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Acoustic bass - carved top


honza992

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  • 2 weeks later...
Posted (edited)

Hi All

 

Bit of a delay in posting.  The front and back are now glued on and i've cut the binding channels.  I forgot to take photos but I use a router and take many passes....

 

Next, a very simple end graft made out of two bits of binding stuck together.  It's not glued yet, first is binding. 

IMG_20240506_122647.thumb.jpg.568fce0ef3f84b871fb441d698126f9e.jpg

 

There was then a slight delay as while I was cutting up some veneers for the binding I managed to slice my finger open.  Turns out surgical scalpels are actually quite good at cutting humans..who'd have thought!  A quick trip to A&E and a few sutures later, I'm fine.  As usual, mistakes like that happen because I was hurrying.  Sharp things and haste do not go together well.  Being a numpty doesn't help of course.

 

Anyway, the bindng channels I cut with a router, the side binding though is done by hand.  First a gremel, then a chisel to clear out the channel. 

IMG_20240506_123427.thumb.jpg.46683cd1bb369c1fec23e452ce59d0f8.jpg

 

 

The binding gets bent on the iron the same as the sides.  

IMG_20240509_102851.jpg.cda3dde2eb3d54e30667b6674b7e4cbe.jpg

 

The binding layout I'm doing has got black/white inner lines that will be mitred to the lines of the back stripe.  The most difficult part is here where they meet at the bottom:

 

IMG_20240509_145113.thumb.jpg.ed8e5318ec1d8f92ab73938b09e7d8db.jpg

 

In the picture above it isn't glued.  I'm trying to get those white and black inner lines to line up nicely so it looks like one continuous line.  The black one is fine, but you can see that the white one still needs a bit more work.  I glue everything together (bindng plus white and black veneers) all at the same time which is not the normal way of doing it.  And next time I may well try doing the purfling lines first.  The back is bound, so we'll see tomorrow how successful the mitres were.  

 

 

Edit - In case you're wondering, the two white strips on the left hand side are teflon.  I slide them into the joint so that when I glue the binding on the right hand side it doesn't gum up the left hand channel.  Dried titebond is difficult to get out of small gaps like that. 

 

Speaking of titebond I've gone back to using it for binding.  For a while I used superglue, which seems easier because you can get everything completely ready and taped into place before wicking in water thin glue.  What it doesn't do is soften the binding, so it's a quite unforgiving process.  Because titebond is water based it seems to soften the binding allowing it to bend into the corners better.  So for now I'm sticking (ooh nice pun) with Titebond (original).  Though next time I may try fish glue which apparently has a longer open time.  Binding can be pretty fiddly so being able to take it more slowly would be good....

 

 

 

Edited by honza992
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  • 2 weeks later...
Posted (edited)

OK, the box is closed, so time to crack on with the neck.  First up is working out the neck angle.  I stick one of he sleeves of my spindle sander onto the guitar top at the position where the bridge will be.  A straight edge and a digital level* gives the required neck angle as being 5.1 degrees.  The sleeve is a bit higher than I need, so a quick bit of maths gives me a final neck angle of 4.2 degrees. 

IMG_20240515_101850.thumb.jpg.e8902410753b9e9684d20ada027de2e2.jpgNe

 

Next I glue up the heel block, with my usual excess of veneers....

IMG_20240515_104158.thumb.jpg.197e44594778443564d9f20893a8825f.jpg

 

Talking of veneers the other thing I've got to do is get a white and black line under the fretboard, so that they meet up with the lines underneath the headplate, like this:

 

IMG_20240515_114112.thumb.jpg.343bb2c6480cfcf9e0a9d6cf4f3ea7be.jpg

 

The fretboard is already radiused so it's not easy to clamp, so I need to use a vacuum bag.  I use one of these skateboard vacuum bag things with a wine pump.  I've used it a lot over the years and it is a brilliant bit of kit, perfect for guitars.  And compared to a proper veneer pump and bag it's a bargain.  Here's the fretboard in the bag, glued with epoxy.  

IMG_20240516_100306_HDR.thumb.jpg.07a6b840b6e8831cb5a80c3304dc6df7.jpg

 

Next I need to cut the neck angle on to the end of the neck heel.  This is a right old faff.  Getting the Radial Arm Saw set up takes ages.  I always do a test cut on a similar sized piece of scrap wood because you pretty much only get one chance.   As you can see in the picture I ended up using a neck angle of 4.6 degrees, slightly different from my initial guess of 4.2.  That's why I always do a test cut...

