As The Wood Moves...

I picked up the red/black strat the other day and noticed a big gap between the neck and body. I could fit my thumbnail in there easily. I was kind of shocked. I didn't know how it got this way. The first guitar (sapele body/maple neck/cocobolo FB) has been rock solid all along. I thought this was how they would all be.

At first I thought the screws had become loose so I tightened the screws but the gap remained. Also, I could see how the neck had bowed forward, something I didn't expect because the maple I used for that neck had a back bow. I was worried because I thought something was going on that was beyond my ability to comprehend. I've had this belief for a long time there's a mystique to building guitars that can only be unraveled after decades of apprenticeship under a master.

Today I took the guitar down to the shop and removed the neck. I found that gap was my fault. Apparently (and I really don't remember this) I had to re-rout the neck pocket a bit deeper (it's coming back to me, vaguely) because there was no evidence of finish in the pocket. When I did that, I left a small lip on one side and so the neck was never fully seated in the pocket. :o I took a couple of chisels and fixed that.

I also found some of the flat surface of the body had ripples in it. The ripples followed the maple figure. So the wood was moving, not with the grain, but with the figure. And one spot had ripples that looked like the lacquer sagged. That wasn't there after 4 weeks of curing. Interesting thing is none of these kinds of things appeared on the first guitar.

Why did the maple move so much? And there's a break in the lacquer where the two halves were glued together. Is this normal?

I've done a little investigating and if what I read was right, the maple stock I used wasn't dry enough when I milled and sanded it. Once it reached equilibrium with the surroundings (and this was in the summertime) the soft cells shrunk more than the hard cells and caused the rippling effect. The split in the lacquer seam may support the theory the wood wasn't fully cured when I began working on it.

As for the sagging of the lacquer in that one small spot, I'm at a loss. It doesn't look like it's from damage.

It looks like the maple wasn't dry enough when you made the body out of it.

These days,Winter is so dry,I have had trouble with wood movement in guitars I have had for years. Guitars that are vintage have had problems with seams opening. A flamenco guitar I made for myself in the 70's got a crack in the top.

I have gotten to where I dread Winter's coming. Or,it could just be the house we are living in now is drier than previous houses. This house has a basement. The others didn't. That could be contributing to the house being drier.

Flamed maple (and other figured wood) changes with age even if worked when perfectly dry. The flames are a sort-of end grain, and change with cycles of temperature and humidity in a different manner than the plain areas. This is similar to what happens when you stain curly wood; the curls (flames) absorb more of the pigment. Feel the back of an old fiddle or cello made of figured maple and as you run your hand parallel to the grain you will feel hills and valleys. It's a beautiful thing!

I agree that old curly maple violins will often have contours in their flames. But,Julie's guitar was not an old instrument. I think her wood was just not really dry enough. An arch top guitar I made in the 80's has not yet begun to show contours in the curly maple.

Maybe in 100 years it may.

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Originally Posted by george wilson

I agree that old curly maple violins will often have contours in their flames. But,Julie's guitar was not an old instrument. I think her wood was just not really dry enough. An arch top guitar I made in the 80's has not yet begun to show contours in the curly maple.

Maybe in 100 years it may.

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You know there's a market for distressed and well worn guitars, and ones that looked aged. Maybe I've discovered a way to make the guitar look 100 years old and can make a fortune selling them. ;)

On a more serious note... I took a closer look at what I described as "lacquer sag" (this is a separate issue from the wood rippling). "Sag" was a bad description. What it looks like is the wood cells shrunk to a degree that it created pits in the finish. It's an area only covering about an inch in diameter and I haven't had any luck getting a good picture of it. But I'm thinking the problem here is the same as the rippling issue, even though I had the wood in the shop for a few months before I started making the body. It was left over from the body I made for Brian's guitar back in Dec of last year. I started the red/black guitar in mid to late February. I looked at Brian's guitar and it doesn't have the rippling but it does have the same pits in the finish, only more of them. But for his guitar I used spray can lacquer, if that would make a difference, I don't know.

I've always allowed newly purchased wood to sit in the shop a month or more and have never seen this kind of thing before. I'm not concerned with repairing it because it is so minor, I'm just trying to understand what happened and determine if it can be avoided.

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Originally Posted by george wilson

I agree that old curly maple violins will often have contours in their flames. But,Julie's guitar was not an old instrument. I think her wood was just not really dry enough. An arch top guitar I made in the 80's has not yet begun to show contours in the curly maple.

Maybe in 100 years it may.

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You have a point there. However, if the wood was scraped rather than sanded, contours can occur very quickly. If you have ever seen/felt a Burgess fiddle you will concur, as his brand new instruments feature incredibly textured maple parts.

