Relocating Calf Rod Clamps

[UpFromOne]

On CZ model Air-Trekkers (similar stilts to Powerisers), the original location of the calf rod clamping mechanism is set in the middle of the upper riser to accomodate a wider range of adjustment for leg lengths. But this is not the most secure position. The most secure position for the clamps is as high up on the riser as possible, closest to the calk cuff. The shortest rod makes the stiffer setup. And most adult legs don't need the clamps located mid-rail.

So I merely unbolted the 4 original location bolts (M5), inserted a plastic 30mm long bushing (hardware store) in the 2 uppermost center holes of the rail, and used M8 x 40 allen bolts to re-mount the clamps. It now feels more secure on the legs, as the calf rods don't move as much. Eventually I'm inclined to cut off the excess rod sections (i.e. below the clamps) so they don't catch on anything.

Depending on your rail system, you might be able to do something similar if you're so inclined.

Photos here:
http://imageshack.us/g/259/rodclampsfinished.jpg/

[XDvandalDJ]

This looks like something I might try. As it is I have to full extend the knee bars to fit me properly. This has lead to me bending the bars on cuffs, and knee bars since they're so far extended.

[Joe Legg]

I do like this one. ill keep it in mind.  something so simple.

[XS]

while you're at it might as well replace the whole block with a metal one from Powerisers or 7's instead of the quick release clamp for even more security.  I like where this is going.  I guess you could also do the opposite and move it down for shorter users as long as the top of the spring doesn't get in the way of the back of their knee.

[Jason]

Nice one mate

I replaced my clamps with some I machined up (same as the Powerskip ones) as I don't change them once set

Powerskip ones are placed higher than the CZ ones but lower than yours about half way between they clamp through the holes in the frame with U bolts like an exhaust clamp

Nice to see a good mod keep it up

Jason 

[UpFromOne]

Hey thx all. Yeah I'm gonna go for it even more and remove the clamp mechanism, narrow down the inner saddles, and do a simple bolt-through on the rods with a 105mm long bolt. I'll weigh my stilts after that & report back.

[Jason]

Not sure if you are thinking of drilling through the cuff bars (it sounded like that but I always get things wrong  ) but do be aware that the bars are on the limit of their strength when people get extreme with them

I have bent a set quite a few times in falls so if you weaken them with say a 6mm bolt I think you may have problems with them fracturing in use which could cause a nasty ankle injury

But I may be totaly wrong so feel free to ignore me  Just don't want to see a fellow inventor damaged

Jason 

[UpFromOne]

Appreciate the cautionary tales. The stock rods on my stilts look to be a thick-walled 6061, which is why I'm ok with drilling them at the mount area and using concave washers to spread the load.
If I were to hit hard enough to cause damage to the rods, I would venture to guess that they would bend or at worst crack rather than snap (like more brittle 7000 series).
I agree that the stock clamps, in providing "just enough" clamping force, do allow for these rods to twist rather than suffer direct damage. But I think that once you find your own preferred location of the rods, it makes sense to secure them with a minimal amount of material.
Again, one of my goals is overall lightness of the stilts, so I'm willing to compromise a bit with the fixed-location design.

Ultimately I still like the idea of fixed carbon calf wraps, which would offer more support and can be easily replaced if broken. Certainly not suitable for general public, but hey, this is the MODS section! It's up to us to push the boundaries!

[XS]

I wouldn't assume they're 6061.  These stilts are made of the cheapest crap alloy possible.  A machinist friend told me that milling the frame felt like milling plastic, he'd never worked with any metal so soft.

[Jason]

The kneebars were made from a (not to bad Alloy) depending of which stilts they came from

My best guess would be HE30/60 for the better ones (don't ask about the cheep ones someone gave me think they were made of butter  )

The frames were made of a much lower grade (unless you count skips which I thing are HE30 ) but as they were fairly substantial they did the job at a low price (and yes I agree your mate XS they stuck to the cutters like the proverbial to a blanket)

I make most of my bits from HE30 as it is easily available and I must admit I wouldn't trust a tube of it to do what you are hoping as a hole weakens a tube a great deal but then I weigh a lot and do stress my stilts a lot

But it's your legs not mine 

Just so you know the differences in the alloys have a look here

http://www.aircraftmaterialsuk.com/data/aluminium/6082.html

But heres a couple of exerts

"Alloy 6082 is a medium strength alloy with excellent corrosion resistance.  Alloy 6082 has the highest strength of the 6000 series alloy. Due to the higher strength of Alloy 6082 it has replaced Alloy 6061 in many applications.  Alloy 6082 is typically used in highly stressed applications, Trusses, Bridges, Cranes, Transport applications, Ore Skips, Beer Barrels, Milk churns"

"SPECIFICATIONS

Aluminium alloy 6082 also corresponds to the following standard designations and specification.

AA6082

HE30

DIN 3.2315

EN AW-6082

ISO AlSi1MgMn

A96082"

Jason 

[UpFromOne]

Great info, thanks!

Here's a couple more pics of the finished setup, having cut the excess off the rods.
http://imageshack.us/g/198/rodclampsside.jpg/

BTW, Air-Trekker says that the rail alloy is "Lithium". I have never of that, nor do they say exactly what that means.
My rods sure seem to be the same alloy as better bike handlebars. I just can't see them snapping off like a brittle alloy.

[BitLord83]

That's actually really weird looking, but kinda awesome. Does it actually help keep them from slipping being higher like that?

[UpFromOne]

Good question. Not really, because the "lever" effect of the rod, from the clamped vertical axis out to the point of the cuff attachment, has not changed. But the shorter vertical rise does feel firmer. Which to me means there is some flex from the longer rod in the stock clamping position.

I'm not saying this is the answer, as I intend to make a bolt-on fixed cuff of some kind or another. But it's definitely "better than stock" for the time being.

[Jason]

Looks very good mate and looks like you can save a fair bit of weight that way

Have you had a look at the Powerskip method of attaching the bars

It is hard to describe and awkward to make but it is somewhat like an exhaust clamp

The advantages are it is light and the bars will bend before they move or slip (it really is that strong)

The disadvantage is they are patented to Bock so no one can produce them

But you can make your own ones just don't start selling them 

Jason 

[UpFromOne]

Thx again. I don't see alot of info for that brand, they seem more esoteric (wait, aren't all these jumping stilts esoteric???)

[Jason]

Have a look here mate

http://www.projumpforum.co.uk/index.php?board=88.0

The whole section on here it about Skips

And if you type Powerskip into google you will get loads of into and pics

They still are the best machined, made and finishes bocks on the market
I personaly think Exo springs are better but that is me and it will be a long running argument as to which are better

The only downside is the £800+ price tag for Skips and the springs costing £300 a pair

I mean you can get 3 pairs of Exo springs and a decent dinner for two for the same price
And the Exo springs come with a warenty in my weight range 

My mate Clive has skips and I have Exo's and we can't decide which are best (until he has to but new springs  )

Jason