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Discussion in 'Acoustic Heaven' started by Freeman Keller, Oct 2, 2019.
I guess gluing the top and closing the box is something of a one-way trip, although there would still be access through the sound hole?
I'm eager for the next phase!
A quick comment on bracing. Years ago I worked on an old (early 50s) Gibson LG-2 that had a sinking top. I tried various non-invasive methods to get the top flat, but nothing worked, so I took the back off the guitar, removed the braces, straightened the top using cauls, time, and heat and re-braced it. The guitar was originally ladder braced, but I changed it to X-bracing. I also braced it pretty heavy to avoid having a repeat of the same problem. In addition, I made a new, slightly oversized bridge for it. When I put the guitar back together the difference in tone was... non-existent. It still sounded like the same guitar. I was expecting radical changes given all the major structural changes that had been made to the guitar, but the tone, volume, and bass response were all the same.
Don't know what that means... Is it a bunch of different changes all canceled each other out, or that these things make less difference than we think?
I'll go out on a limb. I think several things might be at work here. First, in my opinion, the primary thing driving the sound of any acoustic guitar is the amount of air in the box. Thats another way of saying the size of the guitar, size of the sound hole - what people refer to as the "main air cavity resonance" or the Helmholtz resonance. Thats the reason every dreadnaught sounds more or less the same regardless of what woods or bracing or anything else. And why a parlor will never sound like a dreadnaught.
Second, I think the size of the top is the second most important thing in the sound of a guitar. A bass drum is bigger than a snare drum and sounds different, but most bass drums sound pretty much the same. If you do glitter patterns on the top I'll bet that main monopole didn't change much.
Third, you said you braced it heavily for structural reasons. I'll be it was relatively heavily braced before (even tho it deformed). Ladder bracing doesn't do particular well with pinned bridges compared to X bracing - I would expect it to deform, but most of the ladder braced guitars that I have seen have pretty large braces.
Lastly, and here is the kicker, it sounded the same to you when it was finished as it did two months (or whatever) before you started. That is the whole realm of psycho-acoustics that I alluded to earlier - sometimes we hear what we want to hear and certainly listening to a guitar several months apart can greatly influence what we hear. Not saying you did or didn't hear something, but what you remember, what you think you are hearing now....
What I would speculate is that if you could hear two recordings of that guitar, before and after your work you would hear subtle nuances and if you took some careful frequency based measurements you would see some difference, but that the size of the box and the size of the top would dominate.
Here is my little anecdote. I built two Weissenborn style guitars but changed the bracing. One has the traditional '30's bracing (ladders within an X) one had more modern X bracing with angled tone bars. They were built at the same time out of literally the same hunk of wood. Both of them sound like Weissenborns but when played side by side for many hours by sever very good players - there is a difference. It is subtle, very subtle, but the interesting thing is that every player likes the old bracing better.
This is a good point and I had thought of that. There is no way that after 2 months (how did you know it took me 2 months?) I would be able to reliably detect subtle differences in the guitar's sound. Still, I was surprised at how little change I detected.
I also like your point about the Helmholz resonance not changing even though the resonant frequency of the top may have changed slightly.
This was very educational. Thanks for sharing. I love acoustics (just got a Pre-War Co. dread recently) and hope to one day build one. I am looking forward to the next posts!
We could talk about bracing all day but I'm going to move forward with building this guitar. Took the body out of the mold and buzzed off the top overhang. It looks like this
As I mentioned earlier I have done about all the operations I can on the neck with the sides flat and straight. Cut off some of the waste to start the taper
The pieces of blue tape are just a way of making straight lines on the curve of the heel that I can follow with the band saw.
With planes and chisels and a carpenter's level with some sticky back sand paper I work the sides of the neck down to the two critical widths - the nut and 14th fret (actually the 12th but I extend it to the body joint).
I'm going to leave the neck a few thousands wider than the finished width while I make the fretboard. I find it easier to shape the neck to the f/b rather than the other way around.
This makes me want to buy a Stew Mac kit...
Can I help lead you astray? Kits are a wonderful way to build your first (couple) of acoustics - you can avoid some of the really tricky operations (bending sides, thicknessing plates, maybe rough shaping the neck...). You also don't have the hassles of trying to source all the different woods and other stuff you'll need. There are still some tricky things to do (setting the neck, binding, finishing) and you will need some special tools - but you'll use them on the second one you build. And the third. And...
StewMac kits are fine but limiting. LMII's kit wizard lets you spend as much money as you want, er, choose exactly the guitar you want to build.
