Tom Hoelle: Harp Guitar!

 This page has lots of pictures!  Please allow time to load!

...go back to Page 1: Fretboard Inlay, Neck and Sides (Framework)

...or go back to Page 2: Top and Back (with bracing, binding and rosettes)

Page 3: Components, Assembly, Finish and Setup

This is where it all comes together.  There's still lot's of work to do, but the instrument is taking shape and there's definitely light at the end of the tunnel!  I'll start by making the bridge.  It'll be a "tie block" design, with a recess in the rear to accommodate a ball ended string (there'll be no string pins).  Solid ebony, it'll position all 20 strings in 3 banks, each bank with it's own bone saddle.  The center saddle will be angled to provide compensation for proper intonation.  And of course, the bottom surface will be arched to match the contour in the guitar's top.

I'll prep the tuners... and install the fretboard before actually positioning and gluing the bridge in place.

French Polish will be used for the finish and set-up will follow.

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The Bridge: 

 A nice piece of ebony has been drying in my shop...  With another harp guitar in my possession (a vintage piece) that's in need of a replacement bridge, I split this piece length-wise to yield two suitable pieces.  After sending them both through the planer, they're again left for further drying...

After several more months of drying, the ebony is now ready to be worked into a bridge.  I selected one of the two pieces, trimmed it to rough size on the band saw, and then put it through a few more passes on the planer to true it up.

I set up a series of "guides" using nice straight, flat pieces of wood that's been marked to locate critical features of the bridge.  This includes locations for all 20 strings and all 3 saddles.

Routing a half-round groove on the back edge for the string's ball end to seat in...

Fitting saddles to the slots...  Bone is used for the saddles. First the pieces are trimmed to length, then sanded to thickness and finally rounded on the edges until all three pieces fit snug within their respective slots.  Fretted steel string instruments require a shift in saddle position to compensate for the amount of 'stretching" required to fret a string.  This compensation varies with the thickness of the string, so the center saddle has been positioned at a specific angle.  This should provide proper intonation when fretting the strings of varying thickness.  Of course, the other 2 saddles, being set up for "harp" strings (that won't be fretted), can be put in straight.  The tops of all these saddles will be shaped later after the bridge has been installed on the instrument.

Cutting a string trough... I took a piece of 2 x 12 and cut it at a 45 degree angle.  This was then used to position the bridge at an angle with similar clamps for routing the front edge of a trough between the tie block and the saddles.  Finally, 20 holes are drilled in position through the tie block for the strings to pass through.

Shaping the "wings" on the ends of the bridge.

Roughed out bridge... a scroll saw and a Dremel tool are used to cut and shape ornamentals on the ends.

Recall that we intentionally put a slight arch in the top when installing the bracing.  Now we need to sand the bottom of the bridge to match that arched contour in the guitar's top.  Sandpaper is taped (rough side up) to the guitar's top and the bridge is sanded directly on the instrument to obtain a perfect match.

The finished bridge... ready for installation.

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The Tuners: 

Transferring the pattern of the tuner mounting holes to the headstock.

Drilling the tuner mounting holes... pilot holes are drilled first, then successively larger sizes are drilled until the holes are up to size.

The finished tuner mounting holes...

Schaller planetary geared banjo tuners were chosen for the 12 tuners on the main headstock along with matching Schaller "5th string" banjo tuners for the 8 super-treble tuners.  These are high quality tuners, but with a problem... the buttons were too big for such close spacing!  So an abrasive roll on a Dremel tool allowed re-shaping of the buttons.  The 2nd picture below shows a reshaped "narrow" button next to one with the original shape.  And finally, all 20 tuners with their buttons reshaped.

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Installing the Bridge and Fret Board:

Properly positioning the fret board and the bridge in relation to each other is a critical step.  It will determine if the fretted notes will play in tune up the fret board or not!  The fret board will be installed first, then the bridge will be positioned relative to that.

Installing the fret board... The truss rod is placed in it's slot with a drop or two of silicone caulking at the ends to assure there's never a chance of a rattlle coming from the truss rod inside the neck... and glue is spread evenly on both neck and fret board surfaces.  A piece of tape is placed over the truss rod while spreading the glue to keep glue from seeping in to the truss rod slot and later hampering the functioning of the truss rod.  Once the glue is evenly spread, that tape is removed and the fret board positioned.  Multiple clamps will hold it firmly in place while the glue sets up.

