Need Help on Helmet mount

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Need Help on Helmet mount

Postby rbryant » Sep 3, 2007 10:50 pm

Ok..totally rookie question here, so take it a little easy. I ordered a Princeton Tec Apex light and a Ecrin Roc helmet. How does the light mount to the helmet, do the Ecrin Roc's even have mounts on them? BTW, I have received my order yet, just wanted a heads up when I start putting things together.
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Postby fuzzy-hair-man » Sep 3, 2007 10:59 pm

No problem the Ecrin Roc has 4 clips on the sides that you can use to keep the headlamp on.

I found that the Apexes battery box often came undone from the elastic, there is a adjustment buckle that adjusts how tight the elastic is around the helmet/head if you put the battery inside this loop of elastic then the battery pack stays put. :kewl:

Others have also gotten rid of the elastic on the Apex and mounted thier Apex to the helmet permanantly.
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Postby volica » Sep 3, 2007 11:01 pm

Apex comes with strap, and Ecrin Roc have sort of clips to put strap underneath so light doesn't slide.
That was easy way.
I use electrical zip ties to mount my light to my helmet, but that requires drilling holes and I guess voids warranty of helmet
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Postby Jeff Bartlett » Sep 3, 2007 11:04 pm

fuzzy-hair-man wrote:I found that the Apexes battery box often came undone from the elastic, there is a adjustment buckle that adjusts how tight the elastic is around the helmet/head if you put the battery inside this loop of elastic then the battery pack stays put. :kewl:


i hadn't seen that particular trick, but i'm definitely getting tired of my battery pack working its way loose. are you saying to just put both straps into the battery box clips so it's really tight?
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong
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Postby fuzzy-hair-man » Sep 3, 2007 11:26 pm

xcathodex wrote:i hadn't seen that particular trick, but i'm definitely getting tired of my battery pack working its way loose. are you saying to just put both straps into the battery box clips so it's really tight?


No, you know the elastic that runs around your head or helmet it has a adjustment strap, as you tighten the adjustment strap there is a loop in the elastic that grows I put the battery box inside this loop so the elastic goes completely around the battery box, which makes it just about impossible for the battery box to come off the elastic (hasn't done it since). The downside if the elastic might be a bit tighter than otherwise but I don't think it really matters.

I managed to find a picture of the back of my head....so like this: (the green front light is a Tikka held on with a piece of a plastic peanut butter jar :grin:)

Image
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Postby chrismc » Sep 14, 2007 9:24 am

volica wrote:I use electrical zip ties to mount my light to my helmet, but that requires drilling holes and I guess voids warranty of helmet


Ditto. That's the easy way, unless you have a need to remove the headlamp from the helmet... It won't budge no matter hard hard you knock your head against hard things.
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Postby incavenow » Sep 14, 2007 2:45 pm

10 minutes after I got my Ecrin Roc home, I done voided my warranty! I've drilled several holes in my helmet over the years as I added or changed lights. I want things to stay put on mine when I'm mud crawling!!
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Drilled Ecrins

Postby cavedoc » Sep 14, 2007 3:37 pm

My Ecrin cracked in baggage on the way to convention. Used it there but got another. The info that came with it ways the warranty was for 3 years but they thought I should buy another in 10. I bought mine in 1985, so it was a tad beyond manufacturer's specifications. Anyway, at the last Grotto meeting I brought it and did some improvised UIAA testing with a sledge hammer. It took two blows roughly at the forces/shapes used by UIAA (but sitting on a carpeted concrete floor, so not a real comparison). It broke on the 3rd strike with a pointed, blunt hammer from 2 m and about 5 Kg. Two large pieces separated out completely and lots of cracks going elsewhere, only one of which went through one of the 4 extra holes I had drilled over the years. Interestingly the original break on the airplane went through one of the ventilation holes but stopped there. Not sure what it all means but I had a good time doing it.
Last edited by cavedoc on Sep 18, 2007 12:57 am, edited 1 time in total.
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Re: Drilled Ecrins

Postby Scott McCrea » Sep 14, 2007 4:01 pm

cavedoc wrote:Two large pieces separated out completely and lots of cracks going elsewhere, only one of which went through one of the 4 extra holes I had drilled over the years. Interestingly the original break on the airplane went through one of the ventilation holes but stopped there.

:pray: Please say you took pics and will post them later. :pray:
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Re: Drilled Ecrins

Postby cavedoc » Sep 18, 2007 12:53 am

Scott McCrea wrote: :pray: Please say you took pics and will post them later. :pray:


Let's see if I can make this work.

Image

The original break starts at the brim under the rivet in the foreground and ends in the right anterior ventilation hole. The empty space is from the 3rd hammer blow. It doesn't show up well but the crack in the foreground goes through a drilled hole that once supported a Petzl L1 bracket. The crack from the hammer blow terminates at the crack from the airplane flight. Interesting that the catastrophic failure/major cracking ends at one of the other ventilation holes. The photo is from a friend who now has the helmet but it looks like I probably drilled either 4 or 5 holes over its life.

It would be really nice if light manufacturers and helmet manufacturers could decide on a common set of mounting holes so that any common light could be screwed into any common helmet without having to use a drill. We can't be the only people who like to hard-mount their lights!
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Re: Drilled Ecrins

Postby fuzzy-hair-man » Sep 18, 2007 2:12 am

cavedoc wrote: Interesting that the catastrophic failure/major cracking ends at one of the other ventilation holes.


A member of our club had an explanation for this after we had a similar argument about the pros and cons of drilling holes in helmets.

So if I remember correctly once tearing / cracking starts it is relatively easy to continue the tear, all the forces are concentrated at the tip of the tear, if the tear runs into a hole I think the forces are redistributed around the hole's edge in some way. Sort of counter inituative holes = strength "sort of" probably better to say holes may stop or slow failure once it starts...
ie if I had a crack and drilled a rounded hole at the end of it it would be stronger than just the crack alone even though I've taken more material out.

I don't have much knowledge of physics or engineering stuff so I didn't argue and don't really know if it's correct or not but sounds pausable.
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Re: Drilled Ecrins

Postby Scott McCrea » Sep 18, 2007 6:49 am

cavedoc wrote:The original break starts at the brim under the rivet in the foreground and ends in the right anterior ventilation hole. The empty space is from the 3rd hammer blow. It doesn't show up well but the crack in the foreground goes through a drilled hole that once supported a Petzl L1 bracket. The crack from the hammer blow terminates at the crack from the airplane flight. Interesting that the catastrophic failure/major cracking ends at one of the other ventilation holes.

Thanks, Roger! It's always fun to see how stuff breaks. Not to mention how much fun it is to actually break it (in controlled conditions).
:calvin:
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