Mounting NNN BC Bindings

[Stephen]

Update here:
viewtopic.php?f=21&t=5334

[Stephen]

Post removed for clarity.

[GrimSurfer]

I see where you’re going with this and agree… kind of. My only concern is that the wood core of skis are so unforgiving. Poplar or paulownia are light (good) but not strong (bad),

One could either clamp or pre install the screws fully in the binding before screwing to the base. The first makes 100% sense based on the current screw configuration. The second would work like a charm if the screws had a rebated shank (these would fit snugly in the binding holes but could turn without reaming any of the binding materials.

Binding screws are cheap and readily available. Maybe the next time I do this, I’ll measure everything with a set of callipers and machine a rebated shank into both screws (the top/front screw doesn’t seem to be a problem). I doubt that I will need to machine things down until the shank is smooth. Probably knocking a few thou’ off the threads in the notional shank area would be enough.

It’s unusual to see a rebated shank on a wood screw (shanked screws are common enough though). Not unusual on machine screws and bolts though. A typical application is cylinder head bolts when the engine is one material (cast iron) and the heads are another (aluminum). These are angle torqued and they stretch to provide more consistent clamping force with two materials of dissimilar expansion rates.

[lilcliffy]

I must say that I have never had any issue mounting NNNBC bindings tightly to the ski- as long as I am paying attention and applying enough downward pressure.
I mount them entirely by hand- driving the screws with the appropriate pozi-drive.

[Stephen]

Post removed for clarity.

[GrimSurfer]

I must say that I have never had any issue mounting NNNBC bindings tightly to the ski- as long as I am paying attention and applying enough downward pressure.
I mount them entirely by hand- driving the screws with the appropriate pozi-drive.

A few people have had the problem of the binding not being installed flush to the ski.
I am hoping this info would help someone avoid that in the future.
Because the screw thread engages the plastic in the binding, extra care needs to be taken.
I don’t think there is any other binding that has this issue?

So much has been written about this lately its become a whirled blur.
This is really pretty simple.

The mounting screws engage the plastic in the binding and stop turning once the underside of the screw head contacts the binding. The screw never clamps the binding to the ski, it simple attaches the binding (there is a difference).
With any other binding, the screw clamps the binding to the ski because there is no interference between the binding and the screw. The screw is free to turn until the binding is pulled tight to the ski.

What this picture shows is that the screws will not pass through the plastic portion of the binding material.
They engage the plastic and this is what causes the problem.
.
88A6D7F3-80D3-43C6-90B6-E4469A5E2CB0.jpeg

Yup. 100%. Thanks for posting that.

Perhaps the trick is to pre-screw the binding. This will establish a thread pattern in the binding material.

Then back off the screws a bit, press the binding onto the ski by hand (after a bowl of Wheaties), and snug the screws down. Once it’s been established that everything is nice and flush, back the screws out of the ski, pop some glue in the holes, and torque it down for real.

That’s how it was done at the GrimSurfer OCD school of engineering last year. Don’t know if it’s better than any other method (we’ve kicked a few around here).

Thoughts?

PS. Once we can come to a consensus on what works and what doesn’t, it might make for a good sticky on NNN BC binding mounting.

[GrimSurfer]

I must say that I have never had any issue mounting NNNBC bindings tightly to the ski- as long as I am paying attention and applying enough downward pressure.
I mount them entirely by hand- driving the screws with the appropriate pozi-drive.

Yeah, pressure important. The pic posted by @Stephen shows the camber of the binding that must be overcome to have any chance of doing this without drama.

The following is intended for others who don’t have as much experience with tools or mounting bindings…

1. Certainly agree on using the right driver (pozi). Other considerations…

90% of screwdrivers and 95% of driver bits are junk. If it’s chromed, it’s junk. If the ends aren’t treated by blasting, hardening etc. it’s junk. If it isn’t made by Wera, Klein, Wiha, Gedore or a few other mid to high end tool makers, it’s possibly junk. If it’s a driver bit and comes in a pack, it’s the tool makers way of saying that the bits are soft and will cam out if you look at them the wrong way. A junk tool will lead to problems, so get a good screwdriver or bit before starting the job.

2. I have used a pozi bit with a 3/8” ratchet and an extension. The ratchet head is wide so I can get down on it. Gets me 90% of the way (I’d never use a ratchet for final torque… too long a handle. I’d bugger it.)

3. That camber does get in the way of things, especially with the screw at the mid sole and heel plate. The mid sole is more critical though (the heel plate can be adjusted and being a few mm off isn’t cause for any concern).

4. You can use the template. Or you can put painters tape on the ski, use a square and steel ruler and add registration marks before using the actual binding as the template. I like to do the latter because you’re mounting the binding to the ski, not the template to the ski.

5. Drill one hole at a time and place the binding on top as a check. Realign the marks for the remaining holes as needed. Having a binding out by 1 degree of arc is better than having the holes off by 1 mm of distance when fasteners enter the equation.

[Stephen]

Post removed for clarity.

[Stephen]

Yeah, pressure important. The pic posted by @Stephen shows the camber of the binding that must be overcome to have any chance of doing this without drama.

3. That camber does get in the way of things, especially with the screw at the mid sole and heel plate. The mid sole is more critical though (the heel plate can be adjusted and being a few mm off isn’t cause for any concern).

The "camber" of the binding is an illusion.
The bottom part of the binding that contacts the ski is made of three pieces of plastic.
There is plenty of flexibility here, and the "camber" you see offers no resistance during installation.

The ONLY problem is the interference between the screws and the diameter of the hole in the plastic part of the binding.

Let's not complicate this.

[GrimSurfer]

Yeah, pressure important. The pic posted by @Stephen shows the camber of the binding that must be overcome to have any chance of doing this without drama.

3. That camber does get in the way of things, especially with the screw at the mid sole and heel plate. The mid sole is more critical though (the heel plate can be adjusted and being a few mm off isn’t cause for any concern).

The "camber" of the binding is an illusion.
The bottom part of the binding that contacts the ski is made of three pieces of plastic.
There is plenty of flexibility here, and the "camber" you see offers no resistance during installation.

The ONLY problem is the interference between the screws and the diameter of the hole in the plastic part of the binding.

Let's not complicate this.

Let’s not.

If you don’t know what you’re doing you can mess up a lot of things. So better to be exploit and help prevent somebody making a mistake.