I have to glue wooden speaders to a brass plate on my semi-scale schooner. I plan to use epoxy which means I have to get some “tooth” into the brass. What is the best method of doing this? Sandblasting,acid etching,sandpaper? If just sandpaper what grit? Should I acid etch for cleanliness? Am I beind too paranoid?
Thanks
Don
Don Case
Vancouver IslandYes, Yes, No, Maybe and Yes ! [:D]
60 grit sandpaper should be fine, and wipe with acetone to remove body oils from handling. I use WEST and it works fine. Gougeon recommends an acid etch on areas for strength or high loads especially on aluminum which has been anodized. If you know anyone who can sandblast for you - even better. I might suggest a thick paste (silica or similar) to thicken epoxy on the two joined/mating surfaces. Just use a small rounded dowel to fair in the radius of any thick mix that squeezes ot - I usually have a variety of popsicle sticks of varius widths and radii that I use to round fillets around joined surfaces such as where keel trunk meets hull, or rudder log exits the hull. Fairing while the epoxy hasn’t cured eliminates a lot of sanding after it hardens.
Hopefilly this is not a plate to end grain glue joint as this is very weak. Re-engineer or be ready for failure. To rough up the brass use a wire brush at low rpm in a dremel tool, clean with epoxy thinner, wait at least 1 hour for the thinner to evaporate, and glue the wood to the brass. do not touch the brass after cleaning, the oils on your skin will not allow a good bond. Clyde
Thanks guys. I was on the right track.
Don
Don Case
Vancouver Island[:-clown] Hey DON I have a couple of suggestions which you may find useful[:-scared]
PLAN A… If you can remove the brass ring off the mast then you could fit a brass sleeve to each side into which you could glue your wooden spreaders. =II= sort of like this.
PLAN B… Drill through the mast including the brass band and fit a piece of brass or stainless wire through with enough sticking out on either side to fit inside the wooden spreders which you have previously drilled. This would be considerbly stronger than the other methods presented so far. --II-- sort of like this. [:-wiltel]
Good Luck.[8)]
Do it NOW before it`s too late.
Years ago, the chemist for System 3 used to post to the rec.boats.building newsgroup and on one occasion stated that the five minute epoxies adhered better to metal. FWIW.
I would suggest silver soldering a short brass sleeve to the plate using Stay-Brite low temperature solder (available from Micro-Mark) and slipping the spreader into that. Solder the sleeve to an oversize piece of brass and then use it as a reference to cut the plate to size – this will be a lot easier than trying to precisely locate suc a small part. (Don’t raise the bridge, lower the river :-))
Good luck, always great to see another traditional watercraft hit the water.
Cheers,
Earl
I have drawings of the original hounds/spreader mount.It has a metal plate sticking out either side of the mast. The spreaders are attached to that. I wound up with a brass plate about 1/4"x 1" to glue to. I used 30 min. epoxy mixed with wood flour. It seems strong so we will see what happens.
Don
P.S. Earl I have a question for you. I will post it on the Scale Sail list
Don Case
Vancouver Island