Need advice on how to repair the tail on this twin and the glassed fin crack.
I cut loose shattered bits out at the tail but the bottom of the tail remains damage free , just the top part of the tail. Do I sand the bottom down and make a cone shape with fiber and patch it on? or do I cut the corner glass from the bottom off as well ?
The fin is not loose , but a hair line crack runs to the back in the hot coat.
Any advice is appreciated.
Thank You
Can’t really tell from the pictures what I’m looking at.
Need advice on how to repair the tail on this twin and the glassed fin crack.
Okay, while larger and clearer pictures would help, a lot, lets get you started -
Our story so far:
I cut loose shattered bits out at the tail but the bottom of the tail remains damage free , just the top part of the tail. Do I sand the bottom down and make a cone shape with fiber and patch it on? or do I cut the corner glass from the bottom off as well ?
Bzzzzt- wrong answer. If I’m making sense of the picture, you cut the foam and crunchy glass away flat to the bottom, with a saw, right?
Wrong, you don’t want to do it that way. In the future, ditch the saw and get out the x-acto knife.
Lots of well meaning people do untold damage by ‘cutting away anything broken’ - which loses the shape it was, loses the color it was and gives you this major chunk you need to replace. It’s kinda like stubbing your toe and amputating your foot to fix it.
In the future, take an x-acto knife and use it like a scalpel to pull the crunched glass out to the original position as best you can, then fill ( cabosil/aerosil and resin is best ) behind it, then glass over the whole thing after sanding it a bit. Salvage as much as possible, always. Among other things, the old glass usually has the color and such, which means you can make an almost invisible repair.
For future reference, the less work you do on a repair, the better it generally comes out.
In any event - chuck the saw. Break out the sandpaper. If you can get a wee chunk of compatible foam, stick that on there, shape it with coarse sandpaper, then glass over it. I wouldn’t try to match the color.
If it happens that you’re a reasonably skilled woodworker, I might make a matched set of mini-tail blocks and install them on both swallowtails, as swallowtails are notorious for getting those tail crunches and a tail block arrangement will not only help prevent that in the future but if you do those, chopping off the tail like you did can become an ‘I meant to do that’ kind of thing. It’s always good to look good, y’know?
As for
The fin is not loose , but a hair line crack runs to the back in the hot coat.
The key words here are ‘not loose’. No major work required, so don’t do any major work.
What you want to do first is sand the hotcoat some, and down onto the bottom a bit and up the fin a bit. No more than an inch and a half on either one.
Cut two strips of glass the length of your fin base. One maybe twice the width of the other, same as the width you sanded from up on the fin to where you stopped on the bottom. . With a 1" throwaway brush, brush in a very little resin thinned with a very little acetone. That’ll fill the crack nicely, whatever remains of it.
Then, brush on full strength resin while that thinned stuff is still wet, set the wide strip on that straddling where the fin meets the bottom and kinda baste it with resin. Put on the second strip, brush it with a very little resin so that there’s no air bubbles and the weave of the second layer is saturated but not so much that it’s drooling resin, y’know? Let that dry to a hard gel, cut the cloth even with the leading and trailing edges of the fin.
Let it dry hard. Sand what you’ve done, feather the edges some so it’s nice and smooth. Then, hotcoat it with a fairly fast batch of resin. When that has dried hard, sand and wet sand to the point of ‘good enough’ and there you are.
Hope that’s of use
doc…
Hi Doc,
I would like to thank you for your time with the response to my repair question.
If I'm making sense of the picture, you cut the foam and crunchy glass away flat to the bottom, with a saw, right?Sorry about the small picture , Actually I took a blade to the shattered corner of the tail- no foam is missing! I took the shattered piece off the top and with a blade cut across the damaged edge. Like peeling an apple,looks like a skylight has been removed.
From the bottom you can`t see the damage. The corner foam and bottem glass remains in original form.
I live in Japan and bought a repair kit that included acetone, clear resin, resi cleaner, powder cell , fiber , hardener , sand, paperband tape. THe directions are in Japanese and it is difficult to find specific items to repair as they have different names or the pronunciation is different.
I understand the basic ratio for resin and hardener( the small eye drop size bottle) ,but is hot coat a different resin?
I will try to post better pictures later this week . I don`t mind saying this is my first repair and just want to learn as I have the time and paitence to improve.
thanks to anyone who takes the time to help a rookie.
Ah, now I understand. Okay, good. And, a few things.
First off, the resin in your ding kit is almost certainly sanding resin. That is, polyester resin with a bit of styrene wax in it, that floats to the surface of the resin like soap film on water and allows it to harden completely. Hot coat resin is the same thing, gloss resin is pretty much the same thing.
Powder cell - yep, that’s what you mix with resin to make filler goo. What I referred to as ‘cabosil/aerosil’. For what it’s worth, it can retard the speed that the resin hardens at, but usually you’re putting in the filler fairly thick which makes it harden a lot faster - so go easy on the hardener.
Ahmmm- did they give you any fiberglass cloth with it? A little of that would be very useful, ideally 4 oz weight or 6 oz weight.
So, how I’d tackle it:
Hopefully, you’ve saved or still have the piece you cut off. If so, good. Make a little bit of resin/filler mix, mix in a minimal amount of catalyst/hardener ( and mix it well ) and butter the back of the piece with it and set it in place. Press firmly to get the excess goo out, scrape a little if need be.
If you don’t have the piece, use filler powder and resin mix to bring the ‘skylight hole’ up to the level of the surrounding glass plus a little. Like buttering bread. Then carefully sand to the shape you need once it’s completely hardened. .
In either case, sand it so that there’s a little scuffing all along the surface there, so the new glass cloth will adhere. Don’t use a sanding block, they make for disasters on curved surfaces. 100 grit paper is good for this.
Then, put the new cloth to it over the patch/cutout plus maybe half an inch to an inch all around as I described with the fin repairs, use the chip brush for that, with as little resin as you can. You just want the cloth translucent, ideally the weave texture shows .
a 1" chip brush. Not to be mistaken for a 1" chipfish.
Sand the edges, sand lightly overall, brush on a coat of resin and then sand and wet sand as I described.
That help a little more?
Oh, and as for helping a rookie. I kinda owe it to everybody that helped me when I was a rookie…
doc…
