Ken - thanks so much for sharing this information - as a bass builder who builds the occasional archtop, I find Archtoppery to be a priceless contribution to guitar making. Thank you for so generously sharing such detailed knowledge, information and experience. Who knew an episode on lute necks would be so interesting and so much applied to your ingenious necks? Thanks!
Intriguing stuff! Great insight into Lute construction and, it seems, some of the the inspiration for your astonishing neck design! Love the arch tops! 🍷🍷🥰🥰
Innumerable brilliant, problem-solving humans have made important contributions to our field over the centuries. There is so much to learn from unpacking clever solutions in ancient work.
Do you mean driving in the smokin' hot nail? Just build a lute shell and neck, bring it over, and we'll do it together! Doesn't take long. Don't forget your liquid cup earphone protection, it sounds like a pistol range!
What a fun story! What a fantastic transfer of knowledge. As always, your videos are so important for the collected knowledge of instrument makers. Thank you so much. You are doing God's work. Keep it up.
It's great fun to see how the evolution of the guitar is brought here from its roots, and not only (as often) from the classical guitar (Europe) or the folk guitar (America) - as in -this explains that- this gives full meaning to your research and the quality of these videos and teaching is absolutely perfect, current, and a whole beautiful heritage which offers -new- to our profession and which will make its path over time. Sincerely congratulations on such an achievement - and thank you for inspiring us in this way. A beautiful day Kp.! T.
Fascinating stuff Ken. I perform a similar process when I make custom lathe-turned handles for my chisels and files. I put the chisel iron in a vise with the tang sticking upward and then heat the tang with a blow torch until it's red hot. Then I pound the new handle down onto it. There is a lot of hissing and some smoking but after it cools down the new handle is there for ever. It's easier than pounding the iron into the handle but then I have the luxury of modern vises.
Vises are usually taken for granted, th-cam.com/video/plRgBrEHi3g/w-d-xo.html but not by you and me! The use of high heat to join steel and wood borders on miraculous.
Your story about witnessing the “spike nail” being driven into the neck and neck block of the lute sounds like it must have been a pretty intense experience! I need to see if they have any videos of this on here. Good stuff, thanks Ken!
I looked myself, and was very disappointed by the demo I found. The gentleman didn't really understand the method, and seemed afraid to use a proper length nail, also he fussed around pre-drilling the neck blank with silly jigs, and I think he missed the whole exercise. Done correctly, this is a ballsy move, kinda like blacksmith meets marksmanship and something that i imagine happened very quickly at the hand of a builder who had witnessed or performed this many many times. The result was an amazing structure assembled with Alchemical fire, not at all the careful, precious, overprotective first or second attempt I found online.
Ken these videos are indispensable! The knowledge you're passing along here is another notch it your growing legacy. I own one of your NiteFly models from 1997 and it's one of my dearest instruments. I'm afraid I'll probably never be in the same room as one of your archtops, but these videos really tickle my brain. The tools and jigs you've devised over the years are ingenious and I'm sure many many luthiers will be taking notes from a master. What a cool deep dive into the ancestry of guitar and its future.
Nails, what do you think, should we bring them back into modern building? Back then they were made by blacksmiths, although the little bitty ones they used to attach violin and viola necks were sized like small jewelery.
Why can't we just agree on a NAME??? As a young student of furniture-making, I was frazzled by European writers casually suggesting using lime for drawer sides (What the hell are they talking about??) and could never figure out how a little stick shaped tree with limes on it was ever going to be useful in a cabinet! You're most welcome, and at least there's one less thing to worry about now.
I wonder if those medieval lute makers were performing some advanced metallurgy unbeknownst to them. That spike when made was probably quenched and hence quite martensitic. Reheating and pounding into the wood to then cool naturally is essentially an annealing process.
