Scarfing and laminating wing spars

Discussion in 'Wood Construction' started by Jeff R, Feb 8, 2007.

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  1. Oct 15, 2010 #21

    davidb

    davidb

    davidb

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    Hmm, ok. That's where I'm looking and the diagrams depict 15:1. The doublers are 10:1. If the inspector is happy, I'm happy.

    Can you post some pics of your scarfing jig? I'm trying to figure out a good way to make one. Thanks.
     
  2. Oct 15, 2010 #22

    flyboy67109

    flyboy67109

    flyboy67109

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    That's referring to the grain deviation. I took it to my local EAA meeting and asked and they agreed that 10:1 was what was wanted and I wasn't just lucky.

    The way I made the scarf joint was I made the jig first from these plans: http://home.comcast.net/~kathymatsu****a/amateurluthier/htmlpages/scarfjigplan.html

    I had to change it a bit to make sure the ratio was 10:1 but I don't remember what it was. I think these plans are a 8:1 ratio so check before you cut the wood to make the jig. I also changed it so the blade didn't cut into the jig as these plans show but right next to it. I thought that was stupid as there was a guide that kept it straight underneath and a risk of the jig kicking if I didn't have the blade adjusted just right.

    Here's my picts:
    After the cut - [​IMG]

    Clamped and glued:
    [​IMG]

    Sanded and done:
    [​IMG]

    This was actually one I did for the rear stinger. I did a test one earlier to see if it would break. I broke outside the joint. I tested this with a 50" long piece of 3/4" by 3/4" cut in half and the glued back together with a scarf joint. I then used a scale to see that it would take 150 lbs. I then got on top of it and started jumping up and down on it (showing off ) and that's when it broke. I hear that if you do the joint right, it is actually stronger then the wood itself. I believe it.
     
    Last edited: Oct 15, 2010
    fly_boy_bc likes this.
  3. Oct 15, 2010 #23

    flyboy67109

    flyboy67109

    flyboy67109

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    The censor tried to clean up what it thought was a dirty word but was actually a Japanese last name. :) Use the bad word for doo doo to replace the stars and it will work.
     
  4. Oct 16, 2010 #24

    davidb

    davidb

    davidb

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    Big thankyou, flyboy! I'll check out that link.
     
    Last edited: Oct 16, 2010

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