Crawls Backward (When Alarmed)

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Making a Tortoloid Pickguard: 1931 Martin 0-18T Restoration and Repair, Pt. 7

While the glue was drying on the repair cleats, I took the old pickguard off and made a new one.

Seems like whenever I work on an old guitar, I keep finding things to fix. I'd rather get them all done in one shot, rather than put it back together and find something I missed.

The old pickguard looks bad. I'm pretty sure it's made of Hawksbill tortoiseshell, and I know that it definitely was painted over with clear nitro lacquer when the body was.

To remove it, we use moderate heat. Note that I've put artist's tape all around the pickguard so I don't scratch the finish during removal.

The pickguard was glued to the top of the body with hot hide glue, so we can use heat to loosen the glue.

Once the pickguard is warmed up a bit, we can slide some removal spatulas under it. Note that I'm using one on top of the other. I get going with one and then slide the second one on top of the first and move along that way.

Note the amber-colored lacquer chips lying on the tape. You can see how that paint is peeling off the pickguard.

I try to go slowly and carefully, but for sure some of the top wood will come up with the guard, it's almost unavoidable.

The pickguard came off intact, except that small pointed part. Drat.

I hate it when that happens.

The guard is pretty brittle - it's 85 years old so it's not too surprising.

I freed up that corner, but a couple chips of the finished top came off.

One thing I've learned over time is not to react quickly when something like this happens. Step away and ponder the best way to fix what happened. Better to do that than just try to make a quick fix right away.

In this case, I can reglue these chips.

It's best not to handle these kinds of pieces too much. That way the broken pieces don't fall apart or lose small pieces and tend to go back together more closely. These are small, fragile pieces of wood and will break easily.

This goes for bigger pieces like broken necks - the less handling the better. Don't try too many test fittings - each time you may lose tiny pieces of wood. In some instances you may only get one shot to do the repair.

Here's how I glued the pieces down still attached to the pickguard. Note the waxed paper under the guard - there's glue under the chips and I don't want the guard to get glued down also. (Look a couple pictures down and you'll see how I clamped this piece down).

After the glue dried, I cut the pieces away from the pickguard.

It's a delicate repair. Most of the chips went back into place.

You can see that one of the fragile pieces popped off. Drat.

I'll touch it up with toning lacquer. There are a lot of dents on the top already, so this won't look too bad.

I just hate to lose chips like that.

Note the paint ridge is between the bare wood and the finish on the top. I should have measured it! It's a bit less than the thickness of the original pickguard, but quite noticeable with the guard off.

As predicted, some hunks of wood remained stuck to the pickguard. I probably should have used more heat, and 'read' the top grain better. Going with the spatulas from the other direction may have avoided some of this.

But I'm always leery of using too much heat near a vintage finish. I'd rather have some hunks like this to fill rather than blister the original finish.

Some of the pieces can be glued right back down.

I lifted them carefully with those wonderful Japanese tooth/sushi picks. Be careful not to break pieces off!

I used hot hide glue under the chips and small cauls to clamp those pieces down - including that end of the pickguard with the chips attached.

We need to get the surface as flat as possible so the new pickguard will lay flat.

So we file some spruce repair wood to make a sawdust fill.

Glue it down with CA (super) glue.

Then scrape and sand until it's flat.

You'll have blotchy marks, but they'll be covered by the pickguard.

It's always interesting to see the color of the bare wood versus the old aged finish. This guitar is particularly dark.

I thought the original guard was a reddish color, but holding it up to the light shows that's it's a brownish amber.

The new piece of tortoloid is on the right. It's the closest thing I've seen to the old color and pattern.

I may experiment with the old guard and see if it can be restored.

I taped that cracked tip back to the old pickguard, then taped it on a cutting mat with the tortoloid material to trace a pattern.

Use a silver marker so the marking will show up.

The tortoloid needs to be warm when it's cut. If it's not warm, it will shatter like glass. (As me how I know this).

So I put the heat gun on the bench so it will stand up, and heat the material. It will get soft and start to flex. Then you can cut it - I use scissors.

Cut a couple inches, heat, cut, etc. This stuff costs a small fortune and I don't want to ruin it.

The original guard has a soft curved bevel at the edge - not a sharp angle like you'd see on a Gibson or Fender guitar.

It's hard to photograph, but you can see the curve here.

When I cut the guard, I leave a little material to work with to trim to exactly the right fit. And when I file the final shape, I can also file that tapered edge.

After the new pickguard is shaped, I like to warm it a bit and put it between some waxed paper and then some wood blocks and clamp it flat.

All of this is to make it lie flat on the guitar.

Then I use double-sided 3M tape on the back of the pickguard and trim it to shape.