Early renaissance blacksmiths made nails of wrought iron, which doesn't have enough carbon in it to behave this way. The only way to harden this material would be work-hardening, and any vestige of that kind of hardness would be annealed away with the low red heat needed to install the nail correctly. I don't think any of this would be unbeknownst, or any surprise to the smiths, who had to perform a challenging and deliberate "seat of the pants forge alloying", or whatever you would call it, to introduce enough carbon and create a steel to behave the way you're suggesting. These forge alloying techniques varied widely, with varied results, as it was tricky to get the recipe just right for creating tool steel that can be hardened and tempered. This extra work wouldn't have been needed to make a nail, which, as you suggest would be softened at the red heat required for installation.
I have wondered that too. It occurred to me that there might be a connection, as the violin and lute construction was being developed, at the same time people designed and built wooden barrels and boats with curved and bent parts. Any thoughts on that Ken or anyone else?
Wood is such an exceptional engineering material! So many ways to persuade it to your use. I think you must be right about the cross-pollination of woodworking discoveries and methods.
Thank you, I'm enjoying this series and getting something out of it. I started on a similar path in 1990 using carbon fibre formed around a core timber for mandolin necks. In the last six years I've resurrected the project and my core wood has been Hard Maple or Queensland Maple. I want to increase stiffness so I'm extremely keen to try old growth Douglas Fir now. We call it Oregon because that was stenciled on the packs. Interesting history, west USA sent us soft wood and eastern Australia returned the ships loaded with hard wood. Also in my town there is a whole port side suburb built on a filled mangrove island using Ship Ballast, rubble from the big San Francisco earth quake.
Wow, Queensland Maple is new to me, and I'm just reading that it's also called red beech, in very short supply, and was favored for the props of the heroic WW2 Mosquito bomber. Flindersia brayleyana, wow, that's a mouthful. Cool stories about the distribution of wood and stone. What a world. Lots of "Oregon Pine" took trains out east and built 19th century hotels and summer mansions which gave good service and aged gracefully, than burned very well in insurance fires when out of style.
@@kenparkerarchtoppery9440 It has always puzzled me as to why it was called Queensland Maple. Nothing like true Maple, I and others use it as a substitute for Honduras Mahogany as it has very similar properties. I use it for my mandolin head/corner blocks etc. The two big acoustic guitar manufacturers here, Maton and Cole Clark use Queensland Maple on many of their models instead of Mahogany ie, blocks, necks, backs and sides. All my old growth Douglas Fir is reclaimed from house and warehouse demolition. Please keep these great videos coming.
Good show!! Your right about that Fir, we use it in our necks also. Pretty tough stuff, around here it was used extensively for stairs/steps, floors and thresholds, and spindles too!. Curiously,,,not for furniture though, no chairs or tables hmm, it makes me wonder. About 10-12 years ago I confiscated Douglas Fir broom handles from a defunct/abandoned mop company the wood was from Mt St. Helens "before the volcano", I had 6,000 of them awesomely tight grain and arrow straight. I still have enough for the rest of my life. Well,,,about 1900 or about, piano makers experimented with Douglas Fir for soundboards, and was good except for the color! = ???.
Color, schmolor, I bet they liked the lighter Sitka's sound better, don't you suppose? In a lot of smaller pianos, you can't even see the board unless you look for it. It's an exceptional building material for nearly anything, as you mention. Why use anything else?, it's so stiff and durable apart from its relaxed beauty and color. Don't tell anybody, but I bet we could equip an army with spears made from your stash and take over Canada in order to steal all their tonewood, that is, if you have enough left.
Yeah they must have = I never saw Fir piano SB. Well-Eastern spruce is what we find in almost all the older pianos only Mason&Hamlin Co. Boston, we identified as Sitka/Western spruce. And we watched your vid a couple of times. Very cool. Thank's for the research effort. @@kenparkerarchtoppery9440
Hello again! In what orientation is this nail inserted? It seems to be flat versus conical, so I would assume that it is inserted "vertically," correct?
These old tapered nails (spikes?) are hand forged, not made from wire, so they could be either square or rectangular in x-section. If rectangular, I think you could argue it either way on orientation, as the non-vertical would offer more area in support of the forces on the wood, especially in the block, and the vertical would be stiffer. I think you could size the nail to take advantage of the non vertical orientation, and as I remember it, (? long ago?) that's what was done, as I drew it in the film. I think it might be pretty tough to prove that one was meaningfully superior to the other.