I don't understand what you mean by pits,Julie. Are you using silicone spray in the same room as the guitars being made? Getting wax on anything?

Sometimes you learn more about guitars after you build them.

Figured maple telegraphing through finish is pretty standard stuff regardless of how dry it was prior to finishing. This is not to say that the condition won't be worse if you have "wet" wood. You will minimize this phenomenon if you build in a climate that replicates your playing climate. To that end I managed the humidity in my shop and in my guitar room to within 5% for years.

Acoustics can really show off the mapple under finish but lots of builders give the inside of the guitar a shot of sealer to reduce the moisture uptake on the inside.

As for you lacquer "crack" at the glued edge of the book match I'd be willing to bet that you actually don't have a crack (a picture would likely make a fool of me). I would bet that you used PVA and what you are seeing is "creep". This is also standard stuff and something that you can reduce greatly by managing wood moisture better as mentioned above or by using a different glue.

Personally after years of building I would say that a tight neck pocket 0/0 is a bad idea. Lack of adjustability and finish chipping at the pocket edge are most oftern the results.

Spring and fall, two times that every guitar needs adjustments to compensate for pretty radical swings in relative humidity, in the fall the truss rod gets tensioned in the spring it gets loosened.

Humidify your house and concentrate on your guitar room and you'll see less of all of this.

I thought that being able to buld a guitar meant that I understood the instrument as a tangible object. It sort of did but living with the instrument over time and after playing hours really showed me that I had simply made something that then went on and did it's own thing - then I actually began to understand more about the guitar. Seems that you have too!

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Originally Posted by Chris Fournier

Personally after years of building I would say that a tight neck pocket 0/0 is a bad idea. Lack of adjustability and finish chipping at the pocket edge are most oftern the results.

Spring and fall, two times that every guitar needs adjustments to compensate for pretty radical swings in relative humidity, in the fall the truss rod gets tensioned in the spring it gets loosened.

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Pretty much. Because of the jig I use to cut my neck pockets, they're more or less perfect every time. Look up David Myka's neck pocket jig. It's a brilliantly simply and effective design! I shamelessly stole the idea from David, and it's hard to imagine doing it any other way if you're cutting them by hand with a router. They're so tight, in fact, that I can't even glue them...there's just no room. I have to loosen them slightly to glue them, and I tend to loosen them more for bolt on necks. I'm always afraid that someone will crack something on a bolt on trying to get it in and out of a tight pocket.

But the truss rod thing is definitely not abnormal in climates with huge humidity changes. When your house is heated in the winter, the RH typically can drop close to single digits, believe it or not. Contrast that with 50%, or maybe even more, the rest of the year. :)

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Originally Posted by John Coloccia

Pretty much. Because of the jig I use to cut my neck pockets, they're more or less perfect every time. Look up David Myka's neck pocket jig. It's a brilliantly simply and effective design! I shamelessly stole the idea from David, and it's hard to imagine doing it any other way if you're cutting them by hand with a router. They're so tight, in fact, that I can't even glue them...there's just no room. I have to loosen them slightly to glue them, and I tend to loosen them more for bolt on necks. I'm always afraid that someone will crack something on a bolt on trying to get it in and out of a tight pocket.

But the truss rod thing is definitely not abnormal in climates with huge humidity changes. When your house is heated in the winter, the RH typically can drop close to single digits, believe it or not. Contrast that with 50%, or maybe even more, the rest of the year. :)

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Agreed wholeheartedly about your neck pocket observations John. It didn't take me long to see that relative humidity plays a critical role in instrument health, heck likely even my health. I have spent some $$$ keeping the humidity in my house moderated. In the winter I shoot fo 45% RH as a minimum, the instruments appreciate it!

As a craftsperson I pride myself in 0 tolerance work but over the years I have been reminded with objects in service over and over again that 0 tolerance ususally leads to heartache and needless failure. A craftsman figures out what actually makes a piece work in situ and then builds accordingly. I am still learning to loosen up.

I just haven't had trouble with figured maple telegraphing through the finish. It might be the way you sand it smooth before lacquering ? A sanding block is better than loose sand paper,which will ride the grain. This might seem a simple solution,but then,there's Occam's Razor.

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Originally Posted by george wilson

I just haven't had trouble with figured maple telegraphing through the finish. It might be the way you sand it smooth before lacquering ? A sanding block is better than loose sand paper,which will ride the grain. This might seem a simple solution,but then,there's Occam's Razor.

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I agree that sanding figured maple without a hard backing is a poor practice!

Some interesting info.
https://www.youtube.com/watch?v=Y_jaWKEGhoc