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PostPosted: Tue Jul 23, 2013 2:29 pm 
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bad kitty!
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So, I guess it's time to make a dedicated thread for this project.
It started out with the idea to modify a RockShox Revelation, but seems to have ended up a whole lot different.
As I went through the different parts of the fork, more and more substandard solutions were revealed, so I decided to go all in, and simply make a new fork.
Service intervals seems to be pretty short, compared to what is common in the industrial sector, and the more I looked into it, it became obvious as to why it is so.
Even top forks are smothered in low budget solutions, and many of the latest technological solutions are not even close to what is used today.

The short version goes along the lines of this:

1) Use the stanchions from the Revelation, as they're actually quite fine.

2) Make a carbon crown/steerer, with a wider stance, in order to get reasonable tire clearance.

3) Shim stack type circuits all around, coupled with orifice valves.

4) Make more consistent shims, of a material that does not fatigue like the current 20C shims does.

5) 20mm through axle. Probably going to be either a Maxle, or a souped up version of such.

6) Pressurizing the hydraulic circuit.

7) Considering to implement an electronic version of the RockShox travel adjustment system, just without the seal issues, and with more steps.

8) Carbon lowers

9) A system that allows oil change, without taking the fork apart, or even removing the wheel.

10) A double bridge on the lowers, heavily inspired by the DVO solution.

11) Better sealing of the stanchion/lowers interface, in particular longer service live under heavy contamination.

12) More durable seals in the internals, sporting some of the more modern technologies.


Any suggestions as to something that would be a nice addition?


Magura :)

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PostPosted: Wed Jul 24, 2013 2:52 am 
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yappin' kitty
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Buy a CTD fork and wrap it in vinyl that looks like carbon? All your dreams will come true.

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PostPosted: Wed Jul 24, 2013 4:14 am 
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lurkin' kitty
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I'd prefer a syntace X-20 axle.
I think that are great having used them on an x-fusion vengeance.

Problem is where to get them without buying a fork.

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PostPosted: Wed Jul 24, 2013 7:18 am 
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bad kitty!
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Why do you prefer the X-20 axle over Maxle?

If you can point me to a pic or two, getting one would be no problem, as I'm sure I can find one inside a piece of aluminum.
A Google search just didn't really give much info about it.


Magura :)

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PostPosted: Wed Jul 24, 2013 9:00 am 
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friendly kitty

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I suggest you make a white carbon upper for my Maverick DUC32


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PostPosted: Wed Jul 24, 2013 9:14 am 
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bad kitty!
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Why don't you just make one yourself Richard?


Magura :)

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PostPosted: Wed Jul 24, 2013 9:48 am 
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friendly kitty

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Magura wrote:
Why don't you just make one yourself Richard?


Magura :)


That does sound like my kind of fun to be honest, perhaps someday after I catch up on the projects I've already started.

This is an extremely cool DIY Magura, can't wait to see how it turns out. :clap:


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PostPosted: Wed Jul 24, 2013 12:00 pm 
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bad kitty!
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Jon Richard wrote:
Magura wrote:
can't wait to see how it turns out. :clap:


Me neither ;)

I am so sick of forks that needs service all the time, and hydraulic/pneumatic circuits that are not made by the book.
All the technology is out there, but for some reason forks are made with stone age technology.
Just the fact that they use O-rings as dynamic seals, pretty much says it all.
No industrial product made like that, would have a chance on the market.


Magura :)

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PostPosted: Wed Jul 24, 2013 12:55 pm 
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They sell whatever they can get away with. Stone age technology == they will be able to make small updates next year and sell you new stuff as a breaking improvement. Rinse and repeat.


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PostPosted: Wed Jul 24, 2013 1:13 pm 
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bad kitty!
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Exactly!
...and it makes the temperature of my urine increase dramatically.


Magura :)

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PostPosted: Wed Jul 24, 2013 4:33 pm 
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friendly kitty

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Magura wrote:

I am so sick of forks that needs service all the time, and hydraulic/pneumatic circuits that are not made by the book.
All the technology is out there, but for some reason forks are made with stone age technology.
Just the fact that they use O-rings as dynamic seals, pretty much says it all.
No industrial product made like that, would have a chance on the market.


Magura :)


I'm no engineer but I've often wondered about this as every hydraulic ram I've serviced or rebuilt has square rings and Wiper seals.

What you end up doing with your fork and the materials you use will be of great interest to me.