FAscinating journey indeed, this nail reinforcement is awesome would you consider that stronger than a carbon fiber insert in terms of rigidity ? I was wondering how comparable would be the string tension on a traditionnal luth compare to a steelstring guitar ?
Steels and Carbon/epoxies of similar size have roughly similar stiffness, or Modulus of Elasticity (MOE), however, Carbon composite weighs only about 20% of comparable steel, so there you go, kinda apples/oranges. Also, fabrication methods couldn't be much more different than between these two materials, plus, steel rusts like, well, steel, whereas carbon/epoxy is quite inert and doesn't really corrode in normal environments. String forces for modern strings are easily available online, whereas the lute string tension (quite low) info would have a jillion variables, such as scale, pitch, material qualities, etc., etc. Sorry, you're on your own, it's a very complex thing to answer.
YES! I have been silent about your unusual neck since the beginning of this entire series, hoping that you would divulge what most people would think to be a trade secret! Having (as I have already said, perhaps far too many times) worked for a boat manufacturer in both wooden and composite, I could mentally guess the process, but only had hints from scattered online posts what it even looks like. Having made molds and laminated wooden ribs, it seems that would be the correct method for a stiff, lightweight, temperature insensitive way to go. The only thing in guitars is the customer isn’t given any options on thickness, shape, radius etc. Unless you’re making multiple molds………but as a very famous pioneer in engineering said, “you can have any color that you want, if it’s Black “. 😂. Great to see you spilling the beans of your exploits in the art of vibrating strings 😊. Wonder what the string tension was on 24 gut strings? Cheers
Lutes are typically strung very lightly from what I’ve seen of them (noticeably lower tension per string than classical guitar) whether that was consistently true historically I’m not sure.
With that being said, some extended range versions of classical guitars will absolutely match or even exceed the overall tension of a 12-56 set (or similar) of steel strings. It ought to be possible for 24 gut strings to get up there, just maybe not the particularly low tension variety used on lutes.
ive found douglas fir such a joy to work with, its also very plentiful on the west coast and not too expensive. I wonder if youve ever auditioned it for a guitar top or brace material? Really looking forward to the break angle chapter of this series. Thanks!
I don't see why it wouldn't make a good soundboard, but you might be tempted to go a little thinner since it can be quite stiff, and it has a tendency to split.
I have to agree with Olli, the ability to push people backwards with 110+DB while they're dancing and screaming cannot be over-rated. Just ask Dick Dale.
i think the reason that "fir is underutilized" is because it is a bit miserable to tool/carve by hand due to the great hardness contrast between the bands of xylem and phloem, ie "the grain"...this can result in an interesting 3D texture when abraded(either in a booth with a sandblaster, or naturally on a beach). it also seems to be full of resin, which can cause problems with finishes.
Your experience with and irritation with Douglas fir is showing! Let me first say that I haven't had any issues with finishing, although I agree that it seems like it could be a problem. I believe that somewhere in one of these films I observed that DF varies in physical qualities more than any other species I have ever worked with. I guess I misspoke, and should have used the correct term "genus". I believe there are (about) six species of the genus Pseudotsuga, and they vary markedly in their physical character. Some are as you describe, almost seeming like laminates of alternating hard plastic and soft sponge. When this wood is cut for vertical grain, it's almost as if a clever engineer designed and manufactured it to alternately bond two very different materials to achieve an unusually high stiffness-to-weight ratio piece of material that sounds great. I agree that this unusual structure can give a woodworker some challenges, but I just downshift and play nice because I really like how it works as a neck core. It's like having a friend who's a little crazy, but will never let you down. Other species don't have the hard, thick late growth, and are quite homogeneous, tending to be much softer and pleasant to work with. I have used this material also, and I think it works well. Anyway, having rambled about my affection for DF, go ahead and use any core material you want, but I think it should be fairly light. More than a century ago my grandfather worked for the Ostrander Railway and Timber Company in Washington State, a large logging company that built railways into the virgin wilderness, and specialized in the harvest and delivery of the largest DF trees for building bridges and other huge structures. The biggest trees were 330 feet, (100 meters) long, and 14 feet, (4+ meters) at the base. He told me that the largest timbers required three 89 foot (27 meters) flat railway cars to hold the trunk. The timber was secured with the butt end at the front of the forward car in a rotating cradle, did not touch the center car at all, and was supported at the third car in a greased "V" block to enable turns. These old growth trees were also harvested for lumber, and long ago was marketed as "Oregon Pine". In the 19th century here in America it was widely used for building hotels and other large buildings due to its strength and beauty. It proved to be an economical choice because the quality and uniform appearance was exceptional compared to other species. Harvested from very large trees, and usually sawn vertical grain or rift, it tended to be straight and defect-free. it didn't need paint on interior surfaces to look handsome because it ages to a lovely dark honey color all by itself.
