Re-setting a Mandolin Neck
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 Italian bowls
  After removal of the top, the neck and heel are removed using heat and/or steam where necessary. It will make a reset much simpler if the top section of the heel can be removed leaving the bottom section in situ. Once removed it needs to be cleaned of old glue and bits of the stringing that often come away with the heel.

   The two diagrams below explain the Italian heel construction, and shimming between the two heel sections to alter the neck angle. Plane a few thin shims to place between the two sections of the heel, allowing varying angles for best fit.

   Here the heel can be clearly seen to be in two sections, after removal and then cleaned.

   The most difficult element in a neck reset, is to calculate how much you need to tilt the neck and head back. When viewed from the side, there are several planes/lines on the mandolin. The most crucial is the line of the top, which, even though it is not there, can be fairly accuratley gauged by the line of the side clasps.

  There are a couple of things to remember before proceeding:

  • The top is domed laterally, so you must allow for this extra height, though remember also, that the string pressure will depress this height a little.... (Its good to have rebuilt the top with its curved struts first, as top domes do vary quite a bit in height, to give you an idea of how much extra to allow for....)
  • The bowl should have been repaired, and its shape verified... (when collapse happens, the bowl is often pushed out sideways, and loses its shape. The correct line of the bowl must be established before the neck can be reset.)

   Assuming you have the lower half of the heel still in place, proceed as follows:

  •  Place the neck/heel in its seating. (I use masking tape around the neck of the bowl, over the heel top, to hold everything in place. It gives a little so adjustments can be made.)
  •  Insert one of several thin wedges between the 2 parts of the heel.
  •  Lay a ruler along the neck (which should be flat!!) and observe where the line of the ruler is over the bowl.
  •  Allow space for the dome, between the ruler and the line of the sides. (The top thickness will be irrelevant because of the dome, and most Italian bowl-tops are almost flush with the sides.)
  •  Change wedges until you are happy with the proposed line of the neck and top. (Be absolutely sure of the seating of the wedge, it must make good contact with both top and bottom sections!!)

   In the final analysis, there is some latitude when you align the neck, as any inconsistencies can be sanded out later, or in the worst cases, even shimmed. The worst thing to do is push the neck back to far, better too little than too much.... always err on the side of caution!

  

   In order to glue up after determining the correct wedge size and angle, you will need some simple jigs. I have used others, but these have evolved as the easiest to make and use.
  • You will need downward pressure between the two parts of the heel. (I would recommend gluing the wedge to the top section first, before gluing the heel back in....)
  • You will need pressure longitudinally, to ensure good contact between the heel and the neck of the bowl.

   Side wedges to enable you to apply press on the sides. Cut to fit the shape of the bowl, (they do vary) and tape on.

   I use one of these, with a wide groove chiselled in its long face to tape to the mandolin back, enabling down pressure to be applied to the heel.

   Neck clamp, also used to clamp fretboards, provides a solid block against which the wedges can be pushed so that they don't slip.

   It also provides a flat surface against which to apply longitudinal pressure to the back of the heel.

Here I am using a straight length of edging wood to judge the new set up of the neck. For ease of use it is taped to the neck..... otherwise you need 4 hands!!

   The back wedge in place, to allow down clamping pressure.

Another jig, this time used to reglue the lower portion of the heel back in place. Can also be used when resetting the heel.  

   Here the heel was still in place, but the sides had been pushed out. I am regluing the heel sides, but it illustrates the set up for a complete heel reset.

Gluing Up

Before final gluing up, make sure everything is double checked for fit, and all cauls and wedges are selected and to hand. A quick check list is as follows....

  • Add a long panel pin to the tail-block, on the centre line, and another just above the nut on the centre line.
  • Run a thin string between the two and use this to keep checking the neck is straight whilst gluing up.
  • Tape on all the wedges and neck block.
  • Apply glue to the heel and to the seating in the neck of the bowl. Allow plenty to fill any small cavities.
  • Insert heel, clamp up, and check for angle and straightness

   Here the heel is being reset with just a back wedge, but it is not as easy to get a good pressure without the neck clamp in place.

  Side view of the same set-up. The tape and elastic was to ensure the bowl stayed true.

    Here I am gluing in an end plate, to improve the structural integrity of the new heel set up, after the glue has set.    In this view, the small wedges that I often use to strengthen the lining-heel joints are visible.