Figuring out hole overlap issues before buying used skis?

[muted]

What's the rule of thumb for figuring out if you will have mounting issues on a used pair of skis? You probably compare BSLs and if there is a x amount of difference (old and new bindings are almost the same or are the exact same ones) you feel good buying the ski, but what is 'x' for most people?

[adrenalated]

10mm between holes for standard mounts.

15mm between holes for inserts.

Avoid having old holes in front of your toepiece if you are the type that breaks skis (I'm not and don't worry about it).

If you are using the exact same bindings, and mounting the boot center at the exact some location on the ski, the old BSL will need to be at least 20mm larger or smaller to yield 10mm between holes.
(For example, old mount is for 300mm. New mount is for 320mm. Toe goes 10mm forward, heel goes 10mm back.)

Best way is always to overlay paper templates.

[mall walker]

Avoid having old holes in front of your toepiece if you are the type that breaks skis

qft I broke a ski this way

[counterfeitfake]

Someone had a PDF that had layers for most of the popular bindings, you could see whether the holes overlapped. I think it was posted here.

[MyNameIsAugustWest]

Someone had a PDF that had layers for most of the popular bindings, you could see whether the holes overlapped. I think it was posted here.

I have the overlap PDF saved. PM me with an email address and I will send.

[XXX-er]

If you gotta move boot center 1 cm forward or back I would go for it

[summit]

Dps pure and some metal skis is ok to have some holes touch if you aren't 6ft 4 or. A fwt competitor

[galibier_numero_un]

Dps pure and some metal skis is ok to have some holes touch if you aren't 6ft 4 or. A fwt competitor

You beat me to the punch. Add skis with beefy cores/reinforced mounting areas to the list, of course. This, coming from a 160 pounder who rarely exceeds 45mph and doesn't drop cliffs.

The last time I had close spacing to deal with, I adopted XXX-er's technique of plugging holes with a mix of chopped up fiberglass and marine epoxy. I used to use a mix of JB Weld and steel wool.

I seriously doubt that the fiberglass matrix restored the integrity of the top laminate of glass, but it made me feel better ;-) It certainly doesn't hurt with respect to hole pullout.

.... Thom

[smooth operator]

here's the very cool template from Knut:

http://www.powderguide.com/community...nhang1803.html

[skizix]

I adopted XXX-er's technique of plugging holes with a mix of chopped up fiberglass and marine epoxy. I used to use a mix of JB Weld and steel wool.

Years ago, Russel Rainey (the tele binding guy, who should know) advised me that holes filled with a mix of epoxy and sawdust could reliably have holes drilled right next to them, or even overlapping. I've not needed to overlap yet, but have drilled new holes 1-2mm away from ones patched this way, with no issues.

Which makes sense (as does fiberglass mix), as these are the materials the ski is made of (plus it forms a structural matrix, like concrete). Sawdust seems a lot easier to obtain than chopped up fiberglass though, at least in my garage (and who wants to deal with chopping up fiberglass?). JB + steel wool sounds like it would work great too, but would seem tough to get fully into the hole and fully wet the sides/threads. All on the same track here though.

At the very least (even if you don't need new holes right next to old): fill holes with epoxy, not those stupid plastic plugs shops use (epoxy without stuff mixed in is easier to cram into the holes). I don't trust those plugs for a proper seal, and they provide zero structural integrity. Preferred technique for epoxy: fill hole just shy of the top with slow-set epoxy; seal top of hole well with packaging or duct tape. turn skis over, bases-up, and let epoxy cure; remove tape and notice a perfectly flush, epoxy-filled hole.

[galibier_numero_un]

Yeah, wetting all of the steel wool with JB Weld was a time consuming nuisance. It involved feathering it into fine wisps.

I got smart and picked up a square yard of glass from Amazon for under ten bucks (delivered). I forgot to mention earlier, that I used a hardwood dowel in the middle of the hole - contoured to match the bottom of the hole, and shorter than the hole depth so the top mm or so was filled with this matrix.

I masked off the area and smoothed off the top with a file and then an orbital sander


Obviously, those plastic plugs are expeditious for a shop (and they must work, from a sealing perspective), but you won't find me using them.

... Thom

[skimaxpower]

As much as possible, I try to re-use old drill holes. Thankfully I have an average sized foot, so I can usually avoid adding holes, or only have to re-drill the heels.

The obvious downside of this strategy is that it limits binding choice.

[XXX-er]

I use slow set & FG cloth to fix spinners not to fill un-used holes or fix overlapping holes

Once you've cut the core of a ski with a hole its cut, the structural integrity is lost period and you ain't getting it back with wooden plugs or sawdust or FG or any fucking thing. You just hope there was enough overkill in the engineering of the ski for you to still use it without the ski breaking, sure someone will say they mounted with an overlapped hole and it held but I would suggest you don't need the hassles or problems

If normaly mounting a binding means you have effectively cut 1/4 of core material with 2 screw holes, now you have cut 1/2 " of core with 4 screw holes overlapping holes AND you don't have solid material to mount in ... just move the binding 1/2".

I just plug holes with plastic plugs, its good enough, you can even epoxy them in if you want

To give structure to a spun screw hole sawdust is probably better than nothing , steel wool is better and 1/2 chopped pieces of FG is even better, you can buy FG cloth at most hardware stores, its easily cut with scizzors and its by far the smaller part of fucking with messy epoxy & tools

[skizix]

Once you've cut the core of a ski with a hole its cut, the structural integrity is lost period and you ain't getting it back...

I think you probably don't get all of it back, but I suspect with epoxy/aggregate, you get the majority of it back - unlike with plastic plugs.

