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Andyjr1515

Dreadnought Acoustic

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Hi again!

Apart from the single-cut bass I've just posted, the other project on the go - albeit a longer-term project - is a dreadnought acoustic 6 string.

It is due as a surprise present for our old-guys-band's vocalist who has a special birthday in July next year.

The spec is:

  • Lacewood (London Plane Tree, specifically) back and sides
  • European spruce top
  • Mahogany / Walnut / Mahogany neck
  • Ebony fretboard
  • 25.5" scale
  • Built-in pickup(s) and pre-amp, make to be confirmed

So far, I've:

  • built a simple plywood mould
  • thicknessed and joined the top and back, waiting final sand.
  • thicknessed, sanded and bent the sides

Haven't finally decided but, after I've made a jig and tried it out on a couple of scrap pieces, I might try my first dovetail neck joint - my other acoustic build (an OM in spruce and walnut for my own use) was bolt-on tenon construction.

Here are some progress shots...but it might be come time before you see any more :rolleyes:

 

Here's the mould in construction - even without fixing brackets, already useful for working out which way round is best for the figuring on the back sheets

8MF67uql.jpg 

 

Here, the back and top are thicknessed and joined, waiting final sanding.  The line down the middle of the top is just greaseproof paper stuck to the glue - it will sand off.  It's a LOVELY piece of tight and vertically-grained spruce:

Z65pNVhl.jpg

 

The sides are matched to the back but have some additional figuring:

gu9Mgj9l.jpg 

 

I thicknessed them down to about 3mm, then hand-sanded down to 1.9mm - 2mm.  Then hand bent on an electric bending iron with a stainless steel support strap:

UjJ4qull.jpg

 

Thanks for looking

Andy

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4 minutes ago, Prostheta said:

Very nice! What kind of bracing approach are you taking?

Thanks, Prostheta!

I'm afraid I'm going fully 'conventional' Martin-based 'X' brace pattern.

I've only built one acoustic before, the OM model below having assumed it would be well beyond my capabilities. So I followed every standard tip and hint and design I could find and - even though I would have been happy and amazed with the achievement if it had sounded like a rubber band across a baked-bean can - to my utter surprise, it actually sounds GREAT!

So - because this is a special one, I'm sticking, for once, with known and well-trodden paths.

I built the OM for my own use and couldn't be more happy with it (and still have to pinch myself and think - did I really build that???).  The walnut back was another piece from exotichardwoodsukltd...and like the camphor, he's never had anything like it in since :rolleyes:

IMG_2917_zpsa09f1268.jpg

IMG_2914b_zps81e9cb91.jpg

Since these early pictures, the top has matured to a rich orange-brown.  I'm delighted with it on all counts :)

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On 11/20/2015, 4:28:39, ScottR said:

Wow.  You set the bar pretty dang high for your second one, didn't you.

SR

:lol:  I know what you mean, Scott

The basic construction should be similar to my OM.  I was also pleased that the lacewood has proved to be OK to work with and bend - I had thought it might be a bit brittle but it has been OK.

The only really high bar, is going for a dovetail.  I'm going to build a proper jig (simpler, but based on the O'Brian / LMI concept) and do two or three trial runs with scrap timber and blocks before I finalise on the dovetail rather than a bolted or glued tenon.

This one is running very much in the background so lots of time to ponder between steps!

Andy 

Edited by Andyjr1515

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Accurate marking and sharp tools. A well-planned dovetail is easier than hacking away at one....ask me how I know ;-)

This was from my workbench project three years ago. I learned so much about clean work from this one project. Worth it's weight....all 400kg of it!!

progress6.jpg.62444f98830dc0760a8267ad37

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Since finishing the Camphor single-cut bass, my priority is back to the 'birthday present' Dreadnought.

I started with the top.  First of all, after final thickness sanding and multiple checking of the thickness, I sorted the soundhole roundel and surround, using a Dremel and the basic-but-OK radius attachment they have in their standard sets:

YhGLqyLl.jpg

 

F1x5KJrl.jpg

 

I rough-cut the braces and then sanded the final bottom curves with some 120 grit stuck to my 25' MDF radius dish.  Then onto the home-made Go-bar deck:

5i8O0iel.jpg

 

...and the bracing was ready for carving and the dark art of tap-tuning:

rLhqQGrl.jpg

 

I only do the basics for final carving and tap tuning - I don't really understand all of the nuances to go much beyond thinning for bass response, leaving a little stiffer for treble, and thinning generally until I can hear clear and varied harmonics as well as the variations in base-note when tapping in the various parts.

The final carve looks something like this, prior to the all-important finish sanding and X-brace cap:

LuYv4rGl.jpg

 

Next post, the shaping of the sides to take the top and the start of the back, which will pretty much bring me up to date with present progress...

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If it's not too late, I think that (@verhoevenc) Chris might have some practical input on that.

Man, I'm too chicken to even do an archtop (yet) never mind an acoustic. Maybe it's because they have too many strings?

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3 hours ago, Prostheta said:

If it's not too late, I think that (@verhoevenc) Chris might have some practical input on that.

