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I ran into a shortage over the weekend of Mahogany for neck blocks. Short story is a screwed up the last one I had. I've since solved the problem but began thinking in other directions.

Has anyone considered Indian Rosewood or Paduak for neck blocks? I was brainstorming some sort of laminated neck block using these two species since it was what I have.

I think Padauk is an incredibly under rated tonewood.

Chris

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OOOOW! rather heavy why not a lamination of birch ply? less weight and more strenght.

Hmmmm....I want to push this thinking a little.

It could be said that since everything guitar 'marries' at the neck block....one could consider all options.

For example: Honduran Mahogany is listed as having a lower weight, density, crush strenghth, and specific gravity over Padauk. Here are the numbers via the web.

Species Weight (lbs / cuft) density (lbs / cuft) crush strength specific gravity
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H. Mahog 31 36 6465 .59
Padauk 45 46 7720 .72
Sapele 42 42 8788 .62
EIR 53 53 6910 .85

I have all of these woods in my home....dimensioned to every imaginable state. Of the 4 mentioned...nothing 'pings' like the Padauk and EIR. By 'ping' I mean rap your knuckle against it...assuming you can find the node....and what you get is a ping. There seems to be a correlation between the specific gravity and the ping-tivity of the wood species...I just made that up....did you see that?...I made a word!!!!!!!

I don't have brazilian so don't go there.....

I want to try it. I know there is a weight sacrifice to be made but not much. I have heard it stated that necks made out of East Indian Rosewood change a guitar to a great extent. Why not the neck block too?

Chris

PS - I can't get the numbers to fall where I want them too....

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I have played an OM with IRW neck and I believe but am not sure the neck block was IRW as well. It stunk like 3 day old road kill in the middle of July. The bass was weak but sustain was good. I am not sure how much to attribute to the neck or the box. Mass can aid sustain but does not necessarily translate into more energy transfer.

I have made several guitars with Sapele. They were just fine. Padauk may very well be a good choice. I personally just don’t see IRW as a good option.

Another way to analyze this is to ask your self; How many top end guitars have I seen with IRW necks and or neck blocks? Then ask your self; Is there a reason? Is that reason cost> IS that reason stability? Does the reason have anything to do with performance?

Mmmmmmmmmmm where's my mesquite? it's time for some BBQ.

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Bill Hodge


One does not simply, own enough guitars!

Stability is the key with the neck block. I've been laminating mahogany for my neck blocks lately. It's easier to get thin mahogany and to laminate it (costs less too). I've done 2 and 3 ply laminates.

I wouldn't have an issue but for ascetics using laminated birch plywood too. Actually, 2 pieces of birch plywood with mahogany veneers to make it look mahogany (just to alleviate that "ew, plywood" syndrome) as a neck block. It would be lighter and more stable than a solid mahogany block.

It's my understanding that we want the neck/fb and the block to be as rigid as possible so as not to rob the top of vibration. Yet weight is also a factor. So stiff but not heavy is the key IMO.

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Light and stiff right?

Mass can sometimes be good!....to paraphrase Mario.

Herein lies the Voodoo.

I don't know....admittedly I don't know. One thing about this guitar making thing is that funding your own R&D SUCKS!....

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I always make my neck block from the same wood that I make the neck from, so for a mahogany neck I use mahogany neck block, cherry necks get a cherry neck block etc.

The neck block is underated in its importance to the overall guitar, every major component attaches to it, neck, top, back, and sides. It plays a part in transferring neck vibrations to the top and adding harmonic colour and aiding sustain. For that reason alone I would be wary of using birch ply, the damping effect of all those glue layers would concern me.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I do a three piece laminate just like the neck for mine.Usually ASH,walnut,maple,cherry,and mahogany are the woods i use for blocks.They all do a fine job.

Many (If not most!) archtops use a spruce neck block and I think Mario wrote one time that that is what he uses as well. Just another option! It is in Benedetto's book and I have discussed this with some of my high end archtop customers and they report no issues at all with using spruce, aside from the added benefit of decreased weight!

