Squareneck Resonator - Detailed Build Notes

[Mike Conner]

We made our own binding from a 0.250" thick curly maple board and 0.050" thick walnut, glued with Titebond 3. Sliced off the binding strips 0.075" thick on the table saw. Got about a dozen binding strips from this one glue up.

After treating overnight with SuperSoft 2, four strips of binding were bent on the hot pipe just like we did the sides. Clamped to the mold to set for a couple of days. Was a bit concerned with this glued up binding and the curly wood, but likely due to the SuperSoft everything was controllable and smooth.

[Mike Conner]

This is the binding rig I used for the archtop instruments. The body is clamped on the rims with padded bolts in threaded inserts in the blocks attached to the 3/4" plywood frame. With my archtops, the rims are a uniform depth around the perimeter (2-7/8" for a guitar), and the arched plates extend into the open hole in the frame. A trim router is mounted in the tower, and the Stew-Mac binding bit with bearings is installed in the router. The guitar body in the frame slides around on the bench surface as I feed the body into the bit.

Unfortunately, due to the taper of the sides from neck to tail, and the 25" radius arch of the back, this setup doesn't work for the resonator guitar body. I could not get the elevation to be precise enough relative to the binding bit.

The trim router came with a round base. This means a semi freehand cut while the router base rides on the plates.

At least the frame and clamps provided stable support for routing, and this ended up working really well.

[Mike Conner]

My lovely and patient bride Dianne helped wrangle the tape as we trimmed and glued the binding and purflings. Titebond original applied with a trimmed flux brush. This Scotch Edgelok tape is thicker and stronger than typical blue masking tape, and holds up well to pulling the binding tight.

A tip in removing the tape: warm the tape with a household hair dryer. Makes a big difference in releasing the tape, and especially to reduce the risk of pulling fibers from spruce plates.

The bindings and purfling are sanded flush to the plates and sides on the sanding station and ROS sander.

I did not attempt to miter the walnut purflings. That would mean a much more precise and detailed effort installing the bindings. I hope to try that challenge some day...

Now I can turn my attention to the neck and fretboard...

[Mike Conner]

Been a while, busy with other projects, but back to the dobro...

Our neck dovetail tenon fixture was designed with the 3 degree angle needed to match the archtop guitar geometry and bridge height. The Dobro needs a 0 degree angle - in other words a square cut at the heel. So we need a new fixture.

Repurposed the neck dovetail tenon guide plate and attached to a new box with the 0 degree angle.
Also glued up some scrap framing lumber to make a dummy neck to test the fixture before committing to the actual neck.

We could reconfigure the dovetail mortis fixture from the archtop builds for the deeper dobro body by moving around the front plate supports and making wood shims to align the body in the fixture. Here we are setting up the fixture and router to make some test cuts into some more scrap lumber.

The router is a standard plunge router, set up with 3/4" dovetail bit and a guide collar. I set this up with the prior archtop builds and haven't changed the bit height since. Haven't needed the plunge router for any other projects and have another PC router I use for everything else.

[Mike Conner]

Test neck in the fixture, ready for the router. A wood screw through the guide and into neck heel locks it to the guide plate, and a 3/4" dovetail bit in the router makes the cuts.

Test neck and body mortis look pretty good after some trial runs.The test neck heel block was extra thick so that the test dovetail tenon cut could be chopped off at the miter saw and another cut attempted until the neck tenon drops into the body mortis just a bit proud of the front surface.

[Mike Conner]

We need to check the neck angle geometry, so the spider and cone will need to be assembled.

The spider from Resophonic Outfitters (Beard Guitars) is cast aluminum and very good quality. As received, the spider legs/feet were rough leveled, and we can refine this with some sanding to 600 grit by using the table saw as a flat surface plate. This ensures that all the spider legs make firm and smooth contact with the lip on the cone.

The cone is the spun aluminum "Legend" cone from Resophonic Outfitters (Beard). A tension screw connects the center of the spider with the center of the cone. As received, the tension screw head only catches the bridge saddle slot at a couple of points.

Milled out a clearance hole in the spider using the drill press to create a chamfered seat for the tension screw.

[Mike Conner]

With the cone and spider assembled, we can lay the fretboard blank on the front plate and use a straight edge to project where the strings might meet the bridge saddles. We did this same measurement on the Wechter-Scheerhorn and Mastereso dobros, and based on that this looks pretty good, and confirms that a 0 degree neck angle should work.

With the neck geometry confirmed, we can start on the actual neck. The neck is cut from a blank laminated from curly red maple and thin strips of walnut. The "billet" we glued up will make two necks. The ends are chopped off to use for the neck heel, then the billet is ripped lengthwise on the table saw to create the main neck shaft.