For what it is worth, this is my first home made guitar, a kit. It is now 13 years old and I play it frequently. There are a few things I would do differently today but not many.
How much of it was ordered pre-assembled or pre-cut? Just curious as I am looking at LMII. My issue is I just don't have the room for the tooling. A radius dish for example (unless I turn it into a table haha).
That first guitar had a lot of the work already done. The neck and neck block were pre shaped, the top and back were joined and thicknessed. The rosette channels were routed but the rosette was not installed. Sides were bent and brace stock was ripped to thickness but not shaped. That is actually pretty close to a StewMac kit, I just didn't buy it from them.
Its kind of interesting that I have dealt with a couple of guys putting kits together and they spared no expense - the bear claw in that guitar is really stunning and I was even offered some Brazilian from one supplier. The nice thing about LMII is that you can keep messing with it until you get exactly what you want. Also, there are some ways to get around all the tooling - I have built that up over several years of doing this. You can get by without the go bar deck and its possible to clamp against some simple cauls that you make out of 2x2's.
There actually is a kit guitar forum, I haven't been active for years but I do know and recommend the guy that runs it.
I didn't take many pictures of that first guitar being built but here is my second, an LMII classical
Here it is with the first one
Maybe I've inspired someone to want to build an acoustic guitar. I promise that if I can do it, anyone can. Meanwhile, back to the OM. Neck building is pretty much the same regardless of what kind of guitar we're building. Start with a big hunk of wood and remove everything that doesn't look or feel like a neck.
I've made a couple of templates off a neck that I really liked and have used them on almost all of my acoustics. As wood is removed they slowly settle against the back of the neck - in that last picture the nut end is still a few thousands too wide so the temple is still sitting high. Its getting close however.
You definitely got my wheels turning. And I think Stew Mac is reading because they sent out an email this morning, $100 off guitar kits. Those psychics.
Your comment on the cutting made me laugh. Wayne Henderson says something like, I just cut everything off that's not guitar. Uh huh, you guys make it look easy
Man, nice heel! I used a large Shinto for reshaping a Tele neck and smaller files. The transition to headstock and heel were the most difficult for me.
I realize that I didn't take any pictures of putting the inserts in the neck heel, but they did get installed
That lets me bolt the neck to the body and make sure I have good access to the truss rod
I can also start worrying about the geometry, however the without the back the box is pretty floppy. I just want to be close at this time
The cards on the fretboard simulate the height of the frets - my goal is for the fret plane to just hit the top of the bridge, maybe be a tiny bit over set at this time
Its starting to look like a guitar
Closed the box
I knew I'd get to see a spokeshave eventually..
It is great to see the process unfold, I can't wait to see more!
Just a little plane that you pull instead of push. Great tool for rough shaping necks.
I'm learning a lot from this thread. Going to pull the trigger on some wood this week.
By the way, what bicycle do you having hanging there? That's my other hobby too. Looks like you got Speedplays and Salsa stem plus that bar tape looks like a late 90s early 00s bike.
Wow, you've got good eyes. The bikes (there is a second one hanging next to it) are from my old racing days. During the 80's and 90's I was a mediocre USCF Cat 3/Masters "racer" (I mostly went on long fast tours with a bunch of other old men with no hair on their legs). Anyway, always the anal engineer I became interesting in racing bicycles and decided to build my own frames. They are both double butted Columbus tubing, mine had fairly steep angles and was particularly good for crits, the one I made for my wife took into account the fact that it was very hard to find quality women's bikes at that time. It was fascinating to learn how the various angles and geometry worked and it was also fun to learn the manufacturing techniques - silver brazing, mitering all the tubes, finish (they are powder coated). The lugs were all cut in fancy little scrolls with my initials in them. Any of this starting to sound familiar?
I raced/toured on that bike for many years, finally hung up my cleats and pretty much stopped riding on the road. I have a very nice titanium mountain bike now (I didn't make the frame but a friend who worked at Moots did) and I still ride more or less daily.
Oh, and to go along with your sharp eyes - the pedals are SPD's - when I stopped racing I switched to shoes that I could walk in. I think the stem is 3T, what I can say is that there isn't a Campy or Shimano component on either bike besides the pedals - they are all a bit off the radar.
The parallels in my bicycle and guitar building (and a bunch of other hobbies that I've had) are kind of interesting. In both cases I was "doing" whatever it was (racing, playing) before but always curious - how does this thing work? Can I fix it? Heck, can I make it? Hot damn, look what I made! Holy crap, I'm going down hill at 50 miles an hour on a frame that I built, I wonder if it will hold together....
Lets get back to the guitar.