Man, I'm too chicken to even do an archtop (yet) never mind an acoustic. Maybe it's because they have too many strings?

Actually, an archtop is the last 'must do' on my list.  In many ways, I think they are more difficult than full acoustics.  Thanks for the link to Chris - especially if it relates to tap tuning...I'm always eager to steal other people's ideas and experience! :D

Bringing this build up to date, I shaped the sides for the top in the same 25' radius dish fitted with the abrasive cloth and cut clearance in the kerfing for the brace ends:

t1pIgrOl.jpg

 

Prior to gluing, I then checked that it was a good fit without bend strains on the dished top:

RML7fLHl.jpg

 

Then glued it with titebond and violin clamps, and when that was dry, rough trimmed the edges ready for the final flush trim routing:

sYw2HQ2l.jpg

 

There are quite a few things to do with this before closing it, but I also started preparation for the back.  Before adding the braces and strengthening strips, while it was flat, this was the time to rout the slot for the central strip of purfling.  I used a 3mm cutter, and spaced the precision router base another 3mm from the guide with an allen key:

N0Ay01Tl.jpg

Two passes with the router - one with spacer and one without, and I had my 6mm slot:

JD3vR3Gl.jpg

Quick clean up of the edges of the slot with the corner of a cabinet scraper and titebond in the channel, insert the strip and wipe off the squeeze-out with a damp cloth, and we have the central strip in place :):

Tay5raQl.jpg

 

That's up to date as of today :D

 

Andy

 

Edited by Andyjr1515
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If Chris can't give you specific advice, he will at least have something practical to add to the conversation. This is completely not my field. I understand the structural demands and processes, but none of the finesse and voicing.

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Tuning an acoustic top is really, really hard to relate to another human being... especially on a first build. However, something you said already has me thinking you're on the right path: what you said you were listening for as you carved. I call that "flutter". That wavering, responsive je ne sais qoui that a well-carved top has.

However, I can give you some pointers regardless. The first of which you've already done wonderfully:

1- Keep everything in front of the X fairly stiff. There's not much the top is doing up there and stiff is good IMO. So it looks good that you haven't scalloped in front of the X, and you left your UTB chunky.

2- My biggest recommendation for you would be to make your brace carves more triangular. Stiffness increases linearly with width, but exponentially with height. Therefore, if you look at the edge of a brace down it's length you'll get almost as much strength out of something that has an arch-like profile (think the shape of praying hands almost) as you will with a squared profile. The only reason you need braces as think as people say is because you want a good glue surface. So get in there and taper! Lose that extra weight.

3- Don't think you're done tap tuning until you have your bridge plate on. You'll glue that thing in and go "holy hell everything has changed!" Remember, your other braces are fairly small, spread out, and made of light wood. A bridge plate, although thin, is a HUGE and heavy "brace" (usually maple, rosewood, something dense). I think you'll find that once you put your bridge plate on and get back to tapping you'll find you can get away with a much more aggressive scalloping scheme right behind the X.

Here is a great picture for reference about what I'm talking about:

Preliminary-Brace-Shapes.jpg

Photo credit to the man that taught me everything I know about acoustics, one of the most under-rated and under-known builders, and most accomplished voicers I know, Todd Stock of Greenridge Guitars.

Hope that helps,

Chris

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Hi, Chris

Hugely helpful :). Thank you so much!

 Yes - I have put the bridge plate on now, and also the slightly controversial tiny sliver of spruce across the X-brace join.

 There's plenty of ringing of various pitches so I think I'm at least 'in the zone'.  The one thing that I don't think I have as much as my previous OM is the unmistakable bass/treble difference.  Your suggestions, especially ref the triangularity are enormously helpful.  I'll have a go tomorrow.  Quite exciting because I'm getting very close to closing the box time....

I'll let you know how it goes :)

By the way, what's your take on the X-brace cap?  Views seem to vary between 'the most important ounce of wood in the entire guitar' through to 'you hear what you want to hear'...

Andy

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The other thing I'd missed, Chris, was scalloping the main X-braces in the lower bout!  Not sure why, because I certainly did with the OM!  Those two changes will make a big difference :)

Thanks again @verhoevenc :D

Andy

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I got pretty much straight onto it.  

I triangled up (new verb) the main X-braces and scalloped them both behind the join, with the bass side scalloped a little deeper than the treble.  I also took a little more out of the scallops at the ends of one or two of the bass braces.

It's made a BIG difference :D  

I've now fully got the bass treble differentiation - it sounds more like two tones from bongo's now rather than one mush.  There is probably a 5 semitone difference of the root note tapping the bass vs the treble halves of the lower bout.  More importantly, the harmonics are ringing loud and varied wherever it is tapped.  Pleasingly, they are at their loudest and most complex when you tap above the bridge plate.

I probably could go a little further, but I've learnt over the past couple of years that quite an important skill in this game is knowing when to stop, based on prevailing skill and experience and result.  For me, at this stage in my learning curve, this is the point to stop!

