Acoustic Guitar Construction

Number 10, the Parlor Prototype Will Reyer 07/16/22

I went off to college in 1961 with an $18 Sears Silvertone parlor guitar, birch with black paint. In those days about the only real playable acoustic guitars, Martins, Gibsons, or Guilds, were light years beyond my financial means. Amazingly my Silvertone was not only playable but sounded pretty good for what it was. The tuners would hold pitch, the bridge stayed put, nor did the soundboard buckle, etc.

More recently I had a Gretsch Jim Dandy for about 15 minutes that I bought at Strait Music in Austin just because it was $150 and I wanted to see if it was playable. It also was. You could learn on one.

I've been building orchestra models, but wanted to try a parlor of my own design.

A real luthier and mentor here loaned me the remnants of a 12-fret 1929 Martin Style 0 and I took measurements and made a drawing of the bracing for the soundboard. I took some of this and mixed with an approximation of the silhouette of a Jim Dandy.

I also played around with numbers concerning the fret cutting fixture I had a machinist friend make me that works with a cross-cut sled and a machinist's slitting blade on my table saw to create fretboards with a 25.4” scale. Discovered that if I used the first fret as the zero fret I'd have a scale length just under the 24” scale a Jim Dandy uses, 23.974”. Well, that's nominally 24”.

Made preliminary drawing in plan and elevation to the above specifications. See first photo with fretboard on drawing. Dimensions from the Martin drawing in back, the cutout overlaying the drawing being my proposed silhouette. The Martin X-brace angle wouldn't pick up the ends of the bridge, as is apparent in the cutout overlaying the drawing.

Made a revised X-brace angle to pick up the corners of the bridge for my proposed parlor. See second drawing photo.

I had a piece of red oak from cutoffs salvaged from something long ago, 30” long and I needed 27”. It had a discolored nail hole in one part and was about half an inch narrower than the depth indicated in my layout drawing comparing the depth from the '29 Martin, but used it anyway for the sides.

Half-inch plywood tail block, laminated head block from yellow poplar. Mortise and tenon neck joint. All soundboard bracing from #2 common white pine. My usual basswood reverse kerfed linings but this time .25” x .625” rather than the .25” x .75” I use for the OM's.

Soundboard and back are 3mm Russian Birch plywood, also on hand in sufficient size. I maintain that rosettes were created to help avoid splits and cracks where the soundhole interrupts the top, unnecessary in plywood.

Household appliances like vacuum cleaners et al now days are usually designed from plastic with snap-tab interlocking fasteners, rather than screws. Assembly with screws is expensive. Your grandmother's vacuum cleaner was screwed together from metal parts, could be disassembled for repair. Now you just throw the plastic away. Mechanical engineers like to keep the screw count down.

Looking at the mortise, you'll see one hole in the head block for the cross-barrel nut and .250-20 UNC screw to retain the neck. I normally use two, but there are two small diameter pilot holes in case I have to retro fit the neck attachment if one screw proves insufficient. Black spot at the back binding is discoloration from the nail hole – yeah, it's wood, not plastic, viva la difference.

I made two sets of bindings for the body, one from clear, straight-grained very white maple and a second from a thin scrap of maple with wonderful stripe and color in it from grain that ran pretty much like a sine wave except that near the center of the length the grain was seriously across the width. Used the second.

It was ornery to plane to .250” thickness to create the binding width, then more so to thin the bandsawed strips to the .093” thickness I settled for when adjusting my binding planer which utilizes an old Harbor Freight laminate trimmer. It cracked and split and pulled out chunks doing this that I could fortunately hide on the inside (glued) faces. And the last of the 4 needed pieces tore the end of the strip off in the binding planer leaving me with 27.5” of length where I needed 27” so could fortunately use it.

Due to the parlor silhouette, gluing short sections of .100” thick binding at a time is extremely tedious (photo) so if the design proves feasible I'm going to have to go to thinner bindings that could be clamped with tape or rubber banding.

I masked off the bindings on the sides with green Frog masking tape, stained the red oak with ZAR “Vintage Modern” oil-base stain, applied a coat of Zinsser Seal Coat with a rag, then 3 coats of satin wiping urethane.

The neck next...

That sure looks nice. Good going, another tree finds its voice.

Lopping off the first fret...I was fortunate enough to wake up to that before I built anything. Heaven-sent.

Got a start on a neck (two photos)

Have a couple pieces of teak on hand, courtesy of my late older brother-in-law's stash. He made some small furniture items after he retired and a cabinet shop in Battle Creek let him pick their dumpster as he was in a wheelchair (his step-father pulled it out for him).

I tried using some of this for bindings on my #2 build but would NOT bend, just broke. The neck width is actually 5 pieces but the teak was 2 pieces already glued together. A piece of red oak makes the center stripe. I like a neck of at least 3 laminations, with the center one being .250” wide so I can use it for a guide to rout the channel for a double-action truss rod.

I didn't intend to make a heel cap for this neck and the teak stack was just short of the required height so I added a couple thin strips of maple.

I have both 1/4” x 1/2” steel rod and double-action truss rods for 12-fret necks on hand but the teak is so stiff and this is a prototype so am just skipping reinforcement. Also hoping the decreased tension of the strings at concert pitch with a shorter scale will aid.

Tenons are 15/16 “ long so they don't bottom out in one-inch mortises. First I install a .250” dowel centered on the tenon 5/16” from the designated end. This may be paranoia on my part but I've done this from #2 forward as reinforcement to help prevent the cross-dowel nut from “pulling the tongue” of the tenon if I tighten the .250-20 UNC screw too tight when retaining the neck on the guitar. The dowel penetrates the tenon past where the screw or screws retaining it will be. I'm hoping I can use only one screw on this parlor size instead of my usual two. This dowel shows clearly on the bottom surface of the tenon in the first photo.