IMG_20240520_110303.thumb.jpg.d49d6f7f80434484035d97fbc80a640f.jpg

 

Once that's cut, I've then got to fit the neck to the body.  I'm happy that he angle is right, but I've also got to refine the left/right alignment.  In other words the neck has got to be pointing exactly at the bridge.  It doesn't.  I stick the neck in the clamp, and rest the neck on the body. I put a thin strip of scrap wood into the trussrod channel so that it points down to where the bridge will be.  I can see from that how I need to sand the base of the heel to get alignment.  The sanding I do with a triangular strip of sandpaper, so it progressively sands one half of the heel.  Hard to explain, but a picture may help:

IMG_20240522_162720.thumb.jpg.d42a689818e1c2e691052b087df09853.jpg

 

Rinse and repeat until the stick points straight down the middle of the guitar:

 

IMG_20240522_171752.thumb.jpg.10c29163400ab028c2f388b0f5bddcb5.jpg

 

(I know the top looks a mess.  I put on a couple of layers of shellac just round the edge before binding.  This helps pulling the binding tape off without getting tearout on the spruce top. It'll clean up nicely.  I hope....)

Edited by honza992
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Posted (edited)

For the neck joint I will have a single screw holding the heel against the body, then the fret board extension will act a long horizontal tenon, held by a single bolt through the body.  Sounds complicated, but isn't.  It worked really well on the last build, it's completely stable and seems to be plenty strong enough. 

 

 I rout the mortise for the fretboard extension/tenon in one go.  A simple MDF jig with a locating strip of wood that slots into the truss rod channel.  This makes sure everything lines up, and makes clamping a lot easier. I've already drilled the hole for the wood screw through the heel and into the neck block.  Again, the screw helps with keep everything aligned while I rout. 

 

Here's the jig:

IMG_20240524_171602.thumb.jpg.1327c1330acd3b999826d49c57fef377.jpg

 

Routing:

IMG_20240525_161123.thumb.jpg.cd27298d8267ccc9f493356214862337.jpg

 

Once the tongue/fretboard extension has been glue and sanded flat, it looks like this:

 

IMG_20240528_113307.thumb.jpg.11f2d87aa53e256de74446ebe1034e51.jpg

 

The fretboard then goes on top.  I haven't glued it at this point, still a few jobs to do first......

IMG_20240525_164430.thumb.jpg.96e7c95d33fbfb6a0b1ace724e5e6587.jpg

 

 

 

IMG_20240525_164327.jpg

Edited by honza992
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Just to very quickly finish the neck joint description, I put a T nut onto the fretboard extension to hold it down.  So a screw through the heel and bolt through the back.  It's quite a lot to get all lined up and the neck pointing in the right direction.  One of the biggest steps up from making electric to acoustics, is that with acoustics there's no flat surfaces. Everything is curved and nothing is in the same plane.  

IMG_20240529_120239.thumb.jpg.07398a9850face5ac159605dc57f774e.jpgIMG_20240529_120247.thumb.jpg.a7291095cdec1b919ed7bc4cda29d298.jpg

 

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On 28/05/2024 at 21:50, honza992 said:

Here's the jig:

IMG_20240524_171602.thumb.jpg.1327c1330acd3b999826d49c57fef377.jpg

 

Routing:

IMG_20240525_161123.thumb.jpg.cd27298d8267ccc9f493356214862337.jpg

 

Once the tongue/fretboard extension has been glue and sanded flat, it looks like this:

 

 

 

 

What a clever way of getting that angle accurate!

 

Consider the idea stolen :D

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Posted (edited)

Neck Carve!  

 

I always cheat when it comes to neck carving.  I start by carving a series of facets onto the neck.  These are carefully measured and calculated.  Once they're done there's still quite a lot of wood to take off, but they give the neck it's final shape.

 

Here are the first two facets:

IMG_20240607_110902_HDR.thumb.jpg.ecd744e4fc585f3284a8030fe65d504a.jpg

 

Here I'm starting on the next one.  The tape is there to remind me where the line is I'm supposed to be carving to.  You really don't want to get carried away and go to far beyond the line.  It's veeeery late in the day to start a new neck.  And on dark wood a pencil line can be darn hard to see. 

