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  #1  
Old 03-21-2017, 08:52 AM
emmsone emmsone is offline
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Default Build Number 2 - Tasmanian Blackwood/German Spruce Nylon Crossover

Hi All.

I'm back! After the success of my first build (seen here http://www.acousticguitarforum.com/f...d.php?t=434174) which thankfully ended up sounding nothing like a cardboard box!!! a friend commissioned me to build him a nylon crossover version of the same guitar. He's played that first build quite a few times now and every time he picks it up he finds it hard to put down
Doing a nylon crossover is something that i'm happy about because it was actually something that I wanted to get around to doing for myself at some point!

After I was asked, my original and initial thoughts were that I wanted to use Cocobolo back and sides for this but with the new CITES Rosewood regulations I found it practically impossible to actually acquire some.
In the process of looking for an alternative option non-rosewood option I obviously thought of Koa, however importing that into Switzerland is expensive. Further internet research turned up that Koa and Tasmanian Blackwood are very similar woods as they are both Acacias. Luckily for me a local classical builder who gave me some advice here and there on my previous build actually had some, he recommends it as an excellent wood for back and sides especially for classical's, so that made my decision much quicker. The back is a little on the 'plainer' side yet still some nice grain striping but nothing crazy or eccentric. The sides on the other hand are nice and flamey. I like this idea, you see the sides way more then you see the back so having the more "interesting" wood on the sides makes sense to me

Along with that I purchased a German Spruce soundboard with a nice ringing tap tone.

I have decided to use Rocklite for the fingerboard, bridge and bindings. Its a man-made ebony substitute thats super black, very hard but apparently easy to work with and for the bindings apparently easier to bend than ebony. I haven't received those items yet but i'm pretty confident they'll do their job more than successfully.

My classical builder friend told me not to use a truss rod, but i'm definitely 95% sure I will actually install one. I'm just looking for a lightweight, dual action one!!

For the tuning machines i'm pretty much decided on the Schertlers. And I will be installing a pickup towards the end of the build too.

And yes there will be a cutaway (i'd have to build a whole new mould if I wanted a non-cutaway) and the friend i'm building it for likes the shape of my previous build so unless i change my mind before I actually bend the sides, there will be a cutaway.

I'm still got a few things to get myself acquainted with before I actually start the build, hopefully next week.
One thing is, i've lost my side template both the paper template I made and the original computer file I printed it from. I've seen some of you don't pre-shape your sides before bending, but I haven't worked out how you can accurately cut them to shape after bending, ie when then sides are in the mould. Surely it can't just be sanded down to shape, thats 3 weeks worth of sanding right there!

Here's some pictures of the wood I have
Tasmanian Blackwood back wood
Untitled by David Emm, on Flickr

German Spruce top wood
Untitled by David Emm, on Flickr

Tasmanian Blackwood sides
Untitled by David Emm, on Flickr
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  #2  
Old 03-21-2017, 11:20 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by emmsone View Post
My classical builder friend told me not to use a truss rod, but i'm definitely 95% sure I will actually install one. I'm just looking for a lightweight, dual action one!!
Nylon string guitars don't need a truss rod. I'd advice against it as well.

Quote:
I haven't worked out how you can accurately cut them to shape after bending, ie when then sides are in the mould.
It is very easy to do. You can use a chisel, coping saw and/or hand plane, or any combination thereof. Takes me about 10 minutes or so.
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Old 03-21-2017, 03:26 PM
emmsone emmsone is offline
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Originally Posted by charles Tauber View Post
Nylon string guitars don't need a truss rod. I'd advice against it as well.
Perhaps not for correcting string tension, but this is going to open a can of worms in my head now, like do i have to look at carving relief into the fretboard? if i do that, how does fret levelling work on a non-flat fretboard? maybe I can taper the fretboard so its higher at the nut, but then its a flat trajectory not a curve as would be achieved by either carving the fretboard or by adding relief using a truss rod? Because a string vibrates as a curve surely a tapered fretboard would still get buzzing issues at certain points unless the taper is extreme, but then you get a super high action up the neck. AAARRGGHH my head hurts now. luckily this isn't the first question I have to solve

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Originally Posted by charles Tauber View Post
It is very easy to do. You can use a chisel, coping saw and/or hand plane, or any combination thereof. Takes me about 10 minutes or so.
Ok, that makes sense, but how do you mark, or know what you have to cut to create the right shape? do you just "see" it? or do you put a paper template against the sides and then mark to that and then cut? in which case how is this gaining over cutting the side to shape first when i can do it on a bandsaw when its flat and then bend it on the bending iron? or do I just look at it from the side and cut til the curve looks even?

Thanks again for the help

David
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Old 03-21-2017, 03:38 PM
charles Tauber charles Tauber is offline
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Originally Posted by emmsone View Post
do i have to look at carving relief into the fretboard?
Nylon string guitars usually have much higher action than steel string acoustic guitars or electric guitars. For many players that is all the string clearance that is required. For "serious" concert classical guitars, some carve relief into the fretboard.


