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Acoustic bass - carved top


honza992

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Hi all

 

The acoustic bass I’ve just finished is such a success that I’m going straight into building another, albeit this next one is a bit more complicated - the top will be carved from solid wood to create the arch,rather than being a thin piece of wood pushed into an arch by the braces, as the last one was. 

 

I’m already a couple of days into building, but just in case anyone is interested, I’ll show the process from the beginning. 

 

First up, a pile of wood:

(apologies for the washed-out pics, my phone takes terrible pictures, I must get a proper camera)

 

IMG_20240219_111415.thumb.jpg.010d66fdba65be3850b386199c73580d.jpg

 

 

For the top, Italian spruce. 

Back & Sides - Italian walnut

Neck - multi laminate, flame maple and walnut

 

Everything else we’ll work out as we go.  But fretboard will probably be crelicam ebony….

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First job is gluing the back together.  To get an invisible glue line the joint has to be pretty perfect.  The best way I’ve found is using a hand plane.  For any plane nerds out there, up till now I’ve used a number 4.  I’ve just bought a number 6 though which is joy to use, and nearly as long as the back itself.  You can see it here with a single shaving it’s taken off from the entire length of the board

IMG_20240222_114028-1.thumb.jpg.5cb65fe36ab4f8ba5c7c7e65b2f98c52.jpg

Joining the two boards together I used the ‘tape method’, which is the easiest clamping technique ever - raise one edge of one board off the table and put tape across the join.  Add glue, then put both pieces flat and the tape pulls the boards together.  Here it is taped, already glued:

 

IMG_20240222_130338.thumb.jpg.753ab479d09cc96d21d4528ef39d6339.jpg

 

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I’m not quite sure why, but next I made the kerfing.  It’s not the obvious next step, but there you go.  Making kerfiing is pretty tedious.  And mostly pointless.  You can buy a guitar’s worth pre-made for about a tenner.  You can’t though buy flamed maple kerfing which is why I make my own.  Bugger me it’s boring though.  I cut the blank using a radial arm saw.  Each. slot. Cut. one. At. a time….

IMG_20240222_180319.thumb.jpg.3eb4359c62abaad44d95b27957aea851.jpg

 

I then cut the blank into four strips, then onto the router table where they get tidied up and the round over added till they end up looking like this:

 

IMG_20240223_103147.thumb.jpg.19ad6a2dfa76133eee88c22c97c5dbf1.jpg

 

Job done!  

 

Was it worth it?  For something that probably only I will ever see?  No clearly not.  Just buy the bloody stuff, John, for god's sake. 

 

(Kerfing, if you don't know provides more gluing surface for when you glue on the back and top.  Here the last one with the kerfing glued in, waiting for the back to be glued:)

 

IMG_20231211_115804-2-1.thumb.jpg.d3cf37783384b4459cb4e9c3340ec436.jpg

 

Edited by honza992
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3 minutes ago, honza992 said:

Making kerfiing is pretty tedious.  And mostly pointless.  You can buy a guitar’s worth pre-made for about a tenner.  You can’t though buy flamed maple kerfing which is why I make my own.  Bugger me it’s boring though.  I cut the blank using a radial arm saw.  Each. slot. Cut. one. At. a time….

If you have the time and materials and the power tools, why not?

Some of us only have a workbench and an idea to carry us through. hahaha

 

Mark

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Thanks @LowB_FTW and @AndyTravis.  Guitar building is a solitary sport, so company is always appreciated. 

 

Apologies that all this is coming in one go.  Daily updates would obviously be better, but come cocoa time I'm shattered....

 

Anyway, up next is side bending.  My experience of guitar building is that it's mostly one bum clenching task after another.  Each one perfectly capable of taking your expensive 'tonewood' and turning it into kindling with frightening speed.  Side bending is definitely one of those tasks.  I'm doing it now because I bollocks it up and have to throw the sides away, it also means any work I do on the back is also wasted (since they have to match).  So get the bending done now......

 

I use a bending iron and do it by hand.  

