Thread: Plum Guide vs 2012 Dynafit Radical?

Not ready to retire mine and stick them to the refrigerator yet, but considering how many pairs of Guides are in use in North America at the present two failures is significant. Lee, any more details on the BC pair? Skier weight, # of days?

Four years of use of Plum 135/145's by 65 kilo French guys on 160 race skis might not be too meaningful in this context.

Guys - I've asked my friend who's binding failed. Since these aren't my personal Plum bindings I will just be passing along information. It's up to my friend who had the failure mode to pass along the info. Thanks for the understanding in advance

I posed a similar question and was told by plum that they put the guides through testing which is pushed beyond the limits. Several professional freeskiers ski on them regularly and this is the first failure they have heard of and are concerned with remedying the situation right away. They have been very accommodating and responsive so far.

Originally Posted by thin cover

I posed a similar question and was told by plum that they put the guides through testing which is pushed beyond the limits. Several professional freeskiers ski on them regularly and this is the first failure they have heard of and are concerned with remedying the situation right away. They have been very accommodating and responsive so far.

Good news. Sounds like they are concerned and want to do it right. Hopefully they deliver.

I'm sure they'll sort this out, but in the meantime I'm glad to have tried and true FT12s. Anyone can make a solid binding that's heavy, but pushing the weight envelope as Plum has done can require some experimentation.

Originally Posted by D(C)

I'm sure they'll sort this out, but in the meantime I'm glad to have tried and true FT12s. Anyone can make a solid binding that's heavy, but pushing the weight envelope as Plum has done can require some experimentation.

Just make the binding out of solid titanium...problem solved

Well to be fair there have been ft 12 explosions recently as well. I think the popularity and ease of tech bindings and the BC in general has attracted a style of skier and accompanying size of ski being skied on terrain that mAy beyond the scope of any stated "rigorous" testing.

Originally Posted by thin cover

Well to be fair there have been ft 12 explosions recently as well. I think the popularity and ease of tech bindings and the BC in general has attracted a style of skier and accompanying size of ski being skied on terrain that mAy beyond the scope of any stated "rigorous" testing.

Fair enough.

Originally Posted by Jonathan S.

Right, the Dynafit wings are steel and the Plum wings are CNC'ed alu. (Pincers on both are of course steel.)
I don't think that by itself has any great meaning though -- I mean, something made out of steel can be weak, and something made out of alu can be strong. So many other factors involved...

Well, if the cross section is the same, and assuming good QC, the proper steel alloy for the application will be far (typically 2-1/2 to 3X) stronger than the proper Al alloy for the application. So, in rough theoretical terms, assuming UTS of 42,000 vs. 110,000, an Al alloy member needs to have a 2.6X bigger cross section to achieve the same strength. That's obviously oversimplifying things because there are design variables. Of course, Al alloy is less (roughly 1/3 as) dense so there's no weight penalty if the cross section is 3X as big. (Note that I've chosen UTS of 6061-T6 vs. 4130 (normalized), two materials with which I have experience. I don't know what materials Plum and Dynafit use.)

Fatigue is another matter. Al alloy is significantly more prone to fatigue failures in many applications.

Has anyone every seen a Dynafit break through the pincer socket?

Originally Posted by thin cover

Well to be fair there have been ft 12 explosions recently as well.

All but one of the FT12 failures I've read about resulted from a defectively designed plate which Dynafit has addressed with the Power Plate and which should not be a problem with Radical. The other FT12 failure chronicled on TGR resulted from bashing a rock so hard that it bent the hell out of the steel alloy plate, an impact that likely would have broken any tech binding.

Originally Posted by thin cover

Well to be fair there have been ft 12 explosions recently as well.

I do recall one that bashed a rock. To be expected.

In any case, keep in mind that there are probably at least 1000 times as many Dynafit bindings in use as Plums and they have a very solid record of reliability. I'm sure Plum will iron out the weak spots in time but it does take a while to engineer out the failure modes.

BC.com has a closeup shot of a FT12 toe (I've never looked at one up close):
http://www.backcountry.com/dynafit-t...ft-z12-binding

The wings almost look die cast...could they be zinc, or can steel be die cast Big Steve? Wouldn't think zinc could be strong enough. Spendy steel parts are sometimes investment cast with one-time ceramic molds, can't imagine Dynafit would use an expensive process like that though. Given the fine parting line they don't appear to be forged. The triangular window appears to have draft, which also suggests a cast part.

The blue tone looks like zinc plating, do the wings rust or do they corrode where scratched?

Originally Posted by AweShuksan

I do recall one that bashed a rock. To be expected.

In any case, keep in mind that there are probably at least 1000 times as many Dynafit bindings in use as Plums and they have a very solid record of reliability. I'm sure Plum will iron out the weak spots in time but it does take a while to engineer out the failure modes.

I have ft 12's also aside from some unwanted heel releases here and there in deep powder they were great and never did this. I am baffled by what happened with the plum. Clearly something was weaker then it should have been. not sure if there is anything that will get me back on any tech binders on terrain of consequence.

Maybe the wing was "cut" by a hard ski edge impact, then broke under load later. Might be hard to see a cut right at the crack, but Plum will probably be able to see it if there's one there. A thin layer of flexible epoxy on the outside of the wing would probably stop edge hits from getting into the aluminum.

^^^^ that seems like a good idea but that added weight may deter me

seriously I will would not mind doing that as an added measure of safety, thanks. I do not see any impact, I was thinking the same thing. It could have cracked on the way up, some of the side hilling I was doing or the firmer snow coming into the gully we were skiing may have created some sort of hair line fracture that was just exacerbated by the following steep turns.