After I get my sliding T-bevel set to what I think the neck angle at the heel ought to be, I set my table saw blade to that, then, using a cross-cut guide, I cut that angle on the heel of the neck.

Before cutting the tenon I double check the distance from the soundboard top on the head block mortise to the center of the longitudinal hole that the the screw inserts from. In the head block in the upper bout this hole is diameter 3/8” for screw clearance.

I use this distance to locate the transverse hole or holes to insert the cross-dowel nut or nuts. These transverse holes are centered 5/16” from where the shoulders of the tenon will be, and are drilled purposely before the tenon is cut.

The diameter of the cross-dowel nuts is 10mm so I use a 25/64” drill to cross-drill the neck, for these nuts. This results in a .003” press-fit so the nut can't rotate easily.

Then I cut the tenon by cutting the shoulders while the sides of the neck are still parallel with the butt end of the neck against the rip fence and then the tenon width by also spacing the distance from the rip fence but with the neck standing up and the butt end down on the saw table. One hand on the neck and a push block with the other. “Be here now”, as Ram Dass said, when you're doing this.

For the screw to access the cross-dowel nut in the tenon I drill a 5/16” hole longitudinally aiming at the center of the transverse nut hole by using a doweling jig clamped on the sides of the tenon and drilling from the end. I put tape on the drill bit to limit the depth of this hole at 1-3/8” so it won't protrude from the heel of the neck.

The nut and screw at Menard's here – not a national chain – are listed as:

cross-dowel nut 3/8 x 5/8 x ¼ P/N 87842

joint connector bolt 1/4-20 x 2.36 P/N 84364 (length indicated is in inches)

These used to be less than fifty cents each but I just bought more yesterday and they're a dollar now for the screw and more for the nut.

Headstock will be my usual simplified version of a Spanish Vee Joint at 15 degrees. Tongue shown here is 1” x 1-1/2”.

The 4 of us in 4 Guitars Alone Together are playing the local Farmers Market tomorrow and by the time I get home and stash the gear my daughter and family will be here for a week from Austin, TX. Haven't seen them in almost a year.

The teak for the neck planed nicely using a spokeshave with the grain, but when filed or rasped it was like grating cheese. Lots of better choices for neck stock, but I had the wood, and hey, it's a prototype.
The fretboard and bridge are osage orange, from down limbs on a quarter mile fencerow a mile and a half north which the owner gave me permission to take. Added maple end cap after all.

The fretboard was slotted with an .032” machinist's slitting saw back maybe 9 years ago when I was starting building and using unknown fret wire from a now defunct guitar store. I currently use StewMac #0148 which hammers nicely into a .023” kerf. To use the existing fretboard I cut off the nut end end, making the first fret on a 25.4” fretboard the zero fret, giving me a scale just under 24” (23.974”).

To install the current frets on hand (undersize, above) I went back to my Don Teeter method, waxed the fretboard with paper in the kerfs to keep out the wax. Pulled paper and masked off fretboard except for the slots. Screeded two part epoxy into the slots, pulled the masking tape and pushed in the frets with my fingers, adding a 3/4” piece of plywood on wax paper on the frets and clamped the neck in my vise.

Fretboard was flat so used it that way, easier to clamp. I guess if you're an electric rocker, you'd expect a nicely radiused fretboard but I can play either without any trouble, and again, it's an untested design.

Except for the life of me I couldn't recall what two part clear epoxy I used that would take longer than 5 minutes to set so I bought two Dollar Store
5 minute epoxies, and did 5 frets at a time, which I could just about do with the procedure above. Tedious.

The zero fret is StewMac #0152, .009” taller, which saves a lot of trial and error filing slot depths in a nut.

The peghead is yellow poplar with a red oak veneer and a white spray paint logo. The protruding wedge from the neck is sawn off the veneer side of the headstock and glued on the back to complete the (misnamed) volute without having to make the neck blank thicker at that end.

The open gear tuning machines are the cheapest of the cheap from the cigar box place. I had two sets I'd never used. They were lots more trouble to install than the enclosed tuners, which have actual threads and a washer to retain the capstans.

And the 6th tuning machine was about dia .020” too large to poke thru the already pressed-in plastic bushings that are visible on the headstock face, so I robbed the last package of the needed machine. You sometimes get what you pay for.

I made a .25” wide temporary saddle to determine the correct height. I usually use maple but had a piece of pine on hand and used it. Strung the guitar up to concert pitch about 3:30 pm out in my shop
Friday. Bass was awful, as usual.

Brought it in the house about 5:30 and played Carter style a couple songs for Pam, the bass already improving. Made an m4a file then, using the iPhone Voice Memo utility, temporary saddle, not compensated, quarter-inch wide white pine. Attached: Truck Driving Man_parlor.m4a

Better sound from better players and more fidelity forthcoming when I get the Corian saddle installed and intonated. Tuesday morning now and even with the temporary pine uncompensated saddle it sounds an order of magnitude better than the m4a. It's going to be a talker.

Like one of my former Texas bosses used to say, “All's we lack is finishing up”.

I forgot to add, and it's important:

I had no idea how much compensation to add for a nominally 24" scale. I consulted with R. M Mottola of Liutaio Mottola via email and he graciously assisted me in working out the necessary compensation.

He joins several other big-name luthiers who have freely and promptly given me advice to unsolicited inquiry. It's an excellent brotherhood to aspire to.

Great looking and sounding guitar! I love the headstock joint. I have been afraid to try one like that. Yours looks great.

Ain't it nice when the reality of the instrument's sound confounds a whole bunch of 'rules'?

The guitar sound clip was a treat. Picker wasn't half bad, either.