Then place the new pickguard on the guitar, and make a couple of hinges with artist's tape so the guard can 'swing' up and the paper on the tape can be removed.

Swing the pickguard up and remove the paper. I started a corner of the paper before I put the guard on so it would come off easily.

Then carefully put the guard down, and press it flat.

It came out well - it's flat and looks good I think. I have that tiny area near the tip to touch up, but it's ready to go otherwise.

NOW I'll glue the neck back on.






 
 

Repairing Acoustic Body Cracks: 1931 Martin 0-18T Restoration and Repair, Pt. 6

I decided to do some body repairs before I reattach the neck on the 0-18T,  It's a lot easier to handle the body alone without the neck attached.

There's a crack on the lower bout on the bass side of the body. As it turns out, someone had previously squirted some glue in the crack, but I wanted to back up the crack with a cleat.

The sides are mahogany, so I used a piece of mahogany for the cleat. I cut a small rectangle and traced the curve of the side onto it. Then I cut the piece on the bandsaw, following the curve, then I thickness sanded it on the ROSS.

The sides of the guitar are quite thin - about .050 of an inch or about 1.27mm. So I sanded the cleat to be just about that same thickness.

I also sanded some small chamfers on the edges of the cleat (the arrow points to one).



Here's the cleat lying on the outside of the body near the crack.

Since it's thin and light, the cleat will flex and follow the shape of the side when it's clamped in place.



The problem now is how on earth to get the cleat in position? I can't reach the crack by hand from the inside.

After a couple of failed attempts trying to tape the cleat to long needle nose pliers which were too clunky, I came up with this approach.

I put a small pin into the cleat, then used my parts grabber claw tool to hold onto the pin.

It worked well.

I put a piece of masking tape under the crack so I'd have a visual reference as to the crack's location.  Then I lined up the bottom of the cleat with the kerfing - the crack was right above it.

Then I used a pair of repair magnets to hold the cleat in place.

It was during this process, with a light inside the guitar, that I clearly saw some glue that had dribbled down onto the kerfing - where the previous repair was done. I'd guess the repair person realized the crack was virtually impossible to get to.

It's not a bad repair, but this cleat is an improvement.

Look at how well made the bracing is - not a bit of glue squeeze-out or sloppy work to be seen. The craftsmanship on these old Martins is something to emulate when doing repairs or building new instruments.

There are also three cracks on the upper bout on the treble side of the guitar. I used the same approach to this repair.

The curve here isn't as pronounced, but the cleat does have a slight curve to it.

Note that the grain of the cleat is also perpendicular to that of the side, which will add strength to the repair.

All three of the cracks are quite tight, but I was able to open the topmost crack a tiny amount. I put a pin in the opening in order to spread hot hide glue into it before I put the cleat on the inside. I like to get glue into the crack if possible.

Since the sides are so thin, the edges of the crack want to break up - we have to be gentle opening the crack this way.

This cleat was much easier to install.

I taped the top neodymium magnet to the cleat, put glue on it and put it in place inside the guitar.

Then I put a mating magnet on the outside, and then put another pair of magnets to hold the bottom of the cleat.

This is what the magnets on the outside look like.

These things are fantastic for these kinds of jobs. They're incredibly strong - you need to be careful that you don't pinch you fingers if you let 2 of them get near each other on the bench!

Next I'll make a new pickguard and (finally) put the neck back on.

 
 

Caul for Heat-straightening Guitar Neck: 1931 Martin 0-18T Restoration and Repair, Pt. 5

I mentioned in an earlier post that I will be attempting to straighten the neck on the 0-18T. It has a pronounced upbow from about the 4th fret or so down to the nut. So the plan is to heat straighten the neck first to get it reasonably straight, then use compression fretting to keep it straight under string tension.

Since I'll need to clamp the neck straight once it's heated, I figured I should make a caul to fit the back of the neck so it doesn't get all hacked up by the clamps.

First I transferred the approximate profile of the neck to a hunk of pine that will become a caul when it grows up.

You can see I just used a compass to follow the curve of the neck and roughly transfer it to the pine.

Here's the mark I made on the end of the block.

Note that the neck is narrower at the nut end, and it widens toward the body, and naturally, the profile changes too.

So one end of the caul-to-be has the shape of the nut end, and the other end has the closer-to-the-body end.

Then I made lines connecting the two profiles on the ends.

The nut end (narrower) is nearest the camera here and the body end is on the far end.

Now I need to cut the wood following the marks and create a sort of reverse neck profile.

I used a 1/4 inch wide blade on the bandsaw and hacked out the shape.  It's a bit rough, but it doesn't have to be super accurate.

