Crab device

surveyor

Carpal tunnel level member
Location
NC
I think it is likely that the same teardrop used on the crab would work on two Bones (tho I have not actually tried that yet), Then as mentioned, a DMM swivel could be installed on the one teardrop. The neat thing about the Crab is its compact size. I have small bollards on the bottom friction pins (both left and right) and when unweighted, you can pull either rope away from your sides, and the Crab runs right up the ropes. Alternately, with a pulley above, you can pull your self up with one side, while the crab self advances up the other. I use the bottom arms for release, either one at a time, or both together. With a twin rope configuration (separate tips) you can move laterally, as long as the spread is not too far. (30 degrees?). This is with my 165 lbs and Tachyon rope.
 

treesap

Participating member
Location
east TN
will it work with one rope? i.e only using half the device? (In Drt of course)

if it does I might be in on the idea
 

surveyor

Carpal tunnel level member
Location
NC
Yes, it will with my weight on the Tachyon. (just terminate one side of the rope back to the bridge).
 

Bart_

Participating member
Location
GTA
Self engagement could be helped by putting the pre-loading spring on the bird. I think that's the standard rope wrench tweak.
 

treegongfu

Branched out member
That is great!

I wonder if you are gaining anything by having them attached to each other that you couldn't achieve with a camp gyro?

The Gyro, which I've been using as a bridge, would allow for easy separation into two independent devices.

I think the ability to disconnect them from each other allowing for two independently function devices would be of much greater utility than midline attachability.
 

Brocky

Been here a while
Location
Michigan
Maybe a small hole above the large one for attaching a neck tender?

If the arms were attached to the sides of a u channel they could be side by side, or maybe a v orientation by using a 90 degree angle for the spine.
 

surveyor

Carpal tunnel level member
Location
NC
The way the arms are oriented in an opposed direction allow each side to splay apart aligned with with two different tips. I think however that the wider the splay the less it grips effectively.
 

Brocky

Been here a while
Location
Michigan
The angle might put them too far apart, but not having knobs on the inside of the u channel would keep them fairly close, and be easier to operate one handed.
 

moss

Been here a while
The way the arms are oriented in an opposed direction allow each side to splay apart aligned with with two different tips. I think however that the wider the splay the less it grips effectively.
Reality is a climber wants a fairly deep V when hanging between two separated anchors so i think the splay issue is not an issue. We’re all speculating on what additional features it needs, it may be close to perfect as is ;-)
-AJ
 

Crimsonking

Carpal tunnel level member
I wonder about lengthening the spine and shortening the triangle sections on the tops to increase bend. Could this increase the bite on flatter angles? Or flaring the the main attachment point to have nubs that make contact with the rope at flatter angles where the rope goes through the lower triangles?
 

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stheis004

Participating member
Location
WI
So impressed you are able to continue to innovate and not only ideas but to bring them to life! This looks really cool and will allow for some to develop all new climbing styles. Ones tail management game is gonna need to be strong
 

surveyor

Carpal tunnel level member
Location
NC
I wonder about lengthening the spine and shortening the triangle sections on the tops to increase bend. Could this increase the bite on flatter angles? Or flaring the the main attachment point to have nubs that make contact with the rope at flatter angles where the rope goes through the lower triangles?
I have experimented with different geometries having to do with the length of the spine and the shape of the triangle of the friction links (and the spacing). I have been constrained by the available chain link sizes available, as it becomes rapidly expensive to make incremental changes in the geometry and material . However, user feedback is crucial to improvement.
 

surveyor

Carpal tunnel level member
Location
NC
So here is the Crab with the gyro swivel as suggested by @treegongfu. I think it definitely has possibility, but needs to be a proprietary three way swivel, as the gyro allows the two sides to come into conflict with each other when on rope. The two sides need to be held apart like the teardrop I use, and need to swivel in a manner which allows the two arms to pivot up and remain parallel with each other, but not clash. IMG_1558.JPG
 
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