Hi guys
I want to make my own set of polymer spokes.
On a rope splice, which applies to any industry using high performance polymer rope, the bury is held in via a Chinese finger trap method.. this is typical for rope splicing. The glue does not take the load; it's only there to help the rope develop some initial tension and clamp down on the bury holding it via friction.
The devil is in the details. splices tend to take a set and slip a bit, making the length difficult to get right.
On to materials,
After my research, it seems DM20 is the way to go for UHMWPE. It's a new material from DSM with massively improved creep characteristics.
UHMWPE is so bad with creep, standard high performance materials would simply be unsuitable for spokes, until just a few years ago.
I have a 100M reel of 1.8mm DM20...
Another couple of options: Vectran and PBO. Both have good creep characteristics and could be used for spokes.
Everything here applies to those too if you were to source 1.5-2.0mm Vectran or PBO.
I have another idea to get the weight down to ~1.7g per spoke and an even better/easier design. Here is what I came up with:
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I am thinking to take a butted spoke, 2.3mm/2.00mm, and roll or press or stamp the end to 0.8mm thick to achieve an eye where it threads into the nipple. This way one could do a 2nd bury splice here eliminating the long metal bury. This part comes to ~0.65 g each and with a rope weight of about 1.2G = 1.85G per spoke!!
This compares to about 2.5-2.6G per spoke I'm getting with Berd's method because of the longer steel spoke end that needs to be buried.
The strength of the part is still a bit iffy. It would be better if we could find some 12g/14g butted spokes (2.6mm/2.0mm) so there's more material to smash to make the eye... or even 11g or 10g.
That or the part could be made custom from scratch...
I know several manufacturers whom could make such a part but it would need to be a pretty large qty to be cost effective.
For example:
https://www.gallmachine.com/gallery
THB, a spoke manufacter would be best suited to make such a part...
Here is a "quick" FEA assuming 60,000psi yield strength. I know alot of spoke manufacturers get their yeild strength to 120,000psi and up, but's it's still pretty iffy and more material would be nice.
(link incoming)
I want to make my own set of polymer spokes.
On a rope splice, which applies to any industry using high performance polymer rope, the bury is held in via a Chinese finger trap method.. this is typical for rope splicing. The glue does not take the load; it's only there to help the rope develop some initial tension and clamp down on the bury holding it via friction.
The devil is in the details. splices tend to take a set and slip a bit, making the length difficult to get right.
On to materials,
After my research, it seems DM20 is the way to go for UHMWPE. It's a new material from DSM with massively improved creep characteristics.
UHMWPE is so bad with creep, standard high performance materials would simply be unsuitable for spokes, until just a few years ago.
I have a 100M reel of 1.8mm DM20...
Another couple of options: Vectran and PBO. Both have good creep characteristics and could be used for spokes.
Everything here applies to those too if you were to source 1.5-2.0mm Vectran or PBO.
I have another idea to get the weight down to ~1.7g per spoke and an even better/easier design. Here is what I came up with:
I am thinking to take a butted spoke, 2.3mm/2.00mm, and roll or press or stamp the end to 0.8mm thick to achieve an eye where it threads into the nipple. This way one could do a 2nd bury splice here eliminating the long metal bury. This part comes to ~0.65 g each and with a rope weight of about 1.2G = 1.85G per spoke!!
This compares to about 2.5-2.6G per spoke I'm getting with Berd's method because of the longer steel spoke end that needs to be buried.
The strength of the part is still a bit iffy. It would be better if we could find some 12g/14g butted spokes (2.6mm/2.0mm) so there's more material to smash to make the eye... or even 11g or 10g.
That or the part could be made custom from scratch...
I know several manufacturers whom could make such a part but it would need to be a pretty large qty to be cost effective.
For example:
https://www.gallmachine.com/gallery
THB, a spoke manufacter would be best suited to make such a part...
Here is a "quick" FEA assuming 60,000psi yield strength. I know alot of spoke manufacturers get their yeild strength to 120,000psi and up, but's it's still pretty iffy and more material would be nice.
(link incoming)