IMG_20240223_110133.thumb.jpg.44b42f1467c49d432a23ba7c66dd3c62.jpg

 

Ha! Man do take some sh_t photos.  No wonder my Instagram followers all share the same surname as me.  Some guitar makers take photos and videos that are so beautiful it makes me weep, grown man or not.  Me on the other hand, bam!  have a bending iron. Slightly out of focus, teetering on the edge of my table.  Random other junk lying round. No context, no action, adding no value, other than using up a tiny amount of the planets finite resources...I blame my cheap android phone.  Every time i pick it up it makes me long for my old Canon D40 (or even my Canon AV1)....

 

Anyway, learning to bend sides by hand has been really satisfying.  I take it slowly, going back to the guitar mold often to check the fit like this:

IMG_20240223_110144.thumb.jpg.36fc4f1f819dea52397347d5763c2240.jpg

 

That's what I call a nice fit

 

IMG_20240223_110852.jpg.0aaa19b291f1022fc591807a9affc120.jpg

 

And done.  One side anyway, sleeping happily in the mold.  If I get the chance I'll do the other one over the weekend or monday.  The cutaway side.  The difficult one......

 

IMG_20240223_115651.thumb.jpg.1063a503fc1a3bcb770416915a2996ea.jpg

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22 minutes ago, LowB_FTW said:

If you have the time and materials and the power tools, why not?

Some of us only have a workbench and an idea to carry us through. hahaha

 

Mark

True that.  I've got unlimited respect for anyone that does this only using hand tools.  Those are subtle skills that are long in the making!

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Last post for today.  Thinning the top down a bit and this jumped out....

 

IMG_20240222_110800.thumb.jpg.315d798d9c989c95a9f3d74bf734ee79.jpg

 

I like a fish-shaped knot as much as the next man, but I'm afraid not much use in a guitar top that (hopefully) will be only a few mm thick, and under a gazillion kg of compression from the strings.  Time to go wood shopping, again....  

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9 hours ago, benh said:

Following with interest! I have the utmost respect and envy for anyone who can make acoustic instruments. Seems like equal parts skill and witchcraft

Thanks Ben.  I'm really enjoying building acoustic.  And playing.  Bass players never get to just pick up a bass and sit on the sofa.  There's amps, and wires, and annoying the neighbours.  I hadn't expected having an acoustic bass to be quite such a joy.  It's really inspired my playing.  Which believe me can really do with some inspiration.  Or some practise.  One or the other.....

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On 23/02/2024 at 22:04, honza992 said:

True that.  I've got unlimited respect for anyone that does this only using hand tools.  Those are subtle skills that are long in the making!

 

In the late 70s I made a solid electric balalaika and a guitar in woodwork classes at school. Pupils weren't allowed to use power tools, and apart from the woodwork teacher cutting out the (very) rough shape of the guitar body on the band saw everything was done by me using hand tools. I probably spent more time sharpening plane and chisel blades then I did shaping the wood. If I was ever to have another go at making a guitar or similar music instrument, I would invest in every time and effort saving power tool available. Life is too short.

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On 24/02/2024 at 13:10, Owen said:

I am glad this has a central sound hole and not f holes, otherwise I would be in trouble. 

Hi Owen, I know what you mean.  F holes look great, and I thought long and hard about using them as aesthetically it's what you expect on an archtop.  My thinking is that a bass guitar (much more than a six string) needs every square mm of the top vibrating as effectively as possible.  And where the F holes usually go is prime real estate.  Less so the oval soundhole positioned close to the neck.  Here's how a guitars monopole vibrates - as I understand it this is the main way a guitar top vibrates - moving up and down as one - and the way that most of the volume is created.  So that's my theory! 

Screenshot2024-02-2521_57_29.png.5f199cbf9bfeaf2856e5295a6548ce5e.png

 

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23 hours ago, Andyjr1515 said:

Another splendid build.  Can't wait to see the carve - a proper carve top is one of the few things I've chickened out of even having a bash at.  Scary biscuits!  

Thanks Andy.  It was you that tricked me into making an acoustic in the first place.  Not that difficult you said.  Well it's been a journey!  So thanks for that.  I think🤪   

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OK, I managed to get through a few things today. 

