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This evening I started muddling through my first acoustic build. I got some free OM plans online in PDF form and got a few hard copies from my local printers (which is a much cheaper way to buy plans! 3 copies for half the price of 1 ordered online). I also got myself a premade OM mould from G&W - worked out £100 inc shipping, I still need to get myself a couple of radius dishes which I shall order when I need them and I also plan to make a gobar deck - as they're very expensive to buy.

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I'm using cheap wood for this one - black walnut back and sides and a "B" spruce top, which are on route from Maderas Barber, I also ordered a spare set of everything plus a set of ebony back and sides on the off chance that this goes well.

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Talking of going well, I started off by thicknessing down the back and sides to 2.8mm and the drum sander said Up yours.

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They're down to 3.5mm and I couldn't be bothered to change the paper over tonight so I moved on to jointing the top (I'll get them down to final thickness after glue up.  I realised shooting board is only big enough for electric tops so I had to MacGyver something out of mdf.

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I then realised these pieces were not only longer but thinner than any pieces I'd glued up before and my big sash cramps and F clamps weren't going to work, so I did some more happy clamping and came up with this setup - the joint is raised up by 1/2" with those piano keys wedged underneath (they just happened to be in the inlay materials box and the right height), so I glued up, pulled the edges out from under it and put some pressure on the joint to keep it flat.

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That's all she wrote for now, I expect tomorrow evenings antics will start with changing the paper on the drum sander so I can get everything dimensioned, I also need to get cracking on Matts tele which I need the drum sander for too.

 

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6 hours ago, ADFinlayson said:

I had to MacGyver something

Gotta love it when people use their brain to solve their problems instead of whining how they don't have this or that, or paying through their nose for a dedicated tool they'd use only once in their lifetime.

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3 hours ago, Bizman62 said:

or paying through their nose for a dedicated tool they'd use only once in their lifetime.

Like the side mould if this goes tits up :P 

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By God, you don't mess about do you? Did you start that the very day your mold showed up?

I shall be watching closely.

SR

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14 hours ago, Workingman said:

I play a bit of mandolin .  

Those are fun little instruments. I built a StewMac F-5 kit and and an electric Mandolin whilst your were away. You should give it a shot.

SR

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That looks a very sound mould.  I confess, I didn't even know G&W did them!

2.8mm for back and sides...hmmm...what got you to that number  (sounds a bit on the thick side, especially for bending sides)?

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9 hours ago, ScottR said:

By God, you don't mess about do you? Did you start that the very day your mold showed up?

I shall be watching closely.

SR

Of course I did, I popped over to see a luthier acquaintance after work (lives only 8 miles away) - I told him I was going to have a go at an acoustic and he suggested I come over and talk acoustics, I was in awe of his 2 works shops, tools, wood, builds etc and tried out 6 of his classical guitars while absorbing lots of tips (he's now my best friend), came home excited and got crackin'

3 hours ago, Andyjr1515 said:

That looks a very sound mould.  I confess, I didn't even know G&W did them!

2.8mm for back and sides...hmmm...what got you to that number  (sounds a bit on the thick side, especially for bending sides)?

I was hoping you would chime in on this thread :) A communication faux pas on my part - I only meant to get the back down to 2.8, actually looking at the plans it needed to be 2.5 and the sides 2.2 (the top is 2.8 according the plans I'm going from). Anyway I've got the back thicknessed down to 2.6mm and sides down to 2.2mm, I put 120 grit paper on the drum this time so I shouldn't need to remove too much material to get a smooth surface - my sander tends to leave quite deep streaks with 80 grit.

Those streaks are a bit annoying, I should have really flipped it the other way but that would have introduced even more sap wood which I didn't want to do. Glue joint is spot on though.

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Next I cut out the side profile from the plan and scored round it on the sides (I had masking tape and superglued the 2 sides together) then cute it out close to the line on the band saw.

I put the side profile in the mould to make out where the bends were - steeling some ideas from @Andyjr1515 here

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More idea theft...

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and some more... I left those soak in the bath for about 10 mins while the iron warmed up to 250ºC

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and boom :D the bottom one is not brilliant just passed the waste, I didn't want to clamp it too tight with the braces in case it cracked - I made the mistake of bending the front curve first. On the top side I bent the waste first and it came out perfect. 