Quote:
in which case how is this gaining over cutting the side to shape first when i can do it on a bandsaw when its flat and then bend it on the bending iron?
There is no real advantage or disadvantage, just a different way of doing it. If you don't have a template, bending the shape first, then contouring allows you to get the side contour right and make templates for future same-shape/same depth instruments.

The "best" method for marking side contour depends on the building method you are using. For example, are you using radiused dishes in your building method? If so, you just lay the sides, in the mold, on the dish, mark with a pencil in an inexpensive drawing compass.
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  #5  
Old 03-21-2017, 09:33 PM
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rogthefrog rogthefrog is offline
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I'll be watching this as inspiration for my own first build. Your first thread was chock full of information and I expect this one will be too
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  #6  
Old 03-24-2017, 03:36 AM
emmsone emmsone is offline
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So I started actually doing something on build yesterday. The obvious start point, joining the top and the back.

The Tasmanian blackwood back... A bit tricker than I expected due to the wood having a very slight banana to it. Because both pieces were stored as a bookmatch when you open the bookmatch, the banana'd edges are curving in opposite directions.
What I did in the end was to put the back pieces on a large board and hold the back pieces flat with some clamps and cauls. I then used larger clamps to pull/hold the 2 pieces together.
The edges were actually jointed using the very large, very accurate jointer in the workshop. Unfortunately as its a public access workshop, its one of the machines i'm not allowed to use myself and had to be operated by a supervisor, but whatever, the job was done and it created a good joint in the end.

The Black Forest German Spruce top was super easy, it was dead flat and after putting the edges through the jointer the joint came out perfect.

After both the top and back were successfully joined I thought I was done for the day, but the back had this small amount of random curving to it due to the banana-ing which I thought my make things a bit more awkward later. So I decided to do something about it.
I put the top back on the large flat board and rubbed it with a wet rag so it became wetter then damp, but not soaked, and then clamped the hell out of it and for good measure put half a tree that was lying around in the workshop on top to let the wood know i'm in charge and it will go flat.

I was thinking afterwards I should have put a back strip in, but i'm hoping if I decide to do that I can still do that by effectively installing one as an inlay, but i'm not sure if that is the right/best method, especially if the thicknessing is already done, that's scheduled for tuesday next week but my binding material which i'd use also as a backstrip to match, won't be here for at least another 10-14 days as I stupidly paid for the slow postage.
I also thought If I was going to bend the wood to my will, I should have forced it into the radius dish, but thats MDF and if the water leaked out of the wood that would be the end of my dish, and also as I hadn't trimmed the back to near final size, it would probably be too big for the dish anyway.

Well now that i've explained it, here are some pictures.

Jointing on the jointer
Untitled by David Emm, on Flickr

gluing the back with the extra weight of the sides on the top holding everything in place
Untitled by David Emm, on Flickr

gluing the top, i did actually clean up the excess glue after I took this picture.
Untitled by David Emm, on Flickr

back after joining
Untitled by David Emm, on Flickr

top after joining
Untitled by David Emm, on Flickr

the back being 'flattened'
Untitled by David Emm, on Flickr
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Old 03-24-2017, 03:54 PM
KingCavalier KingCavalier is offline
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Looks great, love that jointer
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Old 03-28-2017, 03:41 PM
emmsone emmsone is offline
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Todays plan for what I was going to do changed when I discovered the guy in the workshop next door (who has the super duper giant precision thickness sander) never actually appeared today. That meant no thicknessing got done, and therefore no sides got bent.
I did however cut the sides to a profile shape on the bandsaw and cut the top and back to somewhat approximate "guitar" shapes before creating clean looking (at least clean compared to what I did in my last build) neck block and end block. I used spruce for these in my last guitar and it all seemed to go well so I have done so again.
I decided to go for the "neck block with a top" style neck block for several reasons, 1) it seems to be the 'done' thing these days, 2) its definitely somewhat resemblant of the older spanish neck heel designs and as i'm building a nylon string that seems logical, and 3) it was something extra I could do in the meantime while waiting and hoping the thickness sander guy would eventually arrive.

The plus side of doing no thicknessing today is that my spruce blocks do look tidy.... Perhaps taking some inspiration from the Astrands, Hatchers and others of this world whose guitar insides look almost as good as the outsides.


You don't have to do much for the square slabs to become immediately obvious they are now parts of a guitar.
Untitled by David Emm, on Flickr

Sides before being cut on the bandsaw, unfortunately there is as yet no after shot
Untitled by David Emm, on Flickr

The aforementioned spruce blocks
Untitled by David Emm, on Flickr
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Old 03-30-2017, 03:43 PM
emmsone emmsone is offline
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Todays work basically went to schedule which is a good thing.
Thicknessed the top, back and sides in the extra large super duper sanding machine in the workshop next door. The back and sides came out exactly to the planned dimensions, 2.2mm for the back and 2.0mm for the sides. Unfortunately the top went a bit thinner then the target 1.9, its about 1.8 but even then its a thin 1.8.
Yes its a nylon string, and theres nothing wrong with tops this thin, but going that thin has not left me much (any) leeway or any room for error whatsoever. I also think I should perhaps have installed my rosette first if it was going to end up so thin. Not much depth there to actually rout into to install it.

