Squareneck Resonator - Detailed Build Notes

[Mike Conner]

Started a new build in the new shop in Murphy NC - a squareneck resonator guitar. I have attempted to document all the steps in my process, and humbly present the description and photos below...

This is likely way too detailed and tedious for many participants on this forum. I have received many good ideas and tips from this site, and perhaps there will be some newer folks interested in instrument building that may find this useful.

Here are the reference instruments:

On the left is a Wechter-Scheerhorn (2008). The design is from Tim Scheerhorn, the laminated bodies were produced in Asia and the final assembly in MI. This "Frugalhorn" is considered an "R" body in the reso world. Really a good reso.

On the right is a Mastereso custom build by Phil Dean in Milledgeville GA (2009), solid Sapele body with Port Orford Cedar front. The design is based on a dreadnought guitar body and is considered an "L" body. Louder and "woodier" sounding than the Wechter-Scheerhorn.

Both are open body designs with soundposts rather than a soundwell.

[Mike Conner]

All my building experience so far has been with archtop guitars and octave mandolins. I have the LMII and Stew-Mac dreadnought plans to refer to, and the Beard plan is for an R body. So, I need a design.

Starting with the LMII dreadnought plan, I traced the outline onto white paper and then drew in all the details needed for the reso body.

{getting "file too large" errors when attempting to attach photos. First one worked though, and they are all cell phone images - will be back later...)

[Mike Conner]

{Back to it! Have been posting the build in a FB album, so downloaded the compressed images from there. Maybe there is a better way?}

Design created by starting with the LMII dreadnought plan outline, then working out all the interior body details based on inspection of my existing instruments and web info:

Gluing the drawing to 1/4" plywood creates a template, and used it to build an outer mold from 5 layers of 3/4" plywood. Sealed with many coats of poly:

My mold design opens at the centerline and the halves are attached with screws or bolts as needed. The outer surface shape is intentional to aid in bending the sides (more later).

[Mike Conner]

The donor board is 3/4" thick curly red maple, 8 ft long and 9,5 in wide.

A church friend Mike Martin has some tools we don't have - a large bandsaw for resawing and a 16" drum sander. I broke down the board into 21" sections for front or back plates, and 32" sections for the sides. Here Mike is resawing the maple sides:

The board was fairly flat to start, but cupped quite a bit after resawing. Treated the plates with a liberal application of SuperSoft 2 and wrapped in bown paper and plastic overnight, then stickered with plenty of weight for several days. No heat used and my shop is chilly in the winter. This method worked really well.

[Mike Conner]

Plates stickered after SuperSoft 2 treatment:

[Mike Conner]

The sides are 0.075" thick, 32" long, and taper from 4-1/2" to 3-3/4" before trimming. Each section from the board yielded 4 bookmatched pieces after resawing. From the template I could measure the total length needed, and the apex of each of the bends:

After trimming on the band saw, jointed the edges using a 100+ year old Stanley #6 bench plane. This a #3 and some block planes were my grandfathers, and I use them and nearly everything I build. Here the bookmatched sides are clamped together in the side vise and planed to clean up the cuts.

[Mike Conner]

Bending the curly maple sides on a hot pipe and clamping into the mold to set. I did a video and uploaded to YouTube:
https://youtu.be/NRdh_jVhQUY

The video is real time and 36 minutes of your life you will never get back You will get the idea in the first few minutes and can skip ahead if you wish. I am definately _not_ photogenic!

I use a 2" pipe heated to 350'F with a charcoal starter and light dimmer for the heat source. Lightly spray with distilled water while working through the bending. I bend the waist first and clamp to the outside of the mold to set a bit, then work through the rest of the bends to fit to the mold halves.

My perception is that the SuperSoft helped with the bending, and I had no issues with faceting or breakout like I have seen in the past with curly maple.

The sides are clamped to the outside mold to dry and set:

[Mike Conner]

A 2" thick chunk of red maple from a tree we cut down a few years ago at our home in SC provided the material for the neck and tail blocks:

The neck block is 1-1/2" thick since I am planning for a dovetail joint, and the tail block is a generous 1" thick. The notches are for an interior brace that also provides for the cone support. After a little fitting using a sanding station, the sides can be trimmed and connected with the blocks.

The sides had held their shape really well from the bending.

[Mike Conner]

Side braces and reverse kerf linings are glued in. These stiffen and strengthen the rim assembly and provide more glue surface for attaching the front and back plates.

The linings and blocks are leveled by clamping the rim assembly in the mold. Interior jacks keep the sides firmly against the mold walls. The front plate is flat, and the back plate will have a 25' radius (first use of a radius dish - archtop rims are flat):

The rim assembly is nearly completed:

[Mike Conner]

A 1 inch thick red maple plank provided the material for the interior brace:

Hand planed to level out some cupping and twisting, then planed to 5/8" thick in our Dewalt planer. This is some hard stuff and took a while to plane down with light passes. Laid out and trimmed to create the interior brace, carefully fitting so that it just "snaps" into place:

This interior brace will resist the high compression from the heavy Dobro strings tune to G, and also a ring to support the resonator cone.

