Cerbon fiber spreader bars for bridge
In an attempt to lighten my bridge hammock, I decided to try some carbonfiber speaderbars after seeing what BER had done on his Bridge.
My bridge hammock with bugscreen and everything weighed in at 14.8oz and the 28" and 36" spreader bars weighed in at 9.3oz for a total of 24.1oz.
BER's CF poles were a single rods of CF and weighed in at 4oz. I thought I would try to make some that were segmented and I believe I have accomplished it, although I have not stress tested them yet.
I'll warn you up front this is not an inexpensive project, but if you are a gram weenie or have bad knees or are both like me you may find it worth the cost. Hopefully in the end I will find the weight savings worth the cost of this project.
I purchased 2 CF tubes from http://www.rockwestcomposites.com/ #45166 and #45164. With light sanding #45164 ($28) slides perfectly inside #45166 ($31). I told the company what sizes I wanted each piece to be cut and that I wanted the one tube to act as a ferrel for the second tube and had them sand it to fit. I thought I would have them cut and sand because I wanted them square and to fit great. Cuts were $1/cut and sanding was $10 total. I'll say that their work was excellent, cuts were accurate and the tubes fit perfectly. The kicker which still aggravates me is that on each rod they charge a $12.25 setup fee and then $10.00 handling and $24 shipping for for something that weighed less than 7oz. That sort of thing just rubs me the wrong way.
For my spreader bar tips I am using #4024 0.433" Easton pole tips from questoutfitters.com The 0.625" were too big and these are too small, but I think I can epoxy them in ok to where they will work.
My new bars are 39" and 30". The 39" I segmented into 3 pieces and the 30" bar I segmented into 2 pieces. For the ferrels I cut the smaller bar into 4" length and epoxied 2" into the larger bar, leaving 2" sticking out to slide into the connecter piece. The end result weighed in at 127gm or 4.5oz and they are 5" in total longer than my other spreaderbars made from Easton 0.625 aluminum weighing 9.3oz. This is a very expensive way to lose 4.8oz so It probably isn't really worth it, but I'll keep telling myself that it is.
Attached are a few pics of tubes epoxied together. They slide together nicely and time will tell if they can take my weight in my newest bridge.
Here are a couple of pics of the tip of the spreader bar.
They look great! Let us know how they work.
Awesome Ed! I like the segmented poles. Have you tested them for your weight yet? Did you epoxy the end tips as well? Let's see some pics and measurements of your bridge too.
Edit: so since we both used the same 45166 tubing, I could buy a 45164 tube, cut and sand it and retrofit ferrules....hmmm. Interesting. Good stuff ED!
Last edited by BER; 11-05-2011 at 21:01.
I haven't tested the strength of the segmented tube yet. I am sure the outer tube is strong enough since it holds you up and I am ~175lbs, however, the inner tube concerns me enough that I wouldn't recommend it until I have tested it. I think it would be best to use your current tube size as the ferrel and find a larger tube for the bulk of the spreader bar.
The reason I haven't tested it yet is because I still need to make my new bridge with the 1.15 header ratio. Without the endcaps I can do the bridge in about 6 hours. The endcaps, zipper and bug screen take a lot of time to put together. I know I'll find the ratio ok, because I have altered one of my grizz style bridges and it lays flat enough, but it is too narrow in the middle. I used the 36" and 28" spreader bars and the new carbon fiber bars are 39" and 30". I'll try to start on it after work today, but it will most likely be next weekend before I can tackle it.
The tips of the bars are not epoxied in, but I took a 1" piece ofthe tube I used for the ferrel and epoxied it in the ends where the tips go. Then I took a ~1/2" of one of the 0.433" Easton poles and epoxied it in, so the tip would fit like it did on the Easton pole. The outer section, ferrel material and the small Easton section all fit together perfectly and the weight is negligible.
If my ferrels aren't strong enough, I may use a bit of the 0.433" Easton pole to reinforce the ferrels since it fits perfectly inside the ferrel material. It would probably only take 1.5" per ferrel and shouldn't weigh much, but will lesson the weight advantage even more.
Here is a pic of my 1st bridge and a pic of my 2nd bridge before I put the bug screen on. My 3rd one will be the same just wider and flatter. I'll probably sell my second 2nd orange and black bridge.
I had a chance to test the CF bars and I don't recommend them. I am fairly sure the ferrels wouldn't hold as they were to easy to flex by hand. I ended up cutting a 1" piece of the aluminum 0.433" tubing and epoxying it inside the ferrel. After I did that it was much more stiff and when I tried my hammock both the 39" and 30" bar worked.
I would suggest using a larger set of bars with more strength.
It was worth a try and perhaps BER can take it to the next level.
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