Allen Guitarmaker #41 Article 
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Guitarmaker #41 Article 

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Reso-Resplendent
by

Randy Allen, Luthier 
Re-printed from issue #41 Summer 2000 of Guitarmaker Magazine

Resophonic guitars have been gaining in popularity in recent years. Hardly a song goes by that I don’t hear one being played. Resonator guitars have traditionally been made very ruggedly, using ¼” plywood, very heavy bracing and the like. In my ongoing building of these unique instruments, what I have tried to accomplish in them, is to bring the high level of acoustic guitar making to the resonator guitar. I use high-grade solid woods, fine hardware and exotic wood bindings. Upgraded details of delicate purflings and inlays, and elegant hand engraved hardware makes them easy on the eyes as well! After all, once the rough body is built, what’s left but the details!

Some of the imports I have seen and upgraded have even been made with MDF. (Does this stand for musical density fiberboard??) The idea of using MDF products may have some validity if your are thinking of the resonator guitar body as being that of a tuned port speaker cabinet! I saw one of these once made by Hideo Tateno of the NCAL luthiers group; you should have seen the cool sunburst finish! I think one of the fiberboard producers should have bought this and used it as an example of the highest use for their MDF product line!      cont. below..........

  Basic construction designs generally fall under two types. 1.) The traditional resonator was built with a sound-well construction, which is basically a drum-like structure with holes bored into it and was used for structural reinforcement. 2.) One alternative method is sound post construction. The structure is held up by the use of sound posts transferring the load of the top to the back, which is braced to resist the load. This is the method I prefer and my customers have found them to sound very appealing.

  I am using a body shape that is loosely based on a late1920’s model instrument. I don’t use any type of baffle system and I don’t think my instruments need it. They tend to have very good projection and tonal qualities without any baffle. I use high quality woods, typically flamed maple back, sides, & top. Spruce tops offer a little more cutting power in an acoustic situation. Myrtle, Mahogany, Walnut & Rosewood are also available. I do build my guitars with a fairly deep body, certainly deeper than the depth of traditional resonator guitars. I use a bolt on neck, which I feel has a very good mechanical contact to the body.

 

 Another item that I think is a great improvement over instruments of the past is that I use machine-threaded inserts and actually bolt the coverplate into the top. The traditional method is to attach the coverplate with wood screws that usually strip out over time. Many of the imports I have seen come in brand new with stripped out screws! The extra work and expense is more than justified by the added benefit of creating more structural integrity where it is needed. When you make a hole this big in a guitar it will definitely need some strengthening! (Who knows, this instrument may have gotten its’ start by trying to fix that screwed up sound hole rosette purfling!)

  High quality hardware is important on these instruments. Most of the imports have very inadequate hardware. But when you consider that the overseas factories producing these things are probably getting less than $100 a copy to produce them; it makes you wonder how they can do it at all! But hey, that’s another article! American made hardware can run you between $100 - $300 and basically consists of a spun aluminum cone, cast aluminum spider bridge, coverplate, tailpiece and screens.  We have been supplying mandolin tailpieces for a couple years, one in a Monteleone design and another of my design. We have also been working on a new cast tailpiece for the resophonic for quite some time and should have them available very soon. 

 

Randy's drill press swiveled sideways with shop made sanding disk mounted. Randy uses a disk sander with the table removed to level the legs of a spider bridge. (no animals were injured...) Randy's go-bar deck with a resophonic in progress.

The area that the cone rests on in a traditional Dobro is created by the sound well. In sound-post construction it must be provided for in another way. I have been using Baltic birch plywood to create this ledge area and to provide a place for the sound post to be braced from. This is one place that plywood excels From a conversation with Gene Wooten earlier this year I may be doing some experimenting with a new way of building the top. The idea is along the lines of cutting up Banjos to make Resophonics. I know, it sounds too good to be true! I’m joking of course, actually I love the sound of banjos. (Especially going through a band saw at a high rate of feed!)

  Probably like most of you, I have been buying tools pretty much non-stop since I began building instruments. I got completely out of guitar making for several years and was amazed to find I no longer needed any new tools! It seems like from the day I started up building again, I have been back at my old habits of steadily buying tools.  I have a couple of TOOLING ideas that have proven very fruitful that I thought I would leave you with. The first is a large disc sander, 24” that is pretty much off the shelf. I was in a conversation with Roy Noble when this idea sprang up! Thanks for the inspiration Roy!

 

I was looking into motors to build a hollow form sanding machine and was finding the price to be around $180 just for a motor. I found instead, a 32” swing radial drill press floor mount from Grizzly. ($200; less if you get the bench model) I originally wanted this for use with the hollow forms that Roy makes; for sanding the back of acoustic guitars to the proper radius to mate the sides with the backs. The tool worked so well that I thought I would make a flat sanding disc for the resophonics. It is quite a time saver. The disc is basically made from ¾” plywood and a second backer of ¾” ply was added for stability.

  I used a threaded bolt through the center of the disc for a shaft; not very high tech, just quick & easy.  This is one area that could probably be improved upon.  Make sure you get the chuck key good and tight. On my first attempt I had a two-foot disc hit the floor and take off across the shop! Sort of reminiscent of some of those great old cartoons! I’ll have to tell you about the day the router got away sometime!  “Luthiers have the coolest kindling!!”  Another thought is that if you have the bench mount model mounted to the floor.  You could spin the drill press head upside down and lower the work down onto the sanding surface, or even build an auxiliary table around it. (I think I need to order another one! Where’s that wife of mine anyway! And where did she hide that credit card!...) Besides this application, you wind up with a fairly useful 32” radial drill press to boot!

 

left: Our new cast resophonic tailpiece is finally available. This model will work for 6,7 & 8 string instruments including mando-cello and bouzouki. Comes in a variety of jewelry quality finishes. 

right: installing a neck on a new Allen resophonic guitar.

The second is another inexpensive sander I picked up. Getting the legs of a spider bridge level so that it makes good contact with the cone is one of the more important parts of a good set up. Sanding the legs of a spider bridge to mate up with a cone is just one of those pain in the but jobs! It was time consuming and a real chore trying to keep sandpaper flat, while keeping the spider bridge flat, while keeping everything in motion, arghhg!! You know the drill! Anyway with this little 12” sander I just removed the table and all the extra hardware and I can level a spider bridge in less than 3 minutes! It is THE perfect tool for leveling spiders!

  I used to inlay a 3/8” square steel rod in the neck for reinforcement, but also for the extra sustain it lends to the guitar. More recently I have been using two 1/8” x 3/8” graphite rods inlaid and glued in place with epoxy. It seems to me to be every bit as strong as the steel, maybe even stronger.  Here is a little un-scientific test you can try in your shop. Drop a piece of graphite on your table saw and listen to how it rings. Drop an identical size piece of steel stock and compare the two. I believe that graphite has a slight edge acoustically but judge for yourself.

  Finally, if I had to limit myself to building one type of instrument it would be the squareneck resophonic. After many years of building, I have come to derive much joy from building the resophonic, and I’m filled with gratitude that my instruments have been received so well by the playing community.

 

 

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