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PostPosted: Wed Jul 24, 2013 5:20 pm 
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bad kitty!
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Jon Richard wrote:

I'm no engineer but I've often wondered about this as every hydraulic ram I've serviced or rebuilt has square rings and Wiper seals.

What you end up doing with your fork and the materials you use will be of great interest to me.


Exactly.
Take a look inside any respectable pneumatic cylinder, and see if you can find any O-rings. ;)
A company like Festo guarantees up to 10,000,000 strokes, depending which model you pick.
That many strokes would be the same, as a lifetime warranty for a bike fork.
Yet air forks that sees regular use, needs as a bare minimum annual service. Mostly they need more than that.


Magura :)

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PostPosted: Sun Jul 28, 2013 5:33 pm 
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bad kitty!
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It's a small world :D

http://www.igus.co.uk/wpck/default.aspx ... &C=GB&L=en

Neither the Igus application engineer, nor I, knew this when the Iglidur J was selected for the bushings.
I was a bit concerned that it would not like the load on the edge of the bearings, but that seems to be a moot point.
Also no data was to be found, regarding the transition from static to dynamic friction, obviously that's also not a problem.

New seals/wipers are also on their way to Denmark. What might be of interest, is that they will fit Rock Shox 32mm forks as well.
That is, if they turn out to offer anything over the regular Rock Shox or Enduro seals.


Magura :)

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PostPosted: Mon Jul 29, 2013 3:48 pm 
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friendly kitty

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There is a PTFE Based material called Rulon J with a super low coefficient of friction that I've wanted to mess with that I'm wondering if this Iglidur J is a trade name for the same stuff, kinda like the difference between Delrin and Acetal. Sounds like a winner.

I'd like to know more about the wipers and seals when you get them.


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PostPosted: Tue Jul 30, 2013 12:40 am 
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Iglidur appears to be, from my non professional inspection and experience, shmw impregnated with ptfe.

The static and dynamic friction coefficients seem to be stunningly close


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PostPosted: Tue Jul 30, 2013 3:37 pm 
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Forgive my ignorance but I am unfamiliar with shmw, I know about ultra high molecular weight and have stacks of it, but what's the "s" in shmw? Super?


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PostPosted: Tue Jul 30, 2013 5:18 pm 
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friendly kitty
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Thread's getting good ... When might we see some mock-up ?

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PostPosted: Tue Jul 30, 2013 10:05 pm 
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friendly kitty

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Jon Richard wrote:
Forgive my ignorance but I am unfamiliar with shmw, I know about ultra high molecular weight and have stacks of it, but what's the "s" in shmw? Super?


Actually... turns out it was a typo on my part.

What I meant was UHMW. Where the U is for "ultra"

Same idea... just squeezed it together a little more for a little more reduction of friction and a small bump in strength. At least, that's what my uhmw guy says.


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PostPosted: Tue Jul 30, 2013 10:08 pm 
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bad kitty!
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Jon Richard wrote:
Forgive my ignorance but I am unfamiliar with shmw, I know about ultra high molecular weight and have stacks of it, but what's the "s" in shmw? Super?


Yes.

I have no certain proof, of Iglidur J being SHMWPE or UHMWPE based.
I am fairly sure they contain both Aramide and PTFE though.
Do you have some more certain info on that Axis?


Magura :)

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PostPosted: Tue Jul 30, 2013 10:11 pm 
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bad kitty!
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BikeAbuser wrote:
Thread's getting good ... When might we see some mock-up ?


I'll try to post pics, as the mold parts are coming along.
Currently the mold part for the lower legs is in the lathe.


Magura :)

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PostPosted: Wed Jul 31, 2013 5:46 am 
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friendly kitty

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Magura wrote:
Jon Richard wrote:
Forgive my ignorance but I am unfamiliar with shmw, I know about ultra high molecular weight and have stacks of it, but what's the "s" in shmw? Super?


Yes.

I have no certain proof, of Iglidur J being SHMWPE or UHMWPE based.
I am fairly sure they contain both Aramide and PTFE though.
Do you have some more certain info on that Axis?


Magura :)


I have a few linear guides that have Iglidur J on them. I haven't done ANY testing on them... I'm making assumptions based on my experience with uhmwpe and ptfe-impregnated polymers... it matches the characteristics of both very well. I'd be willing to believe that it has aramid in it as well, though I haven't dissembled a chunk and examined to check for fibers.


