A 5-String, Multi-Scale, Almost Headless Bass

[Dave Higham]

The tuner block is set in at a fairly steep angle so the template had to be made with some wedges under it.

This meant it couldn’t be located using the dowel pins so it had to be carefully positioned and clamped in place. I decided it would be better to do the round-over in this area before routing for the tuner block although I didn’t take any photos. It’s a ½” radius round the front of the treble side and part of the bass side. The rest will be done later.

This is the result.

Next was the neck pocket. (Before starting on it I marked out and drilled the rest of the holes for the neck screws.) The same procedure was used to make the template. Here the template blank is dowelled to the body and the neck is being aligned with the body. Then strips were screwed to the template butting up to the neck and the neck profile routed into the template as before.

The geometry of the bridge and body was such that if the fingerboard were parallel to the top of the body, the underside of the fingerboard would be 4mm (5/32”) above the body so I decided to set the neck at an angle and bring it down flush with the body.

I didn’t calculate a neck angle. It seems to me that there’s no point in calculating a neck angle and finding it comes to, for instance, 1.673° which would be impossible to measure accurately. This is where CAD is so useful. In my drawing I moved the neck to be flush with the body and then rotated it until the surface of the fingerboard aligned with the top of the bridge. From this line and a line parallel to the top of the body I can draw in spacers of different thicknesses between the two lines and the CAD programme tells me how far apart to position them.

I probably didn’t explain that very well, but in this photo you can see the resulting blocks glued under the template.

So after all that, this is what the body looks like now.

[Bizman62]

On 6/5/2022 at 3:57 PM, Dave Higham said:

My usual sort of scarf joint

1. Bandsaw a piece off.

2. Move it round to the back.

3. Glue it back on. The holes are for brass dowels to keep it aligned when gluing and are outside the finished headstock area.

Here it is, glued. It’s the equivalent of a neck and headstock cut out of one piece of wood, although probably stronger because of the glued joint, but without wasting a lot of precious wood.

Funny, just this morning I was thinking about how to make such a joint without leaving marks on the headstock! Thanks for the heads-up! Our course will start in a few weeks and my neck blank is just a little too thin for a steep enough headstock angle. And being a 7 piece multi-laminate block it's crucial the get the aligning right.

 

20 minutes ago, Dave Higham said:

My workshop is so small and crowded that when I’m working on one end of the neck I keep dinging the other end.

At least you have a workshop! There would have been many a summer day to continue my build but...

33 minutes ago, Dave Higham said:

I’ve sometimes thought that unless you have friends who are also forum members, you could shuffle off and the other members wouldn’t know.

Now that you came back I noticed that I've been missing you. Time just flies past so rapidly that a gap of two years seems like you had just posted the last news of your progress on this build.

The timing of your return couldn't have been better, seeing your build quality encourages me to at least try to avoíd sloppiness with my current one when the summer hiatus finally ends!

[Dave Higham]

Moving on to the control cavity. The template for this was made by sticking a drawing to a piece of MDF and cutting the shape out by hand.

The control cavity cover was made from an off-cut of the alder back.

 To make a routing template for it I wrapped the curved side of it in painter’s tape; both sides and the edge. Three sides of it are straight so strips of wood were butted up to them and screwed down. A fourth strip was profiled to the same approximate curve and then spread with a layer of polyester mastic used for car-body repairs (Bondo?). This was then pushed up against the curved surface, screwed down and left to harden. When it became rubbery and started to harden I trimmed off the surplus that squeezed out.

When the mastic was hard I took off the straight strip and pulled out the control cover, and screwed the straight strip back in place.

Then I routed the template on the router table.

Fixed the template to the body (still using the dowels) and routed the recess for the cover.

[Dave Higham]

The cover will be held in place by small magnets so I stuck the cover to a piece of MDF using double sided tape and routed round it to make another template. I marked out the positions of the magnet holes and drilled them through the template and into the cover.

Then I took the template off the cover, turned it over, fitted it into the recess in the body and drilled the holes through the template and into the recess. (You’ll notice that I’d also gone round part of the back of the body with the ½” round-over cutter.)

I fitted the magnets in the cavity cover and the recess. They were quite a tight fit so I pushed them just below the surface and then wicked a drop of thin CA around each one.

 I covered the inside face of the cover with copper shielding foil and stuck some temporary strips of copper foil onto the ledge where the cover sits.

So now when the cavity cover is in place, it sits slightly proud of the back.

So I sent it through the sander a few times until it was flush. The cover turned out to be quite a good fit.

[Dave Higham]

Instead of an arm-rest bevel on the front of the body, I decided to put a cylindrical surface on the whole of the bass half (this is why I had to vary the depth of the cavities I routed before gluing the two halves of the body together). I made this jig for the second bass I made which had a cylindrical surface on the whole of the front, but I think if I did that on this one, the treble side of the body wouldn’t be deep enough for the controls.

