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Designing a resonator
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Author:  Phil J [ Wed Aug 22, 2018 12:17 pm ]
Post subject:  Designing a resonator

I have been looking for some plans for a resonator guitar without much luck. The only decent plans seem to be the Beard plans. Anyone know of any other plans available out there? I'd love to find CAD plans that I can modify if needed.

A friend of mine wants me to build him a reso, with a body size between a parlour and a 00 with a cutaway. He hasn't decided on biscuit or spider yet, so I know that will change the construction. I doubt plans for a small bodied reso are out there so I'm thinking I may have to start designing from scratch but I thought I'd ask in case anyone was able to help. And if there are any major considerations you recommend in the design process I'm all ears.

Thanks for the help/guidance.

Author:  Freeman [ Wed Aug 22, 2018 10:38 pm ]
Post subject:  Re: Designing a resonator

Phil, I have built one resonator (a tricone and I have CADD/pdf drawings of it) and I own both a spider and biscuit. You kind of build a resonator backwards from a normal acoustic, decide on a cone which will determine your body width (I seriously doubt that you'll fit a 9 inch biscuit or 10 inch spider cone in a 0 or 00 sized guitar). Figure out how you are going to support the cone (ie your cone well). Decide on your scale length and whether you want to compensate it at all (ie. what is your playing style). That will determine the end of the scale and the saddle location. Work back from there, where is the neck to body joint (12th, 14th fret) and from there design your neck.

Based on the playability issues, decide on your fretboard width and radius (most reso's are pretty flat and wide) and the kind of neck joint you want to use (most reso's have a neck stick, I used a bolt on neck on my tricone). Figure out your neck geometry, on most reso's you set the action by working with the neck stick and angle, you have very little adjustment at the bridge). Its a good idea to buy your hardware and make sure its all compatible, then take actual measurements to design cone well, neck angle, etc.

I can help with all of this but you do need to make those decisions that you mentioned. Here is my little family


and the guts of the tricone (a biscuit or spider will have a cone well that is both similar and different, I have pictures)


Author:  Freeman [ Wed Aug 22, 2018 10:43 pm ]
Post subject:  Re: Designing a resonator

Oh, I'll add one more thought. If you build to fit an available case you will save one ton of money buying a custom one. Ask how I know


Author:  Phil J [ Thu Aug 30, 2018 12:04 pm ]
Post subject:  Re: Designing a resonator

That tricone is beautiful!!! Thanks for the input. Looks like we need to hammer out all the details before really sitting down and designing the thing. My friend originally got the idea from seeing some parlor size resos on Republic Guitars or some Chinese manufacturer. They must be using a smaller cone and cover. From what I've found there aren't many places to find reso parts other than Stewmac or Beard. If you have any other suppliers in mind please let me know. I'll be back around the forum once I get more info together.

Author:  Freeman [ Thu Aug 30, 2018 3:11 pm ]
Post subject:  Re: Designing a resonator

In my humble, the starting place for your customer is to decide which kind of cone configuration he wants. Spiders and biscuits have entirely different sound. As far as I know, spiders only come in 10-1/2 inch diameter. Biscuit bridge cones are usually 9-1/2 or so in diameter but over the years they have been made smaller to fit other instruments. Very common is to use the 6 inch cones from a tri cone in instruments like ukeleles and mandolines.

Again, in my humble, the best cone are the Beards and Continentals for spiders and National Resophonics for biscuits. The most common upgrade for PacRim guitars is to put a domestic spun cone in them - at one time that was what Republic did (imported inexpensive Asian bodies and assemble them with US cones). At the same time you are looking at cones, its a good idea to spec all the other hardware - I've got a PM from a guy who can't get his tri cone cones to fit a tee bridge that he bought somewhere else.

Once you've selected cones (and scale length) everything else kind of falls in line. Here are pictures of the insides of my old spider and my metal bodied biscuit - you will need to figure out a wooden cone well but that shouldn't be too difficult





Author:  Ruby50 [ Fri Aug 31, 2018 10:30 am ]
Post subject:  Re: Designing a resonator

Listen to Freeman as he does a great job building and also a great job in expressing himself. He helped me a lot in building a resonator. I built mine with a wood body, 12 frets, a biscuit bridge, and removable grills in the upper bout area so I could use a bolt on neck and truss rod with the nut at the body instead of in the head. I sprung for a new Beard cone, but found an NOS Tacoma cover on ebay. From the picture below you can see how much spare room there is with the 9-1/2" cone installed.

My daughter plays a 1937 National Duolian and it is a size I like, so I got a close set of plans from Resophonic Outfitters out of Hagerstown MD, 301-733-8271, and the plans are labeled "round neck metal body resonator guitar". It is 13-3/4" at the lower bout with a 19" body length - a Martin 0 (single 0) is 13-1/2" wide and 19-1/8" long, so this one is approximately that size. A picture of hers is in the set of shots below.

Here is the whole tedious build - right at the end is a clip of my daughter playing it and she makes it sound great:

scroll right and left, text below, click to enlarge.

Great project and Freeman was an essential advisor. I would like to do another.


Author:  Freeman [ Fri Aug 31, 2018 11:47 am ]
Post subject:  Re: Designing a resonator

Remember one big difference between a wood bodied guitar and a metal one like the Reso Outfitters plans is that you need room for your kerfing and however you are going to make and support the cone well. A metal body simply rolls the top into the side and brazes it and the cone well is thin sheet metal. It is worth looking thru Ed's build thread on how he fabricated the cone well, I can show some pics of the tri cone but that really doesn't apply.

Author:  Resophonic [ Fri Nov 22, 2019 12:15 pm ]
Post subject:  Re: Designing a resonator

This may be of some help. I started a build based upon this article and drawings some time ago and found it useful. The build has been side tracked and on the back bench though. Other commitments and repair work have gotten in the way.

If you are good with CAD programs, you should be able to draft your own variation based upon the information provided here. I developed my build drawing as a final Auto Cad project, re-learning to draft at the local Jr. Collage some years ago and leaned heavily on the information in the StewMac Trade Secrets article for the design.

Author:  Resophonic [ Fri Nov 22, 2019 1:36 pm ]
Post subject:  Re: Designing a resonator

Hmm, new here and still getting used to how pages are presented... just noticed the posting dates...looks like I'm late to the party.

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