Glue suggestion for paddle

[SUPvol]

I snapped the shaft of my carbon fiber paddle (3/4 the way up) on a trip to CR back in March. I got a new paddle to SUS, but now ready to repair the old one - figured worse case, I could use it when flatwater fishing on my SUP or to give out as a loaner.

So I have cut off the rigged edges of the bottom and top pieces of the old shaft and I have an 6" carbon fiber tube that fits perfectly in the 2 pieces, so the question now, is what glue should I use to put them all together? Thanks and let me know if more information is needed.

[Badger]

Any 10 minute epoxy from the hardware store should do the trick. Just make sure you use plenty to avoid any leaks.

[PonoBill]

Any good epoxy cement will work. Generally, the five-minute kind is quite a bit weaker and more temperature sensitive. You also want to give the joint a couple of wraps with carbon fiber. Glue the joint first and get the handle lined up with the blade. Let the glue set fully so the handle alignment won't be disturbed.

You'll need a little epoxy suitable for board building and some carbon fiber cloth. It's good stuff to have anyway so you can do real ding repairs to your board. Any shop that builds boards will have scrap, or you can buy small quantities on ebay. You COULD use fiberglass for the wrap if you find carbon hard to come by. It will be a bit weaker and you should use a few more wraps of it, but it will work.

The best way to wrap the joint is to get a piece of carbon that will wrap three or four times around the shaft and about two inches longer than your plug. Sand the joint aggressively near the break and lightly for the width of the patch. If you want to be really slick, cut the carbon as a truncated triangle to spread the force and minimize the stress riser effect (though the inside tube will create two pretty major league stress risers). The easy way to do that is to cut a square the size you want, put it on a piece of plastic film, pour on your well-mixed epoxy (I'd use a medium speed for the hardener), and spread it thin with a credit card or similar thin plastic card. Use a little pressure but don't squeegee it dry. Use a razor blade to cut the truncated triangle so the base is full-width and the top is two inches shorter than your plug. So in your case a triangle with a base of eight inches and a top of four inches. Lift it carefully off the plastic and the epoxy will keep the carbon from fraying much. Wearing medical gloves helps a lot. Don't get the epoxy on your skin. Start your wrap with the base (wide end) of the triangle and wrap smoothly so the thin end of the triangle is centered over the break. 
 
Now take an old VCR tape and pull about 40 feet of the mylar tape from it. Tape one end of the mylar to the shaft a few inches above the wrapped carbon. Start winding on the mylar, overlapping each spiral about half it's width, wrapping in the same direction as the carbon was wrapped. Put some tension on the tape as you wrap. Finish wrapping about two inches below the patch and tape the end of the mylar to the shaft. Epoxy will squeeze off the patch as you wrap. That's a good thing.

Once the epoxy has set fully hard (check the waste bits of carbon to see) unwrap the tape and discard. Your patch will be tight, light, and well incorporated to the shaft. It sounds like a lot of work, but it's not, and the joint will be stronger than the original shaft, though the two stress risers to both sides will make the shaft a little weaker.

[SUPvol]

Thanks PB!

[supuk]

Use a good quality epoxy key up all surfaces to be glued and cut all ends at 45deg including the inner tube which you want a good 6-8 inches long. once glued use a peace of a angle aluminum or similar as a jig to line it all up and tape it down. with good quality epoxy and a spliced joint there is no need to do anything on the out side of the shaft. Done many this way and even down near the blade it provides plenty of strength.

[PonoBill]

If you have a snug sliding fit over the length of the plug then it can work without a wrap, but it needs to be as perfect a fit as a ferrule has. Anything less and you need a wrap. If you wrap the break then you can use anything as a plug since it's only there to align the parts and hold them steady--even a wooden dowel will work.

Having seen photos of your work, supuk, I assume your splice is a perfect fit, and as strong as any ferrule in a three piece paddle or a blade attachment (which, after all, works exactly as the kind of repair you describe)--certainly a fine way to go if you have the skills and proper bits. But for a more casual repair and more typical plug fit, a wrap is where the strength comes from.

[starman]

This video was posted awhile back.  I've used it to repair a couple of paddles and so far so good. I did not use the patch kit as I already had the materials.

http://distressedmullet.com/2015/10/28/quickblade-how-to-use-the-composite-patch-kit/

Oh and make sure you use a good respirator when working with carbon.

[Badger]

I saved this thread from last year just in case it happens to me someday.

https://www.standupzone.com/forum/index.php/topic,29128.msg310194.html#msg310194

.

[PonoBill]

That's a pretty slick repair kit. I like the trick of using regular tape, though Mylar works a lot better. If you don't have an old VCR tape sitting around to sacrifice then tape would certainly work OK.

Most paddle shafts are built on a tapered mandrel using a heat-shrink tape winding to compress the carbon onto the mandrel and give good incorporation of the carbon/epoxy matrix. the exceptions are bent shafts or oval shafts which are generally molded with a flexible silicon rubber core which is stretched and shaken out once the molding is complete.

[PonoBill]

I saved this thread from last year just in case it happens to me someday.

Wow, deja vu all over again. I did all that typing for nothing. That was a much more concise explanation of my method. But since I type faster than I think it's not that big a deal.

[supuk]

If you have a snug sliding fit over the length of the plug then it can work without a wrap, but it needs to be as perfect a fit as a ferrule has. Anything less and you need a wrap. If you wrap the break then you can use anything as a plug since it's only there to align the parts and hold them steady--even a wooden dowel will work.

Having seen photos of your work, supuk, I assume your splice is a perfect fit, and as strong as any ferrule in a three piece paddle or a blade attachment (which, after all, works exactly as the kind of repair you describe)--certainly a fine way to go if you have the skills and proper bits. But for a more casual repair and more typical plug fit, a wrap is where the strength comes from.

yes you want a perfect fit but its not hard if you use a peace of angle ali or steel as a jig just cut one side then cut the other as close as you can and use a two sided file or I like to use a thin peace of metal with some 120 stuck ether side to sand the two sides parallel to get a perfect fit then once glued you will find it hard to even see a join.  Next time I get a broken shaft I in I will do a video