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Hey all,

I read on here about installing frets causing a back bow in the FB and neck. My neck is currently being built and is just a block of 3 lams atm, so should I glue on the fret board, cut the sides to size, fret it, and then cut the back to size and shape.

Or cut the back before I fret it?

I'm just thinking that if I fret it while its still a solid block it is less likly to bow under fretting.

Cheers

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Hey all,

I read on here about installing frets causing a back bow in the FB and neck. My neck is currently being built and is just a block of 3 lams atm, so should I glue on the fret board, cut the sides to size, fret it, and then cut the back to size and shape.

Or cut the back before I fret it?

I'm just thinking that if I fret it while its still a solid block it is less likly to bow under fretting.

Cheers

Joint the fret board side of the neck blank, glue up the fretboard, carve and re-check for fretboard flatness. Adjust if necessary.

You're now ready to fret the thing up. Some people like the fret before carving. I think its a bad idea... but that's just me.

Edited by guitar2005
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Some people like the fret before carving. I think its a bad idea... but that's just me.

Can you elaborate why you think thats a bad idea?

Thanks for all the responces :D All slightly differnt methods, I guess there is no set in stone correct way to do things.

like i said in the first post, if you take a large amount of wood of the back when you carve, it has a great chance of shifting shape. i cut neck to shape, glue fretboard, level, carve, then fret.

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Some people like the fret before carving. I think its a bad idea... but that's just me.

Can you elaborate why you think thats a bad idea?

Thanks for all the responces :D All slightly differnt methods, I guess there is no set in stone correct way to do things.

like i said in the first post, if you take a large amount of wood of the back when you carve, it has a great chance of shifting shape. i cut neck to shape, glue fretboard, level, carve, then fret.

Yeah... what killemall8 said

:D

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  • 4 weeks later...

I start with a block. Add fretboard and frets. Level, buff, etc. Dont touch the frets again.

Then carve the neck.

Never had a problem with a neck moving, but i use very dry timber.

To me, its a pain in the butt to fret after carving, i cant get the installation as consistant, and there is a heel and headstock to get it the way of it sitting nice and flat in the press.

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To me, it's important to have everythng square, straight and flat. I have found it more controllable for me if I fret the board separately and then glue to the almost-completely-carved-neck. Before fretting, I make sure that the FB is dead flat. After fretting, it often is bowed. I correct that bow by clamping with the appropriate spacer that moves the FB back to flat. It usually takes a clamping overnight to get it back to flat.

The neck surface must also be confirmed flat before gluing up. I glue the FB to the neck with West System Epoxy...not Titebond...because I don't want to introduce water into the neck and have it warp or bow. If you can get it all glued up flat and straight then you can control relief and setup issues.

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To me, its a pain in the butt to fret after carving, i cant get the installation as consistant, and there is a heel and headstock to get it the way of it sitting nice and flat in the press.

I want to try this method the neck time, it will definitely make the fretting part easier.

On the other hand, I have a number of prefretted fretboards I'll be using next, so that's a different issue.

I don't buy the 'wood moves after carving' idea, really. I mean, if the wood is going to move like that, then wouldn't that mean it's just not ready to be used?

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I don't buy the 'wood moves after carving' idea, really. I mean, if the wood is going to move like that, then wouldn't that mean it's just not ready to be used?

No, it's just that it has internal tension such that one side of the board is holding the other in a certain position. Remove that side, and the other will move. You will often see this when you run a board through the tablesaw. The two halves may either bend inward or outward. Usually most of this stress is relieved by the time it is cut as small as a neck blank, but sometimes it isn't.

You could argue that such a board shouldn't be used for a neck, but it's not because it isn't dry enough yet.

I bandsaw the back profile about 3/32" oversize after truing up the top face, but before I do too much else.

If it bows more than than 1/16", it goes in the scrap pile, and I haven't invested a lot of time in it.

Usually it doesn't even bow that much, if at all, but that is the moment when you will see it bow, if it is going to.

If it stays straight after that, any further carving is unlikely to affect it, so after truing up the top face again, I leave it like that until I get the fretboard on and the sides tapered. I usually carve the neck before fretting, but not for any particular reason, and I think I may start fretting beforecarving, because it does seem like it would be easier.

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I don't buy the 'wood moves after carving' idea, really. I mean, if the wood is going to move like that, then wouldn't that mean it's just not ready to be used?

Mick,

You have to understand how wood dries and the tensions that form. Some of which balance out some of which store in a balanced(against the volume of wood that makes up the piece). It is easy to see the tension that builds during drying, because it sometimes becomes so great wood will actually rip itself apart (cracks, checks, shake). Those places where the forces became too great are only the places where the wood actually exceeded the threshold, tension and pressure are still working throughout the board. During intitial drying these forces become strongest beause the wood is changing the most volumetrically. As the wood reaches a dryer point it has gone through many changes and tried to balance out those stresses. This does not mean the wood has realeased all the stress, it has just balanced (hopefully very well).

