Top carve completed and more besides

Up bright and early this morning and headed straight down to B&Q to grab a random orbital sander. I’m not half glad that I did. Even with this fantastic piece of kit, finishing off the top took a hard 3 hours. I was so pleased that my routing mistakes (or “opportunities” as Steve Benford described them) were recoverable and I was able to sand them away without breaking through to the mahogany underneath. It was very close though and, at the edge, the maple cap is only 3mm thick.

Next job was to fabricate the rig to allow me to chamfer the front edge of the body to align with the neck angle. This rig is made up of a box to surround the guitar and an MDF plate to sit on top with a slot for the router cutter. The box is shimmed up at one end to make the 3 degree angle.

And here’s the finished chamfer. A quick pass with the sander took out the lines.

Then I clamped a straight edge to the chamfered body face and checked it against the bridge. Note the shims the same thickness as the fretboard to raise the line away from the body. Looks just about perfect to me.

I then spent an hour making a jig for the neck pocket. It was vital to get this absolutely spot on, to match the size of the neck heel and to make sure it is perfectly aligned with the centre line. I’d tried doing this by eye until I noticed, while I was taking the picture with my phone, that it has guidelines on which I was able to use to double check the alignment

I made the first cut…

And here’s the finished neck pocket.

The neck fit into the pocket absolutely perfectly.

A very snug fit, with just enough grip to allow me to grab the neck and hold the guitar horizontally.

I then made a jig for the P90 soapbar pickup, and, still using my angled jig, to keep the pickup perpendicular to the strings, routed the cavity. It is a very shallow cavity, and I still need to rout a slightly deeper channel to clear the cable and the two round-head screws in the baseplate of the pickup.

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The top carve continues

Despite only getting a couple of hours on “Project RockMangle” I made decent progress today. I finished the routing of the final two steps of the top carve and then got busy with the sandpaper. This is going to be a looooong part of the job, although I may cheat and head down to B&Q tomorrow morning and buy myself a random orbital sander.

This first picture shows the state of play after the completion of the step routing and a couple of minutes of sanding.

This view gives a good idea of the shape and depth of the carve.

And this final one shows how far I managed to get before it got too dark to work outside. Taking shape nicely, even if I do say so myself.

Midway through the top carve

Well the last couple of days have been something of an education! Lesson number 1 is that I should have done a lot more practice on pieces of scrap wood. Lesson number 2 is that if there’s something you don’t want a router to do, that’s what is going to happen. It is a sort of woodworking Murphy’s law in action. But looking on the bright side, I’ve still got all of my fingers.

The project is still on track but I’ve got a lot of remedial sanding to do. At this stage my biggest worry is that my first cut (on the lowest step) was too deep. I’d planned to take the maple cap down to 5mm, which I did. On reflection, I wish I’d cut it to 8 or 9mm. Flaws in my router technique mean that I’ve got a lot of sanding to do and there is a real chance that I’m going to break through the maple to the mahogany underneath. If that happens then all that is left to me will be to plane off the maple cap, and do another one. If so, then it is not the end of the world, and I’ll have learned some very valuable lessons. Although I suppose I could cover up with a solid colour.

I am going to do the majority of sanding by hand, rather than my original plan to use power tools. This should give me more control and minimise the chance of sanding through the maple. It’ll be a great opportunity to work on my biceps and triceps too.

Next time I try a carved top I’m going to take a very different approach. This differs from every other approach I’ve seen. I’m going to carve the top before cutting out the body shape from the blank. What I’d do is to mark up the body shape on the blank, draft out the carves and make up the templates in the same way I have done. Then, by adding an “outer template” on to the section of waste body wood, it’ll give me support on both sides of the router and get rid of the need for building extra guides and jigs. Once the top is carved I can then cut out the body shape.

Cutting the top carve templates

I’ve made good progress today but it is just going to be a short working day because I’m meeting friends for lunch.

First off I broke out the 16″ scroll saw and rough cut the templates for carving the top.

And this one gives a rough idea of the shape of the carve. Each of these templates is 6mm thick, whereas the each step will be 3mm, so a exaggerates the carve by a factor of two.

With the templates rough cut I trimmed down the lower horn of the body to the shape I was after. I don’t have access to a bandsaw and was worried that the scoll saw would find it too much, but I took it slow and it was fine.

While all this was going on, the postie arrived with a load of wee packages for me. The chrome wrap-around bridge, P90 pickup, chrome tulip tuners, and the 9.5mm top bearing router bit. Woohoo. I couldn’t resist trying to get an idea of how the finished guitar will look.

Right, that’s enough for now. I’d better get changed and head off to Liverpool for lunch. Mmmmm Thai food.

Planning out the top carve

Inspired by the excellent video I posted about yesterday, and constrained by the weather (it is raining and my “work area” is outside) I set about planning out how I’m going to do the top carve. On a Les Paul there are two different parts to the carve: The first is the traditional archtop shape we all know and love, the second was something of a revelation to me – the top is carved flat, rising from where the neck join starts to where the finger board finishes. This means that despite having an angled neck, the fretboard still runs parallel to that part of the body.

Whilst it is not a Les Paul, this picture from the MyLesPaul forum really clearly shows the two different parts of the carve.

So tackling these two carves separately, first off I taped some translucent paper over the body, marked up the centre-line, and for the top half of the guitar roughed out the two main steps for the carve (highest and lowest) freehand with a pencil.

I folded the paper along the centre-line and then replicated the shapes for the bottom half of the body.

I bisected the two lines to draw the third step, again, freehand. The maple top is 19mm thick and I want to leave the edge at 5mm, so for the low step I’ve got to rout away 14mm. The top step is going to be a depth of 2mm. The centre step therefore will be 8mm. I may yet decide to add two further steps at 5mm and 11mm depth, just to minimise the amount of sanding I’ll need to do. This diagram gives you a rough outline of what I have in mind (not to scale).

The next step will be to turn my paper template into router templates, using 6mm MDF sheet. I’ll start by cutting the paper to lowest step, transferring that to the MDF, cut the paper to the next step, transfer to the MDF… and repeat all the way up to the top step. This will leave me with up to five templates.

One of the things that concerns me is that, while cutting around these templates, it is very easy for the router to tip away from the vertical, and cut too deep, and at an angle. To guard against this I’m going to build a box to fit around the guitar body, and a large footplate to ride on top of this box. This will guarantee (I hope) that the router always remains vertical.

An added benefit will be that hinging the box at the front side, and shimming up the back will allow me to cut the neck pocket and the flat front-to-back carve at exactly the right angle. I was inspired to this approach by reading this “Luthier Than Thou” article about carving Les Paul tops and neck pockets. I’m going to adapt the same basic principle to kill two birds with one… er… wooden box.

Update: I’ve since found a picture of exactly what I had in mind on the MyLesPaul forum.