How much body routing (by hand) to do before putting on the top?

Discussion in 'Luthier's Corner' started by rwkeating, Apr 8, 2018.


  1. Rôckhewer

    Rôckhewer Supporting Member Commercial User

    Feb 28, 2015
    Phoenix, Arizona
    Owner/Builder- RockHewer Custom Guitars LLC
    What a score!
    These little suckers are a joy to use ( if properly sharpened).
    On my last build whilst cutting the truss rod slot... The router I was using...went down...la muerto!
    So I borrowed this to finish the slot that needed an additional 1/4" of depth routed out.
    Took a couple min. max to get the feel of how much to adjust for each pass... then it made QUICK WORK of finishing the slot !! As you can see I was cutting through hard maple and purpleheart. Pulling clean fine shavings. 20180412_110934.png
     
  2. I have been experimenting with two ways of doing it, and I will probably use a mix of both on the next batch.

    First we "pin" the top and back wood together with 4 or 6 brads which we attach on one side and then cut the heads of the brads off, making sure there is a sharp pointy edge. Then we gently push and tap them together to keep the halves in place for band sawing.

    DSC02858.JPG

    Once the bodies are cut out, I like to start with clam shells, top and back, pretty close to equal in width.

    The first way to go is to step rout them using a template like this. The walnut is a 1/16" accent stripe for the mahogany back and maple top:

    DSC02868.JPG

    Eventually you get this:

    DSC02872.JPG

    Top and back step routed:

    DSC02876.JPG

    Then you go after the edges of the step rout with either a hand chisel or a small grinder, smoothing out the inside edges. I bought a small 2" orbital sander that I also use to really get the edges smooth. On the first couple we did a lot of hand chiseling, but discovered later that a small spherical grinder does wonders and speeds things up quite a bit. Eventually you hopefully get this:

    DSC03022.JPG

    If I am going a little thicker with the body I use more of a "picture frame" construction and later glue the top and the back to the frame.

    DSC02954.JPG

    I am playing around with a hybrid version using both concepts together. Will post when I get there....

    So to answer the thread question, I rout until it's smooth and finished - then glue the top on.
     
    Last edited: Apr 12, 2018
    rwkeating likes this.
  3. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    It is amazing how much body wood can be removed and the body still holds up under string tension. My builds are all solid and I still fear one night I'll be woken up by a mighty and thunderous ~~twang~~ as the body and neck colapse under the tension of the strings. Maybe I worry too much? :)
     
  4. Hey RW

    I appreciate your comments. I am probably far too much of a newbie to even speculate on this - but here I go anyways.

    I have always been shooting for tops and backs around 5/8" and yes - I hawg out and waste an awful lot of material. I haven't been able to find a way around it. I wish I could and I think using the frame construction idea will help. On the next round I am going to go further - down to around 1/4" or slightly less. It's a vibration/resonance thing for me. One of my tops got a little thin by accident - turns out it sounds a little more open and natural to my ear - and I like it. Part of that whole trial and error thing I would say.

    But, going thinner could be a problem, we will see. That is why I anchor everything with a pretty substantial rosewood bridge block epoxied way deep into the back/core wood. It really seems to give me that stability that I am looking for - but hey - we will see. "Seems to" and "reality" can be two different things. A few years from now I could have major egg on my face, with warped tops and who knows what - no doubt. That is a big part of the intrigue of building instruments for me. I think I enjoy the risk.
     
    Last edited: Apr 13, 2018
    Jisch and rwkeating like this.
  5. b3e

    b3e

    Sep 5, 2017
    Warsaw, Poland
    That is a great find Bruce, I bet you will have a lot of fun with it. A handy tool to have in the workshop:)
     
  6. 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.

     
    Sep 24, 2021

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