Old Postcard


Bending Ukulele 
& Guitar Sides

Fox Universal Bender - Charles Fox should be greatly commended for his design of the Universal Side Bender (as described in the Luthier's Mercantile Inc. Catalogue). His is a great device. I don't in any way suggest that my changes to the bender result in a superior device; I just tried to make a simpler one. They're ideas which work for me. True to Fox's intentions for the bender, such ideas should simply act as a springboard for others to find their own paths. I further assume that you have the Luthier's Mercantile Catalogue in front of you to act as a basic guide for making the bender, along with all the assorted discussions of it's merits by various users.

Da Bender

  • The first photo on the right shows the side bender in all its muted glory. Once again, no beauty prizes here, but it really works well. The basic elements are the side bender itself and a darkroom timer, the latter picked up at a local garage sale for $1. O.K. , so I spent too much on the timer -- sometimes you just have to go for it, right? Note that the bender sits on a 3/4" plywood sheet which in turn is on two scrap pieces of 2"x4". This higher elevation becomes important later when we're cranking down on the sides. The device looks generally much like Fox's design and it should because it is. But let's look a little closer at several elements I've changed.
  • Inside the bender

    In photo 2 we're looking into the nether regions of the side bender. There are two light bulbs which vary in wattage depending on the size of the bender. For a guitar I might use 75 and 100 watts and for ukuleles perhaps 40 and 60 watts (I've made a bender for every different size instrument I make). We don't want Chernobyl here; just enough heat to warm the heat storage rods and inner sheet to 160-180 degrees Fahrenheit. If it takes a little longer to warm things up that's ok -- it's better to make a device which makes mistakes slowly so that you have time to stop it if you realize you're going in the wrong direction. The bulbs sit in porcelain holders which are wired in parallel and connected to a proper plug. There are semi-circular cut outs on each end to allow the device to breathe a little and to provide a place for the bulbs to stick out a little should that be necessary.
    The underside of the form

    This is not a particularly satisfying photo (#3), but in it goes anyway. It's the underside of the mold and is supposed to show several things: 1) that the inside of the plywood sides are lined with aluminum foil to prevent/reduce scorching; 2) the ends of the solid stainless sheet overlap and are fastened to the bottom edge of the sides; 3) the heat storage rods are let into the upper edge of the mold every 1-2" and made of 1/2" diameter cold, rolled steel - an inexpensive form of cylindrical steel available from the local ironworks. These rods are more easily seen from a side view of the bender a little later on.

    Closer side view Photo 4 shows the mold in place with the side compression device detailed. The two sides of the bender are connected above by a 2"x3" held in place with two drywall screws on each side. The bolt is the longest 5/8" diameter carriage bolt you can find at the hardware store. The bolt is held firmly to the 1"x2" handle with a finishing nail inserted into a hole drilled through handle and bolt. The underside of the 2"x3" has a 5/8" nut friction fit into a hole drilled through the 2"x3". The base of the bolt has another nut again held in place with a finishing nail and having perhaps 1/4" of the bolt sticking out below. The waist bar is made of several pieces of scrap 3/4" plywood glued together and shaped to fit the side contour. A metal washer glued to the waist bar reduces wear from the base nut on the carriage bolt. The peek-a-boo hole on the side allows one to know when sufficient pressure has been applied to the sides.

    Another side and end view Photo 5 is intended to show a number of important features: 1) The ends of the ukulele/guitar sides are compressed laterally during the bending process by a pair of plywood boards using 3/8" threaded rod and wing nuts as the forcing mechanism. Four 1/4" bolts (two on each side of the bender, one at each end) support the threaded rod; 2) The upper metal sheet is perforated. The type of perforated stainless sheet available to me appears to have been used for fruit juice straining; the hole sizes are about 1/2 to 1 mm in diameter. By using the perforated sheet, the sides are bone dry and permanently set in about 15-20 minutes since the perforations allow the water to escape throughout the sheet rather than just out the sides. Each end of the sheet is folded over a very large nail and the fold held in place with pop rivets. A sufficiently large hole is then gradually drilled through the sheet to admit a long, 3/8" eye bolt. 3) Slots in the base of the wooden platform allow the bolt, washer and wing nut to slip in while the 2"x4" base supports now allow enough room to tighten the wing nut on either end of the side bender. What follows now is a brief overview of the bending process. Readers are encouraged to read further discussions of this process in such newsgroups as rec.music.makers.builders.

    The beginning process of bending Photo 6 shows two sets of baritone ukulele sides resting artfully on one of my baritone molds. I bend a pair of sides at a time and generally have little trouble doing so. The side thickness' are about 0.080", a thickness which works for everything from concert size ukuleles to guitars, at least for me. The pair is book-matched with the best matching sides up (later to be out). The pair is held together with masking tape firmly pressed with the back of a fingernail or whatever. Put magic marker line on the "good" side of the tape. The length of the sides is about 2" longer than needed so that some excess is available for trimming. Preparatory to bending I run the pair under the tap, wetting both sides and let the wood drain. Some folks bend them wetter, some drier; your own experience with your wood will end up being your best guide. The timer is also turned on so that the side bender preheats for about 20-25 minutes.

    The bending about to begin... Photo 7 shows the sides in the bender just before the bending process is about to begin. The center seam of the two sides must be parallel to the long axis of the bender, so take a minute to make sure things are lined up at this point; make sure also that the magic marker on the tape denoting the "good" side is up and that your initial marker lineup of the upper perforated sheet and someplace on the bender are also in alignment. This lineup must be done because the upper sheet will shift slightly during the bending process. The length of the upper perforated sheet is about 2" longer than the sides, allowing the ends of the sides to rest against the eye bolts initially. OK. Start bending by cranking down on the waist bar until some resistance is felt and gently but firmly pull down on the two eye bolts for a minute or so.

    The process continues... Photo 8 shows a continuation of the bending process. Continue to crank down 2-3 turns and pull down on the eyebolts alternatively until you can see through the "peek-a-boo" window that the sides are against the form at the waist. At this point you should be able to put the bottom end of each eye bolt with washer and wingnut into the slots as shown in the photo.

    Sides down & cookin'! Photo 9. Now slip the threaded rod/plywood end blocks framework over the top of the bender and allow it to rest on the four bolts on the side of the bender. Tighten the four wing nuts somewhat and then tighten the wing nuts on the eye bolts again. Continue this process until the sides are uniformly against the form and pressed against the ends of the form as well. This whole thing should have taken about 3-5 minutes depending how stiff the sides are. Allow the whole thing to continue heating for another 20 minutes, allowing water to escape through the perforated upper sheet and fill the room with a wonderful aroma. This is now a good time to make sure that the next set of sides is ready to moisten and bend.

    all pau (finished) Photo 10 shows the finished product resting once more on the mold. Note that I became so involved taking pictures that the "good" sides are on the inside! Fortunately these sides were quartersawn with no runout so both sides were the same. It is my intention in all this to suggest that the bending of sides with the bender is a straightforward process once the bender has been made. Comments regarding clarity of text and need for additional explanation of the process or details will be welcomed at my e-mail address on the homepage.

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