If I was really good with the bandsaw, I probably could have followed the curver closer, but I am not, so I didn't.

So I used a chisel to cut away more material in an effort to make the channel more rounded and shaped more like the profile of the neck.

Fortunately it's pine and its soft, so I did ok with the chisel.

During this phase, I tested the fit of the neck a number of times to get it to fit well, so it would sit level when it's clamped.
.

I tried my nice Japanese rasp to smooth the thing out, but it's a bit too short. Memo to self: get a bigger rasp.

Then I got this crazy idea of making a curved sanding block to sand the profile.

It worked ok...close enough that I could move forward.

You always need more clamps.

Here I had cut some cork to use as a facing for the caul. It's really just three long pieces - and it was glued into the channel/profile in the caul.

I though the cork might flex enough the closely follow the curve, but it didn't. It's not critical though. I bet really thin cork would flex more, bu then it might also crush too much under clamping pressure.

After the glue dries, I cut the excess cork off the ends and sides of the caul.

Then it was over to the ROSS to sand the cork smooth with the pine.

Here's the finished caul alongside the neck.

The seams between the cork pieces won't be an issue. The main thing is the caul will act like a little cork-lined bed for the neck and protect it when it's clamped up.

End view showing the profile. The most fun part of this whole thing was sanding the cork level with the pine. Looks really cool I think.

And a test fit.

Since the caul has the neck's profile cut into it, the neck fits nice and level.

After the neck is back on the guitar, I'll pull the frets and heat the neck, put some square blocks on the fingerboard side, and clamp the neck straight. You can see why I needed a caul for the back of the neck - the clamps will need something to grab on to.

I've found I'm starting to enjoy making custom jigs and pieces like this. At first, I wanted to rush and get back to the repair (or construction), but now I realize these special things are rewarding to make.

 
 

Shimming Guitar Neck Dovetail and Finish Chip Repair: 1931 Martin 0-18T Restoration and Repair, Pt. 4

We now have the correct neck angle (aka correct set or pitch). Since material has been removed from the edges of the heel where it meets the body, it doesn't quite follow the curve of the sides of the guitar.

To get a nice fit, we hold the neck in place, and pull some sandpaper through the joint, facing it upward so it removes material from the heel.

If your fit is close, it won't take many more than 6 or 8 pulls on either side.  It's important that you watch to make sure the sides are level. I usually do a couple of pulls on one side, then the other. If you're not careful, you'll introduce a 'tilt' of the neck from one side to the other, and potentially mess up your nice neck set.

I used to use regular 100 or so grit paper for this. But normal paper is thin, and it will tear and break. So I sprung for this paper from Stew-Mac. You get a lot for the money, and it's heavy so it won't tear.

The fit in the dovetail is pretty good, but I want to get it a bit tighter, so I made some thin shims from cedar and glued them to the dovetail.

The shims are thin - maybe .050 of an inch or less.

I had previously made angled cauls for this job.

After the glue is dried on the shims, I put some carbon paper over the shims and fit the dovetail to the guitar. The paper will leave marks on the shims where the shims contact the dovetail.

You can see the marks here.

Then we use a scraper to remove material from the dark marks left by the carbon paper.

Repeat this process until you have a tight fit on the dovetail. The joint should be tight enough that the guitar could be strung without the joint being glued. The reason for that is transfer of vibration, which means good tone.

It will take me 6 to 8 passes like this until I have a good joint where the dovetail seats with a little pressure, stays in place on its own and doesn't wiggle from side to side.

Two things here.

One, you can see the final scraped-down shim. It's really thin - so thin that parts of the shim are gone.

Second, I stupidly chipped a hunk off the neck heel while scraping.

I'm not happy, but I can repair that chip.

File some mahogany sawdust with a rasp.

I used to use sandpaper on the wood for these fills, but you tend to wind up with sandpaper dust in the wood dust.

Pack some mahogany dust into the chip.

Then hit it with thin CA (super glue).

You can see the glue will help darken the color of the fill.

The fill material will tend to sink down as the CA is applied, so it may take a couple applications to fill the chip. This one took three passes. I like to leave the fill a bit 'proud' of the surface so it can be levelled.

Then I'll use some yellow/amber binding toner nitro lacquer I made up. The original lacquer used on the guitar was clear, but it's now yellowed over time, so we can emulate that color to match the original lacquer color.

Scrape and sand the repair so it's flush with the surrounding wood.

I used artist's tape to cover the area around the fill since I don't want to sand that area.

Then put several coats of the toner on the repaired area. It won't be totally invisible, but it won't be obvious unless you're 10 inches from it.

The lacquer can be sanded and polished as you usually would after a week or two.