New Ascender / Descender Device Design: Input Needed!

[Dwight Livingston]

Dwight: Thanks very much for your input on the questionairre. You mentioned re-belays....how often in general caving do you come across rebelays? I have heard that this is important from a couple individuals now, so I figured Id ask.

We do re-belays pretty regularly.

I agree with what Barbara, except I'd also recommend the book Alpine Caving Techniques.

I hope you aren't planning to screw around on rope with an untried device, not unless you already know existing techniques and equipment thoroughly. A lot of surprising stuff happens on rope that takes getting used to. It can be dangerous, even with a belay. I suggest you go read the books, go learn SRT with people who know what they are doing, read the book again, and try stuff out. Nobody picks this stuff up safely without a lot of learning and practicing.

Best of luck.

Dwight

[UCR SeniorDesign]

I'm gonna guess I speak for a bunch of cavers where when I post this. We probably all wish you well, but it's a little puzzling to us. You post up about being a design engineer and that you're going to design an improved device, but you don't seem to know much about the subject at hand if you don't know what a frog is.

Perhaps I should clarify a few things here......I am a design engineering student whose task has been to develop a rope climbing device for ascending and descending a rope with relative ease. I do not claim to be an expert in caving whatsoever, but I am willing to take any advice and knowledge which is offered in order to improve both my understanding and our final design.

You are correct...I do not know very much about caving, but I am trying to learn as much as possible that is applicable to my project, hence why I have come to a forum like this....to ask for input and advice from those who actually do know the sport and who use the equipment on a daily basis. Also, we are reading books like Alpine Caving Techniques in order to get a better idea about techniques and devices currently in use.

Engineering a product does not require that one is an expert in the field in which the product is used. Rather, a firm knowledge of physics, mechanics, and dynamics, paired with common sense, is used to enhance the quality of a product. I ask when I have questions, because it is easy to look up a device, such as a "Frog", on a search engine.....but a search engine will not give qualitative input on the device in question.

Moving On....

Dwight: We have actually ordered Alpine Caving Techniques, and we certainly plan to read it. As for testing and such, our advisor is actually a caver as well as a member of the Riverside County Search and Rescue Team here in SoCal. He will be overlooking our designs as well as supervising any and all testing. Safety is our priority here, both for our selves when testing as well as any end users.

Thank you for your advice

[NZcaver]

Engineering a product does not require that one is an expert in the field in which the product is used. Rather, a firm knowledge of physics, mechanics, and dynamics, paired with common sense, is used to enhance the quality of a product.

That may be somewhat true, however...

I would contend that engineering a successful product requires some significant knowledge in the field that it will be used. This allows one to better understand the mechanics, dynamics, and ergonomics of their design, and gain a grounding for that "common sense" you speak of.

It does puzzle me a little that your advisor is a caver and SAR team member, but has not facilitated caving connections for you and your design team (in person). This would be a good way to familiarize you with the basics of vertical caving and help answer some basic questions. I assume you need to do some independant research, but a nudge in the right direction might go a long way on the learning curve.

You could of course try seeking out a local caving group yourself, and persuade them to facilitate a vertical caving intro/practice session. These are usually very informal, and most grottos have a person or two that are just waiting for an excuse to share their vertical expertise. You could start by contacting the Southern California Grotto - I assume they are the closest to your location.

[UCR SeniorDesign]

NZcaver: I agree completely that a certain knowledge of the field for which a device is beign designed is crutial for success. The point I was making is that one does not need to be an expert in a field to be able to improve upon a previous design, or create a new one all together. Basic principles of friction, heat transfer and dissipation, and material durability can go a long way without actually knowing how to cave, but rather knowing the basic use of the device. I agree strongly, though, that it certainly helps to know how the devices in question are actually used in action. You bring up an excellent point.

As for the input from our advisor.....their lack of intervention is partially the goal of the design project, as it is to simulate a real-world scenario if we were to be doing this for a company, where there wouldnt be an advisor. Their main function is to prevent us from making any blatant, terrible mistakes or hurting ourselves in the process. As far as research, and furthermore how we go about it, it is soley up to us.

Thanks for the information about Southern California Grotto. We would like certainly to at least watch, if not participate a little, in how caving is done on a basic scale, as well as the used of devices. We do not expect to be come experts overnight, as we know that many of you have spent decades acquiring th knowledge that you have (and you have thus far made a great advice and knowlede source!) I will contact them and see what we can get going.

Thanks again for the advice and for taking the time to give us your feedback. It is al much appreciated.

-Jared

[Squirrel Girl]

I think the problem here is that the professor is needing project for his students so he develops a design project. And, afterall, *everything* can be improved upon. Enter Jared who is obvious enthusiastic and burning with the desire to succeed.

