Crawls Backward (When Alarmed)

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Trimming Neck Heel for Guild Neck Reset

When I started on the neck reset, the very first thing I did was to take a measurement on the difference the neck plane was beneath the top of the bridge.

Armed with that measurement (it was .203 inches), I can then calculate the amount of material I need to remove from the bottom of the neck heel in order to tilt it back so that it's aligned, or "set," properly.

The picture above is my sheet of calculations.  This is from Dan Erlewine's repair book.  It's a common formula.

I need to remove about .071 of an inch from the bottom of the heel.  We'll be taking a pie-shaped slice off - wider at the bottom and tapering to zero at the top where the neck meets the body.

The 'crumbs' on the page are small rosewood chips from drilling the steamer access holes.  I plan to glue them onto the top of the fills at the end.

I measured the amount to take off and used low-tack drafting tape as a guideline.  This (obviously) is the heel - you can see how it's wider than a Martin, and you can also see it has a slight radius to it.

With a small-ish (12mm)  chisel, I carefully cut away material.  I start on the inside and work my way outward.

This picture hopefully shows what's being removed - a pie-shaped slice that's wider at the bottom of the heel, tapering to zero at the top.  Visualize the material being removed and you will also picture how this will make the neck tilt backward a small amount, and correct the neck set.

I now have some nice German-made Two Cherries chisels from Diefenbacher Tools.  I honed them super sharp and they easily take the mahogany off the heel.   I'm still on the lookout for some Swedish chisels - they are harder to come by over here.

My method is to remove some material, and then test fit it on the guitar.  As the fit gets closer, and as I get nearer to the tape line, I switch from the chisel to a sanding stick to remove smaller amounts of wood.

The stick is just a paint stirrer with strips of sandpaper attached to either side with low-tack (removable) spray adhesive.  I sanded the stick down so it's more flexible (to follow curves better).  One side has 120 grit paper, and the other has 320.

The last test.  See how the straightedge now sits just on top of the bridge.  When I first measured, the straightedge sat about halfway down the bridge.

Houston, we have success!

Now that the angle is correct, I match the curve of the heel to the body.  This is 180 grit sandpaper.  I taped the body with sign-makers tape to protect it.

Then I hold the neck tightly in place, and pull the paper out.  The heel will take the contour of the body for a nice looking joint.


Post a Comment 2 comments:

  • Andy Stone said...
    February 5, 2013 at 11:00 AM
    Wow! I can't cope with imperial measurements let alone all those maths! (Yes there is an S on the end in English English)
  • Sven Nyström said...
    February 5, 2013 at 3:20 PM
    "...on the lookout for some Swedish chisels"

    I could keep an eye open for you! There are some good new ones from CI Fall, but there are even better old ones to be found. And of course the smaller boutique blacksmiths make good ones too, but I haven't tried any.

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