Repair a guitar with bridge problem

20180417
a guitar came into my workshop for a bridge repair.
This is not the usually bridge lifting off problem, but the tie-block has came off.
Naturally I was surprised as this is the first time I have seen such a problem.
Anyway I thought the fix will be simple: to glue back the tie block
There owner wanted to change the whole bridge but I digressed.

• There were no missing pieces
• There was no problem with intonation / i.e. saddle placement

Hence I stick to my plan to glue back the tie-block
After gluing I strung up the guitar

Tie-block broken

Glue back the tie-block

Strung up

20140424
Unfortunately, after a few days, the tie-block came out again to my surprise.
True enough the glued joint is stronger than the wood itself, but the break as another layer in the tie-block
What this means was that the bridge wood has some sort of weakness in it.
So the solution now is to change bridge entire and build a new bridge.

Tie-block broke off again - different layer

Still with the strings attached

20180507
I began to remove the existing bridge.
Before that I scribed the edges to prevent the lacquer from chipping off as I remove the bridge.
I also took measurements of the scale length / compensation and bridge height.
To my surprise, the bridge began to crumble and broken in pieces as I remove it.
I followed my usual way of removing the bridge heating the platter knife and insert in between the bridge and top.
No heat was apply to the top
This was to ensure no excessive heat was applied to prevent other glued parts from coming loose from the heat
So the problem was with the bridge wood after all.
But I wonder what caused the wood to crumbled like that.

Finally after 45 minutes or so I manage to remove the bridge cleaning.
Surrounding woods are undamaged.

Scribing the edges to prevent lacquer chipped out

Heating and inserting the knife under the bridge. No heat was applied to the top. No water was used.

Done

20180531
I began to work on the bridge blank.
First by scraping and sanding the bottom arc to fit the top.
Also I sanded the top to remove the unevenness of left by the bridge removal.
Finally I sanded the bridge blank to fit the top.

Then I saw away the bridge wings and the bridge began to form in shape.

Scraping the bottom of the bridge blank

Sanding the top

Sanding the bridge to fit the top

Saw away the wing of the blank

Bridge taking shape.

20180619
Half way I decide to use pre-made bridge as I can complete the process faster.
And the fit was quite good.
So I use epoxy to glue the bridge.
Not my usual habit to glue the top but in this case as there were some gaps in the surface, a epoxy glue will be a better guarantee.
So I fitted the bridge and applied the glue to both surface, followed by clamping.

Bridge glued.

20190620

Next I removed the clamp and make a new saddle, change the tuning machine and string up the guitar.
The bridge glue job looks good.
And the guitar sounded nicely.
I touched up some of the finishes but they certainly don't look perfect though.

Bridge glued nicely, new saddle made.

Tuning machines changed

Closing the box

20180430
Finally the box is closed.
Before that I remembered to weigh the back.
However, I forgot to record the tap tone of the box and the back...

I did not do a dry run for the clamping but it was mistake.
As I glue the back, I could not insert the clamp on the heel area as the solera was blocked from below.
I had forgotten to allow some space for the clamps to go in.
Anyway I just clamp the rest first then proceed to shift the woods below to allow the clamp to go in.
So rule of thumb, always do a dry run if you have not been doing the process for a long time.

One last look before closing the box.

Ensure there is enough block to spread the clamping pressure

Apply the glue and heat them up so that they will not gel so fast

Glued and clamped.

20180507
I removed the clamps and check the fit.
No problem with the fit.
After that I proceed to trim the overhangs.
During clamping it helps to have about 5mm or so of overhang.

Trimming the overhang - assortment of tools used: Rebate plane, chisel, LA block plane, scraper etc...

Trimming the overhang

Overhangs trimmed

The back view

Repair a vihuela

20180425
A vihuela came into my shop for repair, as it's bridge had flew off the top.
Should be quite an easy job the only thing is that the bridge took out some of the top.
Also upon inspection the luthier did a terrible thing, that is to scribe several cross marks onto the bridge and top!!!

