Epoxy evening
It is said that one should glue oak as soon as possible after cutting. That is supposedly due to wood oxidation. Anyhow - it was time to move on to the next step: gluing these parts together - apart from the very first, bottom part.
It is always a mess to make such multi-part laminations: not only there is a lot of epoxy involved but all the parts get slippy and start to move when clamps are applied. This is why one should always make the parts over-dimensioned - should anything move it still can be fixed after curing since there is excess material in the lamination.
It was also a moment of truth for my plane jointing skills: if everything is nice and straight there should be less movement.
Well, to put it straight: there is still a lot I need to learn about hand-plaining and making surfaces perfectly matching…
That does not bother me right now since epoxy does not like tight joints anyway - if surfaces are spot-on there will be not enough glue in the joint, leading to joint starvation.
That is not the case tonight as my joinery is on wood-butcher level, still.
The first step was to sand all glued surfaces with 80-grid sandpaper, to give more grip for the glue. Sanding with- and perpendicular to the grain.
Vacuuming was followed with thorough cleaning with acetone.
While wood was evaporating acetone I started mixing epoxy.
For this job I use WEST System G-flex epoxy which was formulated specifically for woods which are difficult to glue. Oak is the king of these woods since it contains a lot of tannic acid - thus characteristic smell.
G-flex is already thickened so after mixing 1:1 (volume) resin and hardener it is ready to go. Tricky with big laminations is that you need a fair amount of glue but you don’t want to mix too much at the same time. First - it is expensive stuff, secondly - if in volume it will start to heat itself and will kick-off pretty quickly. Spreading epoxy over bigger tray slows down this process.
Epoxy applied on each face - and the assembly was ready for clamping. Then the fun begins as all parts start to glide in XYZ directions as there is no friction which would stop them from moving.
Increasing clamp pressure has to be dosed carefully since we don’t want to squeeze out all epoxy from the joints. With my poor joinery skills there was no such danger but still - decent amount of glue is needed for reliable bond.
A good indication of proper wetting is squeezed out glue on each interface. I started cleaning this just after clamping - to have less work later - but that was a mistake since the parts were still moving and this excess glue serves as a reservoir. I had to re-apply epoxy to fill any gaps caused by movement.
After clamps were adjusted and all joints checked for being filled I stayed with the assembly for another half hour - to correct all movements and bring the stack to desired form. After epoxy started to kick-off the movements stopped.
Then I just checked if I haven’t glued all that to my bedroom’s floor and left the thing for the night.
Next steps will be to clean this out, trim to proper thickness (74 mm) and true the top and front surfaces. Then the very bottom part will be adjusted to accommodate keel bolt and glued to the rest of the laminate.
PS Björn just called saying that he started making my new keel bolts. He makes 2 sets so I will have them ready for changing in 15 years from now. Cool!