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PostPosted: Wed Jul 31, 2013 6:09 am 
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friendly kitty

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igus.eu website wrote:
Due to the special structure of the iglidur® materials, which are usually composed of a thermoplastic matrix, fiber reinforcements and the so-called solid lubricants


For iglidur j, density is 1.49 g/cc

Common thermoplastic matrix material:
For uhmwpe, density is around .95 g/cc
For acetal, density is around 1.41 g/cc
For nylon, density is around 1.15 g/cc

Common thermoplastic reinforcing fiber materials:
Aramid fiber, density is around 1.45 g/cc
Glass fiber, density is around 2.5 g/cc

Solid lubricant, assuming it's PTFE only:
PTFE density is around 2.20g/cc

So, there are a few combinations of matrix/fiber/solid lubricants that would make sense in my mind.
I don't think anyone is doubting that PTFE is the "solid lubricant". They didn't use delrin or bronze... because it's a dull yellow in color.

It is long-wearing, so the base matrix is likely not nylon based.

I think we can rule out the PTFE/acetal/glass combo, because the density would be way over. If we assume a PTFE absorption rate of around 15%-by-volume, the remaining materials would require a density of 1.05 g/cc.

Assuming a 50/50 fiber/matrix for the remaining 85% of the material volume:
Aramid/UHMW would give a density of 1.02 g/cc
Glass/UHMW would give a density of 1.47 g/cc
Aramid/Acetal would give a density of 1.22 g/cc
Glass/Acetal would give a density of 1.66 g/cc

So, I would say that it is likely UHMW (or another polyethylene) and Aramid. Based on my reverse-engineering-fu.


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PostPosted: Wed Jul 31, 2013 9:28 am 
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bad kitty!
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That adds up well with my back o' napkin calcs.

Some 10 to 15% PTFE, like 30% Aramide, UHMWPE for the rest.
Fits with the color as well.

Magura :)

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PostPosted: Wed Jul 31, 2013 4:25 pm 
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friendly kitty
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LOL
I've got to give a lecture on plastics and FRP, tonight ... But this stuff would be way over the head of anyone in the class, as I doubt any of them have heard of anything beyond PVC/ABS and Glass/Carbon.

However,
I gotta thank you Gent's ... I think I'll have them do a density comparison.

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PostPosted: Wed Jul 31, 2013 6:05 pm 
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friendly kitty

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BikeAbuser wrote:
LOL
I've got to give a lecture on plastics and FRP, tonight ... But this stuff would be way over the head of anyone in the class, as I doubt any of them have heard of anything beyond PVC/ABS and Glass/Carbon.

However,
I gotta thank you Gent's ... I think I'll have them do a density comparison.


Density comparisons are just ONE of the many tricks up our sleeves.

Bulk modulus, strength ratios, poisson's, weight/strength efficiencies, volumetric strength efficiencies, etc...

You might introduce them to some of the "exotic" materials. Like "nylon"


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PostPosted: Thu Aug 01, 2013 12:52 pm 
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bad kitty!
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Got a setback for our reverse engineering skill to report.

Iglidur J is Acetal based. I just burned a bit of it, and there's no doubt.
So the PTFE content has to be pretty low, or the Aramide content is high.


Magura :)

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PostPosted: Thu Aug 01, 2013 1:48 pm 
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friendly kitty
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axisofoil wrote:
BikeAbuser wrote:
LOL
I've got to give a lecture on plastics and FRP, tonight ... But this stuff would be way over the head of anyone in the class, as I doubt any of them have heard of anything beyond PVC/ABS and Glass/Carbon.

However,
I gotta thank you Gent's ... I think I'll have them do a density comparison.


Density comparisons are just ONE of the many tricks up our sleeves.

Bulk modulus, strength ratios, poisson's, weight/strength efficiencies, volumetric strength efficiencies, etc...

You might introduce them to some of the "exotic" materials. Like "nylon"
If it was a hardcore materials design course, I would go much further ... In depth.
However, this is an overview course that covers many materials, and the processes used to go from raw material to finished product ... The primary emphasis is CAD design within multiple disciplines.

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PostPosted: Thu Aug 01, 2013 2:12 pm 
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-.-


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PostPosted: Thu Aug 01, 2013 5:58 pm 
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Bakelite Fists = Silly Putty Face

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PostPosted: Thu Aug 01, 2013 6:17 pm 
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I got a handful of Iglidur J bushings today.
Tolerances are all over the place, but I will fix that by mounting them on a mandrel, and machine them to a tighter tolerance.
I also got a round bar of Iglidur J, so if the above fails, I'll simply machine the bushings from that.

The other pic is of the mandrel for the fork legs. On the pic it looks a bit tiny, but it's like 290mm long, and 44mm in diameter at the seal end.


Magura :)


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