Here’s an end view showing the curve on the front of the body.

I then turned it over and did the same thing on the back

A side view showing the shape the curved surfaces make.

And one of the other side. I actually put the body back in the jig and swivelled it slightly to bring the outermost part of the upper horn in line with the widest point of the lower bout. I then routed just the upper horn so that at its narrowest point it was the same thickness as the lower bout. I didn’t take any photos of that.

[Dave Higham]

I bevelled the back in the waist, tapering the bevel right up to the end of the upper horn. The bevel doesn’t show up very well in the photo. I cut the bevel using spoke-shaves and sanding sticks and made it so the edge of the body is the same thickness from the widest part of the lower bout to the end of the upper horn.

The edge was rounded using spoke-shaves, sanding sticks and cloth backed abrasive in the shoe-shine style to give this. The white thing in the neck pocket is a sacrificial block of wood which makes it easier to shape the area around the neck pocket without accidentally sanding or rasping the corners off.

After a lot more sanding the back now looks like this.

In case anyone’s wondering how I get the control cover out, it’s like this.

 

[Dave Higham]

The body’s just about ready for finishing, so back to the neck.

I installed some pearl dots in the edge of the fingerboard. A simple drill guide helps to get them all the same distance from the edge.

Fitted the frets. No ‘in progress’ photos but here they are installed with the tools I used to do it. By the way, they’re banjo frets. I thought that if Leland Sklar and Sheldon Dingwall like them combined with fanned frets, I might too. We shall see.

The zero fret is a jumbo one. That should give me string clearance at the first fret. If it’s too much it can be filed down.

Now to shape the neck, starting with the curve of the volute on the makeshift spindle sander.

Here’s the result

On to shaping the neck proper.

That nice crisp edge was formed by fitting the neck to the body and blending the two together.

[henrim]

Beautiful craftsmanship!

The suction cup cavity opener is kinda cool, although something you can't really have in a commercial product. Even if you supplied the tool with the guitar, it would be lost in no time and the next person to access the cavity would use a screwdriver to pry the cover open.

I'm in this boat right now with my current build. I would't like to have any screws or notches on the cavity covers, but then the industrial designer in me tells me I shouldn't make something that is not obvious how to use it. Shouldn't matter in a personal build but what can you do, he's sometimes very loud guy that industrial designer. May have to ignore him.

I once made a design for an industrial electric motor. Small one in that category, but about a meter/three foot long, so not a really tiny one. Anyway I tried to integrate lifting points in to the main body, and while I thought they were pretty obvious points, I learned that you have to use huge elephant ear like eye hooks, or someone on the other side of the world will lift it incorrectly. It became rather ugly thing, but I guess I learned a lesson   

[Asdrael]

Very clean, color me impressed! I particularly like how the belly contour blends into the upper horn. Very satisfying.

[nakedzen]

4 hours ago, henrim said:

I'm in this boat right now with my current build. I would't like to have any screws or notches on the cavity covers, but then the industrial designer in me tells me I shouldn't make something that is not obvious how to use it. Shouldn't matter in a personal build but what can you do, he's sometimes very loud guy that industrial designer. May have to ignore him.

How about a simple mechanical button on the front, with a long shaft that pushes the cover off the back?

[henrim]

23 minutes ago, nakedzen said:

How about a simple mechanical button on the front, with a long shaft that pushes the cover off the back?

Yes, why not. On one of my guitars that has back mounted pickups, the magnetically held cover is released by pressing down either one of the spring loaded pickups. I’m  sorta proud of the design, but if you don’t know the trick you most definitely pry the cover off with a screwdriver  

[Dave Higham]

9 hours ago, henrim said:

The suction cup cavity opener is kinda cool, although something you can't really have in a commercial product.

I don't make instruments to sell (which is why I have too many basses), If I did, I'd have to think of another way. Someone showed me a luthier-built bass a while ago which had a cover you pressed in and it sprang out enough to get hold of it. You pressed again and it stayed in. It must have been a small mechanism like those on cupboard doors which you press to open and press to close.

[Bizman62]

9 hours ago, Dave Higham said:

It must have been a small mechanism like those on cupboard doors which you press to open and press to close.

Something like that popped into my mind as well. They can be made relatively small and still strong - think about ball point pens where you press the button thousands of times! The potential issue with such mechanisms is that the cover has to give in before popping out. That means that the cover would sit on top of a spring instead of being fully supported by the recess which may cause rattle. Then again the rim of the recess could be covered with a length of window seal/draught excluder tape - foam, brush or tubular would all work.

[henrim]

For a show-piece a mechanism like that would be really cool. For an actual cavity cover that may not be ever opened, maybe not so cool. Huge cost with no gain. Cool but bad industrial design.

