I’m doing a repair on a cracked tail. The board has a 1 in. stringer that I need to splice. I want to use polyurethane wood workers glue (sometimes called Gorilla Glue) because it’s slightly expansive and fills cracks, has excellent bond, is durable in water, and remains slightly flexible.
Does anyone know if there is a compatibility problem.
You’re looking to glue the stringer back together, not make a splint alongside it, right? ‘Cos the splint method is ugly and doesn’t do anything. On the other hand, the glue is at least as strong as the original wood, if the manufacturers’ claims are to be believed.
Gorilla glue will work fine for that, though it’ll be a little yellower when it’s gone off than the plain blank foam. It is polyurethane foam, so you shouldn’t have any compatibility probs with it. It scrapes off nicely if ya have excess that slops out. Don’t use much though, it’ll push things apart as it expands if it’s trapped inside someplace…
Dampen one side of the break with clean water, then spread the GG on the other side with a stiff brush to get it into all the crevices in the break. Jig and wedge and clamp, whatever works, the two pieces together in the correct alignment under pressure with waxed paper between the glued area and the jig so the jig isn’t a permanent addition to the board.
It’s best to have your jig prepared and tested before applying the glue, by the way. And I’ll bet you can visualise the panic party I had on the occasion when I figured out it’s a good idea to have the jig set up first…
hope that’s of use
doc…
Thanks doc,
Actually, splinting alongside is the plan.
It’s my buddies board. It’s a three fin set-up with boxes for each fin. It’s got a 1" stringer down the center and two 3/8" stringers about 10" out. He snapped off the tail on a sand bar. The break is nearly a straight line between the back of the outside fin boxes and the front of the center box. The center fin box broke into pieces and some of the center stringer is missing. Oh yah, a good size piece of glass and foam are missing from the bottom.
His choices are to let me have a crack at it or turn it into yard art. The fin box is the same width as the stringer and since the box sits well down into the board the stringer doesn’t offer much strength though that weak area. Actually, I was a little suprised to see that the side stringers run right through where the side fin boxes are, basically interupting those stringers and making them useless for stregth. Anyway I plan to route out most of the old splintered stringer and splice in a new piece. I’ll leave a little of the wood near the deck for cosmetic reasons. Still the fin box reduces the cross section of the main stringer by about 80%. I plan to parallel the stringer and fin box with 3/8" pieces of wood in a way that crosses the break area. I think at least this will make for a continuous stringer through that area.
That’s where the glue comes in. I have to splice in new wood to replace the shattered parts of the stringer. Polyurethane glue is just that ticket for that situation. Once I’ve got the stringer rebuilt with the splint running into the main board, I can back fill the missing foam and route the hole for the fin box. Then it’s on to the the usual glass repair.
That’s the plan anyway.
Gee, that was kinda lousy fin box placement…
Ok, bear in mind that it’s gonna look like hell and not really contribute a lot to strength.
What I might do instead is stick it back together using Cabosil/resin mix and a jig to keep the rocker correct, replace the busted parts of the stringer ( use a sharp paring chisel slightly narrower than the stringer, not a router - the router will almost certainly wander into the foam) run a handsaw alongside the center stringer, both sides, a little way along from the fin box and then carefully push some cloth folded double down and through those slots beside the stringer with a thin putty knife. Cut the fold, pour a little laminating resin between the pieces of cloth in each slot on the top and bottom and work it up and down in the slot to saturate/wet out the cloth inside the slot - use gloves, it’ll get messy. Your inner piece of cloth gets laminated to the inside on deck and bottom, over the box ( which was masked, so nothing will get into it) and stringer, the outer piece over the foam and existing cloth to the outside ( which, I shoulda mentioned, you sanded lightly first so the new stuff will stick. ) This will give you a nice fiberglass box girder that’ll tie in the stringer, the foam, everything, far better than a coupla weak splints, not show up all that much, look good and work well. While the cloth is still soft-ish, cut it around the fin box slot and remask the slot and cut the edges of the cloth neatly - it’s an appearance thing.
