fret work

New Luna Ukulele Is Bent Out Of Shape

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Sophie’s aunt wanted to do something to further her niece’s continuing education and eventual career in music therapy.  This nice Luna ukulele was a thoughtful gift.  Unfortunately, there were many dead notes.  Could the Unbrokenstring Crew bring those notes back to life?

Inside the bag is a ukulele, some picks, a tuner, and an instructional DVD!

 

The words for “Peace” in forty-four languages are engraved into the soundboard of this instrument. All you hippies will recognize the peace sign in the sound hole.

 

Sure enough, there are several notes on the fret board, near the nut, that are muted out.

 

Name, rank, and serial number, please.

 

I am not sure what this number is…

 

The fret rocker shows a very tiny difference in fret height, when checking between adjacent frets.

 

However, a straight edge reveals that the neck is back-bowed. The tape just keeps the machinist’s scale upright so I could take the picture.

 

I recorded the string height for all posterity. This is not far from right for a ukulele. Some authorities say it’s too high, others say too low. Whatever.

 

The fret wire height is not adequate to support a fret level job. The back bow is just too much. Yes, the back bow is more than 0.040 inch on each end of the fret board!

 

My guess is, the fret board will need to be reshaped. Here, I’m recording the width of the fret wires.

 

Concert ukuleles are tuned A – E – C – G, with the bottom string, sometimes called String 1, the highest pitch. This G string diameter is about 0.022 inch.

 

The C string is about 0.030 inch.

 

The E string is the largest, measuring about 0.035 inch.

 

The drone string is tuned to A above the G. This string measures about 0.025 inch.

 

Interestingly, the fret board has about a 20 inch radius, while the nut and saddle are absolutely flat. The Luna Guitars Web site specs this instrument with a flat fret board, too. I’ve decided to re-flatten the entire fret board. The nut must come off. Here, I’m cutting the finish so that the nut can be removed cleanly.

 

I love whacking musical instruments with a hammer. I find it strangely satisfying.

 

The saddle slips out of its slot. You can see that there is no radius in the saddle at all.

 

The Smoking Gun. There is not enough string tension in the world to straighten this neck. It also has a twist. It doesn’t matter that this instrument has no truss rod because it wouldn’t help.

 

Visually, we can see the wavy fret board and a clear radius. How did this instrument leave the factory?

 

Let’s get the tuners out of the way.

 

I made this fret remover from an inexpensive set of end nippers from Harbor Freight.

 

These frets over the body are easily removed.

 

Before the woodworking begins in earnest, let’s tape everything off.

 

Some cardboard protects the entire soundboard.

 

The strategy is to flatten the fret board on the belt sander.

 

This little belt sanding station came from Harbor Freight.

 

Some of the safety covers were removed to enable the instrument to set flat on the sanding belt. Do not attempt this at home, kids!

 

The eighty-grit sanding belt begins to make an impression on the fret board. This fret board appears to be rosewood, but the Web site says that this instrument is all mahogany. Dunno about that.

 

With a twist that bad, we can easily inspect our progress.

 

Now I am wondering what I got myself into.

 

Back to it! Many thanks to my wife Glenda for taking these pictures.

 

Serious amounts of sanding dust are produced, so we are outside today.

 

Another check shows that we are not there yet.

 

The sanding belt is doing its work.

 

What is it going to take to get this straight?

 

Sanding dust is going everywhere. No scorch marks yet!

 

I am pleased that the fret markers are still intact.

 

Very light pressure is used now to clean up the surface.

 

Now we’re getting somewhere.

 

Continuing on, producing sanding dust like crazy.

 

Now I’m thinking that I need to be careful not to go too far.

 

Most of the fret board is flat. There is still some fall-away over the body of the ukulele, which is OK with me.

 

Last few strokes on the belt.

 

The twist is gone and most of the fret board is absolutely flat. I thought that the noise of sanding would drive the cats away, but we see Jack on the bottom step in the lower left corner of this picture.

 

The luthier’s scraper shows that the fret board is flat.

 

The sharp scraper is an excellent tool to finish raw wood.

 

The fret slots at fret six and seven are almost gone. I really don’t think that this fret board is mahogany.

 

Fret slot ten is almost gone.

 

One end of the fret slots over the body IS gone. Yes, it was that bad.

 

My fret saw was set to 0.054 inch, which is the depth of the new fret tangs.

