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.

Routing the Jazzmaster body to shape

Starting with the glued up blank I planed both faces, using the router and my planing jig.

Once I’d got it down to the thickness I wanted (39mm or 1.5″) I drew round the template…

…drilled some relief holes…

…and trimmed the blank close to shape on the bandsaw.

I attached the template with double-sided tape and routed as deep as a I could, removed the template and carried on, again as deep as I could, and then flipped it over and finished off with the bottom bearing cutter.

I finished the day by rounding over the back edge.

And I think I may have sorted out the pickups. Joel from Shanghai Guitars has been in touch and he’s got the chrome Filtertrons in stock. We just need to sort out the shipping costs and how I can get the cash to him.

From PDF to MDF: Making a guitar body routing template part 2

A couple of days ago, where I described the first stages of turning a PDF plan into an MDF template, we got as far as having a printed plan. Now let us turn that printed plan into a template we can use for routing the body shape.

The last step in the last episode was to double check all the measurements – well in my experience double checking is never enough. Stop what you’re doing and go and check it again.

First we need a piece of MDF. The recommended approach to doing this is to first make yourself a master template, and then use this to create a working copy of the template. For the master you’d use 9mm (because it is easier to work with and to sand to shape) and for the working copy 18mm (so you’ve got enough depth for the router bit to run against). Because this build is a one-off I’m just going to go straight to 18mm MDF.

Many people recommend gluing the paper template to the MDF, but I have previously had problems with the glue causing the plan to expand slightly as it dampened. I suspect you could overcome this problem using spray mount adhesive but I now choose a different approach. I tape the plan down to the MDF at four or five points and then hatch lines across the edge all the way round. Once the paper plan is removed it is a piece of cake to join the ends of the lines.

Then it is a matter of using a bandsaw or jigsaw to cut close to the line…

…and finish of by sanding to shape – continually checking against the paper plan.

A word of warning here. Spend time making sure the edges of the template are smooth and exactly as you want them to be. Don’t just look at the edges – close your eyes and feel them too. The first time I made a template I left a couple of bumps, knowing that I could tidy them up when I was sanding the final body. I quickly learned that a sanding job that would have taken a matter of minutes on thin MDF became a herculean task when I was doing it to 1.75″ of hardwood. Get the template right and you don’t have to do it later!

Now you’ve already checked the measurements three time but you know what… Do it again before you put the template anywhere near that chunk of expensive timber.

From PDF to MDF: Making a guitar body routing template Part 1

One of the questions that I have been asked a couple of times is “Where can I find a guitar body plan and how do I make that into a router template”? This series of posts will outline how I do it. It definitely isn’t the only way. It may not be the best way. But it is the cheapest and consequently they way I do it.

The first challenge is finding a good accurate plan. My first port of call for Fender style designs would be TDPRI. There are also several excellent plans available over at www.gitarrebassbau.de.

Most plans are available in PDF format, and that is what I’ll be talking about primarily, but occasionally you’ll find a plan in DXF format (AutoCAD’s interchange format). In these cases you can use the free online version of AutoCAD (requires registration) to convert to PDF.

Download and install Inkscape, a free vector drawing program. Head over to http://inkscape.org/ and download the version relevant to whichever operating system you prefer. Once you’ve got it installed fire it up and we can get started.

The first decision to make is what orientation of paper would best fit the plan. For most guitar body shapes (Strat, Tele, Jazzmaster, Les Paul, etc) I’ve found that four landscape sheets (2×2) is about the most efficient, but for a larger body shape you may find you need six portrait (3×2).

In Inkscape, to change the document orientation, you choose File -> Document Properties (or Shift-Ctrl-D).

Next we’re going to import the PDF plan into Inkscape. Choose File -> Import (or Ctrl-I) and select the PDF file. Accept the default suggestions in the next step.

Now we could just print off the plan just as it is, but to help align the sheets as they’re stuck together I like to overlay the plan with a pattern of diagonal lines.

To draw the lines;

  • Select the Bezier/Straight Line tool (Shift-F6)
  • Click once then hold down the Ctrl and drag the mouse out diagonally. Click a second time and then press enter.
  • Duplicate the line by pressing Ctrl-D and then flip it horizontally by pressing “H”. This gives us two diagonal lines at right angles to each other.
  • We now want to duplicate these lines many times over. First we need to group the two lines into a single object so select them both and press Ctrl-G.
  • With that still selected, choose Edit -> Clone -> Create Tiled Clones.
  • We want 100 rows and 1 column (to repeat the pattern 100 times).

  • On the “Shift” tab we define how much each subsequent copy should be moved. For “Shift X” choose 5% per row and 0% per column. For “Shift Y” use -100% for both row and column.

  • Click the “Create” button and you’ll find yourself with a pattern of intersecting diagonal lines.

  • Drag to select all of the lines and group them into a single object (Ctrl-G).
  • Now drag the grid pattern over the top of the plan. If it is not big enough, you can grab any of the corners to resize.
  • Select both the plan and the overlaid grid pattern and group these together (Ctrl-G).
  • You can now grab the whole thing and move it over the page image, and print overlapping areas of the plan.

You may find that the lines on the plan are much more faint than on the grid. You can correct this by selecting all of the items (Ctrl-A), pull up the dialog that allows you to change fill/line properties (Ctrl-Shift-F), on the “Stroke Paint” tab, make sure the stroke colour is set to black. On the “Stroke Style” tab set the stroke thickness to 1px.

Then it is just a simple matter of trimming the edges (assuming your printer doesn’t print right to the edge) and taping them together. And in best Blue Peter fashion, here’s one I prepared earlier.

And now comes the most important step of all – take a good ruler and CHECK IT IS THE RIGHT SIZE. Please don’t ask me how I know.

The next instalment will cover the making of a template from the paper plan.

Additional resources

BigPrint is an excellent application that can do all of the above for you, working from a picture or photograph. It is not free but is well worth the money.

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.