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I teach an intro woodshop course for 3rd year mechanical engineering students; we build simplified steel-string acoustic guitars for the main project. Enrollment has been growing... it was challenging the last 2 years at ~32 students and this Fall it will be ~48 (3 sections). I'm trying to figure out how to manage the workload and I need to devote more class time to safety. So I need to further simplify the guitar project.

With nylon strings, we could omit the truss rod and bridge plate, also giving simpler bracing and bridge installation. Students say nylon and steel string are of similar interest (but not electrics). I've only built steel string so far and so I have some questions--

1. We'd need to retain the peghead/tuners, as it's good drill press practice and a slot-head is too much work. I know of a few nylon-peghead guitars (some Flamencos, Martin Backpacker). Should I increase the headstock angle (currently 13 deg)? Would stringing be difficult (winding room)? Other issues?

2. I don't see many low-end spruce-topped nylon string guitars -- I'm guessing the lack of upper partials from nylon makes it harder for spruce + a laminate back to sound interesting. Our tops are also constant thickness, other than some optional peripheral thinning. PRT gives us great prices on tops and they only have Sitka or WRC. How bad do you think a constant-thickness Sitka/laminate nylon string guitar would sound? Or possibly I could let students choose, durabilty or tone.

3. I see few nylons with a scale length shorter than 25.5". We've used 25.0" for beginners -- is it problematic for nylon?

Any insight on these issues is greatly appreciated!

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David Malicky

1. 13 degrees would probably be enough. I use 15. Wood friction pegs are great for paddle headstocks. Cheap and easy to install. No drill press necessary, although you can use it if you want. The ones LMI sells are perfectly tapered already, so just drill a 2mm hole in the peg for the string to go through, and you're good to go. Pegheds planetary gear tuners are a good option for anyone who wants higher gear ratio.

2. I've never heard anything good about sitka on nylons, although I've never tried it myself either. I'd stick with engelmann and WRC. Redwood is my favorite, but it's relatively expensive and highly variable, so not good if you're doing constant thickness. Any reason you don't include deflection testing as a lesson in the class? That would be one of the biggest advantages of hands-on instruction, IMO, to have an experienced person help you get your top to a good stiffness, and then you can flex it with your hands to memorize the feel. Also good for engineering students to learn how to deal with variable materials.

3. This style of guitar that I build uses 25" scale, and sounds and feels perfect with Aquila Ambra 800 romantic guitar strings, which are lighter tension than normal. For a full size classical, regular Ambra would probably be better, but the 25" scale would probably still be fine, unless you're really over-building them.

Definitely ditch the truss rod. Solid necks are plenty stiff for nylons, and truss rods are heavy. Lightweight guitars are a joy to play. I'd ditch the bridge plate too. Lot of work for something that's not really necessary, and all that notching of braces would be a pain, assuming everyone's sharing chisels and it's impractical to keep them super sharp all the time.

Thanks, Dennis -- that's very helpful! I hadn't even thought of (or ever used) wooden pegs, but I can see how those might be helpful with nylon. If not, do nylon strings work well with a steel-string tuning post? I wondered if they would run out of room and occasionally slip off.

Yeah, I was hoping we could get Engelmann but I can't find an economical source. I may build two prototypes, WRC and Sitka, to see the pros/cons. I'd love to include deflection testing and other things in the class but class time is unfortunately very limited. I used to thickness all our tops to a deflection target but as the class has grown I couldn't keep up with that. I settled on 0.105" for our Sitka GA bodies; from what I've read so far, a classical WRC would typically be about 0.090" - 0.095"?

Great to hear the 25" scale is ok -- that saves some jig rework and is easier for the beginners. That Coral Snake is elegant.

Yes, it will help a lot to omit the truss rod, and having to notch around a bridge plate would negate much of the simplicity of going to nylon. 5 years ago our necks were just solid poplar (with custom-light steel strings)... I've kept 1 of those and it's still at the same 1/64" relief. I keep waiting for it to bow more... but maybe poplar is good in creep. I wonder what is the highest tension that's ok without a truss rod, assuming a life of perhaps 15 years. We currently use Sapele for necks since it's low cost and doesn't chip easily.

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David Malicky

I recently built a small Torres (630 mm scale) Guitar that is perfect for simplified construction. Actually the original was built that way by Torres - very little decoration, minimalist. It doesn't even have any bracing, although you can put a few sticks on the soundboard if you wish.

