Gluing the neck and raising the grain

Late last night I glued the neck. I gave the neck pocket and heel a final sand with 80 grit paper, liberally coated the pocket with Titebond Original and clamped the neck to the body. Using a damp cloth I removed the excess glue that squeezed out. I’m left with a very clean and neat neck joint.

An hour or so later I noticed that the areas where I’d wiped with a damp cloth felt almost “furry” compared to the super smooth finish yesterday’s sanding had left. This was a perfect demonstration of something I’d only heard in passing before; raising the grain.

What happens is that the sanding leaves the surface covered with tiny torn fibres of wood. Immediately after sanding these are all lying flat, leaving the surface feeling smooth. As soon as they get wet, all of these tiny fibres distort, bend and stick up, leaving the furry feel to the surface.

The solution is to slightly dampen the surface of the whole piece, allow it to dry and then to lightly sand, at a slight angle to the grain, with the finest grade paper you used previously (240 grit in my case). The aim here is to just remove the tiny raised fibres. You don’t want to be sanding into fresh wood, otherwise you’re back to the start of the cycle.

My plan for today is to finish the final shaping of the neck heel (see picture below), and then complete a couple of cycles of raising and cutting back the grain, and get the body ready for the first coat of finish. I’m going to be using Rustin’s Danish Oil.

Hopefully the set of long drill bits I’ve ordered will arrive this morning which will allow me to finish the last scary part of the construction. Because this guitar has no control cavity I’ve got to run a hole all the way from the jack socket to the pickup cavity, a distance of 190mm (7.5″). Keeping the drill tip on target is going to be something of a challenge and my biggest fear is that it’ll veer off and break through the front or back. This is going to be done freehand, but I’m planning to set up a guide in each axis, and enlist the help of a friend to make sure the drill stays parallel to the guides. This step is going to be done very, very carefully. I’d hate to bugger up the previous 100+ hours of loving care and labour that has been lavished on this.

Two days of solid progress on the project guitar

Since I last posted an update I’ve made two good days of progress on the RockMangle and it is starting to look, not just like a guitar, but one I’ll be proud of.

Yesterday, on the advice of Steve Benford, I went out hunting for Titebond Original. This glue is particularly suitable for a set neck. Titebond is not a very common product in the UK and it took me a while to track down a supplier within a reasonable driving distance. I’m glad I put this effort in because it lead me to the most amazing shop, called Graham’s Machinery Sales, on an industrial park on the outskirts of Chester. This place is just full of workshop porn. I used to think guitarist’s GAS* was bad until I stumbled on to woodworker’s GAS.

With Titebond in hand I headed home and spent the rest of the day routing deeper slots in the pickup cavity to clear the two round-head screws in the baseplate, and for the cable. Also because I’ve got a long hole to drill from the jack socket (remember there’s no control cavity in this guitar) I wanted to cut a decent sized slot to give me a reasonable chance of hitting it. The rest of the day was taken up with small fiddly jobs; filling the old screw holes in the headstock, gluing the fretboard to the neck, slightly reshaping the end of the neck to ensure maximum contact area in the neck pocket.

Today I was up bright and early and ready to get cracking. The morning was spend carving body around the neck heel to make sure that reach to the top frets would be as easy and comfortable as possible.

Here it is from the front:

And from the back:

The final shaping of the neck heel will take place after the neck is glued in.

I then drilled the 11mm holes for the bridge posts, first taping up the drill bit to ensure the holes were the right depth:

Next job was to drill the 19mm hole for the jack socket:

And then to tape the jack socket plate to the body and drill the four pilot holes for the screws:

I also drilled pilot holes for the strap buttons, the tuners, and the hole for the earth strap that runs from lower bridge post to pickup cavity.

One common problem with figured maple is that there are occasionally cracks in the surface. I had a couple just between bridge and pickup. I followed the excellent advice at http://www.bladeforums.com/ (a whole community of knife makers – who knew?). I flooded the cracks with Cyanoacrylate glue (better known as Superglue, but this is the key ingredient you need to look for), let it start to go tacky, and then sanded the body, forcing the maple dust into the cracks where it gets embedded into the tacky crack (no sniggering at the back). The glue is transparent when dry and all you can see is maple. I gather it’ll take the danish oil finish fine too, but time will tell.

Next up was hours and hours of unglamorous sanding. Previously all of the body shaping and sanding had been done with 60 and 80 grit paper. I’ve got a lot of marks to get rid of! While doing this I added a very slight round over to the back edge of the body.