Those who use hide glue will know this is a not a recommended action.
Hide glue needs maximum surface fit to have a great adhesion and the vihuela (like any other early instruments) has a small gluing surface.
So the fit becomes even more important.
Finally I decide to sand the top flat taking out those deep scribe marks.
Also when I sand the bridge's bottom surface then I realise the fit was really terrible.
There was deep hollow in the center of the bridge's bottom.
No wonder the bridge will fly out...

So I sand all surface flat and put the sandpaper on the top to fit the bridge bottom to the top.
Finally it was ready for gluing.
I use hide glue for the gluing and apply clamps after the hide started to grab the 2 pieces together.

Bridge off u can see the scribe marks on the top.

Bridge bottom; the surface was not level at all.

Sanding flat the top

Fitting the bottom of the bridge to the top

Applying the hide glue.

Glued and clamped.

Perfecto!

Some pics of the instrument

Inlay on the top

The sound hole rose of the vihuela

Frets using fishing lines.

Prepare to close box

20180208
I glued the reinforce veneer to the sound port side.
I haven't decided whether to include a sound port for this build or not.
But I can glue-in the backing first.

Next I also glued in the middle back brace.
I just need to glue in the tornavoz and I am all set to close the box.

Glue the veneer backing for the sound port

Apply the clamps

20180302
I also make the tornavoz for the top.
Previously I have already thin the tornavoz wood, so for this session I just heat and bend it.
After that I just use the clamp to hold it in shape.
I have not decide the exact radius yet.

The bent toranvoz

The bending equipment. I use an additional iron to apply heat to both sides of the wood.

20180424
I drilled the sound port and glue on the tornavoz to the top.
The tornavoz was previously bent, I just glue up the tornavoz and glue the tornavoz to the top.
I decided to fit the tornavoz to the size of the soundhole instead of bigger and glued behind the sound hole.
So I trim off the excess tornavoz and glue the tornavoz ends together using the soundhole as clamp.

Glue the tornavoz ends together.

Next I glue the tornavoz to the top.
Surprisingly the tornavoz fitted the sound hole very well with no gaps.
After that I glued some peones lining block to support the tornavoz.

Glued the tornavoz to the top

Glue the lining blocks to support the tornavoz

Next I also drilled the sound port on the sides.
I did not follow my usual design as I wanted a smaller sound port so as not to affect the air mode too much.

Marking the location where to drill the sound port.

Clamp a backing to avoid blowout

Sound port done. Not very nice though...

20180430
I glue the first part of back seam support.
After that I paste my label on the back and signed the label.
To protect it I also coat the reinforcement and label with a thin coat of shellac.

Gluing the back seam reinforcement

Paste the label

Preparing the back

20171226
After the box is almost done, I began to prepare the back by thicknessing the back with planes.
I tried to use the scrub plane but it is causing heavy tear outs in the back.
So I had to use smoothing plane and cut at a thin shavings setting.
Man, it's really a workout...
After sometime the back sure looks great; with a golden flame.

Thicknessing the back

Maple back with a golden flame. Beautiful.

20180208
I began to brace up the lower bout of the back after the thicknessing.
finding the right location is always a challenge when gluing the back.
Some makers notched the back after gluing on all the 3 braces but for me, as I did not use the radius dish, my back doming was done with the brace in brace in the rim.
Thus, that method did not work too well for me.

This round I had to glue 2 brace onto the rim itself and glue the lower bout brace on the back instead.
This is to enable me to tune the active back with the lower bout back brace on.
The mid and upper bout are mainly for structural support.
Anyway that was done and I also glued in the angle braces
After that I shape those braces and glued in the seam support.
I choose IRW cut off as Maple is a light wood so it looks nice and in terms of weight it has some leeway to go.
I still need to cut some more seam support for the back but now it kind of look pretty nice.

Gluing the back brace

Gluing the angle braces

Gluing the seam support

All carved nicely