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Old 21-12-2013, 18:29   #1
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Using Dynema with compression fittings

I am replacing Spectra running back stays with Dynema. The existing terminations on the Spectra lines use Selden stainless compression fittings to mate with M16x1.5 male threaded #8 toggle . Has anyone used this type of termination with Dynema? I understand the typical Dynema termination uses an eye splice.

Thanks,
Ben
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Old 21-12-2013, 18:33   #2
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Re: Using Dynema with compression fittings

typically those compression fittings are used on line with near parallel fibers (which are hard/impossible to splice), and splices used with braided line.

the compression fittings are 'supposed' to be very reliable, but I have never personally used or tested one on dyneema line.
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Old 21-12-2013, 18:36   #3
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Re: Using Dynema with compression fittings

Thank you sir for your quick reply...I am also trying to determine how to open the existing fitting, assuming it can be reused...
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Old 21-12-2013, 18:36   #4
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Re: Using Dynema with compression fittings

I tried it once but the dyneema is like teflon (slick as hell) and eventually came loose. And there aren't any adhesives that stick to it either. I ended up putting in small thimbles.


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Old 21-12-2013, 18:44   #5
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Re: Using Dynema with compression fittings

Thank You Delmarrey...is the RH photo of the Dyneema connection that subsequently failed?
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Old 21-12-2013, 18:54   #6
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Re: Using Dynema with compression fittings

Yes!

Using 1/4" dyneema I was able to lift about 400# (first picture) but when I went to load test it with a scale it let go at 585#.

I inserted a tapered fiberglass rod in the center of the dyneema with a ferrel around the outside and used that as a compression fitting. But the stuff is so slick it just slid right out. I even had epoxy glue in there but it just extracted the epoxy right off the dyneema like a wax. And there doesn't seem to be any other adhesives out there that will stick to dyneema, even hot glue comes off with your fingernail.

If you had something to hold a knot, like with soft shackles, it would work. But the load rating would be lower.
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Old 21-12-2013, 19:03   #7
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Re: Using Dynema with compression fittings

The stuff in the picture is Kevlar. Was probably is a black plastic sleeve originally. Never seen these fitting reused with anything but the OEM Navtec Kevlar which I doubt is available anymore.
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Old 21-12-2013, 19:31   #8
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Re: Using Dynema with compression fittings

Thank You for your replies...Yes I believe you are right ...the original material is Kevlar and it had a white plastic sleeve that eventually deteriorated (2003 vintage boat). So you are confirming rigger I spoke to that I need to migrate to a thimble type solution. I have two possible solutions for this using some of the original fiitings but need a (1) stainless eye with a female M16x1.5 thread to mate with existing toggle or (2) a stainless barrel of the same thread size to connect toggle to existing eye (see photo). Tacoma Screw company tells me I wont find these in the US.... the only other option is a new toggle with eye from Selden.
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Old 21-12-2013, 19:53   #9
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Re: Using Dynema with compression fittings

T ball fitting with bails/eyes are pretty common.

Take a look at the navtec products a bit down the page here . . .

APS - T-Ball Fittings and Plates & J-Hooks
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Old 21-12-2013, 20:03   #10
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Re: Using Dynema with compression fittings

Many thanks! My rigger can order new T toggle with eye from Selden at about $65 each (for the #8, largest one shown in a swage version on the APS site).. Lead time is over a month though, the main reason I was trying to use existing toggles...I will try contacting APS directly to see if they can help. Many thanks!
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Old 21-12-2013, 20:11   #11
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Re: Using Dynema with compression fittings

I think you'll see the Aps ones are much too small, but best of luck! I would contact Navtec and see what they recommend as they originally sold these Kevlar type runners.
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Old 21-12-2013, 20:13   #12
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Re: Using Dynema with compression fittings

Thank You ...good recommendation!
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Old 21-12-2013, 21:24   #13
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Re: Using Dynema with compression fittings

If you want some large metric rigging, theses guys have some stuff. They're in Denmark but they deal with the USA all the time.

You can download their catalog (huge download) and see what they have. Some of their open body turnbuckles go up to M36. Blue Wave Rigging Hardware

Catalog Download>> (be patient) http://flipflashpages.uniflip.com/2/...b/document.pdf
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Old 22-12-2013, 00:00   #14
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Re: Using Dynema with compression fittings

Thank You Sir,

Very helpful!
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Old 22-12-2013, 10:05   #15
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Re: Using Dynema with compression fittings

Quote:
Originally Posted by Farr50PH View Post
Many thanks! My rigger can order new T toggle with eye from Selden at about $65 each (for the #8, largest one shown in a swage version on the APS site).. Lead time is over a month though, the main reason I was trying to use existing toggles...I will try contacting APS directly to see if they can help. Many thanks!
I ordered direct from APS. The T-ball fittings arrived within 10 days.

APS - T-Ball Fittings and Plates & J-Hooks
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