Carving the heel and preparing the Jazzmaster for finish

Into the final furlong now and there are just a few jobs left before the Danish oil goes on. To start the day I remove the neck clamps and check the joint.

For the neck heel carve I roughly mark where I’m aiming for.

With a spindle sander in my hand-held drill I start removing wood…

…until it is about the shape I want. I then finish by hand.

That’s the last of the woodworking finished. I drill the pilot holes for the hardware. The only complicated part is getting the bridge positioned correctly. As previously, I use a piece of cotton running from the bridge to the headstock and back again.

Drill the holes for the bridge.

While I’ve got the bridge unpacked I take a few minutes to run the base across a piece of 400 grit paper, to make sure it makes full contact with the body top once it is screwed down.

I mark up the legde of the control cavity and drill the 6mm holes for the neodymium magnets, and fasten them in place with CA glue. I glue magnets in position on the cover too, making sure the magnets are the right way round, so they don’t repel.

Check the alignment and fit.

All that remains is to sand and sand and sand. Working my way up through the grades to 320 grit, and then give the body a wipe with a damp rag to raise the grain.

And here are the first coats of Danish oil going on, using the approach I’ve written about previously.

One last thing, a couple of days ago Gtr1ab asked how I laid out the controls on the template. Below is a picture of the marked up template. If I was building an exact Jazzmaster replica I would have just transferred the positions from the paper plan, but I’m adding my own touches. I wanted the volume knob to be exactly level with the bridge saddles so using a square I extended the line down the body. I placed the centre of the volume approx half way between the bridge and the body edge.

I then drew a line, at a slightly descending angle, towards the tail end of the body. There was no science or measurement to this I just picked an angle that I found pleasing to the eye. I placed the other two controls and the jack socket along this line. When laying out controls previously I had measured equal distance between the hole centres but, because components have a different radius they end up looking mis-spaced. I measured each component and then made sure the gap between the edges of each was consistent. Again there was no science to this I just chose a distance that looked pleasing to the eye – in this case a 30mm gap.

Minibass: Carving the neck and stringing it up

Carving the neck, first with a rasp…

…and then with a spokeshave.

Last night I strung it up (E and G strings) and adjusted the bridge until the intonation was correct. Here are the marks.

I glued the bridge into position and then glued up and clamped in the neck too.

With the spindle sander in the drill I shaped the heel and upper reaches of the neck.

I used the radiused sanding block to shape the top edge of the bridge saddle and nut. First I covered the edge with pencil and then sanded until it was gone.

Then I strung it up to check everything aligned correctly, marked the position of the strings on the nut and saddle and filed the slots for them.

The last piece of woodworking required is to cut the control cavity and cover. I’ve been investigating ways of using a single template to cut both, to guarantee that they match exactly. I finally tracked down the approach, which involves using the 5mm cutter, a 17mm collar and a 27mm collar. I had everything except the 27mm collar so while I’m waiting for that to arrive there’s not much else to do. I’ll write up the details of how I propose to use the two collars and one cutter when I get the chance.

Minibass: cutting the neck pocket and drilling the string anchors

We’ve had intermittent heavy showers today so I haven’t made as much progress as I had hoped. First job was to cut the neck pocket, so I made myself a routing template. I clamp the neck to the MDF and draw lines along each side, extending out onto the board so that I can draw on a centre line. This means that when I match it up to the centre line of the body everything matches up.

I then sticking a couple of guide pieces either side. At this point I unclamp the neck and tap it down into those two guides to make sure it is really snug. I then stick down the end guide.

A few passes with the top bearing cutter to follow those guides, cutting into the MDF sheet below and I’ve got a template that matches the neck dimensions.

The neck pocket needs to get routed in at an angle, so I set up a pair of guide rails, and chock up the back egdes to get the angle I want (a rise of 30mm over a distance of 600mm). The neck pocket template gets secured to the rails and the body flat to the bench below. Rout the pocket to 13mm deep at the front edge and we’re done.

While it was still off the body I trimmed the back of the neck to start the job of carving the profile. The real work on this won’t start until it is glued to the body, so I can shape the neck heel at the same time.

Last job of the day was to drill the holes for the string anchors. I drilled 2mm holes all the way through the body in the positions where I wanted them.

From the back I drilled 10mm holes to for the ball-ends to sit in. These are much bigger and longer than a traditional ball end so these holes are 18mm deep.

Back to the front and I drilled holes for the strings to pass through – these are matched to the individual sting gauges. Sizes are 5mm, 4.5mm, 4mm and 3.5mm.

And this final shot shows the yellow ball-ends seated in their “pockets”.

Next job is to rout the control cavity and then glue the neck on. Once that has been done I can do an initial assembly and rough setup to correctly intonate the bridge. I’ll disassemble, glue the bridge into position and then it is onto shaping the neck, sanding and application of finish.

Sorting out the Minibass neck

The aim for today was to get the neck ready to go onto the body. I started by shaping the headstock top edge (to mimic the body carve) and drilling for the tuners and ferrules.

Here’s the compact layout.

I needed to drill out the machine head slots to be able to accept the thicker strings. After drilling I spent some time with a small round file making sure there were no sharp edges which would damage the polyurethane strings.

Then it was on to the fret markers. I drilled 13mm holes along the top edge.

I had ordered a set of plug cutters but after a couple of hours of trying to get them work I was unable to cut a neat plug of hardwood. Thankfully the eBay seller is going to refund the money, but in the meantime I needed to find a way of making myself some plugs. I cut a square rod of sapele that was 13mm on each side, clamped that down to the bench and ran a 6.5mm roundover bit down each corner. After a bit of sandpaper I was left with a 13mm dowel. Pop through the fretboard and trim to length

I glued in each plug and, while they were drying, I made myself a 5mm dowel of ebony. I couldn’t do this with a router, but with a small block plane I was able to fashion a fairly good approximation from a 5x5mm length of ebony.