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Going back to the back, I scored a line 3mm either side of the seam and went at it with a chisel, took about an hour then realised I have a router and a 6mm bit that would have done this job in 30 seconds.

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Theres a strip of flamed maple binding going in here.

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This is when I realised that the gobar deck needs to be made sooner rather than later

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So far I am finding this whole thing very enjoyable, and I didn't even burn myself!

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Well, I can't match you for speed! :)

This is all very exciting indeed. 

I aim for 3mm for a spruce top, leaving 0.1mm for the final finish sanding to end at 2.9mm.  For the back and sides, I go down to 2mm, with finish sanding getting me down to 1.9mm 

Watching avidly ;)

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11 hours ago, ScottR said:

Those are fun little instruments. I built a StewMac F-5 kit and and an electric Mandolin whilst your were away. You should give it a shot.

SR

I would like to.  My um life circumstances have changed a bit and most of my tools were stolen about five years ago.  I have been thinking about an electric mandolin because of the small size that could be done with hand tools.  My big, but very slow project has been restoring a 1920's aluminum upright bass.  

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Well I'll be slowing down imminently because my spruce tops haven't been dispatched yet and I think I'll be procrastinating over the rosette too.

I forgot to answer re G&W, they've had moulds on their site for about 6 months, there are a few different shapes and I think they're good value for what they are, I figured I would be spending the best part of £50 on materials to make one and there would probably be a few hours involved, £100 including postage seems like good value. That all being said, your design looks to be a lot easier on the materials (I just assumed I would be making something like theirs). They also do radius dishes (you specify your radius) so I will be ordering a couple from them as after watching a few videos, I really don't fancy making them!

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So I've made the gobar deck mk1 from 18mm mdf, M8 threaded rod, nuts and washers, doesn't look much but I think it will do the job. It's adjustable and once I know how high I need to have the ceiling at it's highest point, I'll shorten the rods. By the time I'd bought all the parts I think I was in for around £40. I've also ordered a load of fibre glass rods and end caps which I'll use to make the gobars when the come, another £20 all in .

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and a very tedious job, 100 pegs for the linings

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I've made a heel block out of a walnut offcut, just needto radius the front so it fits the shape.

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One area of concern... After leaving the front clamped overnight and most of today, the front seems to have moved back in. I'm not sure whether to just leave this, glue in the end block and kerfed linings, or get the iron out and see if I can slack up those front bends a bit. What do you reckon @Andyjr1515?

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The front block will be sufficient to hold it square as long as it's clamped square when the glue is drying.

Personally, I go for a flat block and keep the heel joint flat with the neck.  There is some awkward geometry if you have a curve there...

 

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3 minutes ago, Andyjr1515 said:

The front block will be sufficient to hold it square as long as it's clamped square when the glue is drying.

Personally, I go for a flat block and keep the heel joint flat with the neck.  There is some awkward geometry if you have a curve there...

 

I like those answers a lot, that saves me a bit of work, many thanks :) 

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38 minutes ago, Andyjr1515 said:

The front block will be sufficient to hold it square as long as it's clamped square when the glue is drying.

Personally, I go for a flat block and keep the heel joint flat with the neck.  There is some awkward geometry if you have a curve there...

 

And it's glued :D 

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I've left my self a couple of mm to play with on the back (the above pic is bottom up) to account for the tighter radius of the back, I'll probably have to rough it in with a file. 

Once I released the spreaders to tape off the glueing area, I noticed that the front doesn't spring back in at all, it's the force of the spreaders being done up too tight that's affecting the curves, the spreaders fit perfectly into the mould without the sides which makes me think that the shape of the spreaders doesn't account the 2mm of the sides so the radius doesn't quite butt up. Or it could be a crap luthier blaming his tools.

A few things I'm really enjoying about this project - Making the tools to do the project (gobar etc), I'm getting that rush that I got on my very first build, and I'm using wood out of the offcuts bin.

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made an end block from another walnut offcut and got it glued in 

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I've made the centre brace for the back out of the quarter sawn maple, the plans say 20mm wide by 2mm thick and curved, I've got it down to 2.5mm so far but I'm not sure how to curve the thing and get the matching profile in the cross braces, so that still needs some working out.