I still have the back braces to finish shaping, which I will do tomorrow, and then the label will be stuck in and the back will be closed :lol:

Thanks again for your help, @verhoevenc and thanks also to @Prostheta for pointing Chris my way :)

 

Andy 

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I look at conversations like this and keep reminding myself that I have so much to learn. It's very grounding, and importantly so. I've been ruminating over making an archtop bass for a couple of years now, and I know full well that it will go one of two ways very easily. Especially since I am changing some of the more established parameters. At least, that is how I perceive the idea so far. Perhaps I am also conflating the design of an acoustic with that of an archtop too much. Again, revealing how little hands-on knowledge I have. It's easy to watch somebody build a jazz box, but a totally different game knowing the whys and hows.

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16 minutes ago, Andyjr1515 said:

Thanks again for your help, @verhoevenc and thanks also to @Prostheta for pointing Chris my way :)

NP Andy. Chris is a good guy and has been a mainstay of PG for many years. I went through my own development (and still am) and Chris' factual and pragmatic approach has done me many worlds of good. I like knowing that there is so much more to know. I'd hate to know everything or that there is little more to learn because that would be no fun whatsoever.

@verhoevenc - do you still have much contact with David Myka? His influence is quite clear within your personal canon, layered with your own quirky constantly-evolving style. You guys have some good science down and I'd be curious to know if you're still pushing ideas behind the scenes individually or in discussion. One thing that always stuck in my mind was David's experiment with large quantities of graphite/carbon reinforcement (and that it kinda sucked ass); the same idea as is commonly used but taken to its logical extreme for the purposes of observation. That David took an aspect of built practice and pushed its limits to exaggerate its effect was appealing and inspiring. I miss his input.

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Pretty close to closing the box - probably take the plunge this evening.  I'm sure there is more whittling that could be done, but it is more important that - for this build - I have a complete guitar to present to our vocalist rather than getting any more harmonics.

The tips that Chris gave me made a tangible difference to the sound.  This is it almost ready to close:

2YmtowLl.jpg

...and the back now has the all important label 

F6JV22Sl.jpg

 

Once the back is on, I'll trim the sides and start on the binding and purfling :)

 

Andy

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I don't want to hijack a thread so I will try and keep it short, but David and I still keep in touch regularly. He's been pivotal in my learning about, and recently acquiring, a CNC. I'm also hoping he'll be helping QA a new hardware design I'm having made (teaser alert!) in conjunction with thegarehanman (ya'll remember him?) and an F1 engineering friend of his he pointed me to. David is an absolute joy and a wealth of knowledge. There are 3 people in this world that I cannot thank enough for making me the luthier I am today: David, Todd (mentioned above), and Erich Solomon. 3 of the most kind, caring, and generous individuals I've ever met... especially to someone like myself who can often be a force of evil as well (look back far enough into PG history and I haven't always had the shiny rep Prostheta gives me hahaha).

If you guys haven't watched Todd's video series on youtube I cannot recommend any harder searching them out (MDLuthier) if you are planning to build anything in the realm of acoustics or if you're yet to learn how to make a blade so sharp it's ridiculous:

https://www.youtube.com/user/MDLuthier/videos

Best,

Chris

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For somebody who presents themselves more as an "enthusiast", you're very industrious and productive Andy. Whether you think of yourself in this way or not, you genuinely have a rich seam of talent and don't do things by halves. Few are far between.

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Hey, how is Russ? He's another member of the PG old guard whose presence is very much missed.

Reputation, errr....schmeputation....anybody would think that we have to pretend that we were born into this world with inbuilt abilities, feet and egos planted squarely. Hell, there are MANY people here who've been members for over ten years or at least people we see around elsewhere who were here ten years ago. People new to building tend to do a lot of growing in the space of a few months, so think about that in the context of a decade. Some of us might even have wood in the stash older than that....

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1 hour ago, Prostheta said:

For somebody who presents themselves more as an "enthusiast", you're very industrious and productive Andy. Whether you think of yourself in this way or not, you genuinely have a rich seam of talent and don't do things by halves. Few are far between.

Flattery will, of course, get you everywhere :lol:

I do very much class myself as an enthusiast and hobbyist.  It keeps the pressure off and ends up being much more fun than if I was trying to make any money out of this crazy pastime.  And - with such fantastic products available for such crazy low prices nowadays - I long ago realised that it could only ever be just a hobby!

My secret weapon is that I retired from a bonkers-busy international job last year and have time available now that I could barely imagine in my previous life.  It doesn't half allow things to accelerate!  With the occasional paying commission, if I can break-even - or even just offset the cost a little - it certainly isn't as expensive as taking up golf :rolleyes: (cue: "What's your handicap?" "My inability to hit the ball!")

I'm also in awe of the amount of freely given information and time and resources on the internet in places like this.  Seems rude not to take advantage of it all! :) 

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I've checked, and double checked and triple checked that everything than needs to be done before the back goes on has indeed been done.  

With fingers well and truly crossed, it's too late if I've missed something :D:

zf1B4iMl.jpg

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I think that's a good way to be, and you're lucky to be in that position. Very cool. I'm glad that you hate golf also. That goes a long way as a test of character.

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