Shane

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Canada

Using Spruce crossed my mind too....but I don't have any of that stuff thick enough for neck blocks.

BTW - I know Mario laminates his tail blocks but I am not sure about the neck block.

I am going to do a guitar with a Padauk neck block but first I need to settle the rest of my build questions. Right now it's too early to throw that into the mix. Just wanted to know what other's thought about it.

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Chris, I'm going to run the experiment with you on my next build. A while back I set aside some padauk for linings, hhg laminated neck and tail blocks and hopefully back braces. I haven't run any deflections tests yet, but according to what I've read padauk is stiffer than h mahogany so I'm hoping I'll be able to downsize the braces to offset some of the weight gain. If the test results are poor, I'll probably just stick with mahogany braces. One thing I didn't see in your post was a comparison of stability. I believe they are both very good, but mahogany is a little better. As far as the experiment goes, my thinking is that it's worth finding out if there is anything to gain by replacing some fairly major components with what is in my opinion a sonically more active wood. We'll see... One thought about "we use xxxx for a reason." Perhaps we use mahogany not only because of its physical properties, but also because it was cheap and plentiful. And why mess with success until something forces you to change, right? On the other hand, if anyone one can hook me up with some of those $50 sets of old growth BRW I've read about, I'll be happy become a staunch traditionalist.

One thing I recall Mario doing is he drills vertical holes in his head blocks to reduce the weight. He than adds a plug over the holes when gluing the plates on so no gluing surface area is lost. He does this it says on heavier guitars like cocobolo.

Here's a picture from his website.

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"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

The sonic advantage is really what I'm after. Truth is...I'd sacrifice a few more ounces for a better sounding guitar. Tradition has some deep roots in the guitar makers citadel. I'm just challenging them. I'll finish the one that's on the bench now before the 1st week of June...and then it's game time. I'm going to use a Padauk laminated neck with a Padauk neck block. Everything else will be the same (to the extent that I can control it). I would be hesitant to change too many things at once because you loose the ability to attribute changes in tone to the changes you made in the build.

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Unobtainium! Infinitely strong and has no mass!
Seriously, I have used walnut, especially when I made walnut necks...generally on walnut bodied guitars.

And on the custom units I've built with the Harvey Leach "Voyage Air" folding necks I use the fine birch plywood, with the mahogany veneer as mentioned previously. I want those neck blocks to be especially strong and rigid as they take all the folding and unfolding stresses of that folding neck system.

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Hank Mauel

I wish we could all stand around a table and talk about this. Some of this Padauk I have will make your eyes miss a blink or two. An interesting exam would be to make two guitars side by side....keeping the builds identical to the extent that one can....both with Padauk neck blocks and the traditional laminated mahogany neck on one and a laminated Padauk neck on the other.

I hear ya Todd. I really like Mahogany from a furniture making point of view. It's use early on in the craft is a strong testament to it's 'manners' in the shop. Considering that hand work was all they used in the construction of most of the Federal and other mentionable styles of furniture. I even love it for back and side sets.

Remember this whole thought process was born from not having Mahogany on hand for a simple little neck block. Again I was able to obtain some...but only after phone calls and driving and waisting a day. I didn't have the nerve to just simply 'do it'.

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Padauk is a pretty good rosewood substitute, except that it has a tendancy to split. Just that would make me think twice before using it for a neck block.

I'm not sure what vibrations are transmitted to the body via the neck joint. On my 'test mules' I use a simple removable neck: there are a couple of pins in the end of the fingerboard that plug into holes in the stub figerboard glued to the top. A bolt through the bottom of the heel goes into a T-nut on the inside of the neck block, and keeps the neck from rotating upward. There's about a 3-5mm gap between the neck heel and the side otherwise. Putting is a wedge to make the contact more solid doesn't seem to make any difference in the sound. I'll note that at least one other well-known maker uses a similar (but nicer looking) setup, with no complaints about 'loss of tone' because of it.