 

Every slot was taken down to about 0.055 inch.

 

These short sections of small fret wire are perfect for this instrument.

 

Each fret was installed, and nipped to length after installation. The long ends were the pieces at the end of the short strips that weren’t long enough to fill another fret. They get nipped off separately.

 

After nipping, this file embedded in a block of nylon files the fret ends 90 degrees to the fret board. Moving the file to another slot allows the fret crowns to be filed to a 60 degree angle to the fret board. I love eBay!

 

Checking for flatness, these frets are ABSOLUTELY flat, which is not surprising.

 

The fret ends are shaped and burnished by hand, and the fret wires are lightly sanded. As with a classical guitar, the frets are not polished, but finely sanded in the same direction as that of the string.

 

The original nut was reused, and re-slotted to restore the original 0.060 inch string height. The nut was just right as it was. The fret board was oiled. New strings complete the job. All the notes are present and accounted for!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE

281-636-8626

Squire Jagmaster Gets a Total Make-over And Then Some! Part Four of Four

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In Part Three of this project, The Unbrokenstring Crew installed a unique cut-out switch in the pick guard of this guitar. One more thing… Now that the instrument is play-able, the original plastic Squire nut is cracked. Grrrr…

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The old Squire nut came out in pieces.

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Let’s make a new one from Vietnamese water buffalo bone. The blank we’ll use today is shown above the old Squire plastic nut.

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Not to brag or anything, but these bone nuts are truly a renewable resource that I am privileged to legally import from overseas. CITES can go bite it.

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The eighth inch chisel easily cleans whatever glue Squire used to install the original plastic nut.

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This slot is ready for the new nut.

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Sorry, that’s as clean as I can get it.

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The new blank nut is thickness-sanded to fit the slot. I’m doing this by hand because the blank is very close to the proper dimensions to begin with.

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The inside radius is established by using the actual neck as a radius block.

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The side contour is also established by hand, on the actual instrument.

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The actual height of the fret wires is measured in order to calculate the depth of the string slots. This dial indicator measures the installed height of the fret wire above the finger board.

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Here, we’re gluing the new nut right to the finger board using hide glue. A water-based adhesive could cause the wood to swell; shrinkage over the next few months as the wood dries out would throw off the accuracy of the nut slot depth. Can’t have that!

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The old nut is used as a template to establish string spacing. A couple of old strings are used to align everything.

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Now that we know the fret height, string gauge, and string spacing, we can begin establishing the string slots. At the nut, the string slot depth is constant across the radius of the finger board, regardless of the string diameter.

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With a set of old strings in place, the top of the nut can be quickly contoured so that the top of the nut will not protrude above the strings. The geometry of the top of the nut is established in part by the diameter of the strings, which is, of course, not constant across the radius of the finger board. This three-cornered triangular file belonged to my father.

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This old triangular file is just the thing to contour the nut further, smoothing out sharp corners and preparing the nut for polishing.

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Note that the string centers are just below the top of the nut, and that the top of the nut is no higher than any string.

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This is the instrument, as delivered. The Vietnamese water buffalo bone is a spectacular material for musical instruments: incredibly hard, uniform throughout its bulk, and capable of a fine polish without additional waxes or oils, making a visually attractive nut and providing a stable, polished string slot that allows for smooth and stable tuning without binding or sticking. What more could you ask?

I think we’re finally done with the Jagmaster Make-Over!

Thanks for reading all the way to the bottom!

CONTACT – David Latchaw EE
281-636-8626

Warmoth FrankenCaster: It Lives!

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This offset-waist project guitar is playable and is actually very cool.  The owner had ‘gotten in over his head’ and broken a few screws and buggered a few others.  Could the Unbrokenstring Crew whip this instrument into shape again?

The easy part is to install gold Gibson speed knobs on the controls.  There are a lot of good parts in this instrument.

 

Looking more closely, the neck pocket will need some serious attention.  What’s going on here?

 

This is what’s going on.  If you look at the high and low strings, you will see that they are not the same distance from the edge of the fret board.  This neck is not lined up with the body of the guitar.

 

It is easy to remove the truss rod cover because these screw heads are already sheared off.

 

The heads of the screws around this pickup were mangled to the point that a regular Phillips screw driver would not engage them anymore.  Here we’re using a pair of cutters to twist the screw out while a magnet serves as a sentinel to keep pieces of metal that will inevitably shave off the screw head away from the magnet in the neck pickup.

