Blocks and Lining
Archtop Repair, Bending, Side Construction, Molds
After what seems like a month of family gatherings and a diet of spinach dip, chips, and meatballs, Woody is happy to be in a new year and glad to get back to the daily routine of building guitars. So, Happy New Year to everyone.
During December Woody Strings took on some unusual repair and re-finish challenges which dominated at least half the month. Christmas chaos filled out most of the second half of the month with a little guitar making thrown in between for sanity sake.
First, the Challenges:
Woody's Gibson archtop that was mentioned the last couple of months moved to front and center during December. The results were not as planned which means that more work is left to be done.
Briefly, I've been trying to replace the pick ups and wiring on this 50-year old Gibson archtop guitar that I've owned for the last 35 years. The challenge has been to replace the pick ups, pots, wiring and switches that were inside the guitar with new pups, pots, wiring and switches that are, of course, outside the guitar. How to get them inside this archtop?
The process is devilishly painful and I won't go into all the details here but it involves surgical tubing, wire fishing and working upside down and backwards in a mirror. Twice I installed all the hardware this way. Both times, after the electrics were installed (everything through the neck pickup slot), the result was a dead short. Finally, I had to cry "uncle". The last alternative was to open up the back. Now, that was painful.
The silver lining is that, from a player's perspective, the instrument is still in tact and future modifications to the electrics can be easily handled through the "trap door" in the back. For now, all of the hardware and wiring will be replaced. All new pup-to-pot-to-switch-to-jack wiring will be installed directly thus shortening the wiring runs and eliminating the need for splicing that was necessary when installing everything through the pick up slot.
In the end, I didn't get what I wanted but got what I needed (thanks Mick and Keith) and, probably should have planned to open the back begin with.
As it would happen, another archtop came into the shop as I was working on the Gibson. This one, an Epiphone, belongs to a client who wanted to have the instrument refinished in clear lacquer. Many of the same issues with removing the wiring and pickups could have been a problem but, instead of replacing them, I only needed to preserve them (inside the hollow body while spraying with lacquer). I do not own this instrument and, therefore, must ensure that everything could be returned to original conditions once the refinishing was complete. All went well.
Back to Guitar Building:
Three sets of guitar sides were bent and two of the guitars-in-the-making received lining and tops. The bending of the sides went smoothly on the LMI bending machine pictured here. The Woody practice is to cut the sides to the proper taper before bending, i.e. the upper bout is more shallow than the lower bout and, thus, the sides must taper from the butt to the heel (neck) block. The taper is not a straight line because the upper and lower bouts are different widths. That's all that I want to say about the geometry of the back at this point. Templates for the cut of the sides are available.
Last month we discussed some of the precautions and care that must be taken with bending on an electrically heated machine. All went well with the bending this time, in part, because the sides being bent are woods (cherry and mahogany) that are very easily bent. One can see that the machine is at 271 degrees. Other woods will require more heat (300F+) to bend cooperatively. At those temps precautions must be taken to avoid scorching the wood.
Once the wood is bent and cooled, it should go directly into the mold as pictured here in a Woody-Strings built dreadnought mold.
The shop only has two of these molds so, when bending more than two sets, improvisation is necessary. The free-form set up pictured below was generated spontaneously out of need and it turned out to be more than adequate. In fact, as one of the guitars being built is a 3/4 size, the sides could not be held in shape in the standard dreadnought mold shown above. The free-form jig pictured is very simply built. It can hold the sides in any shape while they cool and set before lining.
When building an instrument without a mold, which is how I learned to build guitars...(thank you Charles Fox, 1976), symmetry is always a challenge. This free-form set up also allows adjustment to the shape of the sides as they are drying and cooling. One can see that the shape of each side is nearly identical. That's the objective.
Blocks and Linings:
The shape of the guitar, or any acoustic box (mandolins, violins, etc.) is, in part, determined by the blocks. The heel block and the butt block are the first critical components to be glued to the sides. The sides, however, must be held in shape as the blocks are glued in. To do this on a standard dreadnought is straight forward as I have two heavy plywood molds built for this purpose.
As mentioned, I have no mold for the 3/4 size so, once again, improvisation is necessary. The solution was in cutting out the half-silhouette shape from corian counter top material and then flipping it over to make the symmetrical opposite half. The shape of the entire 3/4 was then traced onto 2" thick styrofoam insulation board and carefully cut out with a band saw. Cutting styrofoam is MUCH simpler than cutting and shaping plywood. The result is both an inside and an outside mold of the guitar silhouette. It's not permanent but it's all that is needed to hold the sides in place as the blocks are glued in.
Notice the string line down the center, the symmetry (and the pink panther styro board). One caution, the 2"-thick styro board is not as rigid as a plywood mold and may need reinforcement to stay exactly on template. This quick-rig was only meant to be a one-time thing until I see how I like the mini. I will go back and cover the top and back of the styro with plywood if I am satisfied with the shape of the final instrument.
Next is gluing in the side reinforcement strips. These strips are made from spruce about 0.080" thick and as long as the full width of the side. I use six strips on each side_ evenly spaced between the butt and the heel.
Below also is pictured a standard WJS D with side strips glued in before the kerfed lining is installed. The lining is then installed between the strips. Finally, a small piece of lining (about two kerfs) is glued on top of the side strip, flush with the edge of the guitar. If you look carefully in the photo on the right, you can see that one of the strips already has the lining section glued in over it.
The last picture above shows the guitar sides in the mold with blocks, lining and side strips glued in. The only thing left to do is cover the strip ends with a short piece of lining stock. It's a handy idea to make your lining strips exactly two kerfs wide so that the stock can be easily cut into standard sections to cover the strip ends.
Of course, the purpose of the side strips is to strengthen the side and prevent, or stop, a split when the edge gets banged (as often happens).
Some guitar makers have gone to a form of cloth tape to replace these wooden side strips. Most guitar makers agree that tape saves time in the construction process but is not as strong as wood, nor as effective in keeping a crack from running the entire length of the side.
Making and installing wooden strips is a bit tedious but, it is my belief that, the best sounding instruments are old instruments. This is due, in part, to the aging (drying out) of the resins and oils within the cell structure of the wood itself. (another discussion)
The point is that an instrument needs to live long enough to age and become mellow (like people). So, one of the first objectives in building instruments is to build a strong box that will last. Wooden side strips help.
That's enough for right now. I guess old Woody did get something done in December after all.
In January I should be getting the lining and tops on all five instruments. Once the tops and sides are together, gluing on the backs is relative straight forward. I've already started the January page. Check it out.
Happy New Year to everyone. May the music of your life be sweet and on key. Hope to see you back here next month.
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