i remember kokua a while back talking about using q-cell for repairs. ever use it as the filler when putting the two pieces of a broken board together? would this work, or does it expand too much? i’ve got a bunch of milled fibers for filler, but i like the way q-cell sands off next to foam.
allen…i thought about this recently when fixing a broken lost from last hurricane season…but i decided not to use qcell…i just used milled fiberglass…i figured it would be better than qcell…i only use my qcell for reg dings…someone thats tried it may have a better answer…but the milled fiberglass works great… dk
i did one snapped board repair and it came out allright. i took dowells and made evenly spaced holes at the foam. but i had a qcell batch that i just mixed the milled fibers in there, it make it easier to hold it together. then used a seperate batch with no fibers and filled the spots were glass was missing and all. worked pretty well. there probably is better ways out there though.corbin.
I have a jig I put snapped boards into to reset the rocker.It is very basic but it works very well.The board is set up in the jig dry, bottom up with the jig on the bottom of the board.When the rocker is pulled back into the board I tape up the deck and pour a mixture of 75% Q-cell and 25% Aerosil into the break.(I don’t use dowels any more, I worry that if the board was to snap near the dowels, one might get impaled on the dowels).This mixture sands easily and is light. I leave the board in the jig for 24hrs, grind 12 - 18 inches either side of the snap,depending on the size of the board and glass one layer of 4oz on the bias top and bottom.I then fill and fair the area with the same Q-cell / Aerosil mix. Then another layer top and bottom 4oz 0 / 90, hotcoat,sand and paint.This is the method I have been using for about 10 years now.Hope this helps. David.
thanks for the ideas. my method for breaks is to stand the long end up next to something like a shaping rack and tape in place. then i apply my filler mix and set the other piece in place. this allows for a 360 view to make sure the rocker is correct. just have to watch out for drips. anyway, i did this once with some cabosil and pigment and it kicked hot and expanded changing the rocker and forcing me to start over on the repair. just wondered if q-cell, being an expanding filler did the same thing. as for dowels, i put the board together using the above mentioned technique, then cut a 1/4" groove either side of the stringer and put in pieces of klegicel or divinycil high dense foam with a layer of glass and resin. then glass over the foam inserts. very strong and lighter than wood. anyway, thanks again for the input.
Qcel should not be used to “glue” snapped board halves together. Qcel is not absorbed by resin, rather it goes into solution. It expands the volume of the mix by creating space between resin molecules. This makes a lightweight fill but also weakens it. Aerosil is absorbed in resin and so does not increase its’ volume or cause loss of resin strength, but since volume is not increased, it makes a heavier fill. Milled fibers will give an even heavier mix, but the strength and hardness of the mix is great, good for pouring plugs, etc. I like the divinicell battens, I use marine plywood the same way but divinicell might be better yet, I’m a-goin’ to try it.
What Dr Dang says about Q-cell and Aerosil is correct. When gluing a snap back together you don’t need to be relying on what goes into the hole to provide much strength.It needs to be strong enough to hold the boards shape and not fall apart when preparing the board for laminating.If the board is going to break on the join it will snap either side of what ever is there,be it Q-cell or milled fibres. All the strength should be comming from the laminate.The mixture of Q-cell and Aerosil I use is a wet mix, I pour it in,so the resin is going to provide a good bond onto the foam.I would not recomend using Q-cell if it is mixed thick. If you are going for a thick mix go 50/50 or 75/25 the other way, or the milled fibres. David.
yeah david, i used a mix of q-cell and milled fibers. i agree, you just need to hold shape for laminating and reinforcing the stringer. i was just concerned that the q-cell would expand and change my rocker. anyway, worked just fine. thanks for the input.
My method for fixing a busted board is this; First, set up a jig on your shaping/repair rack to hold the two pieces in the right alignment, so that the rocker is right and the two pieces are lined up correctly. You’ll have an open area where the old foam was crushed in, don’t worry about that. Now, set some wax paper or something down, so that the whole thing won’t get gooed together. Mix up a fairly stiff ( thick ), fairly slow ( not much catalyst) cabosil/aerosil and resin mix. Butter both sides of the break fairly heavily. Push 'em together in the jig, scrape off any great amount of excess that oozes out, sand when it’s gone off and give it a band or two of glass completely around the board. I use a narrow (8-12" wide) band with a wider band ( 18-24" ) over it, which seems to hold up pretty well. I use 8 oz or heavier cloth, generally. A word on using dowels: Don’t. Four words on using dowels: Complete Waste of Time. More words on using dowels- First, what kind of strength do they add? Here’s an experiment to let ya think about it. Go to your favorite bar. Order an Irish Coffee, with the whipped cream and all. When it comes, grasp the straws sticking up through the whipped cream and, using all your strength, pull them by brute force through the whipped cream. Order another Irish Coffee - they are good, after all, and with any luck you didn’t drag the last one into your lap. Wasn’t real tough pulling the straws through the whipped cream, was it? If you have a couple of skinny dowels in foam, you really think that they add any strength or are they just floating around in there? Right. Strength added? Nada. Zip. Zero. What adding dowels does do is just about guarantee that you will have screwed up alignment of the two busted pieces. No way can you get the holes drilled just right, as you haven’t got any way to align your drill. Like I said, complete waste of time. doc…
yeah, the dowels “float” in the foam. reinforcement needs to be vertical and glassed or glued into place just like a stringer. i’ve never broken a board at the repair, but i have broken 'em right in front of the edge of the repair.
That’s pretty much it- if there’s a decent amount of glass on there the repair is stronger than the original. What i try to do is feather down the edges of the repair so that there’s not an abrupt transition and a ‘kard edge’ which tends to make the board feel funny and serves as an initiating point for more breaks. I think you’ll find that any ‘stringer replacement’ is unnecessary. They always seem to look cobby, add no real strength and have only psychological value. Plus, if you cut through the existing glass from bottom to deck you weaken it some and compromise board strength.The extra glass you’d add at the repair adds more than enough stiffness in that area. At least, that’s how I do it… doc…
yeah, you may be right, but i feel like no vertical reinforcement at the break is like having no stringer at the break although i’ve had friends that do 'em the same way as you and never had one break at the fix.
If you are putting a couple of layers of glass on each side,with full laps, you are gettting alot of strength back with the extra glass around the rails. But as Doc says you have to feather the edges back when you are glassing.When you cut the glass accross the deck and bottom,cut it with a slight radius don’t leave it straight.This will also help to prevent the board from snapping at the edge of the repair.David.
“When you cut the glass across the deck and bottom,cut it with a slight radius don’t leave it straight.This will also help to prevent the board from snapping at the edge of the repair.” Good idea, David, thanks. That hadn’t occurred to me. doc…