 

Wow these are long.  These go most of the way through the body.

 

We are still working on this one.  This is really tough.

 

Note that the head is chewed up pretty badly.  New screws are already in stock.

 

No springs or tubing are underneath this pickup, bur rather a chunk of too-thick too-hard foam.

 

Now we know where this body came from!

 

And the neck is from Guitar Fetish.  Here, I marked where the body ends with a dotted line.  More on this later.

 

So what can we do about these broken screws?

 

No problems removing the tuners…  these screws were busted off as well.

 

To remove the broken screws, we apply heat to the body of the screw.  This dries out the surrounding wood so that it shrinks slightly.

 

I used the same technique with the wire cutters to grasp the body of the broken screw to twist it out easily.

 

Rinse and repeat for the remaining broken screws.

 

Now that everything is apart, I need to fix this neck pocket.  First, we get the bottom flat.

 

Then we get the sides flat.  This body was painted after it left the factory, so we have plenty of over-spray in the neck pocket that we need to clear out with this scraper.

 

I believe that we are down to real wood again.

 

Acoustic coupling occurs best when the neck and body fit tightly, ‘bone on bone,’ if possible.  I really like this wood hardener, which is essentially solid Lexan dissolved in a light solvent.

 

This raw wood will take a few coats to seal and harden.

 

As the old cowboy on the cattle drive once said, “Be sure to look back to see if the herd is still behind you.”  Periodic fit checks are always a good idea.

 

This neck is beautiful because of the thick layer(s) of polyurethane finish.  However, the polyurethane layer may get in the way of acoustically coupling the neck to the body.  Here, I’m hatching the area where I will scrape away finish.

 

Again, the luthiers’ scraper is the perfect tool for removing finish evenly and smoothly, leaving the surface exactly flat.

 

That is much better!  Not shown: the finish on the end and sides of the neck where it meets the body is also removed.

 

A pin vise holds the proper-sized twist drill to resize these holes for the Correct pickup screws.

 

A little canned air clears out the cuttings from the holes.

 

Over-sized screws held the pick guard in place.  The Correct screws are smaller.  Here, a small dowel is glued into each hole, which will be re-drilled with the proper-sized hole.  This is hide glue shown here; just fine for this duty.

 

Once the hide glue is cured, each dowel is trimmed flush.

 

I jumped ahead to show how the Correct screws are nearly flush with the top of the pick guard.  Almost factory.

 

This single-coil pickup reads as an open circuit.  That tiny wire is broken.

 

The tiny wire is broken because these black and white leads can twist around.  Hot-glue now holds them stationary.

 

The pickup is working now.  Here is some new, softer foam in place to hold the pickup in position.  Leo Fender would have used short pieces of vinyl tubing on the screws to act as a spring, but these covers go all the way to the bottom of the cavity route, so the foam is the best option for this setup.  Oh, and you can’t see it, but the copper pulled out when the original foam was replaced, so this guitar has copper in the pickup route and under the pick guard.

 

Here is the actual pickup.

 

And here is the separate cover.

 

The Correct screws are not nearly as hard to drive as the other screws.

 

More Guitar Fetish goodness!  The metal parts of the guitar should be tied to a single point, not at various places along the signal path.  This soldered wire ties the metal body of the pickup to one side of the audio path, and has got to go.

 

That connection is now cut open.

 

A separate layer of foil is wired to the single point ground.  The connection to the bridge and strings is accomplished with another sheet of foil and this outside-star lock washer.  Again, the mechanical ground is not part of the signal path.

 

Everything goes together as it should.  See how the star washer makes the connection between the bridge and foil?

 

The Correct controls are marked T for tone and V for volume.  The switch is ready to wire.

 

The new wiring is accomplished with solid wire in Teflon tubing.  The pickup wiring is the vintage ‘push-back’ wire, which is actually really easy to use and can be very clean-looking as the insulation is cut without resorting to wire strippers.

 

When the control plate is in the correct position, new holes are bored for the screws.

 

The neck plate needs some attention.  This metal polishing paste is also what I use to polish fret wire.

 

These holes are reamed to the proper size for the Correct screws.

 

The tuners are going on!  A bit of red felt is glued to the face of the socket so that the finish is not marred.