Then, wrap that rascal with a wider band of cloth well forward and aft of the break, maybe two of 'em, one narrower band with a wider band over it. As I get the idea that this is a longboard, I’d use 8 oz cloth for the bands, maybe 6 oz for the stuff in the slots.
A really cheezy illustration which may or may not help:
Now, this is if you think stringer reinforcement is necessary. I’ll add that I don’t think it is, the cloth bands around the board will do the job alone without all that extra work. I have done it that way quite a few times, including the break-at-the-fin-box type of repairs, without doing anything with the stringer and it’s worked just fine. One of 'em, the guy liked the board better after I had fixed it.
hope that’s of use
doc…
Doc you always nail it right on the head.I for one appreciate all the work that you do on these drawings etc.This stuff takes a lot of time and my hat is off to you old buddy.
Aww, hell, man, it’s not a matter of extra work, more like it saves me a whole lot of typing and going off on tangents and confusing the hell out of anybody who reads it. The sketches, on the other hand…well, hopefully somebody’ll see 'em and say Aha! That’s what the old fool means! rather than drawing the wrong conclusion from my tortuous prose.
Besides which, they ain’t very good drawings. Done quick and dirty with Paint, my old Mechanical Drawing instructor must be spinning in his grave…
Thanks for the kind words
doc…
Doc,
I like Cleanlines appreciate the drawing as well as the time you put in. I admit that I had to look at the drawing for a minute to my brain around it but that wasn’t because it was bad, it was because it’s informative.
I think I like your idea of a glass/resin beam running along the stringer and fin box. It won’t be nearly as obvious. I’m still having a little touble with the box girder concept. I my mind, I’m looking at the bottom of the board and see two slots parallel to the stringer that don’t go all the way through. Are you saying that the slots penetrate the board on each side of the stringer?
I do have to rehab the stringer though. That is if I want to keep the look of the wood stringer running to, and past, the fin box. As I said, the fin box is toast, so I’ll have to remove it to put in a new one. I think I can get it done with the router. I know how to make a jig that will control the path. Sort of like a jig you would use to make a mortis for a mortis and tennon joint. I’ll route the exact width of the stringer and fin box. The advantage is that I can make a slot with flat sides and bottom. I’ll probably rais the cut depth for a couple inches at each end so I can make a lap splice with the existing stringer.
To add a little more detail, when the board broke, the pieces didn’t completely separate. On the deck, in the center, a band of glass about 6in. wide stayed connected to the tail. As the tail broke and was pushed around by the water, it ripped that band of glass up the deck about 2 ft. It’s like a strap hold the tail to the main part of the board. Before I start the work described above, I’m going to repair that tear, Cabosil/resin the tail back on and repair the deck and rails with one lam’. That should make the tail stable enough to do the rest of the work.
By the way, my local supplier sells Q-cell instead of Cabosil. It seemed to work okay on my board repair. Any recommendations?
I wish I could post a drawing to help with the concept. How did you do that?
Again. Thank you for the help.
Hi Ryan,
As the old saying goes, aha - answers in no particular order…
Ok, the slots do go all the way through, you use the stringer to guide you along - a handsaw or a saber saw with a not-especially-sharp blade is the ticket there - I’d run 'em maybe 6" forward and aft of the fin box, right across the break. If they just went in a little way, well, you wouldn’t have a very strong reinforcement plus you’re trying to jam something down into a slot. If, on the other hand, you have cloth that’s continuous through the thickness of the board, wrapped over the stringer and over the foam and tied into the skin of the board, then you’ve got something stronger than any stringer and much stronger than any splint reinforcement alongside it. Kinda like ( using ASCII )
][
as a cross sectional view, though in practice you’d run the cloth an inch or two out onto the foam. You might want to use something like a knife or chisel to round or Vee the top and bottom edges of the cuts, so the cloth will conform to the bend a little better.
.
