Yes, the neck will go on the new body. Probably a few less photos as there's not much point in showing photos of the same thing twice in the same thread. I'll try to show photos where the new body differs from the first one.
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A short scale acoustic bass guitar experiment.
- Thread starter Dave Higham
- Start date
Post as many photos as you like. I'm interested even if it's steps you just did. Heck, post the new guitar build when you get that far too.
The main difference with this body is that the top and back won't be domed, they will be curved. The sides will be shaped in this sanding dish which is curved across its width, but straight along its length. It's a more natural way for the top and back to be deformed by only bending across the grain.
Some luthiers do this, or something very similar, a notable one being English luthier Stefan Sobell. People call it cylindrical but it isn't. It's the shape you get if you support something at each end and apply force in the middle. I think it's a spline curve (but I'm not sure). Nigel Forster made a lot of guitars working with Sobell and says they were not cylindrical. So maybe Sobell's are this shape, but he tends to keep that sort of information to himself.
I made the 'dish' by supporting a sheet of MDF along each edge and screwing it down along the centre line. The intermediate supports are just glued in place where they touch to make it more rigid.
I now know that this shape is a spline curve, because I drew a spline curve in CAD through two points 500mm apart with a 20mm deflection at the centre. Then I put a straight edge on my dish (perhaps I should call it a trough?), and measured the height of the curve at several points. I put those measurements into CAD and drew a spline curve through them. The two curves (allowing for errors in my measurements) are identical.
Making the back this shape will also reduce the body volume a bit. The green line is the spline, the red line is the radius of the back on the first body.
I made patterns for the sides the same way as before, by placing the mould on the 'trough' and scribing round it. I increased the amount of 'wedge' slightly so this is what an end view should look like.
And this is how the side templates turned out. That would be a lot of wood to trim off if I bent them straight and shaped them afterwards.
Some luthiers do this, or something very similar, a notable one being English luthier Stefan Sobell. People call it cylindrical but it isn't. It's the shape you get if you support something at each end and apply force in the middle. I think it's a spline curve (but I'm not sure). Nigel Forster made a lot of guitars working with Sobell and says they were not cylindrical. So maybe Sobell's are this shape, but he tends to keep that sort of information to himself.
I made the 'dish' by supporting a sheet of MDF along each edge and screwing it down along the centre line. The intermediate supports are just glued in place where they touch to make it more rigid.
I now know that this shape is a spline curve, because I drew a spline curve in CAD through two points 500mm apart with a 20mm deflection at the centre. Then I put a straight edge on my dish (perhaps I should call it a trough?), and measured the height of the curve at several points. I put those measurements into CAD and drew a spline curve through them. The two curves (allowing for errors in my measurements) are identical.
Making the back this shape will also reduce the body volume a bit. The green line is the spline, the red line is the radius of the back on the first body.
I made patterns for the sides the same way as before, by placing the mould on the 'trough' and scribing round it. I increased the amount of 'wedge' slightly so this is what an end view should look like.
And this is how the side templates turned out. That would be a lot of wood to trim off if I bent them straight and shaped them afterwards.
Starting as I did the last time with the neck and heel blocks. The heel block this time is a piece of 'old growth' birch plywood glued to a piece of mahogany. Birch ply, because there's not much wood between the hole and the top of the box and the ply should be stronger than the spruce sandwich I made the first time. 'Old growth' because it came out of a retail shop we re-fitted in the 1970's. The mahogany is there because it's easier to sand , to fit the curve of the sides, than the ply.
The neck block is almost identical to the first one, except that I've moved the triangular pieces out to the edge and the holes for the struts aren't drilled at a compound angle. The struts will be sort of 'parallel' to the top.
The neck block is almost identical to the first one, except that I've moved the triangular pieces out to the edge and the holes for the struts aren't drilled at a compound angle. The struts will be sort of 'parallel' to the top.
That old growth plywood is a real key to good tone. They don't glue 'em up like that anymore. 
Made me laugh @Matt Liebenau, but it's true ! I wouldn't know where to find stuff like that these days (especially in France !). Wish I'd rescued more than one sheet. About 20 more went in the skip! (Does skip = dumpster across the pond?)That old growth plywood is a real key to good tone. They don't glue 'em up like that anymore.
Rarely. I've only heard that used on construction sites for the extra large dump bins that need to be picked up by a special truck. Not for a regular old dumpster out back behind the building.
"Bin" would translate, though.
I know you said this in jest, but I was working in a high-end cabinet shop in the early '70's and recall clearly when "Baltic Birch" first came around, at least in the US Midwest - I expect it was in use in the UK sooner. It revolutionized many designs and made new ones possible. I haven't looked in many years but I would be surprised if that level of "voidless" quality is still readily available.That old growth plywood is a real key to good tone. They don't glue 'em up like that anymore.