I can't stress how valuable this information is for the masses out here in the web. This is fascinating stuff!!!
I love the Lutherie masses! Thanks for being in the number!
I still can’t believe we get to learn all this. Ken is already a legend and this is unbelievable
Yay, Learn! Nothing like it. Big fun.
Ken - thanks so much for sharing this information - as a bass builder who builds the occasional archtop, I find Archtoppery to be a priceless contribution to guitar making. Thank you for so generously sharing such detailed knowledge, information and experience. Who knew an episode on lute necks would be so interesting and so much applied to your ingenious necks? Thanks!
I'm glad I'm not the only one who thinks all this stuff is so cool. You're most welcome!
As a scientist and guitar player, this series really scratches a lot of itches. I could watch Ken nerd out about this stuff all day.
Thanks! I love guitar nerds too.
Intriguing stuff! Great insight into Lute construction and, it seems, some of the the inspiration for your astonishing neck design! Love the arch tops! 🍷🍷🥰🥰
Innumerable brilliant, problem-solving humans have made important contributions to our field over the centuries. There is so much to learn from unpacking clever solutions in ancient work.
I would love to see that operation performed! And then to see Ken and his enigmatic smile...
Do you mean driving in the smokin' hot nail? Just build a lute shell and neck, bring it over, and we'll do it together!
Doesn't take long.
Don't forget your liquid cup earphone protection, it sounds like a pistol range!
That was so fun to hear you explain the background of lute necks and and outline of how they are constructed.
Thanks!
What a fun story! What a fantastic transfer of knowledge. As always, your videos are so important for the collected knowledge of instrument makers. Thank you so much. You are doing God's work. Keep it up.
My Man
It's great fun to see how the evolution of the guitar is brought here from its roots, and not only (as often) from the classical guitar (Europe) or the folk guitar (America) - as in -this explains that- this gives full meaning to your research and the quality of these videos and teaching is absolutely perfect, current, and a whole beautiful heritage which offers -new- to our profession and which will make its path over time. Sincerely congratulations on such an achievement - and thank you for inspiring us in this way. A beautiful day Kp.! T.
Thierry! Delighted to be of service, my good man! Thanks for your kind words!
Fascinating stuff Ken. I perform a similar process when I make custom lathe-turned handles for my chisels and files. I put the chisel iron in a vise with the tang sticking upward and then heat the tang with a blow torch until it's red hot. Then I pound the new handle down onto it. There is a lot of hissing and some smoking but after it cools down the new handle is there for ever. It's easier than pounding the iron into the handle but then I have the luxury of modern vises.
Vises are usually taken for granted,
th-cam.com/video/plRgBrEHi3g/w-d-xo.html
but not by you and me!
The use of high heat to join steel and wood borders on miraculous.
Your story about witnessing the “spike nail” being driven into the neck and neck block of the lute sounds like it must have been a pretty intense experience! I need to see if they have any videos of this on here. Good stuff, thanks Ken!