I’m familiar with the router jigs for mortise and tenon joints: if you use lauan or masonite or 1/4" scrap plexiglass cut with a saber saw, a router collar ot a top-piloted bit of the appropriate length you’ll be fine. I’d still suggest a narrow bit though, 1/4" or less. Then you can run it around the dead fin box and possibly pop it out, rather than cutting the whole thing into dust - which I have done and hated and had trouble with. The trick is in securing the jig to the board against the sideways pressures and such that you get - that’s kinda entertaining. And the smaller the diameter of the router bit you use, the less that is an issue . You also get a smaller radius corner on your cut, which makes life easier
Let’s see now - I’d make a jig to hold the two pieces in alignment for rocker , twist and side/side, use a cabosil or q-cell and resin mix to butter the ends pretty heavy and stick 'em back together. Let that mix go off and then, to work. The q-cell is probably preferable to cabosil, though you can get a somewhat stiffer paste with the cabosil. Whenever a board gets busted, some foam is permanently crushed. I use the goo to fill that gap when I stick the stick back together 'cos otherwise you wind up with a kink or tweak in the rocker. If you can run a putty knife over the seam/break to smooth it when it’s in place on the jig you’ll save yourself a lot of work.
Anyways. Now you can remove any loose or completely gone cloth like that loose band running up the deck, though carefully. You’ll wind up inlaying more cloth - I think it’s a better method than trying to stick it back down - I have had a couple of failures with that. You’ll find some small craters where the foam stayed with the cloth - surprise! this is another place to put a dab of Gorilla Glue, to replace the teensy bits of missing foam. It’ll be a little yellower, but acceptable. Far easier to shape and sand than a resin-based filler, behaves about the same as the foam so you don’t have to sand one little bit of hard stuff with lots of soft stuff all around it just waiting to catch a tool edge.
At this point, I would probably take on the stringer repair, just the way you describe. Then, the fin box replacement, bed the fin box in cloth and resin maybe, or maybe do the glass-alongside-the-stringer thing; if you remove the box, rout it a skosh deep, do the slots and the cloth you could perhaps fold cloth over to under where the fin box will go, stick in the box with a little extra resin and save yourself some steps plus reinforce the whole thing nicely. I can sketch that if you like*. You don’t really have top rout the fin box deep, now that I think of it, just set it in to the original depth minus whatever the cloth underneath takes up, say 1/8", that’s fine, you just have to sand it a little more before putting more cloth around the board.
Then, inlay cloth where it’s missing on deck, then wrap the beast ( you can get away with one layer on the bottom, two on the deck) , then hotcoat, sand and gloss and you’re done.
yeah, right, like it’s that easy. Still, it’s a better setup and less work than carving out foam to stick in a couple of pieces of wood, using glue or resin and goo to hopefully hold 'em and going through the same process otherwise.
*- the sketches/drawings: I just whack something together with Windows Paint, save it as a JPG format graphic to save Mike’s bandwidth rather than saving as the rather-large-file-size BMP format Paint uses by default and then use the really cool Upload attachment setup this forum now has. Vastly easier than the old way, which was to do the doodle, upload it to my site via FTP and then stick a link to it in the message. That was kind of a hassle. I think all operating systems have some sort of rudimentary drawing/graphics setup in 'em someplace.
I could draw something by hand and add text and details with a graphics program after scanning it, but after playing with Paint from Windows 1.04 to now I’m comfortable with it. Plus, for me, scanning adds some extra steps I really don’t want to deal with.
Anyhow, I hope that’s of use
doc…
Doc, you’re awsome! Thanks for all the time and good info.
I’m going to try that jpg upload thing some time. I might scan a drawing though because I’m not versed in Paint. I’ll look into drawing with it. What size file do you wind up with when you save the Paint file as a jpg? I want to upload what works well. If I scan I can crank up the res’ and wind up with massive files. I figure if I use your file size as a guide, I’ll be in the right size range. How do you set the image size so it matches the area in the post?
Regarding the repair details, I think I’m pretty clear on everything now. One area where I might deviate from your recommendation is that deck strip. Now don’t cringe. I’ve got my reasons. It’s my buddies board and he likes the look a lot. It’s got bands of color on the deck and the bottom. If I can do a good job with that strip, it will prevent a massive scar. He’s not so concerned about the bottom. The way the strip is torn is remarkably straight. I figured I would go at it much like the way I just fixed some delaminations on one of my boards.