Link to Brune who restored the original:

http://www.youtube.com/watch?v=RLpEHg1wShk

My copy:

http://www.youtube.com/watch?v=dAhCi0XaQD0

Sitka works fine for nylon guitars. My own personal nylon guitar has a Sitka top (osage orange back and sides), and has excellent tone. You might have to thin the top more and/or use lighter bracing.

If you're trying to save money though, I'd suggest using western red cedar from a lumber yard. You can find some really nice stuff there, and it's dirt cheap compared to what the guitar suppliers want for it. Course you'll have to resaw it, but that's a good skill for the students to learn.

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Regards,
Phillip Patton

http://www.pattonblades.com

The bitterness of poor quality lingers long after the sweetness of low price has faded.

https://hoosierbladesmith.wordpress.com

David, if you introduce another model you're just adding more complexity. Consider, for example, the neck joint and neck angle of classical vs. steel string.

If you want to simplify things I'd suggest going for a wood-only sparse lattice type of bracing rather than X-bracing. Cut the cross-half joints on a table saw jig (simple to make) assemble the lattice off the guitar then just glue the sub-assembly in. That will cut the top bracing time to ~25% of what it is now. Something along these lines:

The bridge plate fills the centre diamond.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Michael, Phillip, and Trevor, thanks very much for the replies! Michael, your copy sounds *really* beautiful. Yes, minimalism is the goal, while still being playable and reasonably aesthetic. Many of you would probably cringe at our design and processes. The closest equivalent is a Taylor Big Baby (Fender neck joint, no binding); we go further with constant-depth siding, flat back, flat-bottom braces (top is braced at lower EMC), CA glue for all braces, butted X-joint (with cap), flat/integral fretboard, etc. My student assistants and I do some steps (join and thickness tops, CNC bridge and neck profile) to fit other key steps within class time. To our beginning woodshop students, though, it is thrilling to build them, and so I can leverage that to have them work harder. The tone is pretty good for a ply back, but certainly isn't solid wood. Our processes are a mix of high and low tech, automated and manual, depending on what skills and tools are useful to mech engrs, and what fixtures I've had time to build.

Phillip, that's good to hear Sitka can work, thanks. I do like using lumber yard materials, but I like to buy the tops ($13) as they do a great job with run-out and quartering, and we're within budget ($55). It would be fun to teach resawing and a few years ago I was hoping to resaw QSWO for back and sides. I love teaching this class but as enrollments grew, I've found I have to carefully choose the skills they'll learn or I just run out of time to supervise them.

Trevor, yes, it's a great question on how much change would be overall beneficial, and I'm struggling to answer it. We do have a lot of experience, fixtures, and videos built around our GA steel string. Switching to nylon would give much more complexity in prep for the next 2 months, for less during class in the fall -- but also more risk during both periods. That's a good point on the neck angle, thanks!, and there are more of those. I'm currently thinking to do incremental change for this fall, and slowly develop a nylon replacement for next year.

That sparse lattice is elegant, new to me, and interesting. We've used CA for braces since it's a good skill for mech engrs and doesn't need go-bar decks or drying time; I'm not sure if we could glue a lattice down with it. I also want students to learn the bandsaw and belt sander, and conventional braces have been a good vehicle for that, but we could still taper the lattice ends. A main attraction of the sparse lattice is the lack of finger braces--those and our soundhole braces cause the most confusion and safety risk. I'd like to replace our 4 fingers with 2 Bashkin-style popsicle sticks (http://www.nichebooks.com/kits/images/bashkinbrace.JPG). Does anyone else do that?

The logistics of what's taught when often determines the most helpful simplifications. Omitting the truss rod would help a lot, as that would free up time in that class period to teach the drill press for the tuner holes. Currently, that's taught outside scheduled lab hours--harder to do consistently. So, one option is to omit it and accept the steel strings will bow the neck in 10 or so years.

Here's a playlist of most of our current process (some steps not shown), if anyone sees inefficiency that we can fix:
http://www.youtube.com/playlist?list=PL ... Xr1Za_8-YL
The steps involving power tools are the most important, as those are done during formal (limited) class periods. Sanding, finishing, and such are usually done on the students' own time. Some key goals are...
- Speed up the initial neck process, so we can get to drilling tuner holes within the class period.
- Change from blind neck bolts to Baby Taylor style screws (or other easy attachment, but I haven't thought of anything close), but find an easy and non-cheesy way to cover the screwheads.
- Simpler finger braces
- Simpler fretting (but we don't control neck humidty, so flush frets are risky)

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David Malicky