I looked myself, and was very disappointed by the demo I found. The gentleman didn't really understand the method, and seemed afraid to use a proper length nail, also he fussed around pre-drilling the neck blank with silly jigs, and I think he missed the whole exercise. Done correctly, this is a ballsy move, kinda like blacksmith meets marksmanship and something that i imagine happened very quickly at the hand of a builder who had witnessed or performed this many many times. The result was an amazing structure assembled with Alchemical fire, not at all the careful, precious, overprotective first or second attempt I found online.
Ken these videos are indispensable! The knowledge you're passing along here is another notch it your growing legacy. I own one of your NiteFly models from 1997 and it's one of my dearest instruments. I'm afraid I'll probably never be in the same room as one of your archtops, but these videos really tickle my brain. The tools and jigs you've devised over the years are ingenious and I'm sure many many luthiers will be taking notes from a master. What a cool deep dive into the ancestry of guitar and its future.
Thanks so much! I'm having more fun than ever.
I finally know some things worth knowing.
Thank you.
You're welcome!
reminds me of the original methods stradivarius used for the neck with the tapered nail, very interesting talk.
Nails, what do you think, should we bring them back into modern building? Back then they were made by blacksmiths, although the little bitty ones they used to attach violin and viola necks were sized like small jewelery.
Never heard anyone say Lime, Bass, Linden, Tilia all together like that before... thank you.
Why can't we just agree on a NAME??? As a young student of furniture-making, I was frazzled by European writers casually suggesting using lime for drawer sides (What the hell are they talking about??) and could never figure out how a little stick shaped tree with limes on it was ever going to be useful in a cabinet!
You're most welcome, and at least there's one less thing to worry about now.
Thanks 🙏
Whelks!
I wonder if those medieval lute makers were performing some advanced metallurgy unbeknownst to them. That spike when made was probably quenched and hence quite martensitic. Reheating and pounding into the wood to then cool naturally is essentially an annealing process.
Early renaissance blacksmiths made nails of wrought iron, which doesn't have enough carbon in it to behave this way. The only way to harden this material would be work-hardening, and any vestige of that kind of hardness would be annealed away with the low red heat needed to install the nail correctly. I don't think any of this would be unbeknownst, or any surprise to the smiths, who had to perform a challenging and deliberate "seat of the pants forge alloying", or whatever you would call it, to introduce enough carbon and create a steel to behave the way you're suggesting. These forge alloying techniques varied widely, with varied results, as it was tricky to get the recipe just right for creating tool steel that can be hardened and tempered. This extra work wouldn't have been needed to make a nail, which, as you suggest would be softened at the red heat required for installation.
That was very fascinating!
Lots to learn from antiquity. Lots.
I wonder if those early lute makers were inspired by boat construction for the body. I've seen some hand built canoes that are still made that way.
I have wondered that too. It occurred to me that there might be a connection, as the violin and lute construction was being developed, at the same time people designed and built wooden barrels and boats with curved and bent parts. Any thoughts on that Ken or anyone else?
Wood is such an exceptional engineering material! So many ways to persuade it to your use. I think you must be right about the cross-pollination of woodworking discoveries and methods.
I’d wondered where your inspiration came from. High tech modern solutions inspired by ancient, awesome stuff.
Did the parchment reinforcement inspire your side bending technique?
You said it. The whole lute construction just blew my mind. So light, and so strong!
Thank you, I'm enjoying this series and getting something out of it. I started on a similar path in 1990 using carbon fibre formed around a core timber for mandolin necks. In the last six years I've resurrected the project and my core wood has been Hard Maple or Queensland Maple. I want to increase stiffness so I'm extremely keen to try old growth Douglas Fir now. We call it Oregon because that was stenciled on the packs. Interesting history, west USA sent us soft wood and eastern Australia returned the ships loaded with hard wood. Also in my town there is a whole port side suburb built on a filled mangrove island using Ship Ballast, rubble from the big San Francisco earth quake.
Wow, Queensland Maple is new to me, and I'm just reading that it's also called red beech, in very short supply, and was favored for the props of the heroic WW2 Mosquito bomber. Flindersia brayleyana, wow, that's a mouthful. Cool stories about the distribution of wood and stone. What a world. Lots of "Oregon Pine" took trains out east and built 19th century hotels and summer mansions which gave good service and aged gracefully, than burned very well in insurance fires when out of style.
