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Andyjr1515

Dreadnought Acoustic Build

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Hi

I posted a pic of a build I've started now that the Camphor Single Cut bass is nearing completion. It's a 6 string Dreadnought Acoustic being built as a surprise gift from our old-gits-band to our old-gits-band's even older git vocalist on a 'special' birthday in July.

I won't do a detailed build thread but, if anyone's interested, will post progress shots as I go along.

This is the progress so far:

First - and essential - task is building the body 'mould'. You can see the lacewood back pieces here too before slimming and joining:



Next, thicknessing the lacewood back and spruce top to 2mm and 2.9mm respecitvely and joining. The mahogany/walnut/mahogany splices for the neck are also in this shot:



Next the thicknessing of the side lacewood - again down to sub 2mm:



Last year I invested in an electrical bending iron. Compared with my previous gas blowlamp into scaffolding tube self-destruction kit, it's LUXURY :) :



Here are the sides bent and drying in the mould. They are hand bent to shape but then clamped in the mould to help prevent 'relaxing' back straight as they dry:



Mahogany heel block and tail block added to the trimmed sides and slotted kerfing added to both sides:




Top is finish sanded and then the soundhole rosette and purfling slots routed:


Then the soundhole cut out:




The top is dished to a 25' radius. The braces are cut and sanded to that radius relative to their respective positions in a carved-out radius dish made from MDF:


The braces are positioned, glued and pressed down on the back of the top into the radius dish in a 'go-bar' rig, made from chipboard and threaded rods/wingnuts using fibreglass and dowel rods:




Result is one subtly dished top and braces ready for shape carving and the dark art of 'tap' tuning....






That's it so far. I'll post pics as I progress :)

Andy

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Wow!
This is not only interesting. It's downright exciting and inspiring.
Thanks so much for posting.

Oh... and... er...
I can't do that [b]at all[/b], but if I could've done it, I could've done it a lot better! :D

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Looking good so far! I haven't seen that style of mould construction before - are you working from a particular method or is it something you've come up with?
I have accumulated wood and bits for a mandolin build, but not quite got around to getting started on it yet, so I will be going through some of these same processes.

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[quote name='BassTractor' timestamp='1453719572' post='2962009']

Oh... and... er...
I can't do that [b]at all[/b], but if I could've done it, I could've done it a lot better! :D
[/quote]
...and I would've too if I could've :lol:

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[quote name='Beer of the Bass' timestamp='1453719741' post='2962012']
Looking good so far! I haven't seen that style of mould construction before - are you working from a particular method or is it something you've come up with?
I have accumulated wood and bits for a mandolin build, but not quite got around to getting started on it yet, so I will be going through some of these same processes.
[/quote]
It's Andyjr1515 you're talking about, so [b]of course [/b]I've stolen it from somewhere else :lol:

It seemed to me a lot quicker and easier than the more traditiional block-built things. Just a few sheets of jig-sawn ply and a dozen cuts or so of some 1 1/2"x 2" timber and job's done. Does the job too as far as I can tell (having never used the other type). :) Edited by Andyjr1515

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This looks awesome!
I've always fancied having a go at one of those kits that Martin do, but not worked up the courage to have a go.
Maybe one day!
Good luck with this one

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[quote name='rubis' timestamp='1453741530' post='2962341']
This looks awesome!
I've always fancied having a go at one of those kits that Martin do, but not worked up the courage to have a go.
Maybe one day!
Good luck with this one
[/quote]
I think the Martin (and Stewmac ) kits are a great way to go!

If I was starting again, that's what I would do for starters. This OM was my first (and only other) acoustic build and I am still utterly delighted with it - but WHAT a steep learning curve!!!!!!:



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[quote name='RhysP' timestamp='1453822943' post='2963137']
Nice work!
I'd love to hear that Om you built, do you have any sound clips?
[/quote]
I do have somewhere. They may be a bit rubbish....if so I'll record a few more.

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[quote name='Andyjr1515' timestamp='1453825961' post='2963179']

I do have somewhere. They may be a bit rubbish....if so I'll record a few more.
[/quote]

Don't go to any trouble.
I've got a lovely high end OM style acoustic & I was just curious as to how yours sounded.

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[quote name='RhysP' timestamp='1453831157' post='2963242']


Don't go to any trouble.
I've got a lovely high end OM style acoustic & I was just curious as to how yours sounded.
[/quote]
If the link works, there are a couple of simple unplugged recording clips on my web site page below They were recorded on a little zoom pocket recorder so no great shakes but will give you an idea :). http://www.ajrguitarmods.co.uk/swift%20iv%20acoustic.htm

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With Kert's single-cut camphor job collected and Kert VERY pleased :D , and the weather cutting out any other decent Sunday activity, I thought I'd have a go at the black magic of brace carving and tap-tuning.

The rough shaping of the braces is like this (there's still a tiny cap to put onto the join of the X brace which is important for tone as much as strength...more later):



In brief, the position of the peaks in the braces is important. Happily, 70 odd years of other people's experience says that this will be OK. Who am I to argue.
Secondly, the thinner the braces, the more bass will resonate. Also harmonics start developing the thinner things are, but that - if taken too far - is at the expense of strength.
So, in very basic principle, you tap the top, holding the top up by the very edge, listening for tonal differences between the bass string side and the treble string side. You shave tiny amounts off the depth of the braces until you start hearing the top ringing more than a dull thud, then thin the appropriate braces more for a bit more bass in the appropriate places.

