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Plascore mess up

Posted by Gkarl1967 
Plascore mess up
November 01, 2015 05:49PM
Need some advice or reassurance please. I messed up my key scarfs on the plascore. Each key has a 1/2 inch gap. Will I be ok filling with epoxy peanut butter covered in glass and Kevlar? Or do I need to start over?

Re: Plascore mess up
November 01, 2015 06:07PM
If this is for a bottom panel it's longer than it needs to be. So you could probably fix the joints and still end up longer than you actually need.

I haven't got a bottom panel to measure right now. But after you cut and bend in at the stem area and similarly at the transom the actual bottom panel is only (approximately) 12' feet long. The waste that usually comes out of the corners of the bottom panel are useful (plywood or Plascore) for locker lids, seat tops etc.

A 1/2 inch is no problem. Just fix it first. If you have to lose 8" that's no problem. Losing 16" might be a little dicey. But it's probably OK too.

Re: Plascore mess up
November 01, 2015 07:03PM
Thanks sandy. I'm building Cajuns kingfisher which has a 14' bottom. After taking off 17" for the additional sides and 8" key scarfs I am right at 14' so no leeway. So I am good to go to fill the 1/2" mistakes in the keys with epoxy? Appreciate it.
Re: Plascore mess up
November 01, 2015 09:18PM
Sure. 1/2" isn't much. So you could do it with putty only. You could even cut a half inch sliver of Plascore on the table saw and slide that in there with a bit of putty. Putty isn't supposed to adhere well to the plastic core (of Placore). But it does. Well enough. I'd be careful not to get too much resin or putty on the surface of the Plascore...

You'll be fine. The carpenter's motto--when I was an apprentice in 1968, at local 1066--was "If it don't fit get a bigger hammer."

The boat builder's motto is "If it don't fit mix up some more epoxy putty."

Re: Plascore mess up
November 02, 2015 08:18PM
Just occurred to me how I'd handle this.

Lay the two panels together end to end on a layup table, so they're joined as well as they do. Glass the top side making no attempt to fill any gaps. Let that cure.

Flip the panels over. Get ready for the second layup. Fill the 1/2" gap with putty, perhaps made with chopped up glass and cabosil, as Tungsten suggested. Now make the layup, on top of the wet putty.

Re: Plascore mess up
November 07, 2015 06:41PM
I would re-do the key joints, then trim the bottom, leaving a gap at the transom, and use some of the waste from the edges after cutting out the bottom, and scarf in a piece to fill the gap at the transom.

Jeremy Christensen

Re: Plascore mess up
November 07, 2015 07:15PM
............smart (Jeremy). Is that a coincidence?

Re: Plascore mess up
November 08, 2015 04:01PM
Good question.

I still like the box joints. Dovetails are definitely a waste of time (in my seldom humble opinion :=))

But now we're treading on hunches rather than test data. Plascore is quite bendable. Hardened epoxy putty is strong but brittle. A long straight line (a butt joint between two panels) seems like an invitation to a crack to me--an invitation that would be at least slightly mitigated by staggering the joint left and right with a box joint. But I don't claim to really know.
Re: Plascore mess up
November 14, 2015 03:46AM
I agree with Sandy

Jeremy Christensen
Re: Plascore mess up
November 18, 2015 08:36PM
I did some stress & impact tests with Nidacore vs. Plascore. Two big differences - Nidacore has seams where the material is joined in manufacturing. Plascore is seamless. Plascore also uses smaller cells, which makes it much stiffer, higher density of PP. With the skins on, the nidacore would fail at the seams. 1/4" plascore performed better than 1/2" nidacore, with identical composite layups.

Jeremy Christensen
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