15 hours ago, henrim said:

On one of my guitars that has back mounted pickups, the magnetically held cover is released by pressing down either one of the spring loaded pickups

The reason I'm proud of this design is that there are no parts that would't otherwise be there. The cavity cover is held in place securely and it's not likely to pop off accidentally.  I'm not saying I'm into back mounted pickups (no need to go there!), but I'm proud of the principle and functionality. 

[Dave Higham]

One of the last things to do on the body was to drill the hole for the jack socket and it’s a big scary hole drilled in an awkward place. What’s more, I couldn’t find a Forstner bit of the right diameter so I had to use spade bits. The way I did it was to build a fixture using the routing templates that I won’t need again (waste not, want not) that I could clamp to the drill press table like so.

I also shaped a caul to clamp inside the cavity to avoid break out as much as possible. Lowering that whopping spade bit was a somewhat sphincter-clenching moment but it turned out OK.

[Dave Higham]

I now had to make a few odds and ends to finish off. First the ferrules for anchoring the strings up at the sharp end. I started out with some pieces of 5mm brass rod and cut off some short pieces of 12mm rod, 6mm long with a 5mm hole through them. I also made some similar ebony pieces. Here they all are.

I then slid the pieces with the holes in onto the 5mm rods and super-glued them all together! Not really what an engineer would have done but this way was much easier than turning a solid brass core and the ebony pieces would still have been glued on.

I put them in the lathe and bored a 2.5mm hole through and then parted them off and chamfered each end of the hole.

I drilled and tapped a hole for a grub-screw in each one using a little wooden fixture as before.

Here they are all finished.

[Dave Higham]

The next things I made on the lathe were these little ebony ‘grommets’ (don’t know what else to call them). They will be glued in the holes in the headstock where the Allen key is inserted to lock the strings. I just think it will look nicer than bare holes in the headstock and may avoid the edge of the hole being chewed up when changing strings.

I also made some ebony and maple control knobs. I didn’t take step-by-step photos of the process; it was almost all done on the lathe, but it is possible to make similar knobs using a drill press.

This was the first time I used this little gadget to cut flutes in the knobs. The spacing of the flutes doesn’t need to be accurate to a thousandth of a gnat’s whatnot so this does the job. Release the woodscrew, turn by one increment, tighten the screw and mill another flute. It’s a poor man’s dividing head.

So that’s about it, apart from finishing which I did with Tru-Oil, applying two coats per day.

However, I got to thinking it might be nice if the tuning knobs matched the control knobs so I made some more. I didn’t put the maple inlay in these.

[Asdrael]

Great craftsmanship really. Do you mind if I steal the little gadget idea to make the side flutes in the knobs?

 

Also, what diameter is your jack socket? Damn using a spade always scared me. And I am lucky enough that I found the fostner I needed for that.

[LFlab]

Cringed a lot a the sight of the spade bit as well, but oh my god, it looks great. The knobs also, really clever fluting jig.

 

[Dave Higham]

I kept putting coats of Tru-Oil on until I’d used the bottle up. After dozens of coats using kitchen paper it had the equivalent of brush marks in the surface.

I now know that I wasn’t putting the coats on thin enough but I decided to rub it down with 800 grit wet-and-dry and went straight through it!  I’d already rubbed the neck down with 0000 wire wool and wax polish which gave a nice sheen, so the rest of the bass got the same treatment. It’s really quite nice. The only slight regret is that you don’t get the same figure popping effect with a satin finish as you do with gloss but I decided I could put up with that.

 

So I finally got all the bits together and it didn't work! It was just a minor wiring problem that Aaron quickly sorted out for me. The combination of Aaron Armstrong's custom pickups and the Glockenklang onboard tone controls gave it a huge range of possible tones from velvety smooth to out and out clanging. It’s now in the possession of  No.2 stepson who seems to quite like it.

So here at the end of the marathon (sorry about the hiatus) are the glamour shots. Hope you think it was worth it, and if you were, thanks for looking.

[LFlab]

Wowsers, that looks great! Love the understated colours, a very refined look.

[Asdrael]

Love it! Natural look is great when you have a nice piece of wood. I think my favorite part is the headstock, clever way to go about it.

[Bizman62]

I've got one stupid question: What purpose does securing the string ends with grub screws serve? The strings do have ball ends, don't they? And the tension should keep them from rattling just as in body mounted ferrules.

[Dave Higham]

14 minutes ago, Bizman62 said:

What purpose does securing the string ends with grub screws serve? The strings do have ball ends, don't they?

No, they are just normal strings. I install the ball end in the bridge, bend at right angles in line with the 'headstock ferrule and cut off the surplus leaving a little less than the thickness of the headstock. Insert and fix by tightening the screw.

[Bizman62]

Ahh, I see. I thought the strings were sort of backwards with the ball end inside the headstock ferrules. Never actually familiarized myself with the headless instruments let alone the tuners at the edge of the body.