A couple things you have probably done would show you first hand how these things work. Have you ever had a wild grain veneer(thinner wood) that was drying warp like a potato chip after it has dried? Thin wood does not store much tension, because the wood is easily moved, it simply moves with the tension. That is a good way to see first hand how radial, tangential, and longtitudinal shrinkage varies. If you had a veneer that was very straight grained(maybe an acoustic soundboard), you would have probably noted the wood changed in dimension as it dried, but did not warp and twist in different directions as much. Now a thicker piece of wood, say a 8/4 body blank, is not about to move as easily as a thinner piece of wood. Where do you think that tension goes? Well if it does not crack or split, it is going to balance out based on how strong the wood will resist bending. The wood is able to hold its shape based on strength and size. How oddly balanced are the stored tensions in the wood? Look back at thin veneers that could react to the tensions (straight grain, probably very little, wild grain will vary a great deal). These things are easy to test and see first hand, no need for voodoo or magic. I can't imagine a wood worker would go very far without experiencing these things.

Now in Perry's case. He understands you need to use clear, straight grain wood and is going to select wood that is not wild or oddly grained(he would be up to his ears in warrenty work if he didn't). He allows it enough time to dry fully before use. He has stacked the cards heavily in his favor. He will probably go a long while before he runs into a board that had a strong imbalance in its stored tension. Most likely he will just toss it and move on, or the dimensional change is small enough that he will square it back up and the wood will be pretty stable in its new shape.

In the case of the hobbiest. I suspect you will find more instances of "mysteries", like "the neck warped on me and it was supposed to be dry and everything, how do I fix this? The wood must have been wet... or I bought "bad" wood". This is going to mainly be a product of not selecting properly or understanding why they should do so. I get a bit worried when I see people selecting crazy neck wood or giving advise that these things make no difference. The fact is they do make a difference, but there is little you can say that will convince someone who is not willing to study up on the whats and whys, then look at what is happening in front of them. Worst case you have an issue with a guitar you built, and you deal with yourself for warrenty issues(not a biggy).

Select wood that is going to be inherantly stable, very well dried, and stored tesion will not likely be a big issue. If you carve first you can get a picture of what it will want to do closer to its new dimension. If you attach the fretboard first, that may help the wood store more tension after carving and not move as much (the one direction a fretboard will not resist moving much though is in back bow FWIW). If you have a crazy grain fretboard, it may be wanting to move all over the place after surfacing, that will leave it up to the shaft to resist those stresses. To me it makes sense to try to see these things, and build in as little stress to a neck as possible. Manufacturers pay attension to these things because they can't afford the warrenty costs. The neck is the heart of the guitar, I try to do anything I can to make it as stable as possible.

Peace,Rich

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Great explanation, Rich!

I think you really nailed it...and it's for that reason why I keep wood seasoning for some time at almost every stage of the neck making process. The original boards may be in house for years. Once the laminate block is glued up it may be 6 months+ before I bandsaw the neck blank. And before I ever begin the initial carve, I check it for flatness and continue to evaluate changes as it gets closer to final shape. It needs to stay flat for a month or so before I glue up the fretted FB.

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You know, I'm sure I've just gotten lucky so far, that's all. So I'll just hush up now. :D

For the moment, I have several blanks laid up, just waiting to be built into necks...don't really have time for that right now though (starting a new band, I need the time to make music), so waiting should only help the wood.

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I've done a few necks, recently, multipart, laminated, quartered, no runout mahogany that I've had stashed for at least 4 years, and was dry when I bought it anyway. I planed things flat and perfect in block form, then carved them roughly to size, and yes, they all moved. A tiny, tiny amount, but they all moved (less than a mm over the entire gluing surface).

I have no trouble believing Perry's necks don't move. First, gluing a fingerboard on is probably enough to counteract this tiny amount of movement. Second, if you glue in CF rods as well (not sure he does, but I'm guessing he does; I do, after rough carving), this adds yet a little more stiffness. So the neck's unlikely to move. But I also believe folks like Rick Turner, who did it the 'glue then carve' way for decades, and have noticed a decrease in any neck warrantee work since switching to carve then glue - and no disrespect at all to Perry, but he doesn't have nearly as many years or guitars in the game. Material selection is 90% of the game, though. I also can't say I've ever had trouble fretting necks in their carved state, but that's down to personal preference I think.

Mick: very, very wise indeed.

I tend to glue up neck blanks as early as possible in order to ensure they're as stable as possible. Grain selection is phase one, then I rough cut to neck blank sizes, then laminate them up when I have a clue as to which guitar they're going to be going on, and wherever possible leave them like that for a few weeks/months. Then rough-carve early in the building process, and get on with the fingerboard/fretwork/body work, so it's been sitting around like that for a while as well. And this is generally with wood that's been in storage for years already.

Edited by Mattia
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