Ideal Multicender

Mark Chisholm

Administrator
Administrator
To create friction for descent, the rappel rack is approaching ideal in my opinion. Modulation of friction is easily managed to accommodate wildly different conditions. They work well on very supple ropes and ropes so stiff you can barely knot them. Dry ropes, wet ropes, ropes covered in mud. Single rope and double rope. Thin ropes and fat ropes. Slick rope and furry rope. Short rappels and rappels of over 1/2 mile. Little climbers and 2 person loads. I see the big challenge to be creating a device with great descent characteristics which instantly and effortlessly converts to negligible friction when moved upward.
I agree
 

DSMc

Well-Known Member
Location
Montana
... I've never used a multicender, but...

That is the problem you should fix first. The tools that have become available in the last few years are truly amazing.

It is interesting, that the perpetual human quest for the "ideal" the mythical and singular 'best', the 'one', is actually at odds with our own individualism and the compound complexity of the world we live in.
 

Christrees

Active Member
Location
New York
To create friction for descent, the rappel rack is approaching ideal in my opinion. Modulation of friction is easily managed to accommodate wildly different conditions. They work well on very supple ropes and ropes so stiff you can barely knot them. Dry ropes, wet ropes, ropes covered in mud. Single rope and double rope. Thin ropes and fat ropes. Slick rope and furry rope. Short rappels and rappels of over 1/2 mile. Little climbers and 2 person loads. I see the big challenge to be creating a device with great descent characteristics which instantly and effortlessly converts to negligible friction when moved upward.
I love how your trying. Do you have a mechanical background? And if this device ever comes. I want to be a tester
 

Dan Cobb

Well-Known Member
Location
Hoover
I love how your trying. Do you have a mechanical background? And if this device ever comes. I want to be a tester
I've always liked designing and building stuff. Have a pretty good professional background in maintenance and engineering as well. Still tinkering with designs. Currently, I have 2 novel approaches. The hardest part is keeping things simple while still meeting all the desired criteria. Seems worth the effort to do as much as possible on paper before making any prototypes. Glad to have a volunteer!
 

Christrees

Active Member
Location
New York
I've always liked designing and building stuff. Have a pretty good professional background in maintenance and engineering as well. Still tinkering with designs. Currently, I have 2 novel approaches. The hardest part is keeping things simple while still meeting all the desired criteria. Seems worth the effort to do as much as possible on paper before making any prototypes. Glad to have a volunteer!
Wow that's awsome. I hope you succeed areyou thinking fully mechanical devices? Or hybrid? Meaning requiring a friction hitch? Probably mechanical huh? Either way it would be nice to have another option. My request would be a hybrid device. But thats me. I feel more comfortable with a hitch. But im trying to get there where i trust a mechanical. I dont have much experience with mechanicals. And yes definitely would be amazing to be apart of something ground breaking.
 

JMerritt

Well-Known Member
Location
santa cruz
I've always liked designing and building stuff. Have a pretty good professional background in maintenance and engineering as well. Still tinkering with designs. Currently, I have 2 novel approaches. The hardest part is keeping things simple while still meeting all the desired criteria. Seems worth the effort to do as much as possible on paper before making any prototypes. Glad to have a volunteer!
Make lots of prototypes if you can. So many things I thought would work great just didn’t and vice versa. Nothing like real world testing.
 

ATH

Well-Known Member
Location
Ohio
Make lots of prototypes if you can. So many things I thought would work great just didn’t and vice versa. Nothing like real world testing.
Did you machine each piece each time or were you able to patch together pieces and parts to mock up what you wanted to do?

I'm guessing 3D printing can help with some of those things now? It really opens up opportunity for someone who is good at design, but doesn't have a lathe, CNC, or funds to keep going back to the machine shop for little changes to tinker around.
 

JMerritt

Well-Known Member
Location
santa cruz
Did you machine each piece each time or were you able to patch together pieces and parts to mock up what you wanted to do?

I'm guessing 3D printing can help with some of those things now? It really opens up opportunity for someone who is good at design, but doesn't have a lathe, CNC, or funds to keep going back to the machine shop for little changes to tinker around.
3D printing is awesome for prototypes, and printers nowadays are really very cheap (less than $300 for a very nice one and less than that for a pretty decent one). Another really nice way to prototype is using a waterjet cutting service. If you find a shop that doesn’t charge a minimum batch charge then getting parts cut is super easy and pretty cheap. Before I knew anything about waterjet or 3D printing I just used wood mock-ups or even cardboard and hand cut aluminum. Wood and aluminum are easy to work with hand and power tools.
 

rico

Well-Known Member
Location
redwoods
My ideal multi-cendor would be able to make Al Pastor and Green Chili tacos as good as the one found at Taco's Moreno's in Santa Cruz..And their salsa.. Dont get me started..
 
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Bart_

Well-Known Member
Location
GTA
Jaime, the closest thing to a (one way) mechanical clutch device I've seen is the RP292 rigging wrench but it is rated very limited in working weight and not intended for life support i.e. to use it as a DRT tip. You can picture applying a rp292-like setup as a substitute for a hitch/wrench combo. There is likely to be a liability/reliability issue putting a ratchet or one way mechanism into a life support situation. Even tooth cogs like on an outboard boat motor "clutch" would have question despite their use in multi hundred hp engine applications. The question always boils back to fail safe, i.e. when something goes south you don't fall. Not directed as criticism, just pointing out a gotcha situation waiting in the wings.