At this point I should probably come clean. I’m a novice at this stuff. Not that I ever indicated otherwise and I am actually handy. My background is just fixing basic dings on my boards over the years. Last year I shaped and glassed a skimboard for my daughter. Last month I repaired several large delams and nose and tail damage on an 11ft. longboard I bought. With the help of people like you, it turned out pretty well. I learned that I kind of like fixing boards. That experience has probably made me overestimate my abilities. And so, I’m thinking I can fix that strip on the deck.
Basically, this is how I think I will do it. Raise the strip and clean any unsound foam or any that prevents the strip from laying flush with the deck. Mask the deck and strip adjacent to each tear. Pour in Q-Cell at about a pancake batter consistency and clamp. After hardened, using a disk sander, grind the joint through the first layer of glass. This grinding will go out a couple of inches on each side of the joint. Inlay glass and resin to fill the ground area. Overlay the whole thing with another layer of glass. Hot coat and feather into deck.
Depending on the jig I come up with I might do it as a first step prior to reattaching the tail, or I might do it in one step. I have really visualized the jig yet.
Am I crazy?
de nada, man…more like I can’t adjust to this daylight savings thing. I’ll apologise for any misspellings and confusion now, 'cos I am a little punchy.
If you scan something, use something like IrfanView to shrink it down ( the Resize/Resample thing) and save it as a .jpg http://www.tucows.com/preview/194967.html - your scanner software may be able to do that too. The image kinda dictates the size it takes up in a post: if you have it at 800x600x14zillion colors then it’s gonna be big, if it’s 200x150 and 256 colors it’s gonna be small. Cropping helps too, you can just use the part of the pic or drawing that’s important and not all of it.
Typically the Paint stuff winds up around 20-30Kb. Bigger than that, I’m more comfortable putting it on line and putting in a link. You can drag the edges of a Paint image one way or another, which is a crop-move to get rid of blank white space that just adds to file size. I am by no means a graphics whiz, I use Paint 'cos I understand it after 10 years plus. Somebody that knew what they were doing could do much better, especially with one of the more full-featured graphics setups.
Ok, what I have done in the past is stick down the deck strip or cut it free and save the glass somehow, but I put lots of cloth over it before I’m done. Best way to save an airbrush design or color. You may want to cut the strip free and hold off on reattaching the strip until you have done everything with the stringer and such.
The method you’re describing sounds okay, though you’ll find that clamping it gets real interesting. After using everything from bricks to clamps to bungees and such I’m getting to where I think that a vaccum bag method would be about the best. As we say in New England, ‘Just for ha-has’ try something with a shop-vac, some plastic sheeting and duct tape around the edges to pull it down without any goo in there and see how smooth it will go. If it looks good or close to good, might be worth buying a little peel-ply and some cotton batting and doing it for real.
Watch out for sanding such a repair, one sand-through and it’s welcome to the land of ugly repairs and filler nightmares and believe me I have been there. I would be more likely to glass over the whole thing once and sand that to get things as smooth as they are gonna get. Use a strip of new cloth that’ll cover the whole area plus 2" on each side plus front and back.
I would most certainly stick the halves together first, before anything else, to get the rocker and such right. What I use for a jig is a plank set on my repair stands, some straps like tie-down straps to secure it and I use wedges and shingles and such to get the heights right. Keeping the rocker correct and not bent is the main thing I aim for, otherwise the board won’t work as a board and it might as well be yard art. Oh, and waxed paper on top of your plank and wedges and such, or else you wind up making a very odd wood-and-fiberglass permanent sculpture for the front yard.
After you stick it back together, that’s the time to attack your stringer and fin box situation. It’s just foam around it then, nothing over it, makes life a lot easier and you can hide more errors. Hiding those little tool slips and such is a Good Thing.
Then have a go at reattaching the strip of glass that was torn loose and that you cut free, then when that’s dealt with you can wrap the broken area in cloth ( two layers on the deck, one on the bottom, with good laps around the rails) to give it the real strength it needs. Do Not expect that just fixing the stringer and beefing it plus fixing the deck will do the job, I’ll tell you for sure that it won’t.
At least, that’s how I’d attack it. Don’t worry about being a ‘novice’ - we all are everytime another board comes in, 'cos every one is banged up different.
Hope that’s of use
doc…