[Mike Conner]

The fretboard is 0.300" thick walnut (a little thicker than the typical 0.250" thick fretboards). The scale length is 25", the same scale length we used for the archtop guitars.

Here we are laying out the fret positions. Measured with a 6" dial caliper and struck across with a knife and square. When we get past 6" from the nut, we clamp on a 6" rule and measure from there, then a 12" further on down the fretboard.

Here is the fixture for cutting slots, created when building archtop guitars. The saw has a block attached to control the depth of cut, and the fixture keeps everything square.

No metal frets needed on a dobro. We are inlaying maple in the fret slots to provide visual marks for the fret positions.

The first attempt was filling the 0.020 wide fret slots with maple. Looked really precise, but harder to see in lower light conditions. Re-cut the slots and opened them to 0.030" with a dovetail saw. Much better

[Mike Conner]

Cutting the fretboard taper using a sled fixture on the table saw.

Glued in small pearloid dot position markers in shallow holes with super glue.

Bound the fretboard with the same curly maple/walnut purfling we used on the body (Titebond glue). Once the glue cured on the long edges, I mitered in the last section on the end. This is the first time making a bound fretboard.

[Mike Conner]

Body clamped in the dovetail mortis fixture. This is really nerve wracking - mess up here and it is really hard to fix!

Success. The dovetail mortis came out really good.

[Just noticed that you can also see the bookmatch of the front and sides pretty well. Thanks again for Mike Martin's help to resaw and thickness sand the curly maple].

Checking the body dovetail mortis and neck geometry using the completed fretboard and test neck. Looks good!

[Mike Conner]

The actual neck in the dovetail tenon fixture. The other nail biter in the process.

[I should probably sweep the floor before taking these photos )

Another sled fixture to cut the headstock angle on the neck shaft. Made this new setup because a lower headstock angle is needed for the dobro.
Measured and set up really carefully to ensure the nut would end up at the correct location.

In the prior archtop builds, we cut the headstock angle first, then located and glued on the block for the heel. The geometry is different with flattops and this dobro, so I reversed the order of operations to allow for a "do-over" on the dovetail joint. Fortunately, making the test neck and mortis block went well and increased the confidence that the actual joint would turn out well.

[Mike Conner]

The neck tenon is carefully filed so that the neck drops into the body mortis to line up exactly at the level of the front plate, and to ensure that the neck shaft stays on the centerline.

Neck tenon fitting completed.

[Mike Conner]

The headstock needs a small extension. A section of the offcut from the neck shaft is ripped to 1/2", flipped around and glued to the neck shaft. Keeping the length long at this point helped with aligning the extension to the main shaft. Chopped the excess off after letting the glue set and sanding flush.

[Mike Conner]

Checking again that the neck and fretboard will all match the centerline of the body.

The final position of the fretboard is determined. Two of the pearloid position markers were not installed, and 1/16" holes were drilled through so that small brads can be used as alignment pins.We will install the missing pearloid dots after the fretboard is glued to the neck.

After the fretboard position is confirmed and pinned, a slot is cut for seating the bone nut. The nut is pretty high and there will be twisting forces from the strings, so the slot should help prevent the nut from tipping.

[Mike Conner]

Some curly maple glued on to widen the headstock.

Under this forest of clamps is a 1/8" thick walnut headplate.

[Mike Conner]

Rough shaping the neck width and the headstock shape.

We used two-way adjustable truss rods in the 8 previous guitar builds. The 5 layer lamination of the necks, combined with 0.300" thick fretboards, are really stable and strong. In each case the necks have remained straight and true under string tension, and the truss rods are just snugged to keep them from vibrating. Based on this experience, we don't think the thick dobro neck will need extra reinforcement.

Carving away some extra material at the back of the headstock.The finished headstock, with the walnut headplate, needs to be 0.600" thick for the Gotoh tuners.

[Mike Conner]

Really looks like a dobro now!

Next, lots of carving to complete the neck thickness profile, and drilling the headstock for the tuners. Also will inlay a MC logo. The neck will not be permanently attached until after the finish is completed.

[Bob Francis]

Better and better!

[Mike Conner]

Garden is doing well, and other projects completed, so now back to the Dobro build...

Now is as good a time as any to install the soundposts. These are 1/2" and 1/4" poplar dowels. Lots of trial and error to fit these between the back braces and maple top ring. Glued in with gel superglue, but I think I got more glue on my fingers than in the Dobro

[Mike Conner]

Now on to the neck...

Added a decorative walnut cap to the neck heel.

A lot of work for only one picture...
Installed a MC inlay in the headstock, assembled from tiny pieces of white binding. Tedious, but it looks cool. Realized later that for some reason I ended up with the inlay off center, but I kind of like it that way. (I have some pearloid to make inlays, but I'll try using that some day down the line).

Confirmed tuner locations and drilled 3/8" holes for the Gotoh tuners.