On the plus side the Tasmanian Blackwood bent pretty nicely, no real stresses involved there. They are also much flame-ier than I initially thought! They are going to look amazing under finish. The back now looks even plainer in comparison. I still like the idea of the sides, which you see more, being more interesting than the back.

After shot of the sides after being cut to profile
Untitled by David Emm, on Flickr

Thicknessing the top on the extra large fitness sander
Untitled by David Emm, on Flickr

Bending the sides on the bending iron
Untitled by David Emm, on Flickr

initial clamping of the sides into the mould before I went and found some better clamps
Untitled by David Emm, on Flickr

Top side being held to shape
Untitled by David Emm, on Flickr

The back, in the terribly orange coloured light of my apartment
Untitled by David Emm, on Flickr

The spruce top looking very orange in my apartment lighting, in reality its very white
Untitled by David Emm, on Flickr
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Old 03-30-2017, 05:12 PM
TEK TEK is offline
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Looking great David, Nice work!
Travis
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Old 03-31-2017, 02:01 AM
emmsone emmsone is offline
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So this project is about to take a massive delay/postponement/possible cancellation because i've made just about the biggest error that can be made.

I've bent the sides into a left handed shape when the guitar needs to be right handed.
I'm not sure I can get hold of any more sides from where I sourced these.
Anyone know where I can buy Tasmanian Blackwood sides?

I've no idea if this can be saved, the likelihood is about 0.04%

looks like game over.
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Old 03-31-2017, 06:59 AM
charles Tauber charles Tauber is offline
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i've made just about the biggest error that can be made.... I've no idea if this can be saved, the likelihood is about 0.04% ....
looks like game over.
Naw, you're not the first person in history to bend two of the same side or two of the same bindings.

Wet the wood, and unbend it on your iron. Get it as flat as you can, then simply bend it in the correct direction.

It'll come out fine.

Stuff happens, we fix it. Carry on.

In future, remember to label each flat side as "left" and "right" or "bass" and "treble". Ditto for bindings with purfling attached.
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Old 03-31-2017, 08:35 AM
redir redir is offline
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Yeah that's actually a common mistake to make. I've come real close to doing it myself, knock on wood.
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Old 03-31-2017, 03:23 PM
emmsone emmsone is offline
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Sooo, I have "corrected" my mistake. The sides don't look as good as I had them bent originally. The process of bending them back 'inverted' to what they were originally is NOT a fun one, I got the impression the wood didn't like it, it initially felt much more likely that the wood would burn, so I added a bit more water, then it felt like the wood was going to rip or tear, the sides seemed to ripple much easier, it twisted far too easily and I had to use a wooden backing board just to reduce the grain ripping out and to keep the sides reasonably flat.
I then ended up not being able to invert the cutaway fully very well and I felt I was going to damage it but it felt very pliable so I went with the option that seemed to work but you are all going to tell me isn't the best idea of just clamping it tightly to the mould shape and forcing it to the shape and leaving it be, i'm expecting it will spring back somewhat if/when I unclamp it on monday, but hopefully not too much. I may even leave it until tuesday if theres any chance that might help.

Its a shame because the wood looks(ed) amazing.

I thought I was going to be fairly happy bending with the bending iron, but this has annoyed me so much i'm about 92% sure i'll have to either buy or build an actual side bender for any further projects. its still possible to make the same mistake, but i think its a reduced chance.

Quote:
Originally Posted by charles Tauber View Post
Naw, you're not the first person in history to bend two of the same side or two of the same bindings.

Wet the wood, and unbend it on your iron. Get it as flat as you can, then simply bend it in the correct direction.

It'll come out fine.

Stuff happens, we fix it. Carry on.

In future, remember to label each flat side as "left" and "right" or "bass" and "treble". Ditto for bindings with purfling attached.
Actually I had them labelled. The problem was that I have TOP written on each piece of the mould. Unfortunately when you precut the sides to a profile, you have a flat side, that needs to be down and on the table to make sure it all comes out level. That means the moulds have to be upside down during bending, something I didn't clock until afterwards.
Also, it wasn't just one piece, it was BOTH.

Quote:
Originally Posted by redir View Post
Yeah that's actually a common mistake to make. I've come real close to doing it myself, knock on wood.
I really, really don't recommend making this mistake.



Heres a picture of the sides wet, showing their figure, complete with burn mark that wouldn't come off. Luckily its on the inside....
Untitled by David Emm, on Flickr

Picture of the other side
Untitled by David Emm, on Flickr
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Old 03-31-2017, 08:42 PM
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rogthefrog rogthefrog is offline
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Quote:
Originally Posted by emmsone View Post
the back being 'flattened'
Untitled by David Emm, on Flickr
What's the purpose of the hugiferous post sitting on top of the whole thing?
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