More Swiss Cheese: JJ/Dynaduke/Axl/inserts

[6CA7x4]

With one insert swiss cheese experiment under my belt, I'm now considering what to do with a new pair of 185 JJ's that will arrive this week. Originally I was planning on Dynaduke plates, but throwing the plates on inserts and adding inserts for a tele binding (Axl) would have me well covered for all powder/BC purposes. Unless I'm overwhelmed by screams of horror, this is the direction I want to go.

My only real concern is over the danger of pull-out with the JJ's that have a bit of a reputation in that department, particularly with tele bindings that are inherently more susceptible. My intuition is that, given enough clearance between holes, inserts will have better resistance to pull out due to increased surface area. However, I also feel that too many holes in too small an area could make an already borderline core more susceptible to failure. I'd love to hear what the collective experience and thinking on hole clearance with inserts in JJ's is.

In this case, I'm assuming I'll need to use B&D tele shift plates since the dynaduke inserts will pretty much determine where the tele inserts can go. The dilemma is whether to go with the 6-hole Axl pattern plate or the standard 4-hole to Axl adaptor/shift plate. Here are some rough sketches of the layouts.





The Axl pattern has the obvious advantage of a couple extra screws, but this comes at the disadvantage of a minimum hole separation of 1.9mm, center to center, and a pretty good peppering of the toe area with holes. The little bit wider spread on the holes can't hurt with the Axl pattern. The 4-hole pattern has the disadvantage of fewer holes but the benefit of larger hole separation (2.5mm minimum) and what seems to be far less disruption to the ski core integrity. So I'm not sure which way to go.

It's worth considering that a pull out of the tele inserts wouldn't be that disastrous to me if it didn't damage the Dynaduke inserts. I'd just do a repair and that would be the end of tele for these skis. That would be an argument for the 4-hole pattern (if you think pull-out has a reasonable likelihood), unless the consensus is that the 6-hole pattern is clearly superior and unlikely to cause any core integrity issues.

It's a judgement call, so I'd really appreciate some input on how to proceed. I'm pretty new to tele and not that hard of a charger in general, but at 6'1" and 185 pounds (and as high as 205 in recent years) I'm not a featherweight.

[HHTELE]

Thanks for doing the research on this one- I may have the exact same issue next season, assuming the injury that has me focused on AT resolves, and I can tele.

Some logic to the four hole pattern with inserts. When tele bindings rip out, it is often because a couple of screws in a 4 hole patter loosen, and the torque on the other screws is just too much. With inserts, checked regularly and threadlocked, this issue is minimalized.

But, I would probably go with 6 holes. HH/Axles stay put with 6 screws. You have nearly 2 cm.

Another option would be using the front and rear holes only. This is probably at least a strong as shift plates, given the increased fore/aft spread. And given the increased strength of inserts, may well be as strong as a traditional 6 hole mount. Just move the mount a few mm back.

Here is another consideration. In contemplating this project, I thought about drilling my Axl holes with the plate on the ski, then removing the plate and putting inserts into the ski. Replace the plate with regular ski mount screws. Mount Axls with M5 screws 6-8 mm longer to account for the extra rise. Swapping to tele will be the same as a dyna-duke swap- no need to remove the plate.

I'll be watching to see what you come up with.

BTW- I have no idea whether drilling through anodized aluminum does to it. In fact, I really don't know what anodized means, but it is kind of fun to say.

[6CA7x4]

Oops, all the "mm" in those sketches should be "cm". To the moon!

[6CA7x4]

Got a reply email today from B&D who said they could drill out the back set of machine screw holes on their 4-hole adapter/shift plate, giving me approximately this:



From an engineering standpoint this looks like the way to go; 2.5 cm minimum separation and more than 3 cm separation on the four rear tele holes. It would be nice to use the standard 6-hole Axl pattern, but I like to be conservative on these things and the modified 4-hole plate looks far superior.

I will loose the rearmost shift position, but with my 315 BSL AT boots centered on the recommended line, this installation will give me +3.5 to -2.75 cm from the line. I was planning to mount the Dynadukes 1 cm back from the line anyways, which will give my tele boot center a range of +2.5 to -3.75 cm from the line, which sounds just about perfect to me.

Problem solved. Hope this comes in handy to someone down the road. Will be sure to post pics when I get around to executing.

[Ivan Oder]

You should be fine with 2.5cm. I've had no problems with 2cm running FKS and DynaFit Radical, and others have done 1.4cm.

Just remember to be extra careful when tapping and drilling, clean the drill bit and tap after every hole etc...

Ideally you want no potential spinners in the critical holes.

I recommend doing a dry mount on a 2x4 to get some practice and to test fit.

Do one set of binding holes at a time and let them cure fully before doing the next set.

While the inserts are curing, attach your bindings loosely (no loctite) and click your boots in and let the whole thing sit level for 24-72 hours.

Repeat for the next set of bindings. It takes some time but the results are great.

[6CA7x4]

^ Thanks. After a bit of 2x4 mounting I mounted up a two-binding setup on some older skis using pretty much the process you outline. With the right tools and lots of double/triple/quadruple checking I'm getting pretty good results for insert installation. Would've just jumped in on this one if I hadn't heard so much about pull-out in JJ's.