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Old 08-02-2010, 22:45   #1
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How to Match a Curve?

Hi All,

I've had to do this several times to build shelves etc. Try to cut a board that will fit nicely against the totally irregular curve of the hull. I need to do it once again, and am wondering if anyone out there has any tips to make this easier.

How do I map the curvature onto a board which I can then cut to shape?

Thanks.
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Old 08-02-2010, 23:04   #2
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scrib it on the board or paper, make paper cut out first.

Dutch
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Old 08-02-2010, 23:14   #3
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This should show you how. Holder 12
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Old 08-02-2010, 23:15   #4
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Get someone to hold the board you are about to cut against the curve of the hull.

Take a block of wood a bit longer than the largest gap between the hull and the board

Run the block along the hull while holding a pencil against the other end - the pencil drawing a line on your board.

cut along the pencil line
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Old 08-02-2010, 23:27   #5
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Depending on how long the curve is, you can use a Profile Gauge
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Old 09-02-2010, 00:28   #6
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Trial and error...

I've found that accurate measurement and oversize cutting followed up by trial and error fitting does a passable job.

For really tricky bits I like to use scrap to make the ends or corners and then screw together a temporary template.

If I really need something to fit well I take the passable piece and use it as a template to do a tight fitting job. It's another reason why I like to work with pine.

Life's too short to do everything perfectly on a big boat.
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Old 10-02-2010, 06:32   #7
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Check out the tick-stick shown Wooden Boat Renovation by Jim Trefethen
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Old 10-02-2010, 06:53   #8
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You can also eye ball it cut the cardboard semi close...then cut a bunch of smaller pieces of thin stuff like poster board (or even paper if your close enough), sliding them over the main piece until they touch the shape then tape them down....one after the other..like a dashed line.....lots of time can be wasted trying to make the template from just one piece....it can be a hundred pieces taped together.
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Old 10-02-2010, 07:23   #9
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How complex is the curve?
Like a lot of these guys are saying you need a template and for complex shapes get 1/8" door skin at Home Depot, rip it into 2" wide strips, cut these strips into lengths short enough to work with individually that you can scribe as sections and while they are in position use hot melt glue to fasten the adjacent pieces together. If the template gets too large or cumbersome make it as 2 or 3 sections that are labeled to reassemble at your work area.
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Old 10-02-2010, 09:57   #10
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I had to repair part of the counter top on Espie, as it had rotted out. The PO had cut away the bad material, and left an odd shape. A parallelogram with one long side curved to match the hull.

I took my carpenters square, and drew a line at 90 deg to the aft bulkhead, and then drew a series of lines parallel to the aft bulkhead spaced 2 inche apart. Then I just measured the offsets at each parallel, recorded them and transferred them to the plywood. Cut it out with the band saw and did a trial fit. Took off a couple of high points with my angle grinder and a sanding disk. I then went along the entire hull side edge and beveled it to fit. Drop in piece fitted perfectly.


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Old 10-02-2010, 10:35   #11
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tick-sticking

Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.
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Old 10-02-2010, 10:36   #12
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I've found the best way to make shelving is to use thin wood strips tacked together with a hot melt glue gun. Scribe the curve as others have said, then remove the one assembly you've glued together and trace to a board.
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Old 10-02-2010, 10:44   #13
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tick-sticking

Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.
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Old 10-02-2010, 10:48   #14
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Quote:
Originally Posted by pwratch View Post
Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.
Its also know as a "joggle stick"
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Old 10-02-2010, 18:42   #15
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Quote:
Originally Posted by Randy View Post
How complex is the curve?
Like a lot of these guys are saying you need a template and for complex shapes get 1/8" door skin at Home Depot, rip it into 2" wide strips, cut these strips into lengths short enough to work with individually that you can scribe as sections and while they are in position use hot melt glue to fasten the adjacent pieces together. If the template gets too large or cumbersome make it as 2 or 3 sections that are labeled to reassemble at your work area.
this is how I have seen it done by professional marine carpenters
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