Last of all, out of curiosity, I loaded up the kitchen scales with the body, neck and all of the hardware. When finished this thing is going to weigh in at a fairly back friendly 7.5lbs (3.4kg).

* GAS = Gear Acquisition Syndrome

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.

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.

Calculating the guitar’s neck angle

I awoke to find it raining heavily and, according to the forecast, it is here for rest of the day. No routing for me today. I’ve used the time to review and add more detail into my plans.

Now that I’ve got the wraparound bridge I can work on calculating the neck angle.

I want the bottom edge of the end of the fretboard to sit flat on the top (there is a short overhang past the end of the neck). The height of the bridge, at its very lowest, is 19mm. The fretboard (incl frets) is 7mm thick. The end of the fretboard is 168mm from the bridge saddles. This means that the neck inclination needs to be a drop of 12mm over 168mm distance which. Reaching back into the dusty recesses of my maths degree (who knew that it would ever come in useful, eh?) this equates to very close to 4 degrees.

If you’re interested the calculation is Angle = ArcSin (height/distance) = ArcSin (12/168) = ArcSin (0.07143) = 4.09604 degrees. I used this online calculator.

Here’s a diagram of what I mean;

Of course with that geometry it would mean the strings were far too low, but I reasoned that this is the very lowest that the bridge would ever need to go.

And just to help me visualise the angle, I tried this;

The matchsticks lift the bridge of the body the same distance as the bridge studs. And yes I know it is worthy of “thereifixedit“, but it works for me.

Update: After an email from the ever helpful and insightful Steve Benford, of Benford Guitars, I realised that I’d measured the thickness of the fretboard at the edge and not the centre! This was a small but significant error. The drop should actually be 9mm over the 168mm distance from bridge to fretboard. This is 3 degrees and not the 4 from my original calculation.

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.

Stripping the neck and further research

Today’s job has been to strip the paint from the neck. I’d originally planned to break out the 80 grit and just sand it off. I immediately realised that 80 grit paper is not very discerning and will happily remove wood as well as lacquer and paint. This would be particularly relevant to the areas of detail around the headstock, where it would be very difficult to just take off the paint without, to some extent, reshaping the wood underneath. I quickly changed tack, popped round to the local hardware store and grabbed myself a pack of Nitromors paint remover. The rest of the afternoon has been spent applying it liberally, leaving it to rest for 5-10 mins and then getting busy with the scraper.

In between times I’ve been doing some more research into how I can carve the top of the body. The most helpful advice I’ve found was in this video by Youtube user “A1373S9865”.

Now I don’t have the infrastructure to do the routing like this but, using those principles I’m going to work out how to do something similar with jigs/templates and a free-hand router.

Here are some of the pictures of the paint stripping in action.

First, all masked up ready to go;

Now after the first couple of “coats” and light scrapes;

Almost done now;

And this is the area that has been most difficult to do, but I’m just taking my time and letting the product do its stuff;

Next project guitar underway

I’ve got a couple of weeks off work and so the next project is underway. I gathered together all of the bits and pieces I need, and put together a shopping list of tools, materials and parts I’ll need.

I’d already got the body blank (above) and had been lucky enough to find a slightly damaged 24.75″ scale neck on eBay for just £4.70. Today I ordered the bridge and a couple of new router bits and picked up a new surform and some MDF for making routing jigs. Whilst I’m waiting for the bits and pieces to ship I’m going to start work on stripping the paint from the neck. As you can see from the picture above, I’ve already marked out the location of the main components. You’ll see a line, about an inch in from the edge of the body – this is to guide the carve – the deepest cut will go from this line to the edge, leaving approx 1/4″ of the maple cap as a faux binding.

The basic plan for the guitar is to build something along the lines of a Les Paul Junior, but with some significant differences. The main one will be that it is going to feature a carved top. The neck I have is of a bolt on variety but the section that fits into the neck pocket is much longer than usual so it is going to be getting repurposed into a set/glued neck. The body shape is going to be different to the standard Les Paul, with a much rounder lower horn. Aside from that, it’ll feature a wrap-around tune-o-matic bridge and a single cream P90 bridge pickup (soapbar rather than the more usual dog-ear). Electrically this is going right back to basics and the pickup will be wired directly to the output jack. Volume and tone controls are for wimps. This thing will be turned up to full all the time anyway.

I’ve chosen to go with chrome hardware, and I’m still undecided about the body colour. I’m going to finish the guitar in Danish oil, but haven’t yet made up my mind whether to have a go at a subtle sunburst.