Intonation verification... before gluing the bridge in place, a temporary set up using a clamp with a piece of saddle material and a couple of old strings are used with an electronic tuner to make sure the calculated position of the bridge will yield a properly compensated bridge position.  This will confirm that the instrument will play in tune up the neck.

Gluing the bridge in place...  glue is applied liberally to the bottom of the bridge.  Deep throated clamps have been fitted with blocks cut to straddle the internal fan bracing and contact directly on the bridge plate.  The contact surfaces of these blocks have cork glued on to minimize marring of the internal bridge plate.  These blocks are held onto the clamp with double sided mounting squares (pads sticky on both sides).  Finally, three separate clamps are used to apply even pressure across the length of the bridge while the glue sets up.

The guitar... bridge and fret board installed.

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The Finish:

French Polish... is an old world finishing technique using shellac, denatured alcohol and a smidge of olive oil to aid application.  On the downside, it's very labor intensive and requires multiple "sessions" over an extended period of time to apply.  But on the upside, it's environmentally friendly, requires no special spray booths or spray equipment and in the end, will result in a better sounding instrument than some of the more common "commercial" finishes like lacquer or polymers.

First, the ebony bridge and fret board are masked off (they'll remain unfinished).  Then an initial "sealer" coat of thinned shellac is applied.

Filling the pores... Mahogany and Rosewood are porous woods and those pores must be filled to achieve a nice smooth finished surface.  A paste "filler" is thinned and applied with a flexible scraper... left to harden then sanded smooth.  Spruce and maple (top and binding) are not porous woods and won't require filling.

A 2nd sealer coat of shellac is applied,  followed by another pore filling with the paste filler... the whole thing is sanded smooth again and a 3rd shellac sealing coat is applied over all of that.

The sealed and pore-filled guitar is now finally ready for the 1st French polishing session.  In all, there will be about 6 polishing sessions, with a 2 day curing time between each session.

The applicator pad... Cotton material (a piece of an old t-shirt) is filled with cotton to form a pad for applying the finish.  The pad is charged with several drops of shellac and then a drop of olive oil to aid application.

French Polishing... small areas are worked at a time and the finish is very slowly built up over the entire instrument in multiple sessions.  After each of these polishing sessions, the guitar is left to cure for 2 days before proceeding with the next session.

After the 2nd polishing session, the finish is wet-sanded with 600 grit paper and mineral spirits prior to the next polishing session. This will help smooth out any surface imperfections and will be repeated between each polishing session that follows.

Wet sanding... using 600 grit sandpaper lubricated with mineral spirits.  (that mustard bottle contains mineral spirits with a few drops of olive oil in it)

More polishing... and the finish is starting to show some depth!

Final Sanding... wet sanding using denatured alkahol with 1200 grit paper - interspersed with polishing using thinned shellac

Final Polish... and a nice warm glow emerges.

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Final Assembly and Set up: 

Making string posts... a block is rigged up to hold the posts while they're trimmed and pinned.

String posts ready to install...

Installing treble tuners... the shelf is masked, marked for tuner locations, holes drilled and reamed and finally tuners and posts are pressed in placed.

Treble tuners in place...

Headstock... bass string posts are pinned in place and all remaining tuners are installed.

All tuners and string posts in place...

Crowning the saddles... The nut's slots are roughed in and the saddle is marked and trimmed for height.  Slots are filed and the top shaped.

Finished saddles in place...

String slots are filed into the bass string posts... and we're finally ready to start stringing 'er up!

Installing strings...  Right up the row... bass strings go on first - standard guitar strings next.

And the "tweaking" begins... adjusting the action and leveling the frets for smooth easy playing.

Installing Super-Treble Strings...

All 20 strings installed!

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The Completed Harp Guitar: 

Finished!!!  ...and it sounds fantastic!  (now I need to learn how to play it well enough to do it justice!)

And some detail...

Oh yeah...

Time to go make some music!

And here's a video of me playing my new harp guitar!  Click here

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...go back to Page 1: Fretboard Inlay, Neck and Sides (Framework)

...or go back to Page 2: Top and Back (with bracing, binding and rosettes)

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