Routing the Jazzmaster for the Gretsch Filtertron pickups

The Gretsch Filtertron pickups from Shanghai Guitars arrived in the post this morning so I have been able to crack on with the next stage of the build.

I had not realised that the baseplate of the neck Filtertron stuck out wider than the pickup itself. Because I want to have this in a tight rout, this needed modification. A few careful strokes with a hacksaw and that was easily sorted.

Next, to make the pickup routing template, I ripped some mdf to 35mm wide, the same width as the pickup and then taped them down, round a pickup, to the piece of MDF that will become the final template. NB: I checked the pickups were identically sized first because that is not always the case.

A run round with the top bearing cutter and I have the template…

…which matches the pickup perfectly.

I marked up their positions on the body, hogged out wood with a brad pointed drill bit, attached the template and routed to around 10mm deep.

Then removed the template and routed the final depth down to 19mm.

I check the fit, with bridge and neck in position.

Next job is to drill the runs for the pickup cables, and not forgetting a hole from the control cavity to just under the bridge, so that I can ground it. Here I drill through from the neck pickup cavity into the bridge pickup cavity. So much easier doing this before you’ve glued the neck in place, as I found out when I built my first guitar.

Final job for the day, with rapidly approaching storm clouds and a fierce wind picking up, was to sand the neck heel and neck pocket with 60 grit, give them a good clean and coat of Titebond Original, and clamp up the neck.

Suddenly it is starting to look like a guitar.

The next job will be to carve the heel to shape, drill pilot holes for all of the components, mount the control cover magnets, and sand it ready for finish.

Jazzmaster fretboard markers and control cavity

The plan was to drill out the black plastic fretboard markers and replace them with some black pearl ones (pictured).

As soon as I drilled these out I could see this wasn’t going to work – the holes were 5mm deep and the little inlays were only 1mm thick. Time for a change of tack. I’m going to make markers from brass tube filled with a black epoxy putty called “Milliput” instead. The putty is on order but in the meantime I got started with fitting the sections of brass tube.

I drilled a 5.5mm deep hole in a piece of MDF and using a hacksaw cut the 6mm tube into small pieces.

I had also bought some 2.5mm brass tube too so that I could make matching side dots. I drilled out the old ones.

With a dab of superglue in each hole I pressed in the brass tubes.

After allowing it to dry I filed the tubes flush with the neck.

Once that was done I tackled the control cavity. I had marked the locations on the MDF template. I attached this to the body and with a 2mm drill, made a hole right through template and body.

I used a 19mm spade bit to cut the countersink for the knobs, and a 10mm bit for the selector switch.

Once those were marked I could tackle the control cavity from the back. I had made a cover a couple of days ago.

Using the techniques I discussed in detail previously I made a template for the cavity “ledge” and routed that.

I made a smaller template and then routed out the inner cavity.

To finish I check the cavity is deep enough to allow the components to reach through to the front.

And that is all the work I can do until the pickups arrive. Once I’ve got those in hand I’ll be able to rout their cavities, drill the cable runs, and then glue in the neck. Once the neck is in I can shape the heel and I’ll be on to sanding and finish.

Minibass: Cavity cover and prep for Danish oil

Before I got started I took a picture of the minibass being held by my son, to give an idea of just how small this thing is.

So putting yesterday’s theory into practice, after a number of test runs on MDF I worked out a slightly different approach. I use the same technique but, rather than cutting the shapes into the final timber I cut them into MDF and then used those as templates for routing with the top bearing cutter. Here’s the main cavity.

I drilled the hole for the barrel style jack socket.

I laid paper over the cavity and using the old schoolboy brass-rubbing technique, traced the cavity shape onto the paper, so that I could draw the shape of the cover itself.

The paper shape was transferred to MDF.

This MDF master was then used to create an oversize template.

Using the different sized collars, I then used the oversized template to cut a male and female template.

Using the female template I routed the lip into the body.

And with the male routed the shape into an offcut of sapele.

Perfect? Not quite, but better than my previous attempts by a large margin.

So after giving the whole thing a good sand, and cleaning up my work area, it was time to apply the Danish oil.

Tomorrow I’ll continue applying light coats of Danish oil and start work on the changes to the preamp. Currently it has the volume and tone surface mounted to the PCB. I need to desolder these and run wire from PCB to pots, so that I can fit everything into the cavity and have the volume and tone where I want them.

Cutting cavity and cover to match

When I’ve previously made control cavity covers, I routed the shape into the body and then, as best as I could, have cut the cover to shape. Getting an exact match is really tough and whilst my efforts have been adequate, they’re far from perfect. Look closely at this picture and you’ll see the ~0.75mm gap between body and cover.

It always struck me that there must be a way of using a single template and router to cut both the cavity (female) and cover (male). I finally stumbled across this page which shows a technique to do it. In essence it involves using an oversized template and different guide bushings (also known as collars).

I hit my first problem – all of the wide choice of router collars only seem to be available for Porter-Cable type routers, whereas I have a Bosch POF 1400 ACE, which has a different fitting in the router plate. I spent many fruitless hours searching for the parts I needed – mainly looking for what is called an “inlay kit” which combines two collars with a matching cutter

The way the geometry of this approach works (see picture below) is that the difference in collar diameter needs to be twice the diameter of the cutter. I currently have a 17mm collar, that came with my router. I finally managed to navigate to the correct page on Bosch’s UK website to see what collars were available that would fit. Put that part number in at Amazon, preceded by “bosch” and I found a supplier of the part I needed. You can find this at bosch.co.uk. Of course as soon as Bosch refresh their website this link may stop working, so I will reproduce the collar sizes and part numbers, should it be useful for you.

