High IQ Nerd Stumped on Simple Problem
High IQ Nerd Stumped on Simple Problem
(OP)
I am trying to find a product or mechanism that already exist that is basically a Chinese finger trap for a sheet of fabric. You feed the fabric into the trap/clamp/mechanism and cant be pulled out. After pondering and asking all the engineers around my office the closest thing we have thought of is a rapid tie down strap like if your securing stuff on your car rack you can pull the strap tighter (easily feeds into the mechanism one direction) but cannot be pulled out in the opposite direction. However, the rapid tie down strap has little backwards pointing or re-curved metal teeth that dig into the material, which is too harsh on the fabric. I need something that accomplishes the same goal that's not so harsh on the fabric - I would love your input on this!
What I eventually thought of was backward pointing or recurved rubber teeth that do not dig into the material but instead use friction and pressure to prevent the fabric from being pulled out. The fabric easily slips in, but when you try to pull it out the friction on the re-curved rubber teeth cause the teeth to "unfold" increasing pressure on the fabric which in turn increases friction. The harder you try to pull the fabric out of the trap the more the re-curved rubber teeth "unfold" > increased pressure > increased friction. How would I ever make this or does something like this already exist or can be modified to build a functional prototype?
Thank you in advance!!!
"Do or do not, there is no try" - Master Yoda
What I eventually thought of was backward pointing or recurved rubber teeth that do not dig into the material but instead use friction and pressure to prevent the fabric from being pulled out. The fabric easily slips in, but when you try to pull it out the friction on the re-curved rubber teeth cause the teeth to "unfold" increasing pressure on the fabric which in turn increases friction. The harder you try to pull the fabric out of the trap the more the re-curved rubber teeth "unfold" > increased pressure > increased friction. How would I ever make this or does something like this already exist or can be modified to build a functional prototype?
Thank you in advance!!!
"Do or do not, there is no try" - Master Yoda





RE: High IQ Nerd Stumped on Simple Problem
One thing that comes to mind for what you are trying to do, is Diamond hollow braid . This material when it is compressed gets larger in diameter , and when it is pulled, gets smaller in diameter clamping tight to anything inserted into the hollow cavity.
B.E.
You are judged not by what you know, but by what you can do.
RE: High IQ Nerd Stumped on Simple Problem
RE: High IQ Nerd Stumped on Simple Problem
Something similar should work on the edge of a sheet of fabric. You might have to use a full length dowel instead of short cylinders to allow release without going out of your mind.
Mike Halloran
Pembroke Pines, FL, USA
RE: High IQ Nerd Stumped on Simple Problem
I could build it out in CAD like I did with the chinese fabric trap concept described above (see below), but I would love to first find the product your talking about to help guide design. I've searched far and wide on google and can't find anything - can you help me find it so I am not taking shots in the dark making 100 prototypes to figure out design principles.
RE: High IQ Nerd Stumped on Simple Problem
Or cable grips used on prestressing strand.
RE: High IQ Nerd Stumped on Simple Problem
Imagine your fabric feeding through a pair of rollers with eccentric bearings.
Spring loaded?
Single roller wedging against a plane?
je suis charlie
RE: High IQ Nerd Stumped on Simple Problem
http://www.amazon.com/Hangman-Clip--Magnetic-Holde...
There appear to be at least two manufacturers, producing the item in several lengths:
Hangman Clip-It Strip Magnetic Note and Paper Holder
ADVANTUS Grip-A-Strip Display Rail
Mike Halloran
Pembroke Pines, FL, USA
RE: High IQ Nerd Stumped on Simple Problem
je suis charlie
RE: High IQ Nerd Stumped on Simple Problem
Many mechanisms that work well for small areas, like a Chinese finger trap, are not suitable for long, drapeable, sheets.
RE: High IQ Nerd Stumped on Simple Problem
RE: High IQ Nerd Stumped on Simple Problem
RE: High IQ Nerd Stumped on Simple Problem
"That which you seek, inside you will find..." -Master Yoda
RE: High IQ Nerd Stumped on Simple Problem
Could I be nosy, and ask why?
A.
RE: High IQ Nerd Stumped on Simple Problem
Unrelated topic - how high is your I.Q.?
RE: High IQ Nerd Stumped on Simple Problem
TTFN
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RE: High IQ Nerd Stumped on Simple Problem
I sitting around ~130-135 according to my Graduate Record Examination scores.
Here is my updated design concept it provides force throughout the column and has less moving parts compared to using rows and rows of the roller system described above.
RE: High IQ Nerd Stumped on Simple Problem
... which is yet another reason that the wedge needs to be full-width not segmented, so that you can use strings or something to lift it by the ends and bias it to one side of the cavity, so you can work the fabric into the gap. It may even be necessary to evacuate the cavity or otherwise provide an airflow to carry the fabric into the gap.
Mike Halloran
Pembroke Pines, FL, USA
RE: High IQ Nerd Stumped on Simple Problem
Increased grip surface area does not equal stronger grip. (F = mu.N)
A lower mu between wedge and frame permits a steeper ramp angle. Steeper ramp angle has the advantage of reduced vertical displacement for a given "grip" displacement.
A planar grip region is more prone to over-constraint and high spots. Roller has line contact. Soft roller seems best option. Lightweight (hollow elastomer?) for easier fabric insertion. (why do you need
je suis charlie
RE: High IQ Nerd Stumped on Simple Problem
Incidentally, an IQ of 140 is probably not especially high around here, and IQ is not in itself a great indicator for engineering, above a necessary minimum. Average IQ for engineering majors is 126, 1 standard deviation is around 10, you do the math.
Cheers
Greg Locock
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RE: High IQ Nerd Stumped on Simple Problem
RE: High IQ Nerd Stumped on Simple Problem
RE: High IQ Nerd Stumped on Simple Problem
1% of the population have IQ >135
je suis charlie
RE: High IQ Nerd Stumped on Simple Problem
Incidentally this is the same sort of mechanism used to hold up X-Ray films on light boxes.