Build Thread: RS Muth Guitars

[Randy Muth]

Bruce, do you mean you know a luthier that is not nuts! Thank you!

[DamianL]

Originally Posted by Bruce Sexauer

I hadn't looked in for a couple of weeks. Randy, you seem like such a regular guy in person, and here it turns out you are genuinely eccentric. Very impressive concept and execution!

It's funny but I was having a very similar thought when reading this whole build thread....But from the customers perspective.

By that I mean - I had a look at RS Muth guitars on the web and on brief inspection, thought they looked relatively traditional, non-quirky...but very attractive...

This thread has given me a new appreciation for what can be going on behind the scenes....would love to try one of these guitars someday..

[murrmac123]

Originally Posted by Randy Muth

Yes they are brass. These are from Woodcraft. I've tried about 5 different types of threaded inserts and have found that these work the best for me.

Randy, I'm sure you know this already, but just a warning to anybody planning to use these inserts, if they are like the type below, with a countersink, do not be tempted into trying to insert them into hardwood using a screwdriver in the slots, you might get lucky, but it is more likely you will break the wall of the inserts.

DAMHIK ...

You need to improvise an inserting tool from a bolt of the same internal thread as the insert, using two locking nuts and a washer, and screw it in with a socket wrench.

[Randy Muth]

Murrmac, the ones I use do not have a countersink nor do I use a screwdriver slot to insert them. I use the tool shown below to insert them. Thanks for the heads up though.

[Randy Muth]

Thanks Damian. I guess the next step is to apply some of my eccentricities to the outside of the box.

Of course there is my Ascent series guitars.

[roberts]

Eccentric? Remember this is a guy who spent a lot of time in his basement with the bunson burner But seriously, the beauty of Randy's guitars is in the impeccable build, complex sound, and solid feel. As I've learned from reading on this forum, the concept of a guitar where all the elements compliment each other (visually and sonically) being preferable to one with a lot of shell is not all that uncommon....Robert

[dlowry]

Originally Posted by Randy Muth

Here I am cutting the slots for the CF rods on the table saw. Notice the spacer since the headstock is on now.

Hi Randy,
I posted a general enquiry about the use of CF rods in Build and Repair, but I'll ask you directly here as well as that subforum is probably less frequented by pro builders.

Just how much added stiffness do you get by embedding 2 CF rods in the neck? I'm curious about how it affects relief adjustment via the truss-rod. Presumably you don't want the neck to be so rigid that its no longer adjustable.

btw - great thread! Always illuminating to see the variety of techniques folks use in the build process.

Regards,
Drew

[Randy Muth]

Shhhh Robert, you're not suppose to say that. Thank you for the compliments.

Drew, the rods don't add so much stiffness that you can't adjust the truss rod, but this requires further explanation.

When you try to bend a piece of wood, or anything for that matter, there is a neutral axis where the wood is not in compression or tension. I've been told that on a neck the neutral axis is about where the glue joint for the fingerboard is. So as the strings are pulling on the neck, the fingerboard is in compression and the neck is in tension. That means that the carbon fiber that is at that joint isn't doing anything. The further you move away from the neutral axis the more effective it is. Many have argued that putting carbon fiber rods in the neck the way I and others do does not have much of an affect. The argument is that it is better to put it in horizontally and the bottom of a channel away from the neutral axis. This is absolutely true. However, I would argue that at 3/8" deep, the CF rods are still doing quite a bit. I splay my rods with the neck taper and they are 1/2" in from the edges. I really wouldn't want to go deeper when you consider the thickness of the neck after carving.

Moreover, I'm more interested in increased stability than added stiffness. Carbon fiber never relaxes over time like wood does. As long as the glue joint between the CF rods and the wood holds, the CF rods will be trying to pull the neck back straight.

[murrmac123]

I cannot recall ever seeing such an intriguing build thread, and I am looking forward immensely to seeing how the fretboard interacts with the top ...

I totally get the carbon fiber insert thing, it gives much more stability to the two glued in neck extensions, right ?

[Randy Muth]

Thanks Murrmac, unfortunately you are going to have wait. I've got a plethora of other things I have to do this week before leaving on a long overdue vacation with my wife for a week. So it will be a two week hiatus in all. Sorry about that.

You are correct, the CF rods are critical to the stiffness of the extensions. I forgot to mention that. I love killing two or more birds with one stone. OK, I actually like birds but you get what I mean.

Here are a couple of more pics. These will be the last for little while. The first one shows the back and the box read to close. The "stain" inside the top is a coat of shellac over my signature. Notice that I have glued a cross grain patch of spruce in the trapezoid formed between the headblock, upper transverse brace and A-frame. This patch is a tight fit all the way around. Again, since this is a cutaway it is not quite a trapezoid. It is through this area that I will be routing the slots for the fingerboard extensions later on.

In the second one the sides have been all trued up and the box is ready for the end graft and binding, and the neck is ready for the headplate and fretboard.

[murrmac123]

Emjoy your vacation Randy, and we will all be looking forward to your return.

[Randy Muth]

Thanks, I will be around this week to answer any questions anyone might have. I'll probably check in from time to time next week as well.

[Bruce Sexauer]

I have done carbon the proscribed way (as you describe) and the easy way (as you did) and neither is a good idea w/o a truss-rod IMO. Even if the rod is only used to affect relief it is still a godsend. Either way adds great stability, but the "right" way has more potential for failure as it counts on a glue joint using material that is notoriously challenging where glue is involved. I am not an epoxy lover, and epoxy is the right glue. Epoxy creeps in my experience, and ANY creep in this application makes the whole concept a fail. That's why I do it Randy's way. If that makes no sense to you, see Randy's comment re luthier sanity.

[studiodunn]

Great show and tell. Thank you for this.

[Randy Muth]

Bruce makes a very good point that I hadn't thought about. Laying a CF rod horizontally in the bottom of a channel does rely heavily on the stability of that bond, whereas the effectiveness of laying them upright, as Bruce and I do, isn't as dependent on the glue joint.

I should mention, in case it wasn't clear, that I do use an adjustable truss rod.

I should also mention that ALL materials creep. It's just a matter of rate. The same is true with epoxies. There are literally hundreds of epoxies designed for different purposes. Some creep a lot more than others. I use Henkel epoxies that are sold under the Loctite / Hysol brand. Henkel makes a large number of epoxies, many of which are sold for industrial purposes including satellite telescopes. I use different ones for different purposes. They provide very good technical information sheets with data such as: tensile elongation, sheer strength, peel strength, etc. Unfortunately nobody really provides good quantitative data regarding creep. I guess this is because acquiring this data would require such long term studies.