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Thread: Scarfing question.

  1. #1
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    Default Scarfing question.

    Hello everyone. When scarfing is required, for long plywood sheets, do I scarf the 4' wide sheet first or cut the template out and then scarf? I see a lot of people scarfing already cut pieces but I'm concerned about keeping the alignment straight. Thanks.

  2. #2
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    Mar 2012
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    Houston, Texas USA
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    Default Re: Scarfing question.

    You can do it either way. Dealing with a 4x16' sheet is a pain. I prefer getting the pieces pretty close to the final size then scarfing together. It creates far less waste and is easier to handle. However, if you are dealing with a stich and glue type design...the panel layout staying in good alignment may be much easier to do on the full sheets. It would certainly be easier especially when they have several plank layouts over the 4x16 area. At that point I would do the full sheets myself. It saves a lot of brain wrecking thought. I am speaking for me on that last line. Some guys love straining over those details and they are almost zealots at leaving no waste. I'm not that zealous.
    Scott

  3. #3
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    Default Re: Scarfing question.

    I never saw plans that gave details for cutting out pieces first, for scarfing after. If your plans do give that info, and you understand what they are describing completely, then it might work. Or ask your designer for guidance.

    Myself, I can't imagine getting getting perfect alignment to two pieces cut separately, and keeping that alignment while doing the scarf. Just saying.

  4. #4
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    Default Re: Scarfing question.

    Quote Originally Posted by tom151 View Post
    I never saw plans that gave details for cutting out pieces first, for scarfing after. If your plans do give that info, and you understand what they are describing completely, then it might work. Or ask your designer for guidance.

    Myself, I can't imagine getting getting perfect alignment to two pieces cut separately, and keeping that alignment while doing the scarf. Just saying.
    Precise alignment isn't needed if you rough size the pieces 1/2-1" over the finished plank shape (allowing for the 2+" scarf lap), glue the joint, then lay out the plank shape on the blank. You can save even more material if you swing the pieces to follow the plank curve -- the scarf bevel is the same whether the resulting blank is straight or crooked.

    Cheers. Dan

  5. #5
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    Default Re: Scarfing question.

    Scarfing a full sheet isn't that bad. The glue lines help keep your planing, sanding, whatever straight.

  6. #6
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    Default Re: Scarfing question.

    My Selway Fisher Thames skiff plans suggested cutting the templates first and then scarfing them, however I opted to scarf the full ply sheets and join them first and I found that more beneficial for marking up the templates/planks in complete lengths.
    Larks

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  7. #7
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    Default Re: Scarfing question.

    Quote Originally Posted by Larks View Post
    My Selway Fisher Thames skiff plans suggested cutting the templates first and then scarfing them, however I opted to scarf the full ply sheets and join them first and I found that more beneficial for marking up the templates/planks in complete lengths.
    Usually works best that way for me.

  8. #8
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    Default Re: Scarfing question.

    I'd say it's 6 to 1. I've done it both ways and as long as you have a pattern for the plank and leave some slop either way works. Less waste with doing each plank tho. On Hylan's Beach Pea I did the first 4 out a scarfed sheet but the sheer I had to make separate as I did it in black locust. I did make a template to align the 2 pieces.
    Steve B
    TraditionalSmallCraftAssociation
    DowneastTSCA.org

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    RIVUS 16' Melonseed

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  9. #9

    Default Re: Scarfing question.

    Quote Originally Posted by snaildrake View Post
    Precise alignment isn't needed if you rough size the pieces 1/2-1" over the finished plank shape (allowing for the 2+" scarf lap
    Roger that. I have scarphed together three full sheets of plywood and I have scarphed three 20-inch x 8-foot panels.

    This confusing photo shows the three scarphed full sheets hanging from the ceiling and three scarphed 20-inch panels being hoisted to the ceiling for storage.



  10. #10
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    Default Re: Scarfing question.

    I also am of the scarf the panels first school. It's easier to me for a bunch of reasons.

    To build Leeward, my Chamberlain gunning dory which was 18' LOA, I had to line up 2-1/2 panels to make finished panels of 19-6 - 1/4" ply 12:1 (3") bevel for the scarf.

    It was easiest to hand plane after getting the panels on a firm rack I made clamped in place with 3" steps. Just follow the glue lines. Seems to me much easier on a nice big surface.

    Then it's also easier to glue up because you can jam everything against a nice straight edge, like the shop wall.

    To each their own.

    G'luck

  11. #11
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    Default Re: Scarfing question.

    I roughed out the ply blanks a bit oversized, overlapped them (to represent scarf) , drew a long straight line along the plank, marked which face scarfs were to be cut from, cut scarfs, then when gluing use a straightedge to align. Worked fine on 16 @ 23’ x 2 scarf planks, some had 3 scarfs so I didn’t build in a zipper. Oversized blank then directly marked on boat, cos I could never trust my templates (fat fingers)
    Probably about the same amount of ply wasteage both ways.

  12. #12
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    Default Re: Scarfing question.

    Thanks for all the insight. It is a huge benefit to find people who have been there and done that.

  13. #13
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    Default Re: Scarfing question.

    You can oversize one of the panel pieces more than the other as well, to ensure your alignment.

  14. #14
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    Brasov, Romania
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    Default Re: Scarfing question.

    I am building the Selway Fisher Kingfisher 14 and decided to cut the hull shapes first, than scarf. Don't forget to allow for the length of scarf on one of the planks and make some markings before the scarf to be able to align the 2 pieces while gluing. The oposite planks i clamped over the first pair and glued so that i end up with 2 identical hull planks.
    See some details on my blog here: https://wulkiesgarage.com/2017/10/10...ng-the-planks/

  15. #15
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    Default Re: Scarfing question.

    #4. +1
    Gerard>
    Everett, WA

    RESIST. FIGHT THE POWER.

  16. #16
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    Default Re: Scarfing question.

    Understanding that both methods work ; it is an interesting choice .The material is not cheap ! I built to a traditional design ,keeping the frames and molds of the original and their spacing but converting to glued lap planking .In this case it made sense to me to scarf each plank separately ( two 8 foot pieces and one 10 ft.). The grain of each piece can then be placed tangent to the curve of the section of the pattern where it's placed . This gives the most longitudinal stiffness :closer to but still less stiff than the solid sawn original .My reasoning was it was then most likely to bend fair and in the same way over the molds ( 3 ft. oc ) as the original plank and add longitudinal strength more like the original sawn plank did .Whether this layout in fact made any practical difference I don't know of course. The planks did bend fair . The layout did no harm .

    I don't like the look of rotary peeled ply finished clear ,but if you do I think it looks better with the grain aligned as I describe .I painted mine .
    Last edited by Bill Perkins; 10-18-2017 at 02:12 PM.

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