Bent Mr Chomps interface

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May 12, 2014 at 5:36 am #579929
philip.ak
Participant
I was just out on an overnight tour with my wife that involved at least one extended crusty traverse. There was no stomping or extreme moves on my part, just a long upward-angling skin across a re-frozen corn crust early in the morning with repeated side loads on the crampons while wearing an overnight pack and me at 180 pounds (w/o gear). At the top, I took the crampons off and noticed that the aluminum upward bend at the front of the crampon (where it wraps under the touring pin) was noticeably flared out on one side: the side that would take the load on the downhill foot. Has anyone bent a Mr Chomps doing this? I figured this was what they were designed for. I should note that they continued to work fine and I didn’t notice a change in function or performance, but I think I should replace them at this point since one of them is pretty deformed.
May 12, 2014 at 10:50 am #676456
BobGnarly
Participant
Pic=1000 words
May 13, 2014 at 8:26 am #676457
philip.ak
Participant
Like this:
May 13, 2014 at 10:25 am #676458
BobGnarly
Participant
Wow.
I think you would struggle to get that dead straight again.
May 13, 2014 at 12:09 pm #676459
firstlight
Participant
philip.ak
Are you using a wide crampon on a narrow board?
Wonder how that would flex that far without hitting the sidewall?
This might be your problem
Adam West
www.firstlightsurfboards.com.au
www.firstlightsnowboards.com.au
www.splitfest.com.au
www.snowsafety.com.au
www.mrbc.com.au
www.backcountryglobal.com
www.alpinefirstaid.com.au
May 13, 2014 at 3:06 pm #676460
philip.ak
Participant
They are regular Mr Chomps on an Ultracraft, which is a pretty standard 260 waist width. Not sure how this would have manifested itself either. I need to mount them and manipulate them by hand to see where the loads come from.
May 14, 2014 at 5:35 am #676461
philip.ak
Participant
I figured it out.
The plastic bar that holds the back of the touring pin had its 3 fixing screws work a quarter turn loose each. I had tightened them before the trip, but they do seem to like to back out on mine. The other binding wasn’t tight, but also not as loose as the one that got damaged. The small amount of play let the crampon get twisted laterally relative to the pin, so all the load was on one side of the aluminum. I will need to use some epoxy for plastic on the screws in the future.
May 14, 2014 at 10:50 am #676462
BobGnarly
Participant
Bolts coming loose or falling out are responsible for 90% of split binding failures IMO.
May 14, 2014 at 2:53 pm #676463
philip.ak
Participant
I’d agree with that. I blue Loctite every thread on my bindings and I STILL had a ladder ratchet fall off recently. Sheesh.
May 15, 2014 at 12:19 am #676464
firstlight
Participant
philip.ak
I had the same issue with mine, helicoil and problem solved, used M3 from memory.
I supprised they didn’t just fall out as mine did before bending the Al.
I suggest you chamfer the tounge too to stop them catching, have a close look you will see what I mean.
Did the same to my verts as the pucks came out with the screws.
10% more engineering effort and the splitboard industry would be bomb proof! (IMO!)
Adam West
www.firstlightsurfboards.com.au
www.firstlightsnowboards.com.au
www.splitfest.com.au
www.snowsafety.com.au
www.mrbc.com.au
www.backcountryglobal.com
www.alpinefirstaid.com.au
May 15, 2014 at 3:34 am #676465
philip.ak
Participant
@firstlight wrote:
I had the same issue with mine, helicoil and problem solved, used M3 from memory.
I supprised they didn’t just fall out as mine did before bending the Al.
I suggest you chamfer the tounge too to stop them catching, have a close look you will see what I mean.
Did the same to my verts as the pucks came out with the screws.
I don’t follow any of this. A helicoil in plastic for what are essentially wood screws? Chamfer what exactly? I don’t have any verts for reference.
May 15, 2014 at 5:41 am #676466
firstlight
Participant
philip.ak
Drill out the plastic with the require size drill to tap the treads in the plastic for a helicoil
You get them as a kit, drill tap and inserts
I think mine were M3
Then use a countersunk screw with the same tread as the helicoil
Here is the chamfer I put on the tongue
Stops it from catching

The ski screw/ self screwing type in plastic will fail on any application where there is a large force.
This was a pain in the verts as they use the same attachmnet eg screw into plastic.
If you can use a treaded screw in a metal insert it will always last longer than just a self gripping screw in plastic.
:twocents:
Adam West
www.firstlightsurfboards.com.au
www.firstlightsnowboards.com.au
www.splitfest.com.au
www.snowsafety.com.au
www.mrbc.com.au
www.backcountryglobal.com
www.alpinefirstaid.com.au
May 15, 2014 at 6:25 am #676467
philip.ak
Participant
Cheers. That makes infinitely more sense now. :thumpsup:
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