I tried to find ramp-pressure clutches similar to in the rp292 and sizing/strength was a challenge. Maybe I didn't look hard enough.

I built a squeeze type "multi" cender a few years ago and found extreme sensitivity to rope dimensionality. I called it the OneWay because it was similar to self engaging cam squeeze devices but had no teeth and was intended for descent as well. It's on the shelf with a protective coating of dust. :)


edit - Jaime, call me coffee deprived if I totally misunderstood and you meant clutch like slipping disc brake substitute for rope surface friction, not as one way or engage/disengage action :)
 
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JMerritt

Well-Known Member
Location
santa cruz
edit - Jaime, call me coffee deprived if I totally misunderstood and you meant clutch like slipping disc brake substitute for rope surface friction, not as one way or engage/disengage action :)
That’s exactly what I meant. A clutch that is controlling a grip wheel of some sort. That way the friction is always a known quantity. I doubt it can be done in a small enough package to make it worth while as a climbing device.
I think as second best the unicender and the zigzag are the optimum designs. They can be incrementally released and each link is such that it doesn’t lock up or self cam into a sticky or wet rope. Obviously they both have drawbacks compared to the imaginary perfect device discussed here.
 

Bart_

Well-Known Member
Location
GTA
Jaime, for fun why not hot rod a rollgliss from speed/centrifugal to actuated engagement? Then see if it can be miniaturized so as not to be a noggin knocker. That's drum not disc.

Or, steal the motorcycle compact powerful clutch secret by stacking plates in a basket arrangement. Miniature might still be powerful enough.

Dry might freewheel ok but suffer heat/material problems. Wet wouldn't freewheel well. Fail safe very viable. Any one way clutch still a (re)-liability conundrum. And you'd need a sheave; could take a healthy dose of copy rollgliss. Mine and their sheaves ended up about the same size independently.

During the OneWay development I danced the stable vs locking itself line on camming and I think the two devices unicender and zigzag stay well back of the line but get enough force by just having enough repetitions of the mechanism acting. And the multiple elements compound in series, like wraps on a porty. Loading hard into a grigri tells you they ride a little closer to the line with a single element. Think about the sensitivity of the Morgan to rope - it's also a single element design.

yep its evening and its dark outside.

Did you go to formed bollards vs cylinder just to not abuse rope shape, or cause you could, or did you get different performance? I'm about to make another zk1 with formed bollards. I think I saw different performance on flattened rope but there was an issue with that old data, but it did basically confirm Kevin's numbers.
 

colb

Well-Known Member
Location
Florida
I briefly considered the possibility of a device with the option of using a cordless drill as the motive source for powered ascent. (Have a socket on the device that could be turned by a drill with a driver bit.) But then I figured there's not much demand for that, especially because you'd have a drill tethered to you while working. Didn't even do the calculations to see how far a typical drill could advance a climber. For me, climbing rope "manually" just isn't a big deal. I know your comment was made jokingly, but is there any market for powered ascent?
Are you a daily driver? I tend to think of cavers as once per weekers at most frequent. Some arborists in the pnw are 4-5days/week, ascending 150-250 for a single tree, then possibly going to another 1 or 2 after that. Without having to worry about wall abrasion, a bulky device is possible for an arborist in some cases. We already carry saws...
 

TheTreeSpyder

Well-Known Member
Location
Florida>>> USA
i think the best arc geometry for rope cam, handling is to Golden Ratio sectioning from the arithmetic compounding of a Fibonacci sequence/tumbling ocean waves/ leaf sprouts/ pinecone(bottom view)/ Nautilus shell type arc to mimic.

O1-6__97565.1522320812.jpg

Euler's number (~2.718) growth pattern is larger than Golden (~1.618) and then exponentially compounded (for rope brake frictions!, disease spread etc.), by contrast . Each a Natural compounding change pattern we have found and defined well enough to define next expectation accurately in Natural occurring events; to then command to own usages.
 
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Dan Cobb

Well-Known Member
Location
Hoover
Are you a daily driver? I tend to think of cavers as once per weekers at most frequent. Some arborists in the pnw are 4-5days/week, ascending 150-250 for a single tree, then possibly going to another 1 or 2 after that. Without having to worry about wall abrasion, a bulky device is possible for an arborist in some cases. We already carry saws...
I used to cave almost every weekend in my younger days. Have lots of caves with 200+ ft pits within a couple of hours drive including the big ones, Fern Cave (Surprise Pit, 417 ft) and Ellisons Cave (125, 586 ft pits near one entrance, 60, 80, 440 pits at the other entrance.) My tree jobs ebb and flow. Might be climbing 6 days straight, then nothing for a couple of weeks. I like to do landscaping, carpentry and stone masonry too. Whatever comes along to keep me busy in retirement. Funny how I rarely get called "sir" when dressed for labor jobs, used to happen all the time when I wore a suit and tie for my corporate job.
 

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