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Telemo binding + ski

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  • #46
    Probably the last outing for this season, did not end well. Added softish extension springs, 60mm, with a wire around the heel. Seemed to be better when carpet tested, but on the hill all was not right. It was all too slack, tightened the cable, a bit better, but still not good enough. Back home discovered why, the carbon fibre leaf spring plates have all cracked!!
    I had chosen a multiple leaf of 1mm pre made carbon sheet, with 6 leaves. This should allow more movement without breaking. The cracks are at the point where they exit from where they are held, the rear of the toe piece, this being where the highest stress is. I did have some shorter plates on top to try and spread the stress, obviously not enough. The top plates need to start quite short, and each below get longer, thus the one below is bending to some extent at the rear end of the one above. Also may need more plates.
    I was thinking that the spring could be slightly shorter and stiffer when combined with the short springs, so holding the ball of the foot down more firmly / compressing the bellows. The weight, complete with heel and screws, about 440g, so still ok.
    I still think there is more potential, though now run out of carbon sheet, so may consider other options.
    Attached Files


    • #47
      Thinking over a cup of tea....perhaps the carbon is just too stiff. I see the Lynx uses glass fibre, so perhaps that would work.


      • #48
        I think the purpose of the fiberglass plate on the Lynx is really to provide a smooth surface that will provide anti-ice properties and also to smooth out a potential hinging affect from the spring pivot to duckbutt clamp. There are composite materials out there combining nylon, carbon fiber and fiberglass as laminates as well as Pebax or Grilamid and with fiber reinforcements. They would probably provide better properties to use as a leaf spring. I haven't really done any research into purchasing sheet stock of it but it might be worth doing some research on it. I remember a material called T-pex (spelling) that combined nylon and carbon fiber or fiberglass cloth into a laminate sheet. We use to 3D mold it and use it as a structural frame sheet in some of the Granite Gear packs. The stuff was very tough, you could literally run it over with your car and not really damage it other than scuffs from the abrasion.
        Last edited by Allan Fici; 26 March 2018, 07:46 PM.
        Function in disaster, finish in style.


        • #49
          Just realised the cracked leafs probably happened before the fitting of the springs. I was skiing some steep slopes, so going low to absorb jump turns, previously had been a bit cautious so as not to stress it too much. So if i can put it back together, the springs should accommodate the full movement without cracking the leafs. Hopefully chance for at least another outing before the end of our season.


          • #50
            If you had a bigger radius for the leaves to bear against as they bend, they could handle the bend better. From description on the failure photos, looks like you have that plastic sheet (as you described earlier in the thread) directly under the toe piece, so that it's only the radius generated by the thickness of that plastic - which gives you a pretty sharp corner still.


            • #51
              Good point Paul, will incorporate that next time. A bent piece of aluminium sheet should do the trick.


              • #52
                Good (and bad) to see this update, TMM. Have been thinking back to this binding as alternative to as yet unsuccessful DIYTT. Before Paulzo's great observation, had a thought that would incorporate it. Have the top spring leaf be one that (virtually) can't kink. Jnicol's putty knife approach make me think of the cake spatula I used the other day. Super light and bendy, but spring steel. They come pretty narrow but could be doubled up.
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                I aslo went back to the YT video I posted earlier and out pops the property of "elongation," deflection before failure. See it at 8 minutes. Carbon has little before it fails, S-glass has a lot.

                Before this update I'd been wondering most about bootjacking with this setup. Doesn't sound like you have used off-piste, where damp snow compaction could be a big problem, true?
                nee, Whiteout


                • #53
                  Thanks, so carbon was the wrong choice. I bought it firstly to reinforce the ski, so almost free. Looks like S glass is best. Though might check out the putty knife option.


