I’m guessing that you posted that design @jamesbisset just to check if we’d spot the deliberate mistake ….

Am I right??

@jamesbisset awesome to see you are working on another guitar. Looking forward to see more 🙂

I originally planned to draw the moulds in a 3D program and then get them cut on a CNC machine. The technique for making this sort of complex shape in 3D is called lofting - from pre-computer aeronautics and boat-building. But once I’d ‘lofted’ the top, I realised I could just cut it out of 3mm MDF layers. 

@tv101 You’re always right.

Posted by: @jamesbisset

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@tv101 You’re always right.

What about when I think I'm wrong @jamesbisset?

Posted by: @jamesbisset

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I originally planned to draw the moulds in a 3D program and then get them cut on a CNC machine. The technique for making this sort of complex shape in 3D is called lofting - from pre-computer aeronautics and boat-building. But once I’d ‘lofted’ the top, I realised I could just cut it out of 3mm MDF layers. 

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Do you then smooth the layers together?  I'm guessing so, else you'd end up with a bit of a ridged top?

Is it right that you'd have an arch that'd be 12mm-15mm from highest to lowest point?  So, if you were cutting the top (perhaps on a CNC) out of a piece of wood, it'd need to be 15mm thick? 

Though on a CNC, not sure how you'd manage to cut out the inside of the carve (at least, not easily without significant risk of cutting through), so it wouldn't be a true archtop-thin top.

According to Mr Bagpress (of whom more anon) a concave mould will be more effective than a convex one. This also means that you don’t have to compensate for the thickness of your lamination when building the mould.

So the layers are built up using PVA and locating screws to register each piece. PVA takes longer to set, so it’s a little easier to take your time and get it right when you’re gluing 6 layers.

Why 3mm layers? Why six of them? Because 5 x 3 plus baseboard gives a height of 15mm and, according to Mr Bagpress (of whom more anon), if Gibson never bent their laminations more than 15mm, then neither should we. 

Oh, the unused inners do give a hint at what the end result might be like.

The unanswered question at this stage was just how smooth that mould would need to be. We’re not using a huge steaming press, just a little vacuum pump. Will a 4-5mm lamination follow every bump or just approximate the general direction of travel.

So, Big Day for Little Plane!

It should have been obvious to me that, if each concentric lofting contour was equidistant, the rise would just be in a straight line. But no, so out came the scrapers to try and realise an elegant arch.

Tiny little planes don’t tend to carve out long smooth curves, and paper-thin MDF can tear, so car body filler is used to smooth out the dips. Mark says that’s what all the professionals do.

Posted by: @jamesbisset

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car body filler is used to smooth out the dips. 

Genius!!!

I'd always thought you'd be sanding and sanding to get the ridges smoothed out into the carve shape you wanted.

Filling it in is so much easier.

Woosh! Didn’t even touch the sides! Oh no, here they are.

Crudely cut lumps of MDF and plywood were copy-routed using the top template I failed to mention earlier.

This time we took the thickness of the lamination into account, and used a bearing router bit to reduce the first layer of the side mould by around 4mm (oh look, is that a top template I failed to mention earlier?).

And then an awful lot of copy-routing ensued.

Now I need something to go onto the moulds. I’m kinda sorta following Making a Laminated Hollowbody Electric Guitar by Jim English, so I’m laminating 3 layers of 0.6mm veneer and one 1.5mm veneer. The 1.5mm veneer is the outer - the pretty one which I’ll need to sand and polish.

Veneers tend to come in around 200mm wide, so the first step is to join pairs of leaves to make 400mm wide layers (the design is 380mm wide).

There’s a full lesson on glue and edge-joining veneers on the Guitar Making YouTube channel courtesy of Mr Bagpress - he makes it look easy:

So soon I have a big pile of joined veneers.

Right, off to make a new mould for the guitar back. More posts when I’m finished with that.

@jamesbisset

All fantastic stuff James. Really looking forward to seeing this unfold

🙂🙏🎸🎶