Mounting NNN BC Bindings

[GrimSurfer]

How does that make sense?

Yes, you are correct, what I wrote was mangled.
I made a mistake in the wording of the post above yours and correct it below:

I haven’t had any problem either but accept that some people have.

I guess that’s where we differ.

And now we come full circle.
Some people either have enough experience working with things to recognize a problem before making a mistake mounting the binding, or, they have already made the mistake, and know what to look for.
A second group of people don't have the benefit of the above.

I wrote the original post to try and help those in the second group.
If I offered bad, or incomplete advice to that group of people (not the group who already know, and for which my post would be unnecessary), then please, anyone add concise, accurate, simple additions.
As it is, I think what I posted in the original post is sufficient, but if not, I have no emotional investment on improving it.
I would just like to not COMPLICATE matters...

I was being a little too subtle.

If you really want to assist someone, don’t tell them what to do. Help them understand why to do something.

[GrimSurfer]

How does that make sense?

Yes, you are correct, what I wrote was mangled.
I made a mistake in the wording of the post above yours and correct it below:

I haven’t had any problem either but accept that some people have.

I guess that’s where we differ.

And now we come full circle.
Some people either have enough experience working with things to recognize a problem before making a mistake mounting the binding, or, they have already made the mistake, and know what to look for.
A second group of people don't have the benefit of the above.

I wrote the original post to try and help those in the second group.
If I offered bad, or incomplete advice to that group of people (not the group who already know, and for which my post would be unnecessary), then please, anyone add concise, accurate, simple additions.
As it is, I think what I posted in the original post is sufficient, but if not, I have no emotional investment on improving it.
I would just like to not COMPLICATE matters...

I was being a little too subtle.

If you really want to assist someone, don’t tell them what to do. Help them understand why they need to do something.

[Stephen]

Post removed for clarity.

[GrimSurfer]

It’s really important to understand how threaded fasteners work. Otherwise, you run the risk of either providing bad advice (which you haven’t done) or explaining that the cause of failure is because something wasn’t done hard enough.

Sometimes things ARE more complicated than this. Sometimes designs are faulty. It might not matter to the people who can avoid failure on the fly, but it matters greatly to those who can’t.

So instead of suggesting that “people are doing it wrong”, a more elegant approach is explaining where design meets reality.

What has been discussed here bounces between two schools of thought: Do it harder and a certain degree of failure analysis. Just about everyone who has commented has dipped their oar into each school. But it hasn’t been complicated. It just stimulates thinking.

[GrimSurfer]

I was being a little too subtle.

If you really want to assist someone, don’t tell them what to do. Help them understand why to do something.

Did I not do this in Post #1?

I don’t know why, but the binding is manufactured without enough clearance in the screw hole to allow the mounting screws to have a snug, but unimpeded fit.
Possibly this was not a problem in the original manufactured product, but then, at some later time, the mounting screws were changed to a slightly different screw, which is now causing the problem.
It’s also possible it’s by design, to keep ski techs from over-tightening the screw and stripping out the screw hole, which would be an even bigger problem.

If one is aware of this potential problem, one can take the appropriate steps to avoid the issue.
The problem is, until it happens to you, you might not know.

For me, the best, easiest solution to this problem is this:
Before mounting the binding, simply put a screw in each hole and turn it until it is completely tight, and then keep turning the screw until it turns relatively freely.

If anyone thinks this is bad advice, please say so.

Why not just drill or ream it to size, instead of using the fastener? Isn’t that the more elegant approach? The whole won’t be ragged as AF, there’s less chance of splitting the plastic (it’s pretty soft and forgiving but using a coarse threaded screw instead of a sharp drill bit comes with risk).

I mean, anything can be turned into a hammer. But hammers work best to drive a nail. Not that any of us haven’t used something than a hammer to drive a nail at least once in our lives. LOL

Seriously though, there are hazards reaming or drilling too. You’re taking material away from a load path (screw head —> dog bone washer —> binding. The weakest part of this load path is the plastic. So best not to mess with this too much.

If it were me, I’d rather take down the threads from where the fastener exits the top sheet to where it meets the screw head. We’re taking mild steel here (don’t let the term “mild” fool you. A lot of mild steel is tougher than stainless steels, which can be hard/brittle).

Removing unengaged threads won’t have any practical effect on clamping force or fastener longevity. In fact, unengaged threads are stress risers. That’s why screws and bolts in single sheer usually break where the threads are not engaged (in tension, they usually break where the threads exit the material into which they are screwed).

You don’t need to be a machinist with a metal or screw lathe to do this. A Dremel and abrasive but can get the job done.

The problem is the fastener. Perhaps doing something about that is easier than changing everything else around it.

[Stephen]

Post removed for clarity.

[GrimSurfer]

Talk of stress risers doesn’t confuse the issue, it informs it. Same with load paths and basic materials science.

Otherwise, you’re playing Kerplunk… taking away stuff until something drops or breaks.

We can do better than that.

The problem with jacking is due to the way in which the fastener passes though one material and into another. Fix the fastener and you fix the problem… or take away material from the weakest part of the binding.

Choice seems pretty clear to me.

(PS. The threads on screws aren’t machined nor are they cut. Not good ones anyway. They’re rolled.)

(PPS. Threaded fasteners with a rebated shanks actually exist. They are made to specifically address jacking, which is a very common problem in applications involving plastics and wood. Even though I’m not aware of any made by Rottefella for its ski bindings, it’s easy enough to modify the original fasteners accordingly.)

[randoskier]

Normally if you buy a binding the shop will mount it, if you have a good shop they have a good tech. Bon ski!