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I've started marking out the locations of the braces from the template too, I've just cut out a little corner at each intersection in the template so I can  mark on the wood where the braces are going to go. Using up some more offcuts :) 

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7 hours ago, ADFinlayson said:

I'm not sure how to curve the thing and get the matching profile in the cross braces,

If I understand correctly the end result is reminiscent to a half round stick, the flat back being glued to the bottom.

For what I've seen various builders do is simply use a mini plane, potentially drawing lines for faceting similarly to shaping a neck. Heck, you can plane a fretboard radius, can't you? Radiusing the strip should be no different to that! Masking tape and super glue to attach it on the side of a plank of the same thickness to clamp it securely to your workbench and voilà...

You most likely also have the tool to transfer the shape to the cross braces: The comb like profile gauge.

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Quick intervention here, @ADFinlayson 

It is the cross braces that will form and hold the radius of the back plate.  To do that, they need to be full width and then your go bar rods will press the braces into the back plate into the radius dish and hold it in shape.  The strip you show is then cut to fit in between the braces - again, glued in the radius dish and helping to hold the lengthwise element of the curve.

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1 hour ago, Andyjr1515 said:

Quick intervention here, @ADFinlayson 

It is the cross braces that will form and hold the radius of the back plate.  To do that, they need to be full width and then your go bar rods will press the braces into the back plate into the radius dish and hold it in shape.  The strip you show is then cut to fit in between the braces - again, glued in the radius dish and helping to hold the lengthwise element of the curve.

Thanks for stepping in Andy, so my research has found 2 methods of doing this and I'm not sure if either is easier than the other:

1). As you mentioned, radius the lateral braces and glue them in on the dish to get the radial shape in the back, then cut the centre brace to fit between.

2). Glue in the centre brace flat (it has a lot of flex), shape it, then cut intersections and glue in the lateral braces on the dish. 

I woke up all excited and ran down and took the clamps off, look at that! :) 

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There is just one area, that bottom front bend where I didn't manage to keep the bend perfectly square, if you look close it's a probably .25mm out. I'm hoping that given the binding is much thicker (2mm) than the amount it's off square that I might just get away with it. But I obviously need some practice - I've got some limba sides in the cupboard so I might try bending those t0o.

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41 minutes ago, ADFinlayson said:

Thanks for stepping in Andy, so my research has found 2 methods of doing this and I'm not sure if either is easier than the other:

1). As you mentioned, radius the lateral braces and glue them in on the dish to get the radial shape in the back, then cut the centre brace to fit between.

2). Glue in the centre brace flat (it has a lot of flex), shape it, then cut intersections and glue in the lateral braces on the dish. 

Ah...that's OK.  I misinterpreted the comment and thought you were planning to cut the braces themselves.  Yes post-notching the strip is fine.

I'll get back to you shortly on the twist.  It's probably not a problem...

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Hi again.

Ref the twist, don't underestimate how much rigidity the kerfed linings are going to give.  As long as the sides are kept in the mould while the linings are glued in place, and left to fully cure before taking it out of the mould, then there should be very little flex when it eventually comes out of the mould.

Another thing you can try if it bothers you, is water spray the slightly offset bend until it is pretty sodden and then clamp it back up in the mould until it is fully dry.

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And a final tip before I forget:

Ref the tail block - are you planning to fit a pickup system?  

If so, then check that it isn't too thick for the standard acoustic barrel jacks (that double as the rear strap pin) if you are planning to fit one of those.  I'm referring to one of these:

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If it is too thick, then the alternative is simply forstner drilling a rebate to allow the barrel to sit deeper in the hole and thus enough threaded length being exposed to the button to fully screw on (which it needs to do to allow the jack to fully engage with the socket).

Problem is (and don't ask me how I know - twice!) that once the top and back are on, it is a real problem if the barrel jack isn't long enough.  A number of plans available assume that it will be acoustic only and are often needlessly 'generous' with the block dimensions.

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coming along nicely and I'm jealous... but not jealous enough to go thru trying to build an acoustic... so congrats!

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17 minutes ago, mistermikev said:

coming along nicely and I'm jealous... but not jealous enough to go thru trying to build an acoustic... so congrats!

Thanks Mike, but save your congrats for the day I strum a chord without the body imploding :) 

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