 

These new screws going into the correctly-sized holes are very well-behaved now.

 

The truss rod cover screws will now live in properly-sized holes as well.  The pin vise is getting a workout today!

 

The customer uses these strings.  We need the guitar strung so that we can get the neck straight.

 

Note that the outside E strings are equidistant from the edge of the fret board.  The screws attaching the neck to the body are tightened at this point.

 

Now that the neck is properly positioned, we can finish the setup.  The truss rod is adjusted to make the neck perfectly straight.  Do you see the slip of paper next to fret 9?  It is used as a feeler to see that the ruler is in contact with the fret board all along the neck.  A piece of paper is about 0.0015 inch thick or so.  It is used to check for fit between every fret on the fret board.  Yes, that makes a difference!

 

This neck is brand new, and so the frets had never been leveled.  Just a tiny bit of sanding was all it took.

 

Here I am taking a measurement of fret wire height.  I need this shortly to file the nut slots.

 

Frets are polished.

 

Fret board is cleaned and conditioned with oil.

 

Here we are cutting the nut slots to depth (about 0.006 inch plus the fret wire height measurement made earlier.)

 

Once the nut slots are at the right depth, the rest of the nut is sanded away to make the slots shallow.  We need to sand a little bit more away near the high E and B strings, and maybe next to the D string.  We’re getting there!

 

The instrument is back together and sounding good!

 

This is a closeup of the saddle barrels.  These are factory intonated and are VERY close to correct.  How do they do that?

 

Our patient is making her debut at the studio.

 

First Note.

 

I think he likes it!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

Jasmine Classical Guitar Needs a Setup

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Sophia’s classical guitar had developed a buzzing string.  Perhaps the humidity changes had changed the geometry of the instrument.  She immediately called The Unbrokenstring Crew to take a look at it!
This instrument has a truss rod, something a little out of the ordinary for classical guitars.

 

This is an Indonesian instrument, with lots of mahogany throughout.

 

Using the truss rod adjustment, we make the fret board as flat as we can get it.

 

My Super Duper Absolutely Flat sanding bar goes to work on some high frets.

 

Can you see where the metal has been removed?  This is near the tenth and eleventh frets.

 

One side of the fifth fret was particularly high.  This was the source of the original buzz.

 

The wreckage was bad over the body of the guitar, where the fret board was probably glued straight to the sound board.

 

Before we crown the frets, the fret board will be taped off.

 

To clean and condition the fret board, Dr. Duck’s Axe Wax goes to work.

 

These strings are going back on the instrument.

 

The strings are nicely tied off at the block here.

 

The stringing process is documented in earlier blog posts.  Everything is going well here!

 

Sophia performs live while standing.  So, we’ll add a strap button to the instrument lower bout here.

 

The hole for the pin clears the body of the screw.

 

This strap pin is just above the center line of the instrument. so that it will hang flat against her body.

 

This strap pin is from an inexpensive electric guitar that had strap locks installed.  It goes nicely with the binding.

 

At her favorite venue, Dunn Brothers Coffee in Friendswood TX, Sophia tunes up with an app on her phone.  Life Is Good!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

Luna Gypsy Spalted Acoustic Guitar Needs Fretwork

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Sophia of “Pretty In Punk” purchased this guitar new, but it was almost unplayable. Could the Unbrokenstring Crew get this beautiful instrument in shape?

Nearly every fret was higher or lower than the one next to it.  To mask the problem, the action was very high.

We straightened the neck itself so that it was absolutely flat, then used the Absolutely Flat sander across the frets.

Here, you can see the large amount of material removed from one fret, but not the others.

More material removed from the high frets.

Oh, look, here is another high fret.

Here, three frets in a row were high.

Getting close to the sound board, we’re running out of high frets to sand.

After sanding, we marked the top edge of the frets so we don’t take any more material from them.

This nifty fret file works only on the sides of the fret to round them over.  This file was reviewed in an earlier blog post.

Now, we’re getting somewhere.  This fret board is flat and the frets are even.

Sophia prefers these strings.

If you look closely, some of the over-wound strings at the end almost crested the top of the saddle.  If they get too close, I have some washers that slip over the string and sit on the ball end.  The string would then be passed thru the hole in the bridge from the inside of the guitar.  However, when tuned to standard pitch, we had no trouble here.  Missed It By That Much!

 

I think she’s happy with the results!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626