IMG_20240607_112931_HDR.thumb.jpg.a11fb650dacbb34470fda1777ec9ae22.jpg

 

I end up with.....ummmm...is it 8 facets, something like that.  I spend quite a long time getting these pretty flat and consistent.  I think it reduces the amount of 'shoe-shine' sanding which is needed, which is the god-awful final stage....

 

So here we are:

 

 

 

 

If I can over the weekend I'll make a start on the headstock transition.  

 

Edit:  Hmm...that video is masssssive!  Does anyone know how to make it smaller?

 

 

Edited by honza992
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Posted (edited)

Since you're all there, here's a few random photos. I realise I fretted without taking a single pic.  So here's the all important preparation before fretting.  I've learned the very very hard way to check every slot is deep enough before starting to fret.  A bent over piece of fretwire with the tangs filed off is perfect.  

IMG_20240604_101703.thumb.jpg.3eb3d3a1a65a73867206ab29051b1bda.jpg

 

When I glued on the black/white veneer on to the bottom of the fretboard, some of the epoxy seeped through into the slots.  Time to bring out the world's tiniest saw...

IMG_20240604_102646_HDR.thumb.jpg.53f95b818a82f66e0ebb8c3967d0bac5.jpg

 

Then side dots.  With another of my fugly jigs.  Honestly, there should be a law against it....

IMG_20240604_121157_HDR.thumb.jpg.284e0e6b8843b72391346f91c681ecfd.jpg

 

Edited by honza992
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If you shot the video on a new iPhone then it defaults to a stupidly high resolution and 60fps frame rate. I think there is a settings change up in the top right where you can change the rate.

Android will depend on the phone, but Samsung has an option under Advanced settings to use HEVC, which should reduce the size.

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11 hours ago, honza992 said:

I always cheat when it comes to neck carving.  I start by carving a series of facets onto the neck.  These are carefully measured and calculated.

There's nothing cheating about that!

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On 08/06/2024 at 09:40, Richard R said:

If you shot the video on a new iPhone then it defaults to a stupidly high resolution and 60fps frame rate. I think there is a settings change up in the top right where you can change the rate.

Android will depend on the phone, but Samsung has an option under Advanced settings to use HEVC, which should reduce the size.

OK I'll take a look.  That enormous video is making me feel queasy....

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Posted (edited)
On 08/06/2024 at 11:03, Andyjr1515 said:

There's nothing cheating about that!

 

On 08/06/2024 at 13:51, Si600 said:

I thought that was how it was done!

It feels like cheating. I feel as though I should be doing it freestyle, with only my keen luthier's eye and maybe a beret.....

 

For some reason I thought most builders just sort of went for it, rather than the slightly over-engineered process that I go through.  Either way, it's really a great technique. Not fool-proof, but probably as close as you can get with neck carving. 

Edited by honza992
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Posted (edited)

Once the facets were done I then used a spokeshave, and sanding blocks to get the length of the neck more or less to its final shape.  Today I started on the transition.  I find it easier that way, taking the transition down to the neck, rather than doing the transition first.  I can see the curves better for some reason.  Here's the development of the headstock transition. 

IMG_20240610_104400.thumb.jpg.a33cfa1b7598b552e2027ec5ca84abc2.jpg

IMG_20240610_111450.thumb.jpg.f82df2d7b8c7c401f7ff96dbbde4c9a1.jpg

IMG_20240610_114623.thumb.jpg.fce720e86c0178ee24f4446de16b8b4c.jpg

IMG_20240610_114628.thumb.jpg.62bf2753bdda2124e17c64674ec902cd.jpg

 

I also made a quick start on the heel transition.  Here it is unstarted.....

  IMG_20240610_144448_HDR.thumb.jpg.e928e3c56bf06f56b012e99d134079d6.jpg

 

One of the last jobs to do on the neck is drilling the holes for the tuners. 

IMG_20240610_164917.thumb.jpg.5b500d6d2c31fecfad90588a90d7c6fd.jpg

 

(I'm pretty pleased with the walnut veneer on the back of the headstock 😁)

Edited by honza992
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