Bending Acoustic Guitar Sides

Crafting an acoustic guitar is not only about design and acquisition of desired wood.  It's about tools necessary to accomplish the project in a way that is successful.

In my short tenure of building acoustics, I've learned one important thing.  You must either have a full piggy bank and a willingness to part with large quantities of cash, or the ability to create unusual tools necessary for a satisfactory outcome.

One of the tools of the trade is a side bender, which is used to form raw wood into the desired shape for a guitar body.  A heat generating tube is one method, which is used by many luthiers, and another more elaborate device is a side bending machine.  I've built both, but I think the 'machine' will work best for me.



The photo above is of the tube style side bender, which I designed and built several months ago.  As you can see, it's pretty simple , , , a heating element, controlled by a rheostat, heats the copper tube to the desired temperature, and the guitar side wood is hand-shaped around the extended tube.  There is a bit of trial and error involved with this type bender, and the final result can be irregular in shape.

The bending machine on the right is a creation I designed and completed today, which takes the 'guessing' out of bending acoustic guitar sides.

The design of my machine is similar to those used by other guitar builders, but I tried to take the best ideas from other machines and to incorporate them into a unit that would work best for me.  I'll try to explain why I designed it a certain way, and how it works.

It's a four-part creation made up of a base (the brown part), a body form, which sits inside the base, (this particular form is for a dreadnought style guitar), a specially designed retainer, which is located at the end of the screw press rod, is used to form the depression at the waist of the guitar side, and four spring-loaded retainers, which hold the raw guitar side wood securely on the form during the bending process.

Yes, those are light bulbs you see on the surface of the base, which are the heat source for the process.  The inside of the body form is lined with reflective foil, and the top is covered with a sheet of stainless steel.  The waist retainer rides smoothly up and down the slotted openings in the base, because of an embedded steel blade in the retainer.  The other movable retainers (the dowel rods are there to protect my hands from being burned on the heated surface during the alignment process) can be strategically positioned at bend points on the surface of the body form to hold the wood side in place during the heating and cooling process.

I chose light bulbs for the heat source, because a luthier with thirty years experience says it's the least expensive and equally efficient way to conduct heat to bend wood.  Another method is to use a heat blanket, but it's costly and requires more pieces to mess around with.  Due to the dreadnought shape, I chose to use a 100 watt bulb in the upper bout position of the bender; a 75w bulb at the waist; and a 150w bulb for the lower bout (this will equalize the heat in consideration to the distance of the wood from the bulb.  And, the temperature can be further controlled by a light dimmer on the face of the machine.  To further control the process, I added a simple-to-use kitchen timer to the face of the machine as well, to control the 'cook' time.

This photo shows the machine set up and ready to accept  raw side material for bending.

Raw wood material is cut to the desired shape of the side pattern (profiled), and sprayed with distilled water to adequately wet it for bending.

The moist side material is then wrapped in craft paper to retain moisture, and inserted onto the stainless steel bender surface, under another movable stainless sheet.  The waist position is marked on the raw wood so as to center it correctly with the waist retainer (the center mark can be seen through the vertical retainer slide opening).

When the desired temperature is reached, the movable spring-loaded retainers are carefully moved into position shaping the side as they are positioned.

The raw material is left to 'cook' for a specified time, and then it remains in the bender to cool down, before being removed to a body mold for a longer cure time.




Why did I build this contraption, which my wife says looks like something Frankenstein might have used in the lab?  Well, the reasons are not complex.  I could pay someone to bend sides for me ($50 a set), but that seems a little foolish.  If I can build a complete guitar, I should be able to build the tools necessary to complete the job.  And, a finished bender similar to what I just created, for about a hundred bucks, sells for $485-$590 on eBay.  It seemed like a no-brainer to me.  And, besides, I love the process.  I think I may have been a mechanical engineer in a former life.

'Cristine'

Why do we name our guitars, and why do we seem to always choose a woman's name?

I don't know, and I've really not put much thought into it, until now.  Perhaps it's because the guitars look really good.  The shape of the body?  Could be, because the usual hour-glass shape is sleek and kinda sexy. How it sounds?  Ya, especially when she's happy, there's nothing that gets your blood moving like a shapely woman purring like a kitten.  How it feels?  Oh, ya, I don't think this needs an explanation.