I drilled a 5mm hole through the centre of the 12th fret marker and glued in the ebony dowel. After allowing it to dry top and bottom of the fretboard were sanded flat.

Now I had all the key tasks done I was ready to assemble the neck. I drilled two 1.5mm holes through the first and last fret slots, down a couple of mill into the neck. This allows me to pop through a couple of thin pins which stops the fretboard moving as it is clamped down. I mask off the truss rod slot, spread the neck top with two part Araldite epoxy adhesive and gently clamp it up. It doesn’t need to get clamped too tightly otherwise it can force out all of the glue, leaving a weak join.

After an hour I was able to remove the clamps. I used a bottom bearing cutter in the router and trimmed the fretboard to match the neck, neatly bisecting the sapele/ebony markers. Next step was to set about the neck with my radiused sanding block, loaded first with 60 grit, rising to finish with 220 grit. To make sure I sanded the fretboard evenly I shaded the surface with pencil so I could easily see which areas were getting sanded away.

I cut the frets close to length, gently tapped them into the slots and, with my caul mounted in the drill press, gently squeezed them into the slots. This was so much easier and more controlled than hammering them in.

I clamped the edges of the frets and wicked in a drop of CA glue to each fret end.

Once that had dried I filed the fret ends. They still need more work but they’re fairly close.

If the weather allows, tomorrow I’ll be routing the neck pocket, control cavity and drilling the string through holes, hopefully ending the day with a neck glued in to the body.

Minibass: Carving the body and testing the pickup and preamp

I didn’t get too much done today. I got the raw bone roughly trimmed into a nut-like shape, and then worked on the body contour carving. I’ve still got more to do, finessing the shape, but it is getting close to what I had in mind.

I also made a few modifications to the bridge, to accept the Artec piezo pickup. I needed to drill the hole for the lead and extend the bottom of the slot slightly because, whilst the slot is 64mm long, the pickup is 70mm. I was able to drill a 3mm hole into the bottom edge of the slot to accommodate it. I then did a quick test to check whether the piezo and preamp would be suitable.

Far from conclusive but at least it is making bass-like noises. I’m hoping the plug cutting set arrives tomorrow and I can get going on the fretboard inlays (after testing my ideas on scrap first).

Routing the control cavity and making a matching cover

Today I planned to get the control cavity for the bass finished, including cutting a matching cover from sapele. I used Inkscape to draw out the shape of the control cavity cover, printed that off twice and on one, drew the shape of the internal cavity freehand.

There were stuck to MDF and cut into templates.

For this job I needed three templates; one for the internal cavity, one for the control cavity cover, and one for the ledge the cavity cover sits on. The last of these two need to match as close as possible. I’m still searching for a way of using the router to create two exactly matching male/female templates, and I spent a couple of hours of experimenting with collets and straight cutting bits, with no success. More research required on this topic. Instead I used the offcut from cutting out the cover’s template, to make myself the template for the cover ledge. Not exact but close enough for me at this stage.

I select a piece of offcut sapele, and planed a couple of millimeters from a portion of it.

I attached the cover template, and routed round it to a depth slightly deeper than I would want for the cover.

I set up a fence on my band saw and sliced the sapele, just slightly thicker than I would need for the cover.

I attached the templates to the body and routed the cavity and cover ledge.

Rather than having a screw on cavity cover I decided to use neodymium button magnets, an idea which I’d seen used to great effect on the Musical Instrument Maker’s Forum (aka MIMF). The magnets are 6mm in diameter and 3mm thick. I drilled a 6mm hole at each corner. Initially these were just 3mm deep. I put pairs or magnets into each hole, put a drop of CA glue (aka superglue) on the top of each, then pressed the cover down. Once the three magnets were glued to the cover I could drill the holes to 6mm deep, put a dab of glue at the bottom of each, and then push in the magnets with a cocktail stick. NB: If you’re doing this then you need to pay attention to the polarity, because you want them to attract the magnets on the cover, rather than repelling.

One the glue holding the magnets had set, I sanded the top of the cover level with the body. I’m really happy with the result of this.

I drilled one small pilot hole through from the back of the cavity and then, making sure the relationship between the two looked OK, drilled the second one through from the front.

I used a 19mm spade bit to drill a “countersink” for each of the knobs. This means that the bottom edge of the knob can sit below the top face of the body, hiding the nut and washer securing the pot.

I drilled the 8mm hole for the pot shaft and then checked that it all fitted together neatly…

…before lightly sanding to round over the edge of the countersink.

Hopefully the pickup and bridge will arrive tomorrow, which means I can get the final routing completed, and glue up the neck. All that will be left to do is the final sanding, applying the Danish oil finish, assembly and set up.

Carving the body of the custom bass

When it comes time to carve wood I have found that the combination three different tools works very well for me. A flat and half-round rasp, a hand-drill with a spindle sanding drum loaded with 60 grit paper, and cabinet scrapers. The hand drill is great for removing large volumes of wood quite quickly. It is a bit of a crude and unwieldy beast so is not suited for fine work or in tight areas – particularly round the neck pocket where there are a couple of sharp fragile corners that would be easily damaged. For these areas I use the rasps. Once the wood is close to the shape I want I’ll smooth the area with the cabinet scraper, and then sandpaper and a sanding block.

The front view.

And the rear.

There is further work to do on the neck heel, but this will be after the neck is glued in place. I can’t glue the neck in before the pickup cavity is routed, so I’m waiting for that to arrive before I can make further progress.

Here are the pickup and bridge that I’ve ordered for it.