@@kenparkerarchtoppery9440 It has always puzzled me as to why it was called Queensland Maple. Nothing like true Maple, I and others use it as a substitute for Honduras Mahogany as it has very similar properties. I use it for my mandolin head/corner blocks etc. The two big acoustic guitar manufacturers here, Maton and Cole Clark use Queensland Maple on many of their models instead of Mahogany ie, blocks, necks, backs and sides.
All my old growth Douglas Fir is reclaimed from house and warehouse demolition.
Please keep these great videos coming.
Good show!!
Your right about that Fir, we use it in our necks also.
Pretty tough stuff, around here it was used extensively for stairs/steps, floors and thresholds, and spindles too!. Curiously,,,not for furniture though, no chairs or tables hmm, it makes me wonder.
About 10-12 years ago I confiscated Douglas Fir broom handles from a defunct/abandoned mop company the wood was from Mt St. Helens "before the volcano", I had 6,000 of them awesomely tight grain and arrow straight. I still have enough for the rest of my life.
Well,,,about 1900 or about, piano makers experimented with Douglas Fir for soundboards, and was good except for the color! = ???.
Color, schmolor, I bet they liked the lighter Sitka's sound better, don't you suppose? In a lot of smaller pianos, you can't even see the board unless you look for it. It's an exceptional building material for nearly anything, as you mention. Why use anything else?, it's so stiff and durable apart from its relaxed beauty and color. Don't tell anybody, but I bet we could equip an army with spears made from your stash and take over Canada in order to steal all their tonewood, that is, if you have enough left.
Yeah they must have = I never saw Fir piano SB.
Well-Eastern spruce is what we find in almost all the older pianos only Mason&Hamlin Co. Boston, we identified as Sitka/Western spruce.
And we watched your vid a couple of times.
Very cool.
Thank's for the research effort.
@@kenparkerarchtoppery9440
Hello again! In what orientation is this nail inserted? It seems to be flat versus conical, so I would assume that it is inserted "vertically," correct?
These old tapered nails (spikes?) are hand forged, not made from wire, so they could be either square or rectangular in x-section. If rectangular, I think you could argue it either way on orientation, as the non-vertical would offer more area in support of the forces on the wood, especially in the block, and the vertical would be stiffer. I think you could size the nail to take advantage of the non vertical orientation, and as I remember it, (? long ago?) that's what was done, as I drew it in the film. I think it might be pretty tough to prove that one was meaningfully superior to the other.
FAscinating journey indeed, this nail reinforcement is awesome would you consider that stronger than a carbon fiber insert in terms of rigidity ? I was wondering how comparable would be the string tension on a traditionnal luth compare to a steelstring guitar ?
Steels and Carbon/epoxies of similar size have roughly similar stiffness, or Modulus of Elasticity (MOE), however, Carbon composite weighs only about 20% of comparable steel, so there you go, kinda apples/oranges. Also, fabrication methods couldn't be much more different than between these two materials, plus, steel rusts like, well, steel, whereas carbon/epoxy is quite inert and doesn't really corrode in normal environments.
String forces for modern strings are easily available online, whereas the lute string tension (quite low) info would have a jillion variables, such as scale, pitch, material qualities, etc., etc. Sorry, you're on your own, it's a very complex thing to answer.
@@kenparkerarchtoppery9440 Thanks a lot !
YES! I have been silent about your unusual neck since the beginning of this entire series, hoping that you would divulge what most people would think to be a trade secret! Having (as I have already said, perhaps far too many times) worked for a boat manufacturer in both wooden and composite, I could mentally guess the process, but only had hints from scattered online posts what it even looks like. Having made molds and laminated wooden ribs, it seems that would be the correct method for a stiff, lightweight, temperature insensitive way to go. The only thing in guitars is the customer isn’t given any options on thickness, shape, radius etc. Unless you’re making multiple molds………but as a very famous pioneer in engineering said, “you can have any color that you want, if it’s Black “. 😂. Great to see you spilling the beans of your exploits in the art of vibrating strings 😊. Wonder what the string tension was on 24 gut strings? Cheers
Them intestine strings are wimpy!
