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Replacing guitar back

Q: Dear Steve,

I have an Epiphone EJ200 I bought with some very bad back damage and I'm wanting to put a laminated maple back on it that I saw in a Stew Mac catalog for $32.90.  I was wanting to know if I have to brace it? 


A: If you are certifiably crazy, and have a lot of time on your hands, go ahead, replace the back. A professional luthier would charge you at least $500 to put on a new back. It is that much work.

The Stew Mac back you are referring to is for an arch top guitar. I don't have a j200 here to measure so you'll have to match their measurements to your guitar. My eye tells me that some arch tops are j200 shaped. If the measurements are close enough, the back should fit. If you order it and it doesn't fit, Stew Mac will take it back, you'll just be out some shipping.

This back is so thick and strong that you do not need to brace it. Guild made a guitar called the D-25. It had exactly this kind of back (except that the outside plys were Mahogany). It made the guitar very heavy but they saved a lot of production costs by not having to cut and fit braces. Fernando Torres built a guitar with a paper machŽ back to demonstrate the importance of the top in sound production. The top is the most important, but there is lots of evidence for the usefulness of a good back. This is not a good back.

Chip off the old back and peel off the old binding. Use a sanding block to cut the gluing surface of the liner strips until there is a perfect fit between the liner strip and the new back. In a perfect world the back should sit in place, held only by gravity, with no gaps showing. In reality you may need to pinch it closed here and there. The idea is that you don't want lots of stress in the plates caused by crushing them together with clamps. The joints should fit and the clamps should just hold them closed.

Be sure that you have enough clamps. Spool clamps are the best thing to use. You can buy them from Stew Mac for a reasonable price, or you can save a couple of bucks by making some yourself. Use the catalogue picture, as a blue print. You will need at least one clamp every two inches. Putting clamps on touching each other is best.

Now you need to trim the excess back and cut the binding rabbet. More Stew Mac things you need: Binding router bits, binding strips, big rubber bands and glue. File the burr off the bottom inside edge of the binding. Dry fit to make sure it fits. Glue on one half at a time, using the big rubber bands to clamp it in place. File and polish off the excess binding.

Now, for finishing the back: You have a urethane finish on that guitar. Nitrocellulose, Shellac, and Oil varnish are made up of solids floating in a solvent. When the solvent evaporates, the solids clump together. At any time in the future you can just add solvent and re-float the solids, making these finishes very repairable. In a can of urethane finish you have particles of epoxy resin and hardener held apart by the solvent. As the solvent evaporates the resin and hardener find each other and make a bullet proof epoxy finish. This process can not be reversed with solvent. You are going to have a witness line where the new and old finish meet. So, choose an unobtrusive meeting spot. The spot where the new binding meets the old side would be my choice.

Any type of finish (except Bulls Eye Shellac) will be fine. Brushing on urethane might be the easiest. I French polish (Freedom polish) or spray nitrocellulose. The new back is going to be lighter than the sides. You can try to add amber stain to the finish, or just give the back a lot of sun. You won't need filler on maple. Stack the finish on, cut it flat with 400 grit sand paper. Put more finish on and flatten it with 600. Then buff. If you sand through, start over again.

If this was my only beloved guitar, I would slop the broken back together with epoxy and wood chips. This is not a valuable collector's item guitar. The cost of virtually any major surgery will exceed its value. Any repair to the old back will be as acoustically sound as this new back. If it's solid from the sides up and has fair action, just making the back not buzz or give you splinters is well enough. If you are looking for a taste of luthierie, I would say, make a Stew Mac guitar kit. It's not a lot more work than you are proposing and when you are done you will have a good, solid wood, guitar to play and you will know a lot about guitar making. Maybe you'll start your next guitar from scratch.

Steve Mason

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