                  • #54
                    The final version of the Telemo carbon leaf tech toe binding? Taking note of the helpful comments I have put it back together with a few changes. It now has a 2mm aluminium plate sitting above the carbon leafs, bent to the minimum radius that (I think) the carbon is happy with. I cut back the cracked carbon plates on the crack line and shortened then, they now only are held by the rear binding screws, perhaps not ideal. There is a hardwood spacer under the front screws. I have also added another plate from the dwindling supply of my initial purchase. So it is now shorter and stiffer and has the bending stress more evenly distributed. One good thing is that it now no longer catches on the underside of the boot, so the ugly plastic top sheet is omitted and the shiny carbon can be seen. It did previously show some snow packing, not too serious, and with a shorter leaf, it should be less, there is a gap between the bottom plate and the ski, so space to add a ridge to break the snow, which should also help. I will fit some anti icing sheet.

                    The pivot is 95mm back from the pins and 35mm below. The pivot can move upwards about 40mm.

                    It has the light extension springs, 60mm long, 12mm added previously.

                    Weight, with screws, heel, leashes = 490g. No doubt a bit of careful engineering could shave a bit off this. The front throw does add weight, but I do like the ease of use.

                    Carpet testing against my HH-TT (Hammerhead Tech Toe) is was similar though softer flexing. It had a short outing in the hills not far from Edinburgh, less snow than I had hoped for, and what was there was neve, though not too hard, though not natural tele territory. From the rather too few turns I got, it is an improvement, a good even flex with a large range, with pressure from the start. As I said before, very much like an improved 3 pin binding. Hopefully get it out for a long tour whilst the snow lasts. For a more gentle tour, it is a joy to climbing with a 1260g ski+binding and a 1060g boot, and is still fun coming down. Also far more effort to skate.

                    In all, I am now happy that I have achieved what I set out to, a light easy to use binding for touring and the occasional Skimo race.
                    Attached Files


                    • #55
                      Nice work, Mark! So many of the homemade bindings folks on here come up with (mine certainly included) are basically just a rejiggering of existing parts & ideas. Way to think outside the box and create something cool and unique!


                      • #56
                        Originally posted by telemarkmark View Post
                        very much like an improved 3 pin binding.
                        i like the sound of that.


                        • #57
                          Nice job and direction on this binding telemarkmark!
                          Function in disaster, finish in style.


                          • #58
                            Skimo ski tele binding #3.

                            Presently self isolating as we have a case of Covid in the house. Benefit is that I have got around to tidying up the Skimo binding.

                            Previously the cable went around the side of the binding, held, not that well, by loops of webbing. It was not neat and getting scruffy. (The original intention was to make the cable removable for long climbs, which in hindsight was never going to be worth it).

                            The cable, Dynema, now runs below the toe piece. This required the toe piece to be raised on a double riser with a slot down the middle. All looking a lot better. A carpet test shows it to be perhaps a slight improvement as the cable takes a better route. (Note that in the photo showing it in action, when actually skiing the bellows are fully depressed early in the action) Hopefully get the the last of the snow on Ben Nevis next week to give it a try.

                            Weighs in at 1240g ski and binding fitted. The ski is 720g so the binding, including riser, heel and screws 520g. The boots are 1020g.

                            One good feature is that there is a lot of pre tension, so boot snaps down onto the binding. (I have a video clip, but not allowed here, posted on Facebook Telemark group) This is possible due to the much longer throw of the front lever. I also like being able to easily flick between ski and walk mode, useful on rolling terrain when the snow is sticky enough to climb moderate slopes without skins. Also comes in when traversing a steep slope, putting the lower ski in ski mode gives more control.

                            I did manage a few days on this set up before the upgrade. Lately I had set up with more tension on the binding, which helped in firm conditions. The last run was down the Spring Run at Glencoe Mountain (Scotland), a steep red, quite icy and rutted that day, and with not untypical poor visibility. Much to the surprise of some young guys on AT kit, all went well, though no points for style! The more I use this ski the more I like it, especially when the hike to the snow at this time of year can be two hours or more.
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