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Thread: Best ways to create a curved trunk lid?

  1. #1
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    Best ways to create a curved trunk lid?

    Everything I've built in my woodshop so far has been straight and square. I'm looking to take on another dimension and try something new by creating a trunk with a curved lid. I thought there would be a lot more tutorials online, but I couldn't find much. Two methods I thought of personally was 1 calculating the angles needed on each board across the top to make the curve. 2, bond a bunch of boards together using t&g, build some curve forms, and slowly bend the panel across the forms.

    The wood I plan to use is oak. The angle method sounds challenging as it would be hard to cut each board to the exact with and angle of the given dimensions.

  2. #2
    > ... but I couldn't find much

    Do a search for "chest with coopered lid" or just "coopered lid". One of the first hits I got is this tutorial: http://www.finewoodworking.com/2009/...ring-a-box-lid

  3. #3
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    The article Warren recommends is a good method. If you want it to look a bit more like an old style chest, I lay up two or more layers of thin planks that can flex to create a compound curved lid. Experiment with scrap timber and see what you can come up with. Cheers
    Every construction obeys the laws of physics. Whether we like or understand the result is of no interest to the universe.

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    I just googled "how to build a coopered lid" and found lots-o-stuff. Here's one:http://www.finewoodworking.com/2009/...ring-a-box-lid

    I find that sometimes I can search in vain until I stumble upon the right term. I couldn't find a string buffer to save my life until I realized it was called a "string buffer"; suddenly, tons of responses to my search.
    "A hen is only an egg's way of making another egg".


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  5. #5
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    I've been working out the mysteries of coopering.My method to get the angles was to make a full scale drawing.Then grab the angles from the drawing.You can even cut test pieces and hold them right up to the drawing and see what's what.
    Its not very high tech but accurate enough for a ordinary woodworker like me and you.
    Aj

  6. #6
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    This Tommy Mac (Rough Cut) episode used coopered legs for a table. While it maybe a larger scale than you need, it provides some insight into jig building to accomplish the glue up. I personally would not trust that I could get enough clamping pressure using tape to put together anything larger than a small box lid.

    forgot the link -- http://tommymac.us/2016/01/episode-0...red-leg-table/
    Brian

    "Any intelligent fool can make things bigger or more complicated...it takes a touch of genius and a lot of courage to move in the opposite direction." - E.F. Schumacher

  7. #7
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    This is the type of box I want to make. The video with the curved legs showed the process the best, and it looks fairly difficult and fairly involved. I may try it, but not sure if I currently have the time or patience. Definitely worth consideration though

  8. #8
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    Michael, this is not a compound curve so will not be as difficult as it seems. The general approach is to machine the boards with a slight (calculated) angle on each long edge and glue them together supported on an appropriately shaped frame. When dry, get stuck into it with a disc sander on an angle grinder and shape it into a curve. Then fit this curved panel to the rest of the chest and job done! Dead easy to write... Cheers

  9. #9
    Michael, how many staves do you expect to use for the top? How deep front to back is the chest? How thick do you want to make the front and back rails of the lid?

  10. #10
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    Quote Originally Posted by Dave Richards View Post
    Michael, how many staves do you expect to use for the top? How deep front to back is the chest? How thick do you want to make the front and back rails of the lid?
    I plan to make the chest about 2 feet deep, and the rails about 2". I haven't gone as far as thinking of the rest of the lid though. The matter that's complicating things for me is that it's so deep. I was reading about using a compass or paint lid as a template, but a wide ark across a 2' span complicates things a bit

  11. #11
    Let me know when you decide how high you want the center of the arc above the front and back edges and how many staves.

    It's not difficult to draw a large arc. You can first find the radius either graphically or by calculation. Then it's a simple matter to make a trammel (a large compass) to swing the arc or there are other ways to strike a circular arc if you don't want to use a trammel.

  12. #12
    This gentleman explains exactly how to do the calculations for the angles on your staves.

    https://m.youtube.com/watch?v=CjQ0CTgQ6E0

    That is the first of two videos -- perfectly clear and easy to follow. (I find it easiest to do some of these calculations in metric. You can translate back to inches at the end if you are more comfortable with them).

  13. #13
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    I'm late to the thread, however, if you are not too far along, I would suggest building your lid first, then make your chest to fit the lid. I have found it much easier to match size of chest to the lid, rather than try to get dimensions of coopered lid dead on.
    There is too much room for deviation cutting the angles and widths of the staves.

  14. #14
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    to add to this I would google, er, ask utube, for vids on steamer trunks

  15. #15
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    Quote Originally Posted by Jim Gallo View Post
    I'm late to the thread, however, if you are not too far along, I would suggest building your lid first, then make your chest to fit the lid. I have found it much easier to match size of chest to the lid, rather than try to get dimensions of coopered lid dead on.
    There is too much room for deviation cutting the angles and widths of the staves.
    This is a proper thinking OUT OF THE BOX suggestion - I love it. I made a curved lid casket in a hurry quite a few years back and my solution was to simply use some tongue and groove boards and allow the curve to form with the slack in the boards. YES, there were some open seams but they were not see through and surprisingly the project turned out very nice. I allowed the seams to be a detail and followed through with other joinery. You can use a board and spline detail to good effect too. Otherwise you are into math and coopering - not all that difficult but certainly more of a process. Build the lid first!
    Last edited by Sam Murdoch; 01-21-2017 at 4:43 PM. Reason: correction
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
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