Diameter (mm) Part Number
13 2 609 200 138
16 2 608 000 471
17 2 609 200 139
24 2 609 200 140
27 2 609 200 141
30 2 609 200 142
40 2 609 200 312

So going back to that equation of the difference between collar sizes needing to be twice the diameter of the cutter, and given that I already have a 17mm collar, the only viable option for me was a 27mm collar with a 5mm cutter.

So how does this magical combo of two collars and one cutter allow you to make the male and female cut from the same template?

This diagram attempts to show how this works. The template needs to be 11mm larger than the final pieces. For cutting the cover we use the small collar, pictured at the top. Here you can see how the left edge of the cutter will trim the piece, to follow the shape of the template.

To cut the ledge for the cover to sit on we switch to the larger collar and here you can see it is the right hand edge of the cutter that replicates that same shape, albeit in female.

There’s more to this than initially meets the eye. Using the same principles you can make an exact sized cover for any cavity or make an exact sized cavity for any cover. For example, I have considered rebating a Telecaster’s control plate so that it sits flush with the surface of the body. I could mount the control plate onto MDF, use the small collar to create the 11mm oversized template, and then use the template and the large collar to cut the recess into the guitar body.

There is one limitation of this approach is that it is not possible to cut a corner smaller than the radius of the router bit. This means that the template corners must have a minimum radius of 22mm. It could cut a square corner on the male part, but it would mean that you’d need to use a chisel to square up the corners of the female.

And that’s the theory. When my 27mm collar arrives in the next couple of days I’ll report back with my experiences.

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.

Minibass neck and headstock

I started off today’s work session by getting stung on the arm by this little b*stard. Not a good way to begin.

Now that I’ve received the tuners and truss rod I can get going on the neck and headstock.

I secured the neck to the bench with double sided tape and then, to the right hand side, a piece of straight parallel timber as a guide. The position of piece to the left is less important because it is only there to keep the router baseplate level. Note where I trimmed out the corner of the right hand piece so that it would fit around the headstock – so that I can rout the full length of the neck.

I centred the 6mm cutter on the neck’s centre-line and checked it along the full length of the neck.

I clamped on an MDF stop, so that the cutter would stop at the right place on the neck, making sure the truss rod slot was big enough but no bigger than necessary.

Here is it after the first two passes.

And finally with the truss rod fitted. Note that the nut end is a couple of millimeters wider than the main part of the truss rod. I adjusted the side guide in and out a couple of mm to enlarge the slot to fit. There was a tiny part of tear out on the left side but this will be completely covered by the fretboard so no harm done.

Now on to the headstock. I had sketched out a rough shape on paper, aiming to keep the tuners as close as possible together. I really want to give the impression of this being a small stubby bass and the squat/wide headstock shape will be a key part. I transferred the sketch to MDF and tested it out. I was happy with it so this became the headstock template.

On the bandsaw I rough cut the headstock to shape.

And this shows the evolution of the headstock, from paper to template to neck blank.

I trimmed the ends of the headstock and neck templates, to ensure they fitted together neatly and attached them to the neck blank with my indispensable double-sided tape

A few passes round with the router and this is the neck ready for the next stage.

It is slightly rough around the scarf joint because it is not possible to get the router to run smoothly across the change in angle, and keep the bearing in touch with the template. This is no problem though because this area will be getting extensively carved once I’m ready to start profiling the neck.

The next stage is to mount the fretboard but, before I can do that I need to install the inlaid fretmarkers. I’m waiting for the arrival of a set of plug cutters so that I can cut neat rounds of contrasting hardwood to glue into the fretboard. Once the inlays are in I’ll glue the fretboard to the neck, trim it to shape, sand in the radius and then install the frets. Once they’re in I can profile the neck, cut the angled neck pocket into the body and the finishing post will be in sight.

Making a radiused sanding block and a fret press caul

If there’s one thing I love almost as much as building guitars, it is making the templates, tools and jigs to make guitars. Today I set out to make myself a radiused sanding block and a fret press caul. Now I could go to any of the reputable luthier suppliers, such as Stew Mac, or LMI and buy these but, because I tend to build types of guitars that you can’t buy I decided that it would be worth the investment in time to work out how to make my own – for that time when I want to build something with a 17.25″ radius.

I had spent a few hours researching ideas for making a radiused sanding block. Most of them are router based, either routing the curve into a single piece of wood, or routing several slices which are then glued together. I tried a couple of these approaches with limited success (i.e. they were a complete disaster). I then hit on a solution I hadn’t seen anywhere else – to use my bandsaw. I clamped a piece of MDF to the bandsaw’s table. I drilled a 4mm hole 12″ from the blade. I then drilled a series of 4mm holes at 30mm intervals in a length of 75mm wide 18mm thick MDF. I popped the drill bit through the holes and hey presto it cuts a 12″ radius into the other end, step to the next hole and cut the next, and the next and the next. I put the first one to one side (more on this later) and glued the remaining eight slices together. Hey presto 12″ radius sanding block.

Last time I made a neck I tapped in the frets with a leather faced hammer and, whilst it worked, it left me with a big job of fret levelling. This time I’m going to have a go at using my drill press and a caul, to press the frets into place. Hopefully this way I can be much more consistent with the fit of each.

I took the first piece of radiused MDF and drilled a 22mm hole through the face, and an 8mm hole from the edge to meet the larger hole. This allowed me to fit a threaded rod and a couple of threaded plugs (both rescued from a long gone Ikea bed) onto it to create a post that can chuck into the drill press. Hey, once again, presto.