 

First up I bent the other side without snapping it or bending backwards, thus ending up with two left sides, and no right.  Go on, ask me how I know this is possible....🙄  

IMG_20240226_122939.jpg.7d62ff681df21904b26157b605f6d347.jpg

 

IMG_20240226_123143.thumb.jpg.1dc26dced71945c3635a22c2b0afa510.jpg

 

 

 

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Next was a bit of work on the neck.  Last week I glued the blank together.  Just in case anyone is interested the neck is made from flame maple with a central strip of walnut.  The lines are made from 0.5mm veneer, a dyed black one and a maple for the white line.  That means 12 surfaces to spread with glue and align and clamp, all within about 10 minutes before the glue starts to set.  It's very stressful. Every time I promise myself that next time I won't try to do it all in one go.  I'll glue half and then glue the other other half the next day.  But of course I never do😟  Next time though I really am going to do it in two halves....

 

Anyway, here's how it ends up.  Before gluing the bits together, I always flip and rotate one of the pieces of maple.  This means that the grain lines are now in opposing directions.  ie like this:

\\\\////

This means that when the neck inevitably wants to move due to changes in humidity, the two pieces are pulling in opposite directions and hopefully cancelling each other out.  It really does make for a very stable neck.  I've marked the grain lines in pencil which will hopefully make a bit more sense....

IMG_20240226_165333.thumb.jpg.1af511343f3141ad238ec80b9a2be8dc.jpg

 

I cut the scarf joint on the bandsaw, then cleaned up the gluing surfaces with handplanes and sandpaper to get it ready for gluing.  This is another one of those jobs where it's important to get everything lined up.  Using a laminated neck means a slightly misaligned join will be really obvious like this:

 

IMG_20240226_110706.thumb.jpg.5d411cc6a44b7b4555b1cd30449cb80a.jpg

 

Gluing a scarf joint, especially with a veneer in the middle, is not straightforward.  The glue makes the pieces slip all over the place, especially when the clamps are applied.  I use 4 toothpicks drilled all the way through the join.  It's the black veneer in the middle which means once the neck is carved, you end up with this beautiful fluid geometric pattern just before the headstock like this:

IMG_20240218_132236-1-1.thumb.jpg.b6ed583fa095d049fb24a211737e8931.jpg

 

OK, prep work ready and into the clamps. 

IMG_20240226_172542.thumb.jpg.194612a8b9693adb513b8782bce9be4e.jpg

 

This is one of the joints where I use West Systems epoxy.  It's strong, doesn't add moisture into the joint, doesn't sink and is forgiving of gaps.  Not that there should be any, but it's more forgiving that titebond in that respect. 

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Lastly, I did some prep work for the braces.  There are made of quarter sawn spruce, like the top. 

 

IMG_20240226_174012.thumb.jpg.87ad09a4f081d6e10bf07c7536256db8.jpg

 

They are all slightly wedge shape because that's how they get cut to preserve the quarter sawn-ness.  It's not a practical shape to work with though so I set up my router table to act as a jointer and joint the sides so they are 90 degrees to the faces.  To turn the table into a jointer all I do is stick a 0.5mm veneer to the exit fence, then align it to the router cutter.  The entry fence is 0.5mm further back, so you end up with a beautifully jointed piece of wood.  It took me years to discover this trick, I don't know why.  I now joint pretty much everything this way.  Square stock is always a million times easier to work with. 

 

IMG_20240226_181052.thumb.jpg.ae84c9cfef154b35911187b38427ea3a.jpg

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1 hour ago, AndyTravis said:

I had a dream last night where I was playing an Epiphone Howard Roberts…but it was a bass.

 

Then I realised I’d been staring at your builds…

 

 

IMG_7560.jpeg

Wow, that is nice!  I've never heard of it but the resemblance is striking.  Just goes to show there's nothing new in guitar making!  Here's another one in stunning sunburst...

 

IMG_0284_9c7c4666-86ad-4981-b682-acaf3d374848.thumb.webp.b11831df64be1037c1a72f9b9ed2a86f.webp

 

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