Originally Posted by 1000-oaks

The wings almost look die cast...could they be zinc, or can steel be die cast Big Steve?

Yes, it looks cast, maybe die maybe investment. And it might also be worked after it is cast? Some sort of steel alloy per magnet test. Maybe a zinc coating. Whatever it is, it's tough stuff.

Originally Posted by 1000-oaks

Maybe the wing was "cut" by a hard ski edge impact, then broke under load later. * * * A thin layer of flexible epoxy on the outside of the wing would probably stop edge hits from getting into the aluminum.

I suppose a surface scratch might propagate a crack, but I've never seen Al alloy fail that way -- Al alloy is amorphous stuff -- think bicycle crank arms, which get the shit scratched out of them. If this is a design problem (rather than an individual material flaw or impact related) a larger cross section around the pincer socket or different material seems the obvious fix.

A brief tangent - has anyone had luck contacting the guys at Plum? I have sent two emails over the past few weeks and nothing via the "contact" page on the website.

If you have had success, can you PM me the email?
Thx.

Carry on...

PM Sent foreal

Snapped a few quick pix of the Guides before shipping them to TC's buddy, if anyone wants to see these little works of CNC art up close and personal. (These photos should be 20 inches wide, don't know why TGR downsizes them, click on the link.) Sorry about the watermarks to discourage piracy, if Plum wants me to shoot their products they need to send me a pair. With brakes. ( ^=

http://www.phototurbo.com/ski/plum-guide-toe.jpg


http://www.phototurbo.com/ski/plum-guide-heel.jpg


http://www.phototurbo.com/ski/plum-guide-bottoms.jpg

A friend told me that PLUM will widen the mounting pattern on the Guide for next year, does anyone have any info on that? Sounds unlikely to me.

Glad ur OK from the pincher failure man, was pretty sure about switching to PLUM next year but I'll follow this and see were it ends up before buying.

you can also say 500.000 times more dynafit around than plum, dynafits are around since 15years without substantial changes, plums since a couple selling a few (maybe) thousands pairs.

Originally Posted by AweShuksan

I do recall one that bashed a rock. To be expected.

In any case, keep in mind that there are probably at least 1000 times as many Dynafit bindings in use as Plums and they have a very solid record of reliability. I'm sure Plum will iron out the weak spots in time but it does take a while to engineer out the failure modes.

Just for you to know ... Tri step was realized by a different company... The Dynafit brand was acquired by the Italian Salewa Group in 2003 just after the Tristep failure and nobody of the people working for Dynafit in that times are in the new company now.

Originally Posted by harpo-the-skier

The plums weigh 6oz less than the Vertical ST and FT12. If I remember correctly, the Radicals weight more than the Vert ST/FT. Also, remember that the last time Dyna made a big change in their bindings (Tri Step) it was a colassal failure and they pretty much had to revert to their old designs.

Originally Posted by Big Steve

Well, if the cross section is the same, and assuming good QC, the proper steel alloy for the application will be far (typically 2-1/2 to 3X) stronger than the proper Al alloy for the application. So, in rough theoretical terms, assuming UTS of 42,000 vs. 110,000, an Al alloy member needs to have a 2.6X bigger cross section to achieve the same strength. That's obviously oversimplifying things because there are design variables. Of course, Al alloy is less (roughly 1/3 as) dense so there's no weight penalty if the cross section is 3X as big. (Note that I've chosen UTS of 6061-T6 vs. 4130 (normalized), two materials with which I have experience. I don't know what materials Plum and Dynafit use.)

I think they use 7075-t6 which is much stronger. But Titanal aluminium alloy is even stronger then 7075 alloy (about 15%) it is used in skis as metal sheets at sandwich construction.

7075-T6 makes sense because there are no welds. So doing the comparo, the next question is what steel alloy is Dynafit using and what is its UTS and YTS. Dynafit may keep that info secret. I used 6061-T6 and 4130 in my hypo because I'm familiar with those alloys. Some 4000 series steel alloys are 2X+ stronger than 7075-T6 and there are some modern steel super alloys 3X. The questions don't stop there because, as previously noted, fatigue potential is more complicated than merely looking at UTS/YTS and cross section size. I'll be watching how Plum responds to these two failures. I'd put a few bucks on a larger cross section at the pincer socket. Looks like Plum has some good engineers so they'll figure it out. Beautiful binding. Competition in the tech binding biz is a good thing for us consumers.

Originally Posted by thin cover

...I think the popularity and ease of tech bindings and the BC in general has attracted a style of skier and accompanying size of ski being skied on terrain that mAy beyond the scope of any stated "rigorous" testing.

IMHO, a really relevant comment. French males, for instance, are about an inch shorter and over 20 lbs lighter than average U.S. male. (Who is a hell of a lot smaller than TC or a lot of other guys here.) And most off-piste over there is on skis in the 78 to 95 mm range, with more of the day spent walking, through a lot less snow. Whole different mission. So if Plums - or Dynafits - are being aimed at Euro bodies on Euro touring skis, wonder if the design parameters, let alone the testing, are looking at the forces many here routinely generate.

There's some validity to that, but most Euro ski tourists encounter more ice than most NA tourists, and ice is the stuff that rattles the shit out of tech bindings and can lead to fatigue failures. There are means to test for fatigue potential via accelerated cycling -- and I'll assume that Plum did that -- but the final product testing of the Plum Guide is occuring on both continents by consumers.