T-88 is probably a good enough glue.
It is that too much was asked of it.
There just isn't enough glue to wood mass.
Guess it would work better if multiple layers of mahogany were laminated together - say 1/2" thick planks in a stack.
More glue area might minimize or almost stop the wood's ability to move.
Could say that this epoxy has limits as a wood adhesive.
There is also the possibility that too much of the wet of the glue was absorbed into the dry wood. Don't know if this can happen with this kind of glue. Penetrating surfaces would be a plus and increase the bond. No? Providing more tooth by scouring the surfaces on mating pieces might have created too much more surface area for the adhesive.
In gluing large pieces - much like biscuits or dowels are used in panel and table top edge gluing - I could have worked in three or four splines along each glue face by cutting matching 1/4" grooves and adding 1/4" splines that would have increased the glue area and maybe helped to stabilize the large pieces I felt I had to use.
The splines would have to be vertical grained. If the grain of the spline is the same as the work then the relatively thin strips might split. I would have to make up bread-slice pieces with short grain 90 degrees to the work.
An easier substitute are 1/4" 5ply Meranti Aquaply strips. 1/4" Meranti made overseas is often slightly thinner 6mm, thereby giving epoxy some groovin room.
Major pieces that these corner posts are will require they be made over again. BUMMER. I would redo them as described. (See later post.)
As a last harrah, mechanical fastenings could be tried to pin the damned post together. But I know the wood will win and delaminate in Tahiti.
Yet one more desperate idea:
Numerous holes could be drilled into the three pieces from the inside face and a bunch of mahogany dowel pins glued in.*
It's a chancey proposition because the main glue-up now has to be considered a secondary and failing fastening - and the dowel-pin quick fix the primary.
So we'll have to think this through. Wood dowels look good at the moment because the all important lags - that will hold the corners to the cabin - are going to go thru some of them.
(I'm going to try this method.)
A good dunking in penetrating epoxy. (for ME - this sucker is falling apart!)
And 20 coats of varnish.
Have tossed the T-88 because the stuff can't be trusted..... garbage.
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* found honduras m. dowels on the net at Constantine's Wood Center. If they fit tight in the drilled holes I'll use the tan glue and have a saw cut relief the length of each dowel pin so they can be driven in wet all the way.
Constantines has been in business for more than 200 years. How bout that!
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What gets me is that I might have missed an important step - using a new product.
However T-88 is a recognizable adhesive type that I've worked with for decades from one manufacturer in particular, but a few others as well.
What really gets me is that this failure trivializes the effort. It could have been something structurally more important - like a spar, bowsprit, boomkin, window or hatch - that could fall apart at a bad time - without warning.
If the proportion of wood mass to glue area was too much - and the glue-up began moving - then at least the adhesive should have pulled wood off the glued faces. Only the glue is cracking as the wood is moving (the tiniest bit).
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