspen, Poplar, etc. Most of your holding power comes from the top threads in the topsheet. Tapping non-metal skis is rightfully a contentious issue which varies from ski to ski.

Epoxy is not required, but it does not hurt anything either. The reason shop techs don't use it often is that it takes time to mix and dab into the hole. Time that most customers do not want to pay for and which can be used for sales or tuning or any other job in the shop. I have had a lot of shop mounted screws come loose. Why wouldn't I use a glue which bonds to the metal screw and seals, and lubricates the threads?

Helicoils can be wicked strong, if properly installed in a fully supported hole (no keyholed holes). In another post yesterday you confused plastic pound in inserts with helicoils. I do not think you have a very good grasp of what you are talking about.

The only statements that you made that I agree with are #2 (glue, steel wool and toothpicks as spinner fixes) and maybe #5 (JB weld). Actually, if you flex the cardboard or paper you mixed your epoxy on a day later, you will see that it will crack also. The dried wood glue on the tip of your bottle will crack off also. JB weld is essentially an epoxy with a filler designed to be tapped and machined. It might work well but I have not tried it in skis

[FlimFlamvanHam]

What a PITA inserts are

[GeezerSteve]

This oft cited pullout test demonstrated that an epoxied ABS screw is substantially stronger. Note that the test also demonstrated that a M8-1.25 machine screw O.D. style insert was not as strong as an ABS screw.

[Dexter Rutecki]

Pretty sure that for mounts onto metal race plates epoxy doesn't help. Not 100% sure, but that's what I think. Don't really see how it could be effective.

[XtrPickels]

Many people around here pretend to be experts and enjoy hearing themselves talk.
This strikes me as one of the douchiest attempts.

Either provide the data to back everything up or get off your horse.

[GeezerSteve]

Zeno's pullout test provides data from which one can conclude that (a) epoxy significantly enhances pullout strength; (b) 3.6mm vs. 4.1mm pilot holes does not matter; and (c) a tapped & epoxied machine screw-based insert* has lower pullout strength than a screw (bare or epoxied and/or 4.1 or 3.6). Zeno did not test helicoil pullout, but my non-scientific DIY tests suggest that a properly installed helicoil has significantly greater pullout strength than screw or machine screw-based insert. Of course, Zeno's tests might be specific to the ski cores tested.

*Note that Zeno tested an EZ Lok 8mm - 1.25 insert, which is similar diameter to Quiver Killer/Binding Freedom, but the EZ Lok 1.25mm thread pitch is a wee bit finer, ~20TPI vs. 18 TPI.

[Jethro]

Not sure to whom that is directed. Zeno's pullout test provides data from which one can conclude that (a) epoxy significantly enhances pullout strength; (b) 3.6mm vs. 4.1mm pilot holes does not matter; and (c) a tapped & epoxied machine screw-based insert* has lower pullout strength than a screw (bare or epoxied and/or 4.1 or 3.6). Zeno did not test helicoil pullout, but my non-scientific DIY tests suggest that a properly installed helicoil has significantly greater pullout strength than screw or machine screw-based insert. Of course, Zeno's tests might be specific to the ski cores tested.

*Note that Zeno tested an EZ Lok 8mm - 1.25 insert, which is similar diameter to Quiver Killer/Binding Freedom, but the EZ Lok 1.25mm thread pitch is a wee bit finer, ~20TPI vs. 18 TPI.

Thanks for posting that test. It confirms my opinion about epoxy usage, but I am bummed somewhat about the insert test. I just mounted new Lhasas with quiver killers, not for binding swaps but because I had read they were stronger than screws.

[gregL]

Come to think of it, this is probably where I got my ideas about tapping and stress on the surrounding material, it's around the time I ordered mine. Kinda like being too fat for your pants, you walk around for a while thinking your ass looks fine, then one day you bend over and the the fabric fails catastrophically . . .

Zeno's Conclusions:

1) The EZ-Lok 453-5 isn't quite as good as a screw, even with tapping and epoxy.
2) Tapping improves performance quite a bit. I was surprised because after tapping the insert went in super easy, almost even loose, but it performed better.
3) The 4.1 mm pilot hole was as good as a 3.6 mm pilot.
4) Placing a screw 1 cm away from an existing hole may decrease strength a little.
5) Epoxy helped the screw, but not the insert. My guess is that screw just engages the wood better and the epoxy helps tie the wood together before failing.
6) This relates to 2 and 3 above. Before testing, I thought that by keeping pilot holes as small as possible and the subsequent required "shoving" and "forcing" the screw or insert into the hole would result in a stronger hold because the fastener would be "tight" or would "densify" the wood as it was installed. I now think otherwise. The less damage done to the wood keeps the wood stronger. This is seen in the results i.e. larger pilot holes performed better and tapping (even when it seemed too loose) actually did better. I will be ordering a ski screw tap from Tognar.

[XXX-er]

Many people around here pretend to be experts and enjoy hearing themselves talk.
This strikes me as one of the douchiest attempts.

Either provide the data to back everything up or get off your horse.

and logicaly these experts would also be the same guys who at some point have fucked up all the skis we about read in the " the-shop-fucked-up my skis" threads ?

ski teching is not even close to rocket science

[glademaster]

Okay, so to take things back to the beginning, why does it really matter? Seriously, how many people on here are actually ripping bindings out of skis on a regular basis, regardless of whether they are epoxied, tapped, mounted with inserts, etc? The thought of that happening has never once crossed my mind, and admittedly there are people are here who charge a lot harder than me, but still, it seems like it would take a hell of a lot of force to pull an alpine binding out of the ski.

[AlpiNord]

Not sure to whom that is directed. Zeno's pullout test provides data from which one can conclude that (a) epoxy significantly enhances pullout strength; (b) 3.6mm vs. 4.1mm pilot holes does not matter; and (c) a tapped & epoxied machine screw-based insert* has lower pullout strength than a screw (bare or epoxied and/or 4.1 or 3.6). Zeno did not test helicoil pullout, but my non-scientific DIY tests suggest that a properly installed helicoil has significantly greater pullout strength than screw or machine screw-based insert. Of course, Zeno's tests might be specific to the ski cores tested.

*Note that Zeno tested an EZ Lok 8mm - 1.25 insert, which is similar diameter to Quiver Killer/Binding Freedom, but the EZ Lok 1.25mm thread pitch is a wee bit finer, ~20TPI vs. 18 TPI.

What is the conversion from ft/lbs to kips to kg?

From Snoli:
Drive-in Brass Inserts: pull-out resistance 300 kp
Brass Inserts 9 mm: pull-out resistance 268 kp, fine screw thread
Brass Inserts 9 mm: pull-out resistance 225 kp
Drive-in Plastic Dowels: pull-out resistance 240 kp

Here's an Italian Forum with a member that tested the QuiverKillers versus screws.
I think it reads: Screws, 280 kg and QuiverKiller, 395 kg

Anyone have a heli-coil test link?