[Mike Conner]

Now on to the back plate. Used some alcohol on the 0.090" thick red maple to select the best match for the curl:

We want these joints to be perfect! Clamped the bookmatched sections together between two pieces of 3/4" plywood. Jointed the edge using the #6 plane set for a very fine cut, rubbing the plane on it's side on the bench.

I "candled" the joint by leaning on a window and looked for sunlight leaking through gaps. Was happy after the second try.

The jointed sections are propped up on a 1/2" thick piece of scrap, and two scrap strips are screwed to the bench at the edges. Titebond glue on the edges, then remove the 1/2" strip and press down the plates. This provides just enough even pressure to close the joint. Wax paper prevents gluing everything together.

Some weights to keep the plates flat while the glue cures:

[Mike Conner]

Once the glue has cured, I scraped and sanded the joined plates to 120 grit. Traced the rims and cut outline with a fine blade in a jigsaw:

Selected some SPF (spruce-pine-fir) as close to quartersawn as possible for the back braces. This wood is harvested during the full moon only in months that end in R.

Just kidding, I dug through the cutoff and stock pile to find SPF lumber with nice tight quartersawn grain. The main brace is 1" wide, and the others are 3/4" wide. This is needed to provide landing sites for the support posts.

The braces are sanded on the 25' radius dish, then glued to the back plate using my GoBar adaption and supported by the radius dish:

By design, my upper cabinets are 48" from the bench surfaces. I use 48" fiberglas rods (sold as driveway markers at Lowes) that provide just the right amount of pressure while gluing. This way I do not need a dedicated GoBar deck, and any convenient clear area of my bench can be used for the GoBars.

[Mike Conner]

The back braces are carved to create a flat area to support the sound posts connecting the front plate sound ring to the back plate, and extra material is removed. No plans available for this, so we are just going with what looks right.

I notched the rims to capture the back brace ends using the Dremel and a 1/8" upcut bit. (I tried a razor saw and chisel at first, but this did not go well and the first notch was really sloppy).

The notches turned out pretty well.

Note that I installed the side braces to line up with the back braces - seemed like the thing to do.

[Mike Conner]

Cross-grain strips to reinforce the center seem on the back, and a red maple patch to support a couple of sound posts near the tail block:

This GoBar thing is really working well!

[Peter Wilcox]

That looks really well done, Mike - lots of ideas there if I ever decide to make another one. Keep 'em coming.

It looks like you have your photo problem worked out, but if you need any more info for posting here, there is this link:

How to add a photo (or sound clip) to your post
viewtopic.php?f=19&t=1656

[Mike Conner]

Thanks Peter! I was in part inspired by your older post on building a reso...
Here we go with some more:

The tail of the rim gets a curly maple tail wedge with walnut purfling. Looks fancy and relatively easy to do, and it hides any errors where the sides meet at the tail - not that I would have anything to hide

The front plate is 1/8" thick, thicker than the back plate, and joined the same way we did the back plate. Here we are gluing the interior brace to the front plate. Also glued some maple reinforcements for the sound ports:

Bought a circle cutting jig and get to try it out to cut the hole for the cone. This is a bit intimidating, cutting a huge hole in some perfectly good curly maple, and the location has to be very accurate to ensure the intonation is correct relative to the fretboard on the neck.

Carefully measured 12-1/2" from the neck block outer surface and drilled a 1/8" locating hole. (The scale length of the Dobro will be 25" and the neck meets the body at the 12th fret). The first setup is 10-9/16" diameter, 0.200" deep, and established the ledge that supports the edge of the cone. Then a through hole at 10-3/16" diameter.

Really like this Jasper jig!

With two 1-7/8" holes for the sound ports, the front plate is nearly ready to go

[Bob Francis]

This is a great tut!
Thanks

[Karl Wicklund]

Another that is on my long list. You post will help a lot. Thanks for sharing!

[Mike Conner]

Did some more carving on the back braces now that we can see how the front and back plates will line up:

Back in the mold to glue on the back plate. The little maple fingers act like cam clamps, tightened with the screws.

Flipped the mold over to clean up any glue squeeze out. The 3/4" plywood open frame has several uses.

After the glue cures we can remove the body from the mold and CAREFULLY trim the back plate flush to the rims on the sanding station. (This is nerve wracking!) (Removing from the mold was necessary because I made the mold nearly the full depth of the rims, which also meant I needed the 1/2" spacers to get this to work with my clamping method).

[Mike Conner]

The interior rims and back get a couple coats of waterborne polyurethane to seal the surfaces, plus it looks cool. Attached the labels by laying them on the last coat.

I realize that this could cause problems for future repairs, but this is for me to play, and I happen to like the way it looks. I suppose I could theorize that the interior finish helps stabilize the body with humidity changes

Gluing on the front plate, the same way as the back plate. I took extra care to ensure the front plate was on center:

The box is closed. Front plate is sanded flush to the sides.

Ready for bindings and purflings.