Balsa core lamination

[powerabout]

Well if you want to talk ancient history. Did you ever mix asbestos with polly to make putty?????

as an Australian, for sure I did that during my apprenticeship, we mined most of it.
Beware anyone grinding a 70's 80's boat.....
Wet sand is an approved method

[Riverratt]

Another thread where someone asks for help and it turns in to pissin match instead of actually helping the person that asked the question. The boat was built with poly so I would be willing to bet poly would be ok to use for the repair. Keep it simple. I used a hull & deck putty recommend by Mertons to bed my core and followed their recommendations on using poly resin and covering it with 1708 and for some reason it worked. just my $.02.

[powerabout]

A poly repair if the same spec as the original will not be as strong due to the poor secondary bonding.
Something to be aware of
Meaning you need to do a better job than original to have the same result.
Whether that is an issue or not will depend of what safety factor it was built to in the first place.
Sorry not an answer but issues to think about if the boat goes fast enough to hurt you.

[dwilfong]

as an Australian, for sure I did that during my apprenticeship, we mined most of it.
Beware anyone grinding a 70's 80's boat.....
Wet sand is an approved method

Dang we had 3 open pit mines where I grew up in the suburbs of Philly with in a bike ride. One was slap right in the middle of Valley Forge park..................Use to play on the slag piles and throw the clumps at each other. Thy would explode in a big cloud of dust when thy hit you......LOL
Was the best filler you could get.....turn black as coal when mixed in resin. Hard as a rock and you could not break it if you wanted. Also light as a feather......AAAAHHHHH the good old days........................Now that was a filler....................that and the 50% peroxide solution MMMM MMMMM good ****.....................LOL
Better bung hole the drum with some extra copper naphthenate or you will have a burn down for sure.......LOL
The shop was in the old back warehouse of OSCO motors in Hatfield PA. You know the guys that make the marine ex manifolds for ever and ever.


Bin around the block a few times.......

[tunnels]

Another thread where someone asks for help and it turns in to pissin match instead of actually helping the person that asked the question. The boat was built with poly so I would be willing to bet poly would be ok to use for the repair. Keep it simple. I used a hull & deck putty recommend by Mertons to bed my core and followed their recommendations on using poly resin and covering it with 1708 and for some reason it worked. just my $.02.

Yeah im inclined to agree , Of cause poly is ok to repair poly boats !! a good scuff with a 16 grit grinding disc takes care of the bonding issue just make sure you don't under catalyze or over catalyze you resin mixes and mix it well !!
Mixing catalyst into resin is another issue all on its own as well !! yeah yeah yeah but everyone is a expert and has never had a problem BUT you can bet they been pretty close to the odd disaster at some time !

[Riverratt]

Prep work and proper mixtures is the most important part whether you use poly vinylester or epoxy. Just because you top of the line materials does not mean you are guaranteed a top of the line job.

[tunnels]

Prep work and proper mixtures is the most important part whether you use poly vinylester or epoxy. Just because you top of the line materials does not mean you are guaranteed a top of the line job.

Never before has a truer line of words ever been written !

[Gmcviper]

Thanks for all the help. I have a method that is working I'm laying 24" x 18" sections up the sides one at a time. Slow and steady but I will get it done properly.

[tunnels]

Thanks for all the help. I have a method that is working I'm laying 24" x 18" sections up the sides one at a time. Slow and steady but I will get it done properly.

Can you post some photos ???

[Gmcviper]

The dark piece I put in yesterday.

[tunnels]

Well done That's looking pretty good ! keep it up !! are you able to cut a strip of balsa to chamfer the edges ?? A band saw is the ideal thing to use at about a 60 degree angle is possible so you can runn the glass over and down onto the hull !
Need more pictures if possible please !!

[tunnels]

http://www.duracomposites.com/brochures/BalsaCore.pdf check out this site and see the picture of the Foam edge they are using !! make sure its hi-density foam not that soft mushy stuff , Balsa is better and want to be more than a 45 degree angle !, 60 degree easer to lay glass over and looks neat !and works better also , There is a reason for the shallower angle and im still searching for the tests why !

[dwilfong]

You can chop some glass cloth up and mix it with the resin. This will make a thick binder putty that you can lay on the edge of the core.
Works like Tigers Hair in body work.
Gust chop it as fine as you can it will lay down more even.

[tunnels]

http://www.montana.edu/composites/do...z%20Thesis.pdf

Man this article took some finding but makes for some interesting reading the whole 217 pages of it , has pictures also (one picture is worth a 1000 words )the transition is quit important as well s the glassing up and over the transition !, so have a read please !!

[dwilfong]

Here are a few pics of the transition and fillet work on a core.
This is h60 but it will be the same for balsa.
You can use a grinder to do the tappers and then very little fillet needs to be done.
You don't want any sharp transitions or gap for air to build up in as you do the final cover layup.
The better the cloth lays on the core the better the load will spread threw the matrix.
Sand the whole core like you where going to paint it. This makes for a smooth surface to do the lay up on and strait even thickness to the skin on top.
This is and important step as it will reduce the air pockets.
Spend the time on the prep work it will make it go easier when it comes time to do the final layup.
The small details are what make it all work.