Yeah, it was both a joke and a sad truth. I've mentioned somewhere else that I've thought it would be funny to get some plywood with a fancy wood facing and use that as the front and back on some Danelectro style bodies just to see what people say.
When I worked construction, we called that a 'bin'. A dumpster then was square/rectangular with vertical sides and face, and had wheels on it. They're used as commercial garbage cans. When I was doing construction, a 'skip' was an engineered work platform that we used on boom forklifts to bring workers up to working height on the exterior of a building. I hated working on skips. We were at the mercy of the alcoholic driver down below.
Got the sides thicknessed and bent and the heel and tail blocks glued in. It's Claro walnut again, but not figured. It's still very nice wood though because it's straight grained and perfectly quarter-sawn. It's also 'old- growth' because I got it from Dave Maize in 2008 and it was re-claimed wood he found somewhere so it's anybody's guess how old it is.
No 'driving the bus' this time, but after quite a lot of pulling and pushing this is what the trough looked like. As usual, I applied chalk to every surface that needed to be in contact with the back and sanded until it was all gone.
This is what the sides and end blocks look like after sanding.
No 'driving the bus' this time, but after quite a lot of pulling and pushing this is what the trough looked like. As usual, I applied chalk to every surface that needed to be in contact with the back and sanded until it was all gone.
This is what the sides and end blocks look like after sanding.
Glued the strengthening pieces in for strap buttons and jack socket.
Made some linings to match the profiles of the sides.
Back linings glued in. The linings are glued in slightly proud of the sides and then it goes onto the 'trough' again to sand them flush. Not really a 'forest of clamps'; more of a hedge.
Once the back linings were done, I turned the 'trough' over and sanded the front to the shallower front curve. Then glued linings in and added two strips of veneer to all the bindings. This makes the side assembly quite rigid, so it doesn't need to stay in the mould any more.
Here you can see the extra layer of lining where the arm bevel will be.
Made some linings to match the profiles of the sides.
Back linings glued in. The linings are glued in slightly proud of the sides and then it goes onto the 'trough' again to sand them flush. Not really a 'forest of clamps'; more of a hedge.
Once the back linings were done, I turned the 'trough' over and sanded the front to the shallower front curve. Then glued linings in and added two strips of veneer to all the bindings. This makes the side assembly quite rigid, so it doesn't need to stay in the mould any more.
Here you can see the extra layer of lining where the arm bevel will be.
Cut the hole in the blunt end and made an access panel to fit. Exactly the same process as the first time, but slightly smaller because of the shallower body. It's just big enough to get my hand through, which is what limits how shallow the body can be. Flamed maple in the middle and sapele either side. All off-cuts from drop-tops. The sapele was one piece of wood, cut in half, but I think I must have got one piece the wrong way up as they don't both reflect the light in the same way.
Seen from the inside.
Seen from the inside.
That's the sides done for now, so I start on the back. I got the back joined and sanded to thickness so now I need some braces. They're made from some of the same quarter sawn cedar as those in the first body. This back only needs ladder braces, as it's only bent across its width. I made this jig for routing the profiles, when I made the first ABG, by cutting the profile as accurately as possible and then applying bondo and squashing it onto the trough (with a piece of non-stick backing paper between the bondo and the trough). This was before the trough got abrasive cloth stuck to it.
Here are the finished braces.
Here are the finished braces.
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Aside from your work, which is impeccable, I love that dust collection gizmo on the router table!
The back has been joined and sanded to thickness and had a cross-grained centre strip glued on. The two longest braces have been glued in place and the rest of them are being glued. The tops of the braces are radiused (? It makes them look nicer) but as cedar dents very easily I made some little bridge blocks for the go-bars to press against. I made them in a strip, cut into pieces.
All the braces glued.
Notches have been cut in the linings to accept the ends of the braces, so the back is ready to be glued on, but before I do that I have to make the front, as that will have to be fitted to the sides too.
All the braces glued.
Notches have been cut in the linings to accept the ends of the braces, so the back is ready to be glued on, but before I do that I have to make the front, as that will have to be fitted to the sides too.
I'm just here for the dumpster discussion.
Just kidding …. Loving this thread. Looking forward to following along and seeing how it all progresses .
Just kidding …. Loving this thread. Looking forward to following along and seeing how it all progresses .
Here's the front: joined, thicknessed, rosette inlaid and sound-hole cut exactly the same process as the first time around except it took less time. It always does the second time, especially if I don't keep stopping to take photos. I say exactly the same process, but not quite, as this time I remembered to cut the forearm bevel profile before gluing any braces onto it.
The first stage in bracing. Marking out the brace positions and gluing on a sound-hole reinforcement, then cutting the hole.
The first stage in bracing. Marking out the brace positions and gluing on a sound-hole reinforcement, then cutting the hole.
