/ New Cam Design

This topic has been archived, and won't accept reply postings.
Wot - on 07 Jan 2013
I'm an engineering student and for my final year disertation I'm designing a new cam. I came up with initial idea last year and have gotten a lot of work done so far.

Any comments on the design/ things that need to change would be helpful. The main comments so far are how would this work with just 1 hand. I'v been chatting with some of my tutors and have got an idea of how to make it one handed.

Here's what I have so far. Just 3D modeling. Photobucket link hope it works.
http://s139.beta.photobucket.com/user/working-on-this/media/Cams/Campic1_zpsdb5f8d47.jpg.html?sort=3...

Also I found out the other day that a similar idea already exists.
http://www.ukclimbing.com/forums/t.php?t=517402&v=1
I'v read through all the comments.
Orgsm on 07 Jan 2013
In reply to Wot:

Seems to me that a force pulling on the stem would cause the cams to come closer together, and so the outward force on rock would be lost and it would fail. Maybe it's the diagrams but if they are correct implies a serious flaw.
Wot - on 07 Jan 2013
In reply to A Game of Chance: Not the best of diagrams sorry. The stem would be threaded it's just very hard to do in solidworks. It would push the cams outword anyway.
Wot - on 07 Jan 2013
In reply to Wot: I just understud what you mean. If if goes beyond the midway point of the scisor jack it would start to pull the cam together.
another_mark on 07 Jan 2013
In reply to Wot: The thing about normal cams is that the force on them acts directly through the pivot axle.

Looking at your design, I think that the long rigid stem will be problematic with forces which are not aligned with the stem.

You could alleviate this by having hte stem fixed at the lower bracket and able to extend above the top bracket - if that makes sense.

I'm still concerned about off centre forces though.
andic - on 07 Jan 2013
In reply to Wot:

Have you ever heard of a big-bro? I am not sure I would trust your device over one
Orgsm on 07 Jan 2013
In reply to Wot:
> (In reply to Wot) I just understud what you mean. If if goes beyond the midway point of the scisor jack it would start to pull the cam together.

Yes

andic - on 07 Jan 2013
In reply to andic:

or a kong gypsy?


both are novel and distinctive approaches to the problem of wide cracks
itsThere on 07 Jan 2013
In reply to Wot: cam stops, dont know if thats the correct term for them. so it can be used as passive protection just in case. i hope you put "the great all seeing all knowing UKC" in your bibliography
cuppatea on 07 Jan 2013


In reply to A Game of Chance:
> (In reply to Wot)
>
> Seems to me that a force pulling on the stem would cause the cams to come closer together, and so the outward force on rock would be lost and it would fail. Maybe it's the diagrams but if they are correct implies a serious flaw.

Yes, it needs a massive spring (or some other type of mechanical wizardry) between the lower arms and the krab attachment point


In reply to Wot:
That'll be 50,000 please.
Wot - on 07 Jan 2013
In reply to another_mark: Ye, that makes sense. Thanks for idea. I did consider adding a flexable bit to the bottom of it.

I'got lectures so back later. And yes UKC will have to in the bibliography
jkarran - on 07 Jan 2013
In reply to Wot:

There are various suggestion for stem adjustments in the other thread that will work one handed and as well as if not better than a thread/nut. The problems you have (and they're the same for all the stem variations) are stability of placement when the cams are well spread and the very high mechanical advantage achieved at small expansions. Of course you can limit it with stops but then you also lose quite a bit of range which is the only real selling point.

Out of curiosity, are I-beams the best structure for resisting buckling? And shouldn't the I-beams all go to a pair of common axles top and bottom to avoid applying bending loads to the stem (which can then be lighter or possibly even flexible)?

What is the actual aim of the project?
jk
Adam Long - on 07 Jan 2013
In reply to Wot:

Looks like a decent idea but you've ignored the problem of stability. Big cams are very prone to falling out due to twisting motions of the head.

If you look at a plan view of a typical 4-cam, the length of the axle is usually greater than the width of the largest placement it can be used in (more so in smaller cams, from 3 up its typically squarish). This gives it the stability your design will lack.
Offwidth - on 07 Jan 2013
In reply to Wot:

Seems to me the design is not really for a climbing cam, it's more for something to lock in a crack with smaller, more aligned loads than you get in a climbing fall. Climbing cams take large loads and adjust well when the load is perfectly aligned and are beautiful designs in that respct. Start looking at the stresses and limits of response in your structure when loaded with realistic forces found in climbing and you'll see problems: to make it strong enough and deal with non-aligned loads it soon gets too big/heavy.
jkarran - on 07 Jan 2013
In reply to Wot:

Why are the top and bottom arms dissimilar lengths? Surely there's no real merit in arranging the thing so the stem can be either in compression or tension depending upon the user setting, it makes the adjustment locking much harder and will result in excess stem/adjuster weight. It's a guess but I'd have thought designing it so the stem is always in tension will provide the simplest lightest solution.

jk
Daniel Heath - on 07 Jan 2013
In reply to Wot:

This reminds me of the Anticam which my mate did his final year project on. There some videos like this one http://www.ukclimbing.com/logbook/crag.php?id=19
JIMBO on 07 Jan 2013
In reply to Wot: I think it wouldn't take much walking before it was compromised or fell out.
morley.10 - on 08 Jan 2013
I think big bros are in common use for big cracks. it might be a option for a beam clamp (irata) if the cams are reversed with little more room above the top bar?
ledifer on 08 Jan 2013
In reply to Wot:
it's just very hard to do in solidworks.

Don't complain about solidworks some of us are still battling on with autocad!
ads.ukclimbing.com
Wot - on 11 Jan 2013
In reply to ledifer: There are a lot of other tricky programs you'll have to learn if you're going for engineering. It's all fun though.

I'm redesigning it when I get the chance (a lot of other work to do). Had a Q&A with some of my tutors over it and they picked up on loads of mistakes. Not even to do with climbing, just material/wear and how it's all gonna fit together. 3rd year's hard :)

This topic has been archived, and won't accept reply postings.