Lutes are typically strung very lightly from what I’ve seen of them (noticeably lower tension per string than classical guitar) whether that was consistently true historically I’m not sure.
With that being said, some extended range versions of classical guitars will absolutely match or even exceed the overall tension of a 12-56 set (or similar) of steel strings. It ought to be possible for 24 gut strings to get up there, just maybe not the particularly low tension variety used on lutes.
ive found douglas fir such a joy to work with, its also very plentiful on the west coast and not too expensive. I wonder if youve ever auditioned it for a guitar top or brace material? Really looking forward to the break angle chapter of this series. Thanks!
I don't see why it wouldn't make a good soundboard, but you might be tempted to go a little thinner since it can be quite stiff, and it has a tendency to split.
I have always wanted to learn to play the lute, i have tried several ones, the sound is awesome. At least for this classically trained guitarist 😊
Yeah, it's a whole new sound, beautiful!
This is University! 🙏🏻
My Man! Blessings and every good wish!
Well...In those old days there was no such thing as sustain. Why did the solid body guitar conquer the world? Sustain of course.
Volume was surely a more significant factor.
I have to agree with Olli, the ability to push people backwards with 110+DB while they're dancing and screaming cannot be over-rated. Just ask Dick Dale.
Yep.
@@kenparkerarchtoppery9440
To understand, “Sustain” is the duration of the sound being produced.
i think the reason that "fir is underutilized" is because it is a bit miserable to tool/carve by hand due to the great hardness contrast between the bands of xylem and phloem, ie "the grain"...this can result in an interesting 3D texture when abraded(either in a booth with a sandblaster, or naturally on a beach).
it also seems to be full of resin, which can cause problems with finishes.
Your experience with and irritation with Douglas fir is showing!
Let me first say that I haven't had any issues with finishing, although I agree that it seems like it could be a problem.
I believe that somewhere in one of these films I observed that DF varies in physical qualities more than any other species I have ever worked with. I guess I misspoke, and should have used the correct term "genus". I believe there are (about) six species of the genus Pseudotsuga, and they vary markedly in their physical character. Some are as you describe, almost seeming like laminates of alternating hard plastic and soft sponge. When this wood is cut for vertical grain, it's almost as if a clever engineer designed and manufactured it to alternately bond two very different materials to achieve an unusually high stiffness-to-weight ratio piece of material that sounds great. I agree that this unusual structure can give a woodworker some challenges, but I just downshift and play nice because I really like how it works as a neck core. It's like having a friend who's a little crazy, but will never let you down.
Other species don't have the hard, thick late growth, and are quite homogeneous, tending to be much softer and pleasant to work with. I have used this material also, and I think it works well.
Anyway, having rambled about my affection for DF, go ahead and use any core material you want, but I think it should be fairly light.
More than a century ago my grandfather worked for the Ostrander Railway and Timber Company in Washington State, a large logging company that built railways into the virgin wilderness, and specialized in the harvest and delivery of the largest DF trees for building bridges and other huge structures. The biggest trees were 330 feet, (100 meters) long, and 14 feet, (4+ meters) at the base. He told me that the largest timbers required three 89 foot (27 meters) flat railway cars to hold the trunk. The timber was secured with the butt end at the front of the forward car in a rotating cradle, did not touch the center car at all, and was supported at the third car in a greased "V" block to enable turns. These old growth trees were also harvested for lumber, and long ago was marketed as "Oregon Pine". In the 19th century here in America it was widely used for building hotels and other large buildings due to its strength and beauty. It proved to be an economical choice because the quality and uniform appearance was exceptional compared to other species. Harvested from very large trees, and usually sawn vertical grain or rift, it tended to be straight and defect-free. it didn't need paint on interior surfaces to look handsome because it ages to a lovely dark honey color all by itself.