Non-metallic slider grommets

[Treejumps 0]

Hi all,

Does anyone have any ideas about non-metallic slider grommets? Carbon, ceramic, nylon? Maybe not even grommets, perhaps rings that could used like on a RDS?

Every other piece of metal on a rig can be easily removed, but I could use some ideas for the slider.

Thanks

[Squeak 17]

Making a smugglers rig
I think there's a good instructional section in a teaching video, called "Cutaway"

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[Nutz 0]

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I think there's a good instructional section in a teaching video, called "Cutaway"

Thats good.

"Don't! Get! Eliminated!"

[Squeak 17]

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I think there's a good instructional section in a teaching video, called "Cutaway"

Thats good.

Like how i referenced 2 of the all time great motion picture events of our life time
The smugglers rig from Dropzone and the smugglers from Cutaway, everything you ever needed to know to become a smuggle-jumper

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[Treejumps 0]

No one is smuggling anything. Anyone with actual answers to the question are encouraged to respond. All others take witty banter to the bonfire.

[Squeak 17]

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No one is smuggling anything. Anyone with actual answers to the question are encouraged to respond. All others take witty banter to the bonfire.

Here's a tip call DuPont ask them to fashion something for you

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[JohnRich 4]

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Does anyone have any ideas about non-metallic slider grommets? Carbon, ceramic, nylon?

What is the motivation for wanting to switch materials?
To save a few ounces of weight?

[PhreeZone 20]

Metal dings and gets sharp edges on it and those cause accelerated wearing on the lines. Plastics on the other hand might melt under then heat of sliding down the lines. Ceramic on the other hand would be an ideal material.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[wolfriverjoe 1,523]

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No one is smuggling anything. Anyone with actual answers to the question are encouraged to respond. All others take witty banter to the bonfire.

I would think ceramics and carbon would be too brittle (Although I could be wrong). There are high temp plastics out there. I've got a plastic ashtray that doesn't melt even when the coal of the cigarette is directly on it. Feel free to call it stupid, but cutting circles out of that would seem to be an idea.

OK, now that I've given a (mostly)serious answer, a serious question-WHY?? The smuggling idea is pure hollywood crap. Short of trying to sneak a rig through a metal detector (and I think the security people would notice the big lump on your back), I can't figure out a reason and curiosity is driving me nuts.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[riggerrob 643]

It is possible ot build a complete smuggler's rig - with zero metal parts - but it will not last very long.
The biggest problem is friction heating slider grommets.
Ceramics might work, but most of the ceramics are too brittle.
There is also the question of abrasion resistance.
Kevlar, Vectran and HMA suspension lines are all too abrasive for brass grommets, which is why the current fashion for slider grommets is stainless steel.

[hackish 8]

I do not think you'd be able to get a nylon or teflon grommet to last under the abrasion of the lines. I believe a slider has to withstand about 1000 lbs of force. That is a lot for the grommets to bear before the slider starts to descend. The last thing you would want is the line cutting into a grommet and causing it to hang up 1/2 way down.

Although you may be able to fashion a somewhat non-metallic grommet it would probably still need metallic reinforcement.

Fiber-reinforced ceramics are pretty tough but I'm concerned about them being able to break - the failure mode isn't too pretty. They would, however put up with the abrasion and as a ring moulded into a plastic carrier could probably be attached with ease. (Sew the plastic carrier to the slider).

-Michael

[councilman24 37]

Non metalic or non ferrous?

Titanium rings on a spider slider with PC controlled reefing. Or other non metallic rings I can't think of to get away from a 'grommet' format.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[DrewEckhardt 0]

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Non metalic or non ferrous?

Titanium rings on a spider slider with PC controlled reefing. Or other non metallic rings I can't think of to get away from a 'grommet' format.

Non-counductive.

[erdnarob 1]

An interesting question. In a way, grommets are like tires: those when they are soft they have the best adherence but wear faster and when they are harder they last more but they are slippery.
The only material I would see is carbon fiber to make the grommets. At home I have a rod of carbon fiber the size of a cigaret for the diameter and 2 and half foot long. Its tensile strength is way more than steel and can hold if I remember 26000 lbs max. For a ring/grommet made of that material it will have to be resistant to flexibility and tensile strength together. It believe that carbon fiber will resist quite well to abrasion since that material is relatively hard. We haven't seen everything yet with material usable for parachute. There is still things to be discovered. BTW carbon fiber is more expensive but lighter than metal. Titanium which is a metal is very strong and light but a 1 inch diameter rod of 3 foot long costs 400$.