Meanwhile... Over here amongst the cavers.... We see Jared come along who, through no fault of his own, is new to a project, doesn't really understand the subject, and want to improve and change things. And especially when it's a device that can KILL YOU, we're a little leery.

Jared, you certainly know a lot more about the physics of the devices than me, but not necessarily any more than a lot of other cavers who are physicists and engineers themselves and have analyzed and designed equipment already.

There's no such thing as a perfect piece of equipment and I still think everything can be improved.

I guess another question is.... Is the point of your project to meet the design specifications of your professor?--ie, then it *doesn't* matter if cavers will ever find it practical. Or is it something that you folks will ever expect to go into production and then you absolutely *need* to know how cavers use ropes?

[Dwight Livingston]

It is a good design project, maybe not for a commercial office but for design school. The physical requirements are severe and the human factors requirements are just as tough. There will be no easy solutions and it should be interesting to judge success.

I spent most of a career as an Industrial Designer, and many times I've had to design equipment for an application in which I had little experience. Sometimes you can find success by taking a new, outsider's look at things. Product users are often proud of their ability to overcome problems caused by equipment they use, so a fresh look may work. Usually anyone trying to do something new that will look arrogant. Users are rightfully skeptical. As a designer hired to do something new, a new perspective is often all you have.

Dwight

[UCR SeniorDesign]

Jared, you certainly know a lot more about the physics of the devices than me, but not necessarily any more than a lot of other cavers who are physicists and engineers themselves and have analyzed and designed equipment already.

Squirrel Girl: Thanks for taking the time to post. You are very correct about this, I am not anywhere an expert in physics or engineering (hence why I am a student), and I know very well that some very bright and educated people also happen to be cavers. My intent is not to come off as being arrogant about the design project....my intent is to solicit the help and intelligence of those with the knowhow and the experience to give useful feedback. Perhaps, by getting insight from those who have used and designed equpiment already, we can avoid making mistakes which may have already been adressed by others.
Also, you are correct....this project is being done with the intent of meeting the design specs outlined by the professor. The chance is there always that if perhaps a functional, novel design is thought up that it could make it the marketplace. Now, despite this fact, we would like to design something that cavers would see as practical and useful, otherwise what is the purpose of designing it.

Dwight: This is exactly the point that I am going for, so thank you for your post. You are correct in that all that I have to go on for this project is an outsider's view and the opinions and information gathered from those in the know, the caving community. And true, this project may or may not have a place in the commercial market, but our intent is to meet design criteria while retaining practicality, not so much to release a product to market. But thank you for your support on this.

[NZcaver]

At the risk of repeating myself, I'm wondering if you could answer my earlier question:

When you say "a device which would allow ease of ascent and descent on a rope" - that seems to imply a single device for moving up or down. As you may have noticed, we all refer to our ascenders in pairs (or three's). Body mechanics and gravity being what they are, I assume you know why multiple ascenders are used in virtually every rope climbing system? Unless... perhaps you are thinking of designing a powered/motorized ascender that can double as a descender?? If not, a second ascender (or more) will be required.

[Bob Thrun]

I like the MIO rope grab for a lot of its features: the bar to spread the gripping force; the top roller; and the swingaway attachment for the cam. The problem with the MIO grab is that it is too heavy. I would like to see a lightweight version.

I could cite many examples where a good designer makes a good design, but misses a few of the small convenience or maintainence.

[UCR SeniorDesign]

NZcaver: I apologize for not answering you on the first go around. The actual design requirement is that the device be lightweight ans convenient, similar to devices already on the market. We had thought about motorized (the guys @ MIT came up with one a while back), but finally we settled that manual would be more lightweight and simple, both of which we assume are crucial for caving.
I understand also what you mean that ascenders come in pairs and triplets, as generally one must allow you to pull yourself up the rope, while the other catches your upward progress and prevents slipping. This is good also for the sheer redundancy, as if one device fails, the caver is not falling. Our design will likely be a two piece combination of a controlled descender which can dual as an ascender (with a cam or latch and handle to controll friction, similar in a way to Petzl ID), and then paired with a second ascender to catch upward progress. Good point you brought up!

[NZcaver]

Our design will likely be a two piece combination of a controlled descender which can dual as an ascender (with a cam or latch and handle to controll friction, similar in a way to Petzl ID), and then paired with a second ascender to catch upward progress. Good point you brought up!

Thanks for your follow-up.

I have a couple of Petzl I'D's - although I have only used them above ground, my impression is they would be less than ideal for caving. There's a brief thread on the forum about them here.

