Bought a used ARC 21 that came with a 14 foot snapped carbon fiber spin pole. Is it possible to repair this? After cutting out the bad area of the old carbon fiber, could I epoxy a carbon fiber tube (ferrule) inside the fractured tube. Then would it be appropriate to wrap/cover the repair with carbon fiber tape or matt that was expoxied over the repaired area? Any thoughts or recommendations would be greatly appreciated.

--
Scott
ARC 21
Prindle 18
Annapolis, Maryland
--

Sounds like a reasonable approach. I would taper back the existing pole on either side of the break probably at least a foot. You may want to consider using unidirectional tape to build back the tapered zone since most likely unidirectional fiber is what was used in the original construction of the pole. Then do a wrap on the outside with woven cloth.

You can use black electrical tape to compress the fibers and squeeze out excess resin while the repair cures. I've done this before on mast repairs. Use a utility knife to punch some small holes in the tape (while it is still on the roll). Then after you've laid up the repair, spiral wrap the tape around the pole so resin squeezes out and wipe away the excess. After the epoxy cures, peel off the tape and give the pole a wipe with an acetone dampened rag to remove the adhesive residue.

sm

The punched electrical tape technique is an alternative to the vacuum bag technique (you tube it) and almost as effective. But the key is a really tight wrap. This works decently on small repairs but electrical tape tends to stretch on a really large repair.

I have had more success on larger repairs with heavier less stretchy vinyl like 1mm or 2mm graphics tape. For a large repair like you are describing 2 or 3 inch wide graphics tape with a 2mm thickness and a really tight wrap would be a better solution. But you still need the hole punches every inch or so to let the excess resin seep out. You can't wrap too tightly. You will end up with a lighter and stronger repair the tighter you wrap.

Lighter and stronger is always better right?

All that said: the vacuum bag technique is best especially on larger structural repairs..

What does Bill Roberts on the ARC forums recommend? Sorry for the cross reference post Damon, please forgive me.

Fair winds,



Edited by bradinjax on Nov 30, 2016 - 12:16 AM.

buddy of mine breaks and repairs his carbon pole a few times a year (lol)
he uses west system 207 and some unidirectional tape (or cloth).
looks amazing for several months (then fades to yellow around the same time he breaks it again somehow)

Thanks for your responses will try to fix it and will post results and pictures.

--
Scott
ARC 21
Prindle 18
Annapolis, Maryland
--

Hello,

Just my 2 cents here to give you more options and possibly a longer lasting result.

You could also add some external "core" and carbon over that for a stringer effect. This core could be a long thin piece of corecell or divylcell with bevel edges or better yet a carbon tube that would distribute the load further - ($16 on eBay). The big thing is just adding a little extra contour for the carbon to do its job. Note this approach will require some fillet bog to accommodate the curves and while epoxy/micro-balloons would be best an epoxy putty would work fine. In this situation, depending on the size of the void to be filled between carbon pole and stringer edge and I might not even hesitate to use bondo as a minuscule filler since I would be wrapping with carbon/epoxy but if using going this route I would precoat with epoxy (Epoxy is chemical bond, Bondo/Polyester is mechanical bond).

With carbon I have found very little difference with vacuum bagging and really aggressive compression/squeegeeing especially on a very small job such as this. To best accomplish this I do recommend you use peel-ply also known as vacuum bag release film and you can cut this into thin strips and wrap tightly achieving the same result as using electrical tape w/holes (Again see eBay). Another advantage of using peel ply is that it leaves the surface ready for additional epoxy bonding or painting although I always sand and acetone anyway.

Best advice I can give is over prep (sand/acetone) surface and have all materials prepared in advance. It is even a good idea to do a walk through.

James
H17+ but more importantly, 2 refurbished F25Cs.