modified malahini

Designs for inboard or outboard power

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Bill Edmundson
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Re: modified malahini

Postby Bill Edmundson » Thu Oct 06, 2016 11:37 am

Bryan

Most of the epoxies I've seen say 80 grit is fine.

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hoodman
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Re: modified malahini

Postby hoodman » Thu Oct 06, 2016 12:14 pm

My understanding is that you want to leave some tooth for the epoxy. I wouldn't think you'd want to go above 220.

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Roberta
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Re: modified malahini

Postby Roberta » Thu Oct 06, 2016 12:46 pm

80 grit, 120 max for epoxy coating. I would long board the surface if you are going for a glossy finish. Lots of work, but you will see every dip and doodle in the wood if you don't. Also, some varnishes, like Epifanes, do not like epoxy. Either use a clear Poly-U on epoxy or use filler stains, Pettit sealer, and then varnish.

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DrBryanJ
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Re: modified malahini

Postby DrBryanJ » Fri Oct 07, 2016 4:28 am

So, I'm using 60 now. Do I go through the progression of 80, 100, 120 or can I jump to 120? Then I can stain and epoxy? I do plan on long boarding before staining.
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Building a malahini "Mona Lisa"

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Roberta
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Re: modified malahini

Postby Roberta » Fri Oct 07, 2016 4:39 am

I would longboard 80 and then 120. Then stain. Not sure what stain you are using, but a good idea is to stain a piece of scrap, let it sit for a week to thoroughly dry. then epoxy a piece of glass cloth to the stained area (leaving a tail loose). When cured, try to pull the cloth loose by the tail. This will help identify any adhesion problems with the stain under the epoxy.

Roberta :D
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DrBryanJ
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Re: modified malahini

Postby DrBryanJ » Fri Oct 07, 2016 5:43 am

I am planning on using general finishes. I have to do some test boards for color. I'll apply some fiberglass to test for adhesion, but I know Carl used this without any problems.
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Re: modified malahini

Postby DrBryanJ » Sat Apr 22, 2017 1:14 pm

Question on sanding. I have been long boarding the sides. When I run my hand from stem to stern it feels very smooth, but as I go from chine to sheer I can feel as each board flattens out. Do I keep going to remove this. If I'm sanding with the grain, how do I get this smooth? :?

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Roberta
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Re: modified malahini

Postby Roberta » Sat Apr 22, 2017 2:22 pm

Put the longboard on a 45 degree angle so you are spanning several boards and sand with the grain.

Roberta
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Re: modified malahini

Postby DrBryanJ » Sat Apr 22, 2017 2:40 pm

Thanks Roberta. This was starting to drive me crazy.

Bryan
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Roberta
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Re: modified malahini

Postby Roberta » Sat Apr 22, 2017 2:46 pm

It takes a lot of sanding to get a fair surface.

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BayouBengal
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Re: modified malahini

Postby BayouBengal » Sat Apr 22, 2017 3:23 pm

As Roberta said, "Sand at a 45 degree angle." What I did to fair was use a carpenter's pencil and scribble lines all over the hull. Then take your longboard and sand at a 45. Then sand at at an opposing 45 (90 degrees away from the first 45). Have all your pencil lines disappeared? If so great, you're either fair or very close to fair. If not, continue sanding in this manner at opposing 45 degree angles until you can sand and all the pencil marks disappear. Once the pencil marks have disappeared while sanding in this manner, scribble pencil marks again and now sand with the grain. If all the pencil marks have disappeared while sanding with the grain, hooray!, you're fair. Now just start to sand up through the grits with the grain (no more cross 45 sanding). Once fair, I would put one coat of epoxy on at 120 grit which will raise the grain and seal the wood and then lightly sand it again with 120. From here, it depends on if you're fiberglassing or just epoxy sealing as to what you do next.

One last thing. I'm not sure of the degree of roughness you're feeling when you run your hand from chine to shear, but If you have a fair amount of depth mismatch from one plank to the next such as I had, you're going to need to use a polisher buffer type tool with the sandpaper over a soft foam pad to ensure you don't gouge. Trying to do this from start to finish manually with a long board would kill you. It would take you many days and possibly weeks. With a large polisher buffer you'll have it down to manageable so that you can longboard it out in a few hours. I'd mentioned this in this thread on my 8/1/16 post and the idea comes from Don Danenberg who discusses this in Chapter 13 of his book. Take a look at it if you have the book. If not, I'll see if I can get the info out of my Kindle and over to you.
Last edited by BayouBengal on Sat Apr 22, 2017 3:45 pm, edited 1 time in total.

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Bill Edmundson
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Re: modified malahini

Postby Bill Edmundson » Sat Apr 22, 2017 3:36 pm

:lol: I'm sure glad that I built the Tahoe before the bar got set so high! :)

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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BayouBengal
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Re: modified malahini

Postby BayouBengal » Sat Apr 22, 2017 3:47 pm

Bill, You and your Tahoe is a big part of what raised the bar so high.

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chugalug
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Re: modified malahini

Postby chugalug » Sat Apr 22, 2017 4:55 pm

:D looks good,Bryan :D
Working on regular-sized Bo-Jest


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DrBryanJ
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Sanding Hell!

Postby DrBryanJ » Tue Jul 18, 2017 9:38 am

Just went back to look at my last posts. I didn't realize that I've been sanding since April. :oops: :oops: . I have transom and starboard side done to 120. Still have to finish port side, then I can finally stain. Questions: should I wet the wood to raise the grain and sand one more time?
What is the best way to clean the dust off before staining?

Bryan
Bryan

Building a malahini "Mona Lisa"

My wife said "If I build a boat, she's getting a divorce."


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