Learn from others mistakes, you will never live long enough to make them all.

[wolfriverjoe 1,523]

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Non metalic or non ferrous?

Titanium rings on a spider slider with PC controlled reefing. Or other non metallic rings I can't think of to get away from a 'grommet' format.

Non-counductive.

Isn't carbon conductive?? Junior high physics was a long time ago.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[Treejumps 0]

Hi John,

This is for a building access rig to get through metal detectors. Even if they only last a few jumps, plastic would be fine. I've picked up a few ideas and will test them before the intended use. For those that asked, there is no hump on your back. They pack up long and flat.

Thanks for the help

[SimonBones 1]

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Isn't carbon conductive?? Junior high physics was a long time ago.

Almost everything can be conductive if you crank the voltage high enough. Even glass, rubber, DI water, plastics, and oil have a threshold where you can get them to conduct.

108 way head down world record!!!
http://www.simonbones.com
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[RMURRAY 1]

first of all I am not a rigger.

to prevent burrs on stainless it is possible to give parts (i.e. RDS rings) it a surface treatment that will harden only a very thin layer - of course adds $$$.

for a rig for one or two openings I would bet that a glass/mineral reinforced nylon would work. check out Dupont. might need more bearing area than your typical thin RDS rings. I would think definately not a good idea for extended use.

[erdnarob 1]

Carbon fiber like all metals is also an electricity conductor but will not be seen by a metal detector. Diamond is pure carbon but is not an electricity conductor while graphite (pure carbon too) is. The reason is that their crystallography is different.
Of course in a certain way all substances are more or less electricity conductor and that changes with temperature but only metals (ferrous or not) (including mercury), monoatomic hydrogen (which has the same electronic configuration than a metal) and carbon graphite are considered as conductor. Other are dielectric which means not good electricity conductor. For instance the "lead" of a pencil is not anymore made of lead but is made of carbon graphite and is a good conductor. Never let a child play with a pencil and a electrical outlet. You choose physics, good. I teach it.

Learn from others mistakes, you will never live long enough to make them all.

[piisfish 140]

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This is for a building access rig to get through metal detectors.

take a short delay and jump without a slider

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[pchapman 279]

Just musing, no good answers for the original poster:

Carbon fibre composite rings (epoxy and fibre) still sound pretty good due to the strength that is possible, compared to say some plastic. Properly, they'd be disks so one can have a few holes next to the main one, to attach the slider fabric to. (In the manner of some RDS rings or Russian slider grommets.)

I don't know how they'd hold up, but I don't see that there would be that much wear over a few jumps. On the other hand, the local heat buildup due to line friction on opening could be more than expected. Light lubrication probably helps, even if lubrication isn't generally liked in skydiving due to dirt trapping.

One would of course want to test that slider descent rate is still OK given the different weight of the slider and drag of the grommets on lines.

The question is whether there really is some existing product out there that is suitable, some engineered product hidden in an industrial catalogue.

As opposed to going to a composites shop and having them make a mold and lay the rings up by hand, or learning composites techniques yourself.

For strength one wants them built with the fibres going circumferentially around the circle, not just cutting a donut out of a flat sheet of carbon composite.

[edge01 1]

Ceramic inlay with a plastic,nylon,carbon ,fiber,etc grommet.

[RMURRAY 1]

good idea. an rds ring like my paraconcepts would be possible. I would say a ceramic insert, place the part in an injection mould and mould glass reinforced nylon. although, it would be relatively expensive to tool up...

R

[Blink 1]

RMURRAY,

What program was that drawn in? CATIA? I do some CAD work and was just curious. Nice job.

[wolfriverjoe 1,523]

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This is for a building access rig to get through metal detectors.

take a short delay and jump without a slider

Yeah, but in a building tall enough to have that level of security that would mean WAY too much canopy time, wouldn't it?

Treejumps- Thanks for the real answer.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo