Affixing the bridge, while making sure intonation is dead-on correct

I put the bridge on the guitar today. Because accurate bridge placement is crucial to making sure the guitar plays in tune all the way up and down the neck, it’s something you need to get right the first time.  I have a trick.  I don’t think anybody else does it this way.

When I install a bridge, it’s actually almost the last step in building the guitar. I’ve finished the body, except for a patch where the thing gets glued on. To determine the exact spot the bridge needs to lie, I’ve dummied up some temporary devices.

  • I temporarily attach a trapeze tailpiece to the guitar so I can anchor the strings.
  • I actually string up the low and high E and tune them up to pitch. Notice, the bridge is not secured to the top at this stage except by string tension. The two little blocks you see are to make sure that the string spacing is correct at nut and saddle since everything’s floating free.
  • I test the tone with the open strings and tune them with an electronic tuner to be precisely E (low and high). I then fret each string at 12 and make sure it is exactly E, but one octave higher. I can adjust the intonation by moving the bridge fore and aft, until it is dead on with both strings. I won’t accept even a penny’s variation.
  • I also slide the bridge back and forth across the belly of the guitar so the strings lie correctly athwart the neck.
  • When I am satdfied the bridge is EXACTLY where it needs to be, I box it in with painter’s tape.
  • I take the strings and trapeze off, and drill 2 tiny holes whee the bridge pins are going in at the 2 E strings.
  • Using glue, 2 wood screws, and clamps, I glue the bridge down.

That’s it. Any variation in intonaton that i find during final setup can be addresed by beveling the saddle one way or the other, strng by string. This mounting method is accurate enough that I find I have no issue with the final tweaks.

The area the bridge needs to attach to is unfinished.
temporary trapexe attachment
The trapeze is just held on with a nylon loop around the strap button.
Once I’m satisfied with bridge placement I block it off with painter’s tape.
Clamps and screws exert respectable gluing pressure.

Getting back in the game

Last April when I had my kidney removed I knew I was going to have to reduce my exposures to chemicals and solvents to near zero.

 

I was very concerned about the luthiery because of course, I used lacquer to finish the wood… very fumey and bad for me.

Today for the first time I tried shooting a low-VOC water based lacquer through a cheap HVLP paint gun, and I am very encouraged with the results. I did lay it on a little too thickly (first try, after all) and so I’m going to need to do a light sanding and respray tomorrow, but in general I’m VERY pleased. I think it looks great and the whole process was easier and faster than I expected, including cleaning the HVLP gun. And there was hardly any smell in the shop, and I’m actually going to save money doing it this way– the cans of lacquer I used to use were 10 bucks apiece (one per guitar, basically) and it looks like I might get 5 or 6 guitars out of this water based stuff , at 30 bucks the can.

Back from a posting hiatus

It’s been awhile since I posted (in fact I took time off from building) because of some personal stuff coming up but anyways I’m getting back into the swing of things.

I mounted the neck on my newest Dreadnought today. Curly Maple back and sides, Sitka Spruce top, mahogany neck. In terms of size and resonance, this thing is directy pointed at the Super Jumbo space.

It sounds like a big old drum when you tap it, but the sound is tight and not sloppy. I’m getting pretty excited.

I have to find a way to lacquer it without exposing myself to solvents.  This is going to be a challenge.

Nearly done

Here’s where she sits… standing up under string tension The initial setup is done, and the action is good. But this was a random collection of stuff a few days ago and now it’s a guitar, so it will take time for the timbers to take a set. I’ll let it hang out for a week or so and play it every day (it sounds nice!) and then change the tension on the neck brace if needed and set up the action again.

Also I need to add fretboard markers. In the past I’ve put in cherry plugs as markers when the thing wasn’t fretted yet, sanding them flush. This time I had the “brilliant” idea that I was going to ‘brand’ symbols on the fretboard and let those serve.  It seemed consistent with the ‘Ostinato’ brand on the headstock and the burned pattern on the rosette. I like the simplicity and directness of burning symbols onto wood, it’s unequivocal and final. Boom. In the case of the fingerboard markers, it turns out the idea was not brilliant at all; the rosewood did not take kindly to the treatment. maybe Pau Ferro or some other fretboard material would work, but not the rosewood.  So anyways  have to figure out how I’m going to add markers to a guitar that’s already complete and already has frets. It’ll be fiddly work but nothing too tough.

Other than that it’s a great instrument. Once I have it completely dialed in somebody is going to want it. Maybe even me, although I’ve been trying to thin the herd. I have too many guitars, both made and store bought.

 

Shellac: done. Lacquer first coat: done.

I laid down the shellac (I mix my own) today and after a long enough time for a hard set, laid on the first coat of lacquer. I usually do 3. I sand a little bit in between each coat.

If I can lay down coats 2 & 3 tomorrow, I may be able to make & install the bone saddle and bridge, and the tuners, on Sunday. Then stringing up and setting up, tweaking, and playing in begins.

I love this color. It makes new Spruce look seasoned and deep, and brings out the grain of the walnut.

Rosette and bridge now on. Bridge is drying (held in place by woodscrews for now).

 

Just running 2 small screws down in the string holes works just fine, I find. A lot easier than messing around with a bunch of clamps that have to bridge over bracing and mar stuff and cause the bridge to slide around to the wrong spot under clamping pressure. When it’s dry you remove the screws: done.

There’s always an easier way to do stuff, if you ponder it long enough.

I’m liking the looks of this thing and I had 3 strings on there while I was checking the bridge placement for intonation. It’s got a nice tone, from what I can tell. Very nice.

This sort of positive feedback helps the build process along. I’m getting excited.

Slight improvement to the physical plant of the shop: there is now a baseboard heater under the guitars there, thermostat set as low as it can go. It’s generating enough heat to keep the shop from dropping below freezing… comfortable enough to work with a jacket on… but right over the baseboard, the air is between 60 and 70. Perfect temp to dry glue at.

 

 

 

 

I got the motors to spin today.

Huge breakthrough: all the hardware, except for one motor coupler, is installed; and I got the motor controllers configured enough to spin the motors. All 3 axes.

This is huge; I have some fiddling around to get the thing moving predictably and smoothly, and to install some movement limiters so it doesn’t self destruct– but in another couple of weeks of fooling around, I should be able to start making test cuts on scrap lumber.

Z and X axes coming along

Spindle mount (really, a bracket for a palm router) and ballscrew is “in the mail”.

We’re getting really close to being able to try to turn motors, though. Kind of exciting.