Your design may do well if it could address/correct a few factors I've noticed with the I'D. Specifically:

- reduce size and weight
- increase the relatively small tolerance of rope sizes/cleanliness
- improve on or discard the "sealed" clutch mechanism, which is not likely to be immune to prolonged immersion in cave mud/grit
- if you choose to have a double-stop mechanism, avoid having only a small "sweet spot" (the mid-point in the mechanism which allows you to descend). This can result in a very jerky descent, as you manipulate the handle between the "let go and stop" position and the "death grip safety stop" position.

[truello]

You may also want to look at the Petzl GriGri. While it is mostly used for belaying a rock climber, it can be used to both descend and ascend a rope. It is far from perfect in both. Descending can be very jerky as its very "stop & go" and it only works on single ropes. Ascending is even more awkward but with a prusik (or ascender) and a GriGri, it can be done.

[Stridergdm]

A comment on the physics (one of the previously posters mentioned something about physics that got me thinking).

Heat. For many of the drops us cavers do, heat is not a problem. But, when you start to do longer drops, well you're converting PE to KE and as you probably don't want to accelerate at 9.8m/s^2 you have to disperse that KE into something... which is pretty much heat.

Now that heat can cause problems like glazing the sheath of the rope, making the descender to hot to touch, etc.

And at least for us cavers, the ability to change over from descending to ascending is an important one.

So for one thing, you want to avoid dropping a 500' drop, and then realizing for whatever reason you need to change over and having your now ascent device sticking to the rope. (ok, pretty unlikely, but the idea is to think about the worst case).

And also, I may have missed it, but google "harness hang syndrome". If you're going to be testing any of these homemade devices yourself, make sure you can get the subject safely down to the ground as quickly as possible in case something goes wrong. (or at least the ability to stand, a ladder in a gym setting may be sufficient.)

Ultimately I think your quest is an interesting one. You need to balance a lot of factors and compromise, just like in the real-world.

You ideally want something lightweight. But you need something strong enough.

You want something that can ascend or descend, yet ideally is simple.

Ever since I saw a Tibloc I've loved the simplicity and minimalism of it. You can't get much lighter than that and still be functional. Yet it compromises on the side of usability.

On the other hand the classic rack is simple and works well, but isn't as light as some other designs.

Anyway, good luck.

[Amazingracer]

Sure why not.

1. What kind of climbing do you do?
a. Caving

2. Why do you climb?
a. For fun

3. What climbing skill/experience would you consider yourself?
c. Intermediate

4. What equipment do you currently use to ascend?
Petzl Hand Ascender + Petzl Croll

5. What equipment do you currently use to descend?
Petzl Stop

6. What techniques for ascending do you like the best?
Frog

7. What techniques for descending do you like the best?
Still torn between the Stop and a Rack

8. What size, type and brand of rope do you use?
PMI, varying sizes(11mm I think)

9. Do you think that a device like this would be helpful and if it was reasonably priced would you use it?
Probably , would cut down on stuff dragging thorugh the cave

10. Have you ever had any equipment failures? If so, what kind of equipment were you using at the time? What were the conditions?
Thankfully, no

11. How much does the climbing kit you usually use weigh and if you were to use this device instead of multiple other devices, do you think you would benefit? (How should we word this?)
Never weighed it, ascenders and the Stop make up most of the weight. Lightweight is good.

12. How much would you be willing to spend on a device like this?
Stop+Croll+Ascender=~$180 So that price or less.

13. i) How do you typically buy your equipment?
a. Online

13. ii) Where?
Inner Mountain Outfitters (IMO)

[Rick Brinkman]

Hope this helps.

1. What kind of climbing do you do?
a. Caving

2. Why do you climb?
a. For fun, exploration

3. What climbing skill/experience would you consider yourself?
c. Intermediate

4. What equipment do you currently use to ascend?
Frog System (Petzl Hand Ascender & Petzl Croll)

5. What equipment do you currently use to descend?
Homemade micro rack (1 hyperbar) or Petzl Stop

6. What techniques for ascending do you like the best?
Frog

7. What techniques for descending do you like the best?
I like the micro rack(more versitile, but miss the auto-lock feature of the Stop)

8. What size, type and brand of rope do you use?
8mm to 11mm, dynamic or static. Whatever brand is brought into the cave. At the moment, I prefer Sterling ropes.

9. Do you think that a device like this would be helpful and if it was reasonably priced would you use it?
Yep. Be nice to eliminate one piece of gear to haul up a mountain.

10. Have you ever had any equipment failures? If so, what kind of equipment were you using at the time? What were the conditions?
Nope, I'm still alive.

11. How much does the climbing kit you usually use weigh and if you were to use this device instead of multiple other devices, do you think you would benefit? (How should we word this?)
It needs to weigh the same or less as the combined weight of the Petzl handled ascender and a micro rack.

12. How much would you be willing to spend on a device like this?
$150-170.

13. i) How do you typically buy your equipment?
Online, Local climbing stores, build my own.

13. ii) Where?
See above.