Squareneck Resonator - Detailed Build Notes

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D047 - Binding Blank - Curly Maple and Walnut.jpg
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.
D048 - Bent Bindings in Mold.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D050 - Binding Jig for Archtops.jpg
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.
D051 - Round base on trim router.jpg
At least the frame and clamps provided stable support for routing, and this ended up working really well.
D052 - Binding and Purfling Ledges completed.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D053 - Glue and taped bindings.jpg
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.
D054 - Binding Completed.jpg
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
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D060 - Existing 3 degree Neck Dovetail Tenon Fixture.jpg
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.
D061 - New 0 degree Fixture and Test neck.jpg
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.
D062 - Body Dovetail Mortis Fixture and Router.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D064 - Test Neck in Fixture.jpg

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.
D065 - Checking Test Neck and Body Mortis Fit.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D066 - Leveling Spider Legs.jpg
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.
D067 - Tension Screw in As Recieved Spider.jpg
Milled out a clearance hole in the spider using the drill press to create a chamfered seat for the tension screw.
D068 - Seat for Tension Screw.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D069 - Checking Neck Angle.jpg
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.
D070 - Neck Billet.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D071 - Marking Fret Positions.jpg
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.
D072 - Cutting Fret Slots.jpg
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
D073 - Inlaying Maple in Fret Slots.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Cutting the fretboard taper using a sled fixture on the table saw.
D074 - Cutting Fretboard Taper.jpg

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.
D075 - Pearloid Markers and Binding Fretboard.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Body clamped in the dovetail mortis fixture. This is really nerve wracking - mess up here and it is really hard to fix!
D076 - Body in Mortis Fixture.jpg
Success. The dovetail mortis came out really good.
D077 - Completed Body Dovetail Mortis.jpg
[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!
D078 - Checking Neck angle with Test Neck.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

The actual neck in the dovetail tenon fixture. The other nail biter in the process.
D079 - Maple Neck in Tenon Fixture.jpg
[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.
D080 - Cutting Headstock angle on Tablesaw.jpg
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
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D082 - Filing Dovetail Tenon to fit Body Mortis.jpg
Neck tenon fitting completed.
D083 - Neck Meets Body.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by 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.
D084 - Extending Headstock.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Checking again that the neck and fretboard will all match the centerline of the body.
D085 - Checking Body and Neck Centerline.jpg

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.
D086 - Pinning Fretboard Position.jpg
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.
D087 - Slot for Seating Nut.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Some curly maple glued on to widen the headstock.
D088 - Adding Maple to Headstock.jpg
Under this forest of clamps is a 1/8" thick walnut headplate.
D089 - Gluing Walnut Headplate.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Rough shaping the neck width and the headstock shape.
D090 - Rough Shape Neck and Headstock Width.jpg
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.
D091 - Removing Excess from Back of Headstock.jpg

Mike Conner
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Re: Squareneck Resonator - Detailed Build Notes

Post by Mike Conner »

Really looks like a dobro now!
D092 - Neck Fretboard and Body Together.jpg
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
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Re: Squareneck Resonator - Detailed Build Notes

Post by Bob Francis »

Better and better!

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