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Broken Finger Joint Repair?

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In gluing up the long hull panels, just to make things extra challenging, I broke off one of the fingers of the finger joints between the #4 and #5 panels, where the gear teeth are for unfolding it, and then lost the missing piece.


I was wondering if anyone has a suggestion for repairing this?  I could cut a replacement wooden finger and then epoxy that into place.  I have some oak that is the right thickness.  Or, I could just fill the whole spot with a sawdust - epoxy mixture.  I could also put just a bit of fiberglass on either or both sides to stiffen it up.


I'm not too worried about it in the long term (since the outside at least will be glassed.)  I'm a little concerned that if the repair is insufficiently strong during the unfolding process, it might knock the patch out when this panel is grinding / flexing against the other panel that it mates to.


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There are multiple correct ways to fix this; I would patch the hole now with a replacement wooden finger:


1.  Using a file, bevel the edges of the panel where you plan to apply the replacement finger for the purposes of increasing the contact area of the applied finger (in effect creating a minature scarf joint).

2.   Bevel the edges of the new finger to roughly match the panel bevels.

3.  Clamp a flat board (temporary gluing reference surface) to the underside of the panel.  Use tape or plastic so the epoxy won't stick to it in the next step.

4.  Epoxy the new finger in place and clamp it to the reference board.

5.  When the epoxy dries, sand everything flush (chances are there will be some misalignment).



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Amos's reply is pretty comprehensive. Looking at the location of the break (they often break on the corners which is less of a big deal as you say) a butt joint repair with a tiny scrap piece i think would be fine. You could put a small piece of glass over it on both sides for peace of mind. Wont matter for the inside and can be sanded completely off on the outside before glassing the hull. 

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