prep a maple burl top for join using only a router...

Discussion in 'Luthier's Corner' started by mistermikev, Apr 19, 2018.


  1. mistermikev

    mistermikev

    Nov 3, 2015
    so, this is a fairly well known trick but I haven't seen too many videos for it so thought I'd document my take. using a router and a fence to cut both pieces using the front and back sides of the bit simultaneously. I'm not comfy with a jointer and don't have one for that reason... if you are like me - this might be a solution for you.



    oh, and before you kick me out... this is for a 32" scale walnut p bass. my first scratch build. might be ready by next winter so... hehe.
     
    Last edited: Apr 19, 2018
    The Ryantist likes this.
  2. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Yep, a router is my preferred method of jointing boards to be glued, especially thin crazy woods. This is my favorite fixture for jointing thin tops. I just used it again about 15 minutes ago to joint a burl top set for Mike Lipe. This fixture has been in almost daily service for at least 10 years.

    img_4724b-jpg.jpg
     
  3. mistermikev

    mistermikev

    Nov 3, 2015
    intersting... that is a method I haven't seen. looks like it'd be good for ensuring the stock is kept very flat. nice.
     
  4. Arie X

    Arie X

    Oct 19, 2015
    nice. you solid body instrument makers have it easy! :)
     
  5. mistermikev

    mistermikev

    Nov 3, 2015
    how does one even join 1/8 or less material? can't imagine how you clamp that up. someday I'd like to build an acoustic... or a 335 or something but we're a long way off from that today. for now... get my first elec under my belt! thanks for the reply!
     
  6. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Edge joining thin boards is generally done with some fixturing, some flat thicker boards to hold the thin wood parts flat and aligned with each other. We often slice and bookmatch and glue up figured wood tops around 1/8" thick.

    In that router jointing fixture that I showed above are the two halves of a buckeye burl top. It was one board about 3/8" thick. I resawed it into two slices slightly over 1/8" thick. Those two slices are clamped together side-by-side in the fixture to rout a good straight edge on both of them. They get edge-glued into a bookmatched top. That top then goes through the drum sander to flatten it out and bring it down to about 3/32". It's very fragile at that point. In some cases we soak the figured top with penetrating epoxy to help hold it together. Then it gets glued onto the top of an electric guitar body, pulled down to follow the contours in a big vacuum bag rig.

    There are some pictures and description of my edge-gluing stack fixture on this thread; Page 3, down at the bottom of the page, posts #57 & #59:

    Inside The Secret Underground Laboratory

    I'm normally using it to glue up tops and backs for my Scroll Bass bodies, which are 0.700" thick, but I've glued boards as thin as 1/8" in this fixture. You can see how it holds the edges of the boards in alignment.
     
  7. mistermikev

    mistermikev

    Nov 3, 2015
    thanks for the info... still mystifying that you can put any pressure pushing together on such a thin top without smashing the edge with the clamp... but apparently it's possible. anywho, cool beans!
     
  8. The other side of this is that it takes a lot less pressure to bring two 1/8" edges together than it does to bring 2" thick edges together. So that helps.
     
    rwkeating likes this.
  9. Arie X

    Arie X

    Oct 19, 2015
    here's a pretty traditional jointing fixture for acoustic guitars and thin boards. LMI seems to have given it some upgrades:

    Plate Joining Jig

    mine's a whole lot simpler. clamping isn't actually the hard part, it's getting the joint "light tight" which takes the time. i do the traditional shooting board thing, making sure both plates are oriented correctly. then i'll fine tune with a scraper and some light burnishing and a bright light to look for gaps -called "candling" it's also used to look for hidden pitch pockets and defects in spruce tops. took me a fair amount of tries to get it right so now i can get tight joints on tops and back within a half hour or so for each set. wax paper is used to keep the plate from getting glued to the fixture and here's a ~trade secret~:
    -don't cover the glue joint with anything while it's trying to dry. run wood stringers on each side a bout a half inch or so away from the joint for clamping. when using PVA glue, the water needs to evaporate quickly from the thin plates. let it set for 24 hours before unclamping and control your room humidity.
     
    Last edited: Apr 20, 2018
  10. mistermikev

    mistermikev

    Nov 3, 2015
    ah, rope. I was thinking bar clamp would just destroy it with any pressure. hehe.
     
  11. Picton

    Picton

    Aug 16, 2017
    Reading, MA
    I’ve had luck using a go-bar deck, which I homemade out of some plywood, threaded rod, and some Fiberglas snow stakes.

    Easy-peasy.
     
  12. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Jun 22, 2021

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