So a single action cavity should be curved, and double action cavity straight?
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So a single action cavity should be curved, and double action cavity straight?
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It all depends on the style of rod, and there are several types (though the cavity itself isn't curved)
Most truss rods (single and twin-acting) are self-balancing (twin rod or rod in a square channel) and need to fit is a slot that's basically the size of the truss rod itself. It needs to touch the bottom of the channel and the underside of the fretboard to work well, and you don't want any lateral movement either. So a jolly close channel fit.
That single rod 20" StewMac adjustable length TR is (I think) really meant for replacement of a broken truss rod in older instruments. According to my acoustic guitar construction book, it needs a channel that's about 3x as deep as the rod diameter. The ends are help up quite high in the channel by passing the rod through wooden blocks and there's a wooden block placed on top of it in the middle of the truss rod that forces it down to touch the bottom of the channel, whilst the top of the block presses against the underside of the fretboard, forcing it into a curved shape.
It's not as stable as a self-balancing truss rod, and the centre of the curve is a bit offset from where it ideally should be to counteract the string bending forces.
You certainly just can't run that basic type of rod type down a channel and hope it will work.
It's probably time to invest is some guitar-making books.
The one I've got, "The Mechanics and Construction of the Acoustic Guitar" by Eddie Green has a lot of stress theory in it, and concentrates on acoustics, but has a fair amount that also relates to electrics (and a couple of sections mention solid body specifics). It's reasonably priced for a big technical book (£24 in the UK) but only comes in hardback form, no Kindle or pdf version. It may not be available in Australia though.
https://smile.amazon.co.uk/Mechanics...ps%2C66&sr=8-1
It also concentrates more on the general theory of guitar construction rather than on practical building techniques, so it's worth looking around for others that focus on the practical side. Unfortunately they are generally limited run books so don't tend to be cheap. I'd definitely recommend the above book, but it is very technical in places, so you just need to ignore some of the equation sections and get to the conclusions and plainer English sections.
So many variations. A lot of the the smaller builders use a strait rectangular channel so the double action truss rod sits flush against the under side fretboard. Some of the larger manufactures use curved channels with single action, or in the case of Warwick, double action rods with either timber curved to press the truss rod against the curve of the channel between the fretboard and the truss rod.I think Gibson did this with the Les Paul, Warwick with their basses. I believe Fender took the approach of having the curve in the neck and the truss rod pressed against the curve from underneath with the characteristic skunk stripe. Rickenbacker do wired things, I believe it's common to their guitars as well as their basses. Twin rods in curved channels, capped beneath the fret board to fit snug in the channel. The modern ones use round bar, the older ones flat bar folded over so the folded end is at the body end and removable . You adjust the neck by loosening off the nuts, physically bending the neck to the position you want and then tightening the nuts to hold in place. The simplest solution is probably to get a standard double action that's too long, route a flat channel, and trim the end and weld...or get someone to weld it for you.
I have a feeling that the Rickenbacker neck bending thing is a hang-over from a couple of years in the late 60s (or thereabouts) where they used too soft a steel for the truss rods so the threads stripped when you turned them if under tension. They then switched to a harder steel and they have been fine (as much as any truss rod can be) since.
I adjusted the only two Rickenbackers I've had to look at in a standard manner without issues. But on a standard width neck (and especially the thin Ricky ones), the two rods are too close together to actually counter any significant level of twist on the neck (which was the case with the 650D I set up). If you did manage to get the fretboard flat from side to side, you ended up with a big back bow. I had to level the frets to get the action down to a reasonable level, but you had flat frets and a wonky board.
I think having the twin single-action truss rod channels weakens the necks and actually encouraged twist. I feel a single double action rod is still a much better solution on standard width necks. Sometimes it's better to dump a dubious practice, even if it is 'tradition'.
Woah woah woah... I don't think we're quite at that point ;)Quote:
Originally Posted by Simon Barden
The internet and this forum will do me just fine for now.
For what it’s worth, you’re welcome to come over and take a look at my Benedetto text regarding a G style single action truss rod…take some photocopies.
Thanks Mark, very kind offer (I may take you up on it).
I think I'm going to start with an 18" dual action. I want to make both a 25.5 and a 27 at the same time, so I'll grab a couple and go from there.
While I'm waiting for the truss rods, I'll need to sort out a new jig.
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A jig, or a reel? Maybe a nice polka? Waltz perhaps?Quote:
Originally Posted by dozymuppet
Some good routing progress
https://i.imgur.com/CYovRnk.jpg
https://i.imgur.com/8t5Lzkf.jpg
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