Tag Archives: guitar truss rod installation

Guitar #30/2

installing truss rod & carbon fiber rods

installing truss rod & carbon fiber rods

I decided to do some work on the neck blank today. The sun was shining into the carport this morning when I set up my workmate and clamped the neck blank in place. Fetching the router I found that it had the truss rod bit already in place and set to go. I attached the fence, made some adjustments to ensure I had the center lined up, and then routed the slot in a jiffy. I went to put the truss rod into the slot next. It didn’t fit! I looked a little closer and discovered that my supplier had changed their truss rod in a very small way, but now it was wider by about one millimeter. Problem: no 12mm router bit. I looked through my bits and found one that was 1/2″. Close enough, so I swapped it into the machine and set the depth, then ran it down the groove, shaving off the millimeter required. Only now the rod was a bit loose. No major deal here, I put electrical tape on the rod, which made it snug in the groove. But if they keep sending me 12mm wide truss rods I guess I’ll have to buy a 12mm bit. I have learned that it is sufficient for a truss rod to be installed without glue, and in fact I think it’s better. That way if it ever breaks it can be withdrawn and replaced. If it were glued, forget it – make a new neck.

neck with truss rod and carbon fiber rods

neck with truss rod and carbon fiber rods glued in

After the truss rod groove I switched to a new 1/8″ bit and routed slots for twin carbon fiber rods I recently bought. I cut one long piece in two, sufficient to do both sides of the neck. These were glued in place with epoxy. The slots had to be widened for these just a bit, which was done by adding tape to the sides of the neck blank and to the router fence for a second pass at the slots. After that the carbon rods dropped right into place perfectly.

neck with carbon fiber rods & truss rod

carbon fiber rods before gluing

the bit for the old truss rod

the bit for the old truss rod

the new wider truss rod

the new wider truss rod

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Guitar#29/11

The neck is almost ready for final carving. I have repeated all steps prior to busting the truss rod. That includes gluing on the head plate and fiddling with the dovetail joint. I previously thought it was correct but further inspection revealed that it needed more work. It was as if the whole thing changed while it was sitting in the shop. This is why we check not twice, but three or four times before assembling anything! As it stands I am ready to say that this time it is good to go. I hope these are not going to be famous last words.

dry fitting neck to body

dry fitting neck to body

Once I had the neck joint down I lined up the fingerboard and clamped it to the neck. Then I nailed it in place with small brads, and cut the heads off. Next step was to do a lot of heavy grinding on the belt sander. I sanded the headstock down close to final thickness, as well as tapering the neck and removing a lot of wood to form the rough shape. After this I will carve by hand from here on in.

Once I was certain that everything was finally aligned I prepared to glue the fingerboard. The objective was to make sure I could slide the truss rod assembly into the slot afterwards.

rough carved neck

rough carved neck

fingerboard tacked to neck prior to gluing

fingerboard tacked to neck prior to gluing

testing placement of truss rod prior to gluing

testing placement of truss rod prior to gluing

The truss rod slid in and out perfectly, with no slop or extra play in the slot. Time to glue the fingerboard.

here we go again

here we go again

A few hours later I removed the rubber band and slid the truss rod into the slot. It went in and came out without any problem. No testing to see if it bends yet, I’m going to let the glue dry for 24 hours at least before putting any stress on it. Carving is next.

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Guitar #29/4

Today's efforts: neck & fingerboard

Today’s efforts: neck & fingerboard

To make a guitar you need a few essential tools. The band saw is one. Another is a combination bench sander; the kind with a belt and a disc. This is the quickest and most reliable way to make flat surfaces. To prep the neck today I first band sawed the angle of the heel. On this guitar it is 2.5 degrees, because the top has an arch. Now that the band saw works reasonably well I made the cut fairly precisely and then finished it up by dressing it dead flat on the stationary disc sander. Next I flattened the upper face, to which the fingerboard is glued. Although the three pieces of the neck had flat surfaces to begin with, after gluing they’re never perfect, so the face has to be made dead flat. For this I used the stationery belt sander. After the face was done I marked the break where the fingerboard ends and the headstock begins. More sanding to get right to this line and the neck was ready for the truss rod.

neck clamped in the workmate table

neck clamped in the workmate table

I decided to go with a hidden truss rod. It will have to be accessed from inside the box, but it looks cleaner. To cut the channel for the truss rod I use my 1 HP router. This is very powerful, but it works perfectly if you set it up right and push in the right direction. Once I set up the jig and secured the neck in my Workmate (another essential) I was ready to cut. This took about 30 seconds. Then it was time to do the worst of all jobs: cut the dovetail. I decided to tackle this right away while I had the router out. For this I have a jig with templates for cutting the male and female dovetails. Although the body is not yet made I can still do the neck joint. I use a special tapered bit and a guide collar that fits the router base. The dovetail is 70mm long and 15mm deep.

Dovetail jig

Dovetail jig

Router and cut slot - the guide is on the far side. Router cuts from right to left, not the other way!

Router and cut slot – the guide is on the far side. Router cuts from right to left, not the other way!

The neck, the hardest parts are done!

The neck, the hardest parts are done!

Next step, glue the truss rod into the slot with 5 minute epoxy. I like fast epoxy for this, because it only takes two or three minutes to apply the 1/4 ounce of glue required, and it sets up fast. Sometimes regular epoxy needs 24 hours to get super hard, and by that time I’m ready to glue the fingerboard. I mixed up a small amount of epoxy, about one table spoon, and with a tiny art spatula I applied epoxy to the sides of the groove and the sides of the truss rod. It dropped right into place, but the epoxy takes up all the extra space, so it then has to be clamped to fit. Waxed paper (essential), popsicle sticks and several screw clamps do the trick here.

Truss rod with epoxy, wax paper and popsicle stick used as a caul for the clamps

Truss rod with epoxy, wax paper and popsicle stick used as a caul for the clamps

While this was setting I got out my little table saw (essential) and cut the neck and tail blocks from the left over end of the neck blank. Then I switched to the fret saw blade, a special blade that cuts a very narrow slot. I made a sled jig that runs on the saw table for fret cutting. I use a fret scale, which is invaluable for this job. The edge of the fingerboard was planed flat first, then I taped the appropriate scale to the blank fingerboard. A few test cuts set the slot depth at 3.5mm. Then I carefully cut the 20 frets and the zero fret. Once they were done I marked the ends and raised the blade to make the end cuts.

Fret cutting jig, with engraved fret scale

Fret cutting jig, with engraved fret scale

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