Glass-on Fins - Should I grind away tack resin?

I just put a new sheet of glass on my 6'10" Surfboards Australia restoration, and then I added the two fins I had

shaped to replace the ones I broke off, as I show you here in the pic.  (I have done FCS plugs but this is my first

glass-on fin job so I'm a little walking on eggs here).

 

When I put the fins on, I simply mixed up some tack-resin, and stuck the fins on, using a jig for the left one.  Now

that it's dry, the fins are in position fine, and I can continue glassing the fins, and then hotcoat.  But I was interrupted

and I did NOT finish the fillet part and the sheets of glass over the fins part of the job right away.

But since the fins do NOT lie perfectly flat on my board due to the fact that they are flat and my board has

rocker, some of the tack resin gets under the front and rear of the fin.  So here are my questions:

 

  1. Should I grind away a little tack resin fore and aft just to make the glass rope fit in better or should I just not

worry about the already dry tack resin, and simply glass-rope fillet around the outside of the fin, and then

add the sheets of fin-glass?

 

  1. Would you have hot-coated right away - I won't be hot-coating until I finish the fins today.  I'm not worried about this, I guess

I just did this project a bit too one step at a time.  If I had had more time, I would have done it all at once.

 

  1. Do you ever shape the bottom of the fin to match the rocker or is that unnecessary?

 

So anyway, I'm not really worried that the fins are just gonna fall off or something, just curious if you would take the

extra step and grind some resin away.  I might just skip it.

just go.

if you tacked w/ lam resin ,you are good to proceed.

lets go.do it > next step …

my take is 1'' strip of bias cut cloth ,then saturated rope of anykind,

roving strands real rope mucho strips of bias cut cloth wracked 

assemble coving two more layers of cloth full size 

skreed with heel of yellow plastic sqeegee making matching coves 

delicately purge bubbles with fingertips manipulating bead of resin

and surfing by saturday evening…

…ambrose…

save is the new post

clik save

Thanks, I will take your reminder and put in some 45 degree bias-cut, others have recommended this!

 

So now I need to go shave and get ready for the glass-on fin job that awaits me - just need to save the razor

blade, and put on my big black gloves so I can pinch a little air outta there!

Trim the base of your fins (in the future) to fit the board surface, at the point of attachment. The use of bias cut cloth, to attach a fin, is the only method I've used since 1960.    I've never had a fin crack, or break, since then. (pre leash, board to the beach era)   The only use of glass rope, was for a bead on the fin.     Use only the bias cut cloth to mount the fin.    It's not a very efficient method, for a production setting, but it is the strongest way to attach a fin.   For full size  D  fins, in the 60's, I used 50 to 60 ounces of cloth each side of the fin.   Smaller fins today, would require less.     I always staggered the layers, largest pieces first, down to smallest.    That way, if you hit the cloth when sanding, you only feathered the ends of a cloth layer, and did not cut strands in the body of the layer.   More work, but Mo' Bettah.  

 

Thanks - I have now added some fin roving, 1" bias-cut strips, and 2 layers of cloth each side of the two fins.

 

I found that twisting the roving made it easier to wet out and apply to the base of the fins.  Luckily, most of my

glass patches were already bias cut so it should be stronger, and they are large so if I add another couple layers, I can

stagger them as you suggest.  I like it thick and strong like you - I am a bigger surfer and can use the extra strength.

 

So I just need to razor and add some more layers - I could NOT do this all at once as I did not go quickly enough

with the patches before my resin kicked off (like 12 minute batch - I should have mixed a 20 minute batch), you live

and learn.  I should have had a big board with all the patches just sitting there ready to put on.  It should go better

next round!

 

Thank you.

Here's a guy on Youtube who makes it look pretty simple.

 

http://www.youtube.com/watch?v=TG1LtSpR9JU

 

Notice that he puts some resin on the fin first, then drapes the 4-layered cloth.  This keeps the

top of the cloth stiffer so it doesn't flop over.  Otherwise, one must be careful to cut the cloth only

a tiny bit larger than the fin so it doesn't flop.

Just thought I'd say that I used about 4 oz. (like < 120 mls) of resin and a little styrene to hotcoat my 6'10" board

which is kind of a reverse fish in shape - like 14 1/2" a foot from tail or thereabouts, but like 12 or 13" in the nose.

So one bottom sheet of glass took that amount of topcoat (this includes all 3 glass-on fins) so it would be

somewhat less than 4 oz. if you did not have glass-on fins to coat or if you had a smaller outline (like a performance shape).  So that amount did the bottom, rails, and fins.  I could have gotten away with somewhat less, I had a little left to pour over the tops of the fins so you might want to even try like 3 1/2 oz.

 

I publish this because I hate to have resin left over at the end of a job.  I always want to underresin by a little bit to make

the cleanup easier.  Just my philosophy of resining.  A lonely stitch or two of fiberglass that doesn't get covered during laminating can wait until the glosscoat or another small batch can be mixed.  It wouldn't surprise me if there are others who could do this job with like 3 oz. of resin so take my numbers with a grain of salt - at least you're in the ballpark with my numbers.  Say 3 - 4 oz…  How much hotcoat is needed DOES depend a little on whether or not you missed some spots during laminating, if so, it takes a little more.  I had been a little thin in one or two spots (where there was a bit of glass showing).

So those are my numbers for a pretty floaty 2 5/8" thick 6'10" board that was at one time 2 3/4" thick.  If that drop in thickness is not humorous, I don't know anything funnier, but one thing for sure, it's a perfectly fast board by Surfboards Australia - it might be a Len Dibbens so I'd like to take this moment to thank him for a fun board!  If it wasn't him, then I thank whoever!

But I think it's hilarious that the board is a full 1/8" thinner than when it was new.  Even the area on the stringer has compressed due to age and surfing.  That's why it's so fast - the deck is triangular more than domed.  It sheds!

My long year of shaping fins, learning how to glass them on, fixing the bottom and rails with a new sheet of glass, and the final hotcoat is finissimo!  The styrene shine is on - well, I may have a few minor spots to sand - oh well, not too bad.  It's a shame I did not tint the brown that got into my ding repairs.  Not sure where the brown spots came from other than could it have been the usual water damage - I don't know in this case.  But the board is seaworthy now.

next time use two excercise balls

to support the board

you are fixing…

they will be more tippy.

( sarcasm)

make a repair rack

please,it is painfull 

watching you work on chair seat

and bending over ,

unless you are quite short.

perhaps tape a piece of ABS

2’’ pipe to the chair back

and pad it will make you

a correct work height rack

to minimalize time and materials investment.

If that is why you resorted to using chairs.

…ambrose…

save is the new post

 

I find your post most humorous as I actually have two pairs of shaping racks both of which do quite a nice job.  The one I built ten years ago is even adjustable at either

end.  This makes it great for levelling!  The new pair that I will grab tomorrow to do some magic marker work for my 2nd blank I’ve ever shaped -  is made of solid white

oak - it even has some cool brackets on it.  I went all out.

 

The chairs though is literally “tacky” I must admit.  The sad thing is that when I did my hotcoat, I only put 1% resin by accident.  I can normally nail my catalyst volumes

really precisely since I have these really nice graduated cheap pipettes that I buy from Israel.  I also have glass pipettes from some chemical supply lab. in England.  So

I should be ashamed that I erred on such an easy task as measuring out my catalyst.  I can normally get it almost exactly 12 minutes or so.  So shame on me - I needed

to warm the board in the sun!  But the sun was only there for like 10 minutes so, anyway, it’s cured now.  I’ve surfed the board twice - and it surfs great.  It takes off like

a rocket - it’s just a grom 6’10" board but it has perfect foil and rocker flow and perfect rocker period.  It’s just a teeny bit too wide in the nose for an intermediate or advanced

surfer.  But I had a blast in our East Coast 4 @ 10s swell the other day.  It is SO EASY to catch a wave with this board - it surfs SO smoothly.  It’s so relaxing to surf

this thing so I’m glad I shaped some fins and restored it with a new sheet of glass.  I only have some very minor sanding still to do.  My lack of experience sometimes makes

me rush and I overlook one small detail and I have to come back and fix something.  But this board surfs like a brand new $600.00 board now that it’s fixed.  It must have

had a really nice piece of foam - light as hell but strong.  I must have caught 30 waves and had rides of 20 seconds or more sideways.  I’m totally stoked.

 

But I’ll never mind the criticism - no standard is too high in our business - surfing.  In fact, I think surfing NEEDS high standards as our lives depend on it good solid

fins and boards out in those double-overhead storm waves that are, well, supposed to be here, now that we are into the 6 month of hurricane season.  Now - where

are the double-overhead waves - I guess they are coming.  We need to be as patient as a shaper needs to be when something goes terribly wrong.

 

I’ll post some pics of my white oak stands - they are pretty cool.  I have to fetch them.  But you just gave me an idea - why not convert those chairs into a 3rd

pair of shaping stands!  Little PVC, …

Rather than using resin to stick your fins to the board before you glass them, try using a hot glue gun. You’ll only need a small amount directly under the fin. You only have to hold the fin for as long as it takes for the glue to cool (one or two minutes). I have a jig that I use to hold the fin against at the correct cant. Once the glue has set you’re ready to glass. No tape. No mess. no waiting.

That’s a very small amount for a hot coat, or am I getting confused with what I call a filler coat? I’d use at least 500mm or resin per side. I like to have plenty to sand with.

I reckon this guy should use a lot more cloth and a lot less rovings. Similar to what someone else had posted on this topic I use at least six layers of glass each side. Starting with half an inch wide, an inch wide, two inches wide and so on until the last bit is about seven inches wide. I use a very small amount of rovings right at the base just to get things started. This ends up being about the same weight but a hundred times stronger. I haven’t knocked out a fin for ten years and I surf in one of the rockiest locations imaginable! Also as I mentioned before using resin to glue your fin on is tedious and wastes time. Use hot glue!

Thanks for the idea to use a hot-glue gun.  I don’t yet have one.  I also have not tried the epoxy route, and I did not roughly shape the bottoms of my fins to conform a little

to the surfboard.  We live and learn.  I’ve already banged my newly-glassed fins so many times and they are still solid.  I raked my left-fin with my 7" angle-grinder and I then tried to squeeze the board through a narrow passageway and I kept pushing and pushing which put a huge amount of pressure on the fin - still fine, and ready for this Friday’s storm-test.

 

I decided for the toe and cant to be kind of lazy and make an entire two-by-four so that the exact spacing was ALSO built-in to the repair.  Lazy man’s way!  Most of you more

proish types probably reach into a drawer and pull out a little piece pine that’s about 2" wide and just set it on your board and stick a little tree sap on the other side and your

off to the races.  I just stuck a piece of moulding and a box of nails on the other side.  Kluge-city!  I know it - I need to try harder each time I do a repair and not screw something

up - but at least I only blew the hot-coat this time (1% catalyst) so I am getting better!

 

I’d like to post my fin jig when the server is responding better.

 

Thanks for the idea.

 

I posted this just in case someone was in a pinch for figuring out the volumes for each coat.  My lamination coat took closer to your 500 ml of resin if I remember

correctly, but my hotcoat only took 120 ml.  Maybe I just spread it thinner.  But I think it’s ok to use less for the hotcoat.  Whatever floats our boat. In my case, I blew

the catalyst and I blew the styrene.  I like to put about 3 - 5% styrene and I should put about 1.5 - 2.5 % catalyst (after all, it should be hot). But I only put about

1 - 2% of the styrene and only 1% catalyst (hence my leaving the board in the sun to dry).  So I really botched this process just due to impatience I guess.  But the

board is doing great.  I like 3 - 5 % styrene so I get that really nice “hardened-soap” look and feel so I can sand it real smooth but my board is only like that

in some spots - in other spots, it’s just like ordinary resin.  So I blew this job but not worried - the board is fine.  But I love the feel of pure styrene under my sandpaper.

 

I like your method better than mine (although I did the little strips thing too, I like the strength/weight ratio, important when I used mahogany to shape my

fins)  - I’m a convert!  But a HUNDRED times stronger?  Now where’s a glue gun to be had - Harbor Freight?  By the way, with yours and McDing’s method

of hot glue, I can probably dispense with the clamps and boxes of nails - I can just hold it there for seconds and remove - that’s a huge advantage as I don’t like

having a jig AND a clamp involved.  Just a jig and some hot glue would be better.

Now that I’ve put a new sheet of glass and some fins on my 6’10" board, I took my caliper and measured the thickness at the thickest

point along the stringer - it is now 2 11/16".  It was about 2 5/8" before glassing.  I believe it was only 4 oz. glass that I used but

I honestly don’t remember.  Can someone help me fill in a table of thicknesses - the reason is that I am shaping my 2nd blank now

and I was almost ready to make the stringer max out at 2 11/16", but I now realize that I need to come down at least to 2 5/8" or maybe

even a smidge less.  I have no problems dealing with all of this (even the concave accounted for), but my problem is I don’t know EXACTLY

how thick my glassing will be, so here goes, this is what I need if you know it.

 

Let’s say I glass the bottom with either of the following:

1 4oz. sheet

1 6oz. sheet (this should be 50% thicker than 4oz.)

Above assumes same weave of glass - ie. E vs. S or whichever

And of course, there is the top which will most likely be 1 4oz. and 1 6oz.

So should I pretty much allow for about 1/8"?  Or can we tune this a little better and say, make it

1/16" for the 4 oz. sheet and 3/32" for the 6oz. or am I a little high here?  I just would like better numbers

before I start planing my stringer down to the profile or the padded profile (the one before I do the concave).  Any help

appreciated.  By the way, a guy named zfennell said .008 to .01".  I’m sure my glass-job is thicker than that.

By the way, I can take a caliper and measure the exact thickness of my 6oz. weave and then assume something

for the 4oz. weave.  I just want to get this within like 20% of the right amount so I can predict the final thickness of my

board - it doesn’t matter a  whole lot but it matters some to me.  But are my above estimates way off - if so, please guide

me somehow.  Thanks.

 

PS Guys, I now realize why my numbers are kind of high - I was glassing over an existing piece of hard glass.  So naturally, I’m thicker

since the resin was not sinking into foam but just through the weave and a wee bit into my sanding marks.  Wow, so I might not

have to worry as much as I though and zfennel might be closer to the truth, but any numbers STILL appreciated.  I realize that my final

sanding of the hotcoat will subtract some too.  And gloss, etc…, and the cold-coat.  Perhaps my 500mL of resin for my laminating

coat was a bit high and my resin pooled too much?  I don’t know yet.

Well, I guess I will just start shaping my stringer again.  I apparently don’t need to account much for the glass-job in accounting

for thickness of my board.  Only a wee bit - like 3/100the of an inch or perhaps 3/64" by the time I resin a hotcoat, gloss, etc…

So I guess to net out a 2 11/16" board, I could start down around 2 5/8"+ 1/64", roughly (for 3 sheets 6oz., perhaps even more

for 2 6’s and a 4 or 1 6 and 2 4s.  Easier than I thought.

 

In any case, I COULD just sand my 6’10" board down a bunch until I get close to the weave and then put the caliper on it.  It used

to be like 2 5/8" so it may wind up only a little bit more.  I think that I’ve proven that I went a bit thick on my lamination coat.  Why?

Well, that’s easy - I was resining over a hard surface and it pooled.  Those of you who are squeegeeing the glass with resin over foam

will easily eat up 500 mLs of resin.  In my case, the weave did NOT eat up all that resin and it got thicker.  This is my take on

all this.  So if I don’t need to worry about this.  I wish I had thought of these ideas earlier today.

 

Okay, I exaggerated a bit. Not 100 times stronger. More like only 99.99 times stronger.  :-)

I reckon you’re making all this more complicarted than it needs to be. When I’m shaping a board I don’t really factor in the thickness of the glass at all. It’s pretty thin. It all seems to come out in the wash in the end somehow.