'Cristine' seems to fit my latest build pretty well.

She started out rough, but with a little tender care and attention she has turned out quite lovely.

Imagine, if you will, the body being a  rough slab of wood, which was in the first stage of a build.  The pickup cavities and neck pocket had been routed on the front, and the switch and pot opening had also been cut out on the back side, but that was the extent of the work, before, as legend has it, that the owner stopped work because of the onset of Alsheimer's disease.  It laid around in my friend Pat's shop for years, until he thought I should have it.  I'm always a sucker for a vintage project.

I don't know where the old after-market 25.5-inch scale neck came from, but it was the only thing about this basket case that led me to think it could be turned into something worth having.  It has real nice Grover tuning machines, so I was sold the minute I saw it.

The other item that interested me was the vintage Leo Quan 'Badass' wrap-around bridge/saddle.  It's a really cool piece of nostalgia, and no longer available on the market.

After acquiring a three-way switch; a couple single-coil magnetic pickups; volume and tone pots; and an output jack, it was time to commence building.

Pickup surrounds, switch base, and the scratch guard are all handmade from rosewood sheeting left over from the 'Elvira' acoustic build.  On the backside, the cavity covers for the electronics were made from surplus wood sheeting.

The wood body required shaping and sanding to remove imperfections, and then it was ready for sealing, priming and painting.  The rosewood pieces were sealed and clear coated to allow the grain to show, which is a nice contrast to the black body.

Magenta, green, and gold are all secondary colors, which work well together on the black surface, which is pretty stark looking as a stand-alone paint scheme.

I like having 'Cristine' in my life, 'cause she brings everything to the party.

Wanna Really Cool Banjo?

I bumped into a lady the other day who wanted to sell a banjo.

Why do I need a banjo?  I don't play one. I don't know much about them.  I've always thought you had to wear overalls and spit tobacco to own one.

Oh, well, "Let me think about it", I told her.  "I'll call you if I decide to buy it."

I beat feet home to Google the banjo details.  Not a lot of info, but what I did learn led me to make a decision . . . I now own a very rare and old (91 years) House of Stathopoulo Peerless 'Supurb' model 4-string plectrum banjo.  This thing is in immaculate condition for its age.  It even came with the original hardshell case, which is beat up, but that's why the banjo is in such good shape . . . it was well protected.

Take a look, then I'll share some details.

Now, that I've peeked your curiosity I'll share a few details about this little devil.

What little information I could find says that the House of Stathopoulos Company was founded in 1873 by Anastasios Stathopoulos, a maker of fiddles and lutes.  Stathopoulos moved to the Long Island City in Queens, NY in 1903, from what was then Smyrna, Ottoman Empire (now Izmir, Turkey).  Anastasios died in 1915, and his son, Epaminondas (Epi), took over the company.  Just after the end of WWI, the company began to make banjos (the period when this banjo was produced - 1923, and it sold for a whopping $102 - a great amount at the time), and continued until 1928, when the company took the name Epiphone Banjo Company, producing its first guitars (Epiphone, named after 'Epi' Stathopoulos) in 1928. Deaths in the family and a labor dispute in 1951 forced the company to relocate from New York to Philadelphia.  The company was bought in 1957 by its main rival, Gibson.  If you insist on knowing more, Google Epiphone guitars for a rundown.

So, you can see that this banjo is vintage.

OK, now to the good stuff.

It's a long scale banjo with 22 frets, which makes it a 'plectrum', rather than a 'tenor', a reason beyond age for its rarity.  It's in exceptionally good condition.  With the exception of the head, which is a newer replacement and the Grover replacement bridge, everything about the banjo is original.  The neck is straight and all the frets are solid and show very little wear.  The Grover tuners are in perfect condition, as is the adjustable tailpiece and all the other hardware.  All binding is intact with no separation.  The stainless body pieces are original and in fabulous condition.  The wood body shows a little crazing of the finish and surface scratches, but otherwise it is in excellent condition.  Geez, I hope I'm in as good shape when I'm 91 years old.

If you like pickin' and grinnin', it's going on eBay for auction.