There are some FASCINATING videos on YouTube on this, including a Physics lecturer going into considerable detail. With me - I get to the point where it rings, where I can hear a number of notes in the harmonics and where there is a tangible difference in pitch between tapping on the bass side and the treble side :) And then I stop... because I don't really know what I'm doing beyond that :rolleyes:

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The sides assembly were shaped to the correct curve on the radius dish with a couple of lengths of 250 grit stuck on with doublesided tape. Then the top glued, clamped and trimmed:





Still quite a bit to do on the top, but also started the back.

A bit scary this - having got the back down to just over 2mm, I needed to inset a 1 mm central decoration strip. I had a 3mm router bit and figured that if I used a 3mm allen key as a spacer, I could cut the 6mm in two passes (one with the allen key and one without) along a straight beam with the Dremel precision router base:



It worked!



Strip safely in, glued and excess wiped off:

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Bit more progress on this.

Got the back braces radiused, rough shaped and into the 15' radius dish with the go-bar deck. Look at that top bend!



Then scalloped them with a sharp chisel:


Finally, added the centre-join reinforcement:




Then used the radius dish again with some 120 grit to shape the body for an all round fit . Some more to do before I 'close the box', but it's starting to look like a dreadnought body:





In the meantime, I've started on the neck... :)

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[quote name='Andyjr1515' timestamp='1455045847' post='2975424']...it's starting to look like a dreadnought body...
[/quote]

Indeed it is..! Excellent topic, excellent write-up, excellent photos. Excellent all round, in fact. Thanks for sharing. :) B) Edited by Dad3353

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[quote name='Dad3353' timestamp='1455046187' post='2975427']
Indeed it is..! Excellent topic, excellent write-up, excellent photos. Excellent all round, in fact. Thanks for sharing. :) B)
[/quote]
Thanks, Dad3353 ! :)

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[quote name='GarethFlatlands' timestamp='1455125447' post='2976218']
Very nice! Acoustic builds look like the hardest to get right but it looks like you've got the skills and gear for it. Looking forward to seeing the finished product.
[/quote]
Thanks, GarethFlatlands :)

Actually, there are a number of aspects that are easier...but you have to get your head around the design musts and must nots. And there are quite a few extra jigs and fixtures to make (body mould, radius dishes, go-bar deck, neck joint jig, etc)!

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Very impressive work, thanks for sharing!

Out of interest, how did you make the radius dish?

The only method I can think of is a router on an enormous pivot or dangled from a piece of rope (what could possibly go wrong! :lol:)

The wood grain on the back looks really nice, I bet that will pop out and look amazing when it's got finish on it :)

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[quote name='6v6' timestamp='1455182310' post='2976671']
(what could possibly go wrong! :lol:)
[/quote]


:lol:
Nothing!

I wondered about the same thing.
Saw a rope type rig many decades ago, with some special type of chain instead of the rope, but I guess that those are extremely very rather obsolete now. The total investment in H&S on that exact rig was a bar that went around it in belly height.

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[quote name='6v6' timestamp='1455182310' post='2976671']
Very impressive work, thanks for sharing!

Out of interest, how did you make the radius dish?

The only method I can think of is a router on an enormous pivot or dangled from a piece of rope (what could possibly go wrong! :lol:)

The wood grain on the back looks really nice, I bet that will pop out and look amazing when it's got finish on it :)
[/quote]
Thanks, 6V6 :)

From memory, I worked out the arc depths, drew some suitable contour circles on the MDF and hand routed the contours, starting with the deepest, middle one, and working my way outwards, reducing the depth of cut each time. With such a wide radius, the maximum depth is only a few mm, but I seem to remember a HUGE amount of MDF dust (a mask is absolutely essential, by the way).

I then finished off with a curved cabinet scraper to smooth down the 'steps'

Andy

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[quote name='Andyjr1515' timestamp='1455144769' post='2976526']
Thanks, GarethFlatlands :)

Actually, there are a number of aspects that are easier...but you have to get your head around the design musts and must nots. And there are quite a few extra jigs and fixtures to make (body mould, radius dishes, go-bar deck, neck joint jig, etc)!
[/quote]

I guess there's less routing which looks fairly terrifying if you're not confident at it but more steps that need taking your time over and gear required. Still, nice work!

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[quote name='GarethFlatlands' timestamp='1455218841' post='2977224']
I guess there's less routing which looks fairly terrifying if you're not confident at it but more steps that need taking your time over and gear required. Still, nice work!
[/quote]
Yes - definitely more gear required...most of which you basically build yourself. I've just ordered the bits to make myself a routing jig for the neck joints on the body and neck - it will probably take me a week to build the jig and 20 minutes to rout the two pieces! :rolleyes:

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I've done some further fine-tuning on the braces, with now a much richer resonance coming from the top. Also fitted the soundhole reinforcement and the bridge plate:



Then finished off the back braces, central reinforcement strip and all-important label:



And then, after checking and double checking and triple checking that I haven't forgotten to do something, glued the back on:



If it's dry tomorrow, I'll trim the excess off and then start to do a bit on the neck blank.

Thanks for the great feedback, folks

Andy Edited by Andyjr1515

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Clamps off, edges trimmed and a quick protective coat of varnish. This will all be sanded off when I do the finishing proper but, in the meantime, it protects particularly the top from dints from things like shavings, etc, when it's being manhandled for the binding, etc..:





Next job on this is the purfling and binding which I haven't ordered yet. While I'm waiting, I'll start on the neck :)

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