Ropetek Hitch Hiker

[pigwot]

Your spring idea is a stroke of genius; such a simple built-in safety.
It seems that dialing everything in: hitch, cordage, 'biners, rope, spring strength/length will likely be unique, as each climber will have his/her own set of variables.
A thought: would a thicker, forged aluminum Ropetek HH, even though it would wear more quickly than the stainless, be able to absorb and thus dissipate more heat, staying cooler overall?

 

[bonner1040]

This old school belay device was designed with cooling fins. I had one of these for years and it stayed cooler on belays than any other comparable device.

 

[PCTREE]

I would love to make them out of aluminum so heat would be a non issue however the constant rubbing of the biner against the HH slot is a critical wear issue. We are leaning towards making them out of tool steel because of this, however you do get the "hot spot" mentioned. How bought this, mill a slot in the HH belly and insert an aluminum "fin" to pull the heat out and make it infinitely more sexy and $100 more Everybody wants perfection without the price tag . I have learnt that one of the foremost design constraints is cost....

 

[bonner1040]

$100 more is too little, can we get some carbon fiber and a bit of velcro?

I understand what you are saying... Is there anyway you could affordably integrate the ridges or fins like on the belay device but with the tool steel? Just increasing the surface area would dissipate heat faster right?

It might be a non-issue I havent tried it but hell; my rope gets hot, the saws are sharp, there are lots of things you just dont hold at that 'certain time.'

 

[SouthSoundTree]

You could shape that aluminum cooling mass like a thumb!








If there is a hot spot, its not hot enough to mess with fibers. I avoid my muffler just fine when I know that its hot.

 

[PCTREE]

Bonner, fins in the tool steel wouldn't help IMO because the heat isn't dissipated quickly enough through the material to get to the fins. This is the reason that one spot that is doing all the work gets hot to the touch. It is not hot enough to hurt the rope or else I would figure out another design. To put it in perspective the hottest I have ever recorded was 190F which is as hot as your engine block, to hot to hold but not hot enough like a muffler to cause a burn and this was with a fast 60' lower with a 350lbs block.

 

[bonner1040]

Doesnt sound like anything to worry about then.

 

[PCTREE]

But I worry, O do I worry.

 

[sotc]

So on a long descent where it heats up, if left on the rope could the concentrated heat affect it?

 

[PCTREE]

If the metal gets above 450f yes. However I have never been able to get it hotter than 190f.

Willie do you really think I would be sending these out if they melted the rope? ?

 

[pigwot]

Even a lower than melting point temperature over a long time can cause issues with some materials.
Maybe that is what you're referring to Willie?
The instances when one might 'heat up' an HH and the rope tend to be episodic, with plenty of cool-down time in between.
That fact and the likelihood that a different section of rope would be involved over several rappels as you work down and through a tree would spread any heat-load over a greater area.
Worth studying, but unless we weighed a good bit more and had much taller trees, it appears it isn't a deal breaker.

Paul, maybe make two models, one a pricier, low-temp, aluminum model and the other a reasonably-priced tool steel one for the mass (as it is) market.

 

[sotc]

Sorry to offend, just trying to help you cover all aspects

 

[MasterBlaster]

I love this thread.

 

[PCTREE]

Willie, I wasn't ofended, just funny tis all...

 

[pantheraba]

When rock climbing in the 70's we used to rappel off biner wraps...no figure eights or anything fancy, just one carabiner (non locking, of course), a 12 foot "sling rope" that we tied into a Swiss seat and off you go (the method the Rangers taught). On a fast, free fall rappel, 60 feet or more the biner would get hot enough to melt into the Goldline rope we were using. I have no idea how hot that was but the color of the biner was often burned into the rope where it got hot. We learned to not stop at the bottom of the rappel but to keep the rope moving through the biner by hand to prevent too much melt on the rope.

 

[Burnham]

I've heard from a fellow who was there that Sillett bombed a fast rappel out of a 300+ foot redwood on a GriGri and hauled up about 15 feet off the ground, hung there for a couple of seconds, and then fell the rest of the way to the ground...rope melted through. Of course, it was improper use of the device, outside operating limits Petzl placed on it...

 

[stig]

On the long rappells out of Sequoias or redwoods the figure 8 gets hot enough that we joked about having a cup of water ready to dip it in, and make tea.

Fortunately both Burnham and Gerry had brought up the danger to ropes from contact with an overheated descending device, so we had practiced gettint them off the ropes FAST.

 

[PCTREE]

OK so all the talk of melting ropes has me scared enough to consider a redesign.......

Found a problem with the HH today. Did a pine tree yesterday and didn't have a HH with me so climbed dDrt. Really didn't do much climbing off the rope as I mainly spurred up then tied in and swung over to get one lead off. Anyways my rope got sappy, you guessed it the HH doesn't like sap. Man I had my hitch completely released and couldn't even begin to move... You West coast guys may not get on so well with the HH

 

[Burnham]

Dang.

 

[flushcut]

How about a removable wear sleeve of tool steel and a ribbed aluminum body for cooling. I would think if you can get the two to mate tightly together the ally would cool the tool steel. But.. that might make it spendy.

 

[pete mctree]

Sounds like a mole hill not a mountain. Would strips of weld or something similar inside to HH running 90deg to the rope work. Points of contact as opposed to the larger piece of metal. May effect the heat distribution in a positive way

 

[PCTREE]

We may be going in a new direction with this, was going to try a bare bones / cheap approach but am starting to think about a luxury model.......

 

[MasterBlaster]

You only live once.

 

[bonner1040]

The Uni is $300, spiderjack almost $400 I think.

 

[kevin bingham]

anyone ever record the temp of ring to ring friction savers?