LMI Help Center

Working with Pre-Bent Sides

Luthier Mercantile’s popular custom side bending service can save you time and help you avoid the risk of breaking an expensive set of side wood! We can bend to one of 8 popular shapes with a Venetian cutaway option for the OM/000 and the Dreadnought shape (so, 10 options total).

We ship the bent sides taped to a make-shift form to help the sides maintain their bent shape, but “spring back” with all bent woods is a fact of life. Bent wood—some species to a greater or lesser degree—will want to ‘relax’ out of its bent shape. Once the guitar box is glued up this is no longer an issue, but getting to that point requires that you take some precautions.

If you are not prepared to work on your pre-bent sides right away, you should be prepared to put them into your mold as soon as you get your LMI package. If you are using the Luthiers Mercantile molds you will find that the ‘spreaders’ apply pressure along most the side’s length. If you not using one of our molds you will need to use a number of clamps (our Klemmsia cam clamps are well-suited to this job) to press the sides into shape inside the mold. You want to store the sides in your mold until you are ready to prepare and glue them to the heel and end blocks.

Our sides ship with only a rough taper and are not cut to the final dimensions. Many customers prefer to have this ‘wiggle room’ to accommodate any slight adjustments to the design of the guitar and because it is customary to nibble away at the sides, carefully bringing them down to their final dimension. One edge of the pre-bent sides will be straight (square to the ends) and the other will be cut approximately ½” or more from size/pattern of the sides as they are shown on the source plan (each bending shape is taken from a particular plan that we sell).  Refer to the plan to gather the width of the sides at several points along the length (heel, waist, butt and a few points in between). Then plot them on the bent sides and connect the dots to create your outline using a chalk pencil.

Next, you will want to trim the sides to length at both ends. Place them in the mold and mark precisely where you want them to join, paying particular attention to the butt joint. This is especially critical if you are not going to install an end graft! You don’t want to see any gaps and it must be perfectly centered.  Make your cuts at the bandsaw (a hand saw will suffice if no bandsaw is available) just proud of the line. Then slowly approach the final length with a sanding block or file.

Once you have the sides prepared in this way, and have glued them to your carefully shaped end and heel blocks, you can use a hand plane to reduce the width of your sides and bring the edge to the outline you have drawn -leaving enough room to sand in the top and back radius using your hollow forms (also called radius dishes).  You will keep the sides snug in the mold the whole time you radius the edge, glue in the kerfing and install the back.

But more on these steps in our blog posts in the coming weeks!