There is, of course, the lowest structural resonance to think about. The whole neck and body system vibrates like a xylophone bar, with the nodes (stationary points) being somewhere around the nut or first fret, and a line across the wide part of the lower bout. This mode does involve a lot of bending of the neck, and it's often called the 'neck mode', even though the body is also in the game. Normally this mode is pitched well below the 'main air' resonance, which is the lowest pitched mode that actually produce much sound. However, if the neck is stiff and the headstock light it can be pitched up around the 'main air' frequency, and then it will effect the timbre of the guitar. It 'spreads out' the main air peak in the spectrum, and the guitar often has a particularly 'rich' or 'dark' low end.

In this resonant mode the neck block is near the antinode; there's a lot of motion there. This would suggest that it would be a good idea to keep the mass of the neck block down, if you want to tune the 'neck' mode high. I haven't done any experiments on this, although I suppose it would be pretty easy to do so. If you support the gutiar at the nodes with foam blocks it's easy enough to drive the 'neck mode', and easy to feel the vibration of the headstock when you hit the rigth frequency. For that matter, if you hold the guitar up by pinching the neck at the first fret and tap on the back of the headstock you can hear this mode. A gob of poster putty on the back at the block location would give you some idea of how much effect more weight in the neck block would have on the mode pitch, and you could play the guitar to see if you liked the outcome.

I suspect that, in most cases, fairly large changes in the neck block mass would not have much effect on the tone, simply because the 'neck mode' is usually not close enough in pitch to the 'main air' mode to couple effectively. When these modes ARE close in pitch, then small changes in mass on the headstock can effect the tone a lot. Maybe the neck block would have a similar effect in those cases.

Alan....are you suggesting that one could 'tune' a neck?....and that if you could get the neck's resonant mode (pitch) to be close to the main air resonance of the box....you might realize a change in tone?

Would an increase in mass equate to a lower resonant mode of the given item? Neck versus body versus bridge blank etc.

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Chris:
Sure you can tune the 'neck mode', and, yes, it does effect the tone. The problem is that it's often hard to move it far enough to be helpful. It's usually too low in pitch, particularly on 14-fret necks, and it's hard to raise it.

The pitch is set by the relationship between mass and stiffness in the system. A stiff neck will tend to give a higher 'neck mode' pitch than a floppier one. Conversely, more mass to move will give a lower pitch. So you have to think about what's moving, and what's bending.

In this mode both the body and the neck are bending. You can't usually do too much about the body once it's together, and it's hard to say what the variables are here. Obviously, a deeper neck, such as a 'razorback' profile, will tend to be stiffer than something that's flatter and shallower. Tapering the neck, making it deeper at the body end than the head end, helps too. CF rods help make it stiffer, but not as much as you'd like. CF is really good in tension and compression, but the way it's usually used in a neck it's near the 'neutral axis', and is mostly in shear (thanks to Dave Hurd for pointing that out). The shorter the neck is the stiffer it is: 12 frets are usually higher pitched than 14 frets.

The thing that moves the most in this mode is the top of the headstock, so mass there can have a pretty big effect. This is why swaping tuners can alter the sound of some guitars. With sealed gear units changing from metal to wood buttons can save the weight of two machines, and that's useful sometimes.

One issue is that the 'neck' and 'air' frequencies have to match almost exactly to have much of an effect on the tone. If they're as much as a semitone off, it probably won't work, and at the low frequencies we're talking about (G=98 Hz or so) a semitone is only about 6 Hz.

Usually the 'neck mode' is too low, as I say, and it's hard to raise the pitch on a completed guitar unless you can swap out for lighter tuners. I did make one short scale Classical with a walnut neck on which the 'neck mode' was high. It had a Red Spruce top (what WAS I thinking?), and the sound was pretty 'forward', so I really wanted to get that low-end match to help smooth it out. Since most Classical machines are not much heavier than the Sloans I used on it, I ended up taking them off, drilling a couple of holes under the tuner plates into the upper part of the head, and filling them with lead plugs. Of course, I used poster putty to figure out how much weight it would take first. It worked nicely, and was not noticably head heavy. Any port in a storm.

Alan thanks for sharing that information. It must have taken you a long time to come to those conclusions.

You've got my mind thinking in all sorts of directions. That was good information.

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