[El Chupacabra]

I use wood golf tees with blunted tips, glued in place, to fill old holes on skis that I care about. Takes longer than the plastic pound-in plugs -- glue in tees, let dry, cut flush with dremel, dab paint over wood plug to seal... No idea if it really helps anything more than the plastic plugs, but I haven't snapped any skis so far.

I use tiny bits of fiberglass house insulation, mixed with epoxy, to fix spinners. Haven't had any binding pull-outs doing this.

[mall walker]

At the very least (even if you don't need new holes right next to old): fill holes with epoxy, not those stupid plastic plugs shops use (epoxy without stuff mixed in is easier to cram into the holes). I don't trust those plugs for a proper seal, and they provide zero structural integrity.

my ski that broke had those stupid plugs in the toe holes in front of my binding toe fwiw

[muted]

Thanks everyone!

[XXX-er]

I think you probably don't get all of it back, but I suspect with epoxy/aggregate, you get the majority of it back - unlike with plastic plugs.

we are talking about continuous laminations of wood not concrete and note that concrete is not used alone they put rebar inside to strengthen it

Where ever you drill a ski is where you cut that continuous grain of the wood, the ski gets its strength from that continuous grain which allows it to bend and not break

glue & filler is not gona bend with the wood so if a ski breaks thats where it will break at the holes no matter what you put in them

which is why its not recommended to remount a ski using different holes more than 3 times

[muted]

i usually put mini-rebar in my holes and then pour concrete in them.

[galibier_numero_un]

we are talking about continuous laminations of wood not concrete and note that concrete is not used alone they put rebar inside to strengthen it

Where ever you drill a ski is where you cut that continuous grain of the wood, the ski gets its strength from that continuous grain which allows it to bend and not break

glue & filler is not gona bend with the wood so if a ski breaks thats where it will break at the holes no matter what you put in them

which is why its not recommended to remount a ski using different holes more than 3 times

With flexible marine epoxy, I'd expect a wood or epoxy fiberglass matrix plug to bridge the gap in the fibers effectively - reestablishing the continuity of the core. I've flexed cured marine epoxy and it's remarkably flexible, but WTF do I know?

I don't think I've ever drilled a ski more than 3 times, and at 160 Lbs. so this is all prognostication on my part and I wouldn't want to generalize for 220 pound cliff hucking beasts.

My guess however, is that the majority of the strength loss would come from the interruption in the fiberglass top sheet rather than the core, but I'd like to see a real structural engineer's comments on this and not just the party line based on anecdotal evidence.

One thing that might point to whether it's the core vs. the top sheet would be to compare statistics of skis with/without some type of metal top sheet (or at a minimum - a metal reinforced binding area). If the weak point is the core, then I'd expect similar breakage statistics, but if it's the fiberglass, I'd expect fewer incidents with metal.

How much of the "reported" core's integrity loss is due to the presence of holes, vs. (for example) mildew rot from bad plugging? How many of these broken skis were plugged with plastic vs. one of the mentioned bonding techniques?

If it doesn't snow around here, none of this will matter ;-)

... Thom

[XXX-er]

Well ski breakages are all anecdotal and i'm not a fucking engineer but how much of the core do you need to sever before it's not a good idea ?

I've seen a big guy drill remount holes too close and go bouncing down mogul field

I folded his broken ski in half, put it over my shoulder and skied it to the bottom for bro!

[Reformed]

Holy shit it needs to snow in some parts of the world... I ain’t no engineer neither, but I’d put my money on the composites, top sheets, base and sidewalls providing most of the strength in skis. Remember foam cored skis? Anybody think that shit added anything but filler for the other components to be formed around? No? How is the wafer thin piece of laminated wood that is a ski core any different? Ever stop to look at how thick old wooden skis are? Ever notice that folks used to carry spare tips in the backcountry? Ski breakage went way down with the incorporation of composites. I’m more concerned with the number and alignment of holes through the top sheet than I am about removing core material, but like I said, I ain’t no engineer.

[XXX-er]

Holy shit it needs to snow in some parts of the world... I ain’t no engineer neither, but I’d put my money on the composites, top sheets, base and sidewalls providing most of the strength in skis. Remember foam cored skis? Anybody think that shit added anything but filler for the other components to be formed around? No? How is the wafer thin piece of laminated wood that is a ski core any different? Ever stop to look at how thick old wooden skis are? Ever notice that folks used to carry spare tips in the backcountry? Ski breakage went way down with the incorporation of composites. I’m more concerned with the number and alignment of holes through the top sheet than I am about removing core material, but like I said, I ain’t no engineer.

yeah I skied down the gun barrel at Apex with a foam core 210cm Kniessel redstar RS folded in half over my shoulder due to complete catastrophic failure, there was just black foam in that ski core, it had completely snapped in half cuz ski bro had tried to cant the binding which made the screw holes touch, the only thing holding those 2 halves together was the ptex base and steel edges, drilling an extra set of overlapping screw holes and a 280 lb wildman would appear to exceed Kneissel's engineering parameters,

Not sure how many skis are made from foam anymore but nobody wants to buy a foam core ski cuz they lose their springyness/their life, in any case wood isnt like foam, it has grain it can be bent without breaking it used to be alive

Modern skis usually use a "composite" of different species/types of mostly wood strips/carbon/ maybe some Titanal laminated togetehr for the characteristics they want in that ski ... composite just means "made up of many parts"

They certainly could make a ski from glue & sawdust but I don't think anybody does, I sure wouldn't buy it

the more holes you drill the more core you cut which is ok if you leave 1/2" between them, but drilling holes that touch cuts the core completely ... much worse than drilling properly spaced holes


we have been skiing since November up here eh

[sb]

If you properly plug an old hole where you put new hole is not of any consequence.

[XXX-er]

from a weakening the ski or weakening the binding mount or plugging the hole perspective ?

in other words the whole hole overlap issue ... is not an issue ?