Amount of stress stilts take.... ( science is required here people !! )

[binop9]

I was wondering what was the max stress aluminum stilts can with stand before they fold up, distort, you name it..

as i am sure if someone was to make their stilts out of a different material like titanium or something it would
need to be able to take the pounding and compression and not to mention the shock but thing is What forces ( no star wars jokes people ) are we talking about here.. i am 10 stone in weight which means that when i jump im for a few seconds 0 stone then when i land im 15/20 stone for a second.. see my point.. i am trying to find out ( with out actually breaking my stilts what is the TOTAL load for the frame

and also could someone also tell me what the stress levels are for all the other size stilts ( the m60 and m70 and so on )


( im playing it pretty close to my chest at the moment.. waiting for patents to go through - but once they are done and if i get Very Good feed back then i will bring you all up to speed on the project(s) i am doing.. )

oh and on a sub post..

how many of you would like to have a better wearing and all round gripping hoof
meaning that dry and wet roads will be a thing of the past and you might even be able to use it in gyms and halls.. with out it looking unsightly like tyre socks and other bodges.. though some Mods do look thought out.. ( i am of course referring to Jasons Hoofies )

let me know what you guys and girls think..

Taaa

Chris - Binop9

[Locky]

The main reason the frames are not titanium is due to cost. I dont know what the aluminium is tested to but it seems to do the job. I've only ever heard of 2 frames snapping under pressure. One was mine and one was bobmans lol.
The frames are all the same no matter what weight spring you buy.

[darfgarf]

  more stress than your legs can, with the support rods being the weak point.  jason is probably the best person to ask about such matters anyway

[Jason]

At one point I weighed 18 stone 

I have never had a frame break in any way unless it had been damaged first (Smashing them against steps does it well  )

I did once try jumping onto a pair of scales and they broke despite being up to 23 1/2 stone

Working on an assumption that landing from 4 ft up my weight would be at least doubled so I would be happy to say that they would stand 36 stone

Now I have landed on one foot from a great height so lets assume that is 30 stone apx

If anyone can be bothered to work out the maths of 18 stone dropping 4 ft I think the weights would be higher and factor in the stamping

You must also factor in the cushioning effect that the springs have and they take most of the weight with the frame being more of a fulcrum

I think that most of the frames on the market at the moment are made of either HE15 or HE30 or the metric equivolent
Both of these are a good general engineering grade of ally and although you can go to things like Mag alloy and Titanium alloy they both have different properties that might actually make them a worse choice for bocks

Before anyone says Titanium is perfect for them remember that some alloy are made to be very light and very strong but not flexable

Take Mag alloy for instance it is ideal for car wheels as it is light and very strong
But most off roaders still prefer steel wheels  "Why" because if you hit a mag hard enough you can break it but a steel wheel willbend and keep you moving

So would you prefer a frame that would give a bit and survive or one that snaps if you push it to far

Bit like cars nowdays they crumple to absorb impact  where as a solid car won't bend but you will when you hit the inside 

I don't know all the properties of Titanium as there are so many mixes of alloy I have always found something cheaper to use but I believe it is very strong and light but snaps when pushed to far (Like Mag )

Last thought I believe they build aircraft out of the HE series (albeit specialy tested ) so it must be fairly good

Jason 

[sprog]

The main reason the frames are not titanium is due to cost. I dont know what the aluminium is tested to but it seems to do the job. I've only ever heard of 2 frames snapping under pressure. One was mine and one was bobmans lol.

They didn't snap, they imploded!

I honestly have no idea, your best bet would probably be to contact a manufacturer.

[Spud]

I have actually been thinking about this. I think what you are asking is a difficult question to answer. If anybody would know it would be the Bock guy..but other manufactures...I'm not so sure.

It' a difficult question..and I think it would need some thought and testing on your part. Probably with some kind of accelerometer..but then..that will only measure the G's that you pull and is much different to that on the bocks.

I think an important point is that whatever the frame takes can only be irrelevant because in most cases, at least with projump frames, the force the spring takes is actually more than the frame.

I know how many G's I pull in a glider but I don't know if this information could have any relevance..maybe I could match the rate of decent while bocking in my glider..hmm..

[Jason]

Simple way to test this is to build yourself an accelerometer as Spud just suggested

All you need is something that moves a certain amount when it is stopped or shifted quickly and locks in that position
Or something that breaks at a certain stress point

This could be built with a tube a weight and some very weak cotton

Tested by dropping it from different heights untill one strand of cotton breaks then repeat with two strands then three etc

once you have a series of heights you could then attach the tube to the frames and test until you find the maximum number of strands that you can break

You will then have an equivolent eg biggest bounce=drop from feet

All you need to do is search the internet then to find how many G of ftlb that drop is equivolent to

That will give you a baseline average for not breaking the bocks (if you do it with several weights)

Next stage is the bit you won't like 

Take your brand new bocks and load them up with weights in a frame and slowly increase the weights while dropping them from say 6ft (max height on average)

When your frames break you will have a weight figure to put in the equation that you formed from the acceleration test

This should be repeated at least 10 times to get a meaningfull average 

This is assuming that the springs don't break before the frames (very unlikely as I have frames that have survived several spring breaks)

So all in all it will cost you about £2000 to get an answer and it will probably be that springs break before frames 

There you go I just saved you £2000 and about a months work 

The weakest link in bocks are the springs so why bother to over-engineer the frames at astronomical cost
It is a bit like putting an 8 litre V8 in a fiesta (Fun but ultimately pointless)

If you did manage to develop a spring that was stronger than the frames (as they are at the moment) your main problem would be medical rather than metalergic as you can't upgrade your bones 

Good question though mate got us all thinking 

Jason 

[NightCrawl]

The weakest link in bocks are the springs so why bother to over-engineer the frames at astronomical cost
It is a bit like putting an 8 litre V8 in a fiesta (Fun but ultimately pointless)

You never tried the Speedjumper Professional, right?

Normal frames have lots of small errors, even powerskips or velocity stilts.. I dont say the prof is perfect, but pretty close to.

[Jason]

Thats what you get if you buy substandard 

Ever tried turning a screw with one of those cheap screwdrivers 

I have tried PJ, Powerizer, Poweriser and Powerskips (oh and 7's)

The Skips have the advantage that the holes are bored and reemed rather than being punched which make the bearings last much better

but I am interested about the small errors what do you class them as (apart from the bearing holes varying of course)

Jason 

[NightCrawl]

Did I ever mention that I love the funny people here?

Sent you a PM

[toddy]

just a quick note
some of you lot may know why i did this working out befor.
but from a 8ft high you will pull about 4G when you land/lanch. and i CBA at the mo but i could work out the amount of G that is pulled in the idea world and the real world woundnt be that far off.

and i think it was worked out that you would pull about 4G for about 0.8sec landing and lanching. but i may have that one wrong as i wasnt in the need to rember that number

[Jason]

Four G does sound about right with the spring cushioning Toddy

But I think of it this way have a look on the Seagate hard drive web site and see the amount of G the hard drives can stand
Then take your Hard Drive out of your computer and dtop it from 6 ft  on to concrete

I'd put money on you not doing it 

But if you do take it as revenge for the jump into the sand episode 

Jason 

[toddy]

well i can assure you that my laptop has been droped 4-5ft, but the it is a toughbook 

and sand, i thourght you would have thourgeten that by now