Build Thread - Travel Guitar

DaveR

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I've been inspired by @Ripthorn 's Quark build thread in which he set out to make a guitar with a folding neck. He ultimately settled on a small guitar with a removable neck that is held in place by pins. I was so intrigued by this prospect that my gears have been turning on making one of my own ever since he first started his thread months ago. Where I diverged from Rip's design philosophy was when I got the bright idea to stuff an onboard amp inside the guitar.

This past holiday season, I hauled around my newly finished Les Paul build and showed it off to a lot of friends and family, but I didn't bring an amp, and turned down multiple requests to play. I'm primarily an electric player, but I also tend to play and sing a lot of acoustic staples. Acoustics are big and cumbersome, and electrics require too much extra junk to sound good. Pedals, cables, amps, etc. My ideal travel guitar will break down small enough to fit in a large backpack, and would not require any tools to assemble while also having a built in amp and effects that will run on batteries. Also, I want the option to bypass the internal amp and plug in to a real amp, as well as use headphones with the internal amp.

During this pandemic, I'm working from home, so I have a bit more free time and a brand new iMac in my home office on which to do graphic design work (my day job). When the inspiration struck, I've spent many evenings over the past few weeks designing this guitar.
 
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DaveR

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On to specs...here's what I'm shooting for:

Gibson scale length (because I'm tooled up to make those)
12" radius (again, tooling)
24 frets
1 bridge humbucker. I'll likely go with a Duncan '59, just because that is my go to jack of all trades pickup. I still have to purchase one for this build, so I'm open to suggestions. I mostly play hard rock, but want to also be able to get a halfway decent clean sound for "acoustic" type songs...maybe a humbucker that can be coil split with a push pull pot would be a good idea...
Single volume knob, single tone knob
Flamed Maple flat top
Ash body
Maple and Paduak laminated neck
Bound Ebony fingerboard (maybe, haven't decided yet)
2 way low profile truss rod
Carbon Fiber rods
Wide flat neck profile, I'll probably model it after a 90's Ibanez RG I have laying around.
Medium frets
Double cutaway, heavily chambered body
Tru Oil or comparable finish (since this will ride around in a backpack, I don't want to bother with high gloss. I want something cheap and easy that won't make me cry when it gets scratched or dinged).
 
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DaveR

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Here's the layout I've been kicking around. The body curves mostly came from superimposing a PRS, a Les Paul, and a Tele. Then tweaking for days on end until I was happy with it. It's has a smaller lower bout but a thicker waist than a Les Paul. The neck joint is way different than PRS, and the Tele has mostly been diluted out of it by now.

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The spiral pattern is the "speaker grille" which I plan on just drilling through the top. If that turns out poor or doesn't let enough sound through, I'll route out a circle and put in some kind of metal grille. I plan on practice drilling all 153 of those holes in a piece of scrap would before committing to the top.

In cross section the guitar is really thick at about 2.5". I wanted to do a proper carved top, but the internal geometry of this thing is hard enough as is, so I'm going to leave it flat. I may do something along the upper edge akin to this Kiesel...but not as drastic.

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I purchased a KD patent Chinese fixed bridge designed for headless guitars. It's pretty inexpensive, but I've seen several builds that have used it and I think it will be suitable for this design. Still waiting on it to arrive, so I can finalize the plans.

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DaveR

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I had previously demoed both the Blackstar Fly 3, and the Boss Katana Mini. The Blackstar is a fair bit smaller, and would be easier to fit inside the guitar (or so I thought) but the Boss sounds MUCH better. After reviewing some gut shot pictures online, I noticed that the Blackstar board and pots were oriented in such a way that it would be pretty hard to fit inside the guitar, so I pulled the trigger on the Katana instead. The board is a little big, but I think I've got it worked out so it will fit. And the Katana Mini is a three channel amp with a 3 band EQ and built in delay, so that's nice.

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I disassembled the main components of the amp and added a battery box that i picked up on ebay. I've spent a lot of time puzzling over how to squeeze these inside a guitar body. It's about to get weird...

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The idea with the amp controls is that they will be accessible from the back of the guitar, with the knobs slightly recessed below the flat back so they don't get bumped. I may wind up removing the knobs entirely since a bare pot shaft is much harder to turn by accident.

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DaveR

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Since there are many things that can go wrong with this design, I didn't want to go all out and spend a lot of money on this one. My previous two builds turned out phenomenal but cost an arm and a leg and took an eternity to complete. I decided to mostly use leftover junk wood that I have laying around. I'm also starting this build thread on day one of construction rather than waiting to catch it all up later. Hopefully this motivates me to keep making forward progress, but knowing how I work on projects, I'm sure this will stall out at some point.

I bought a couple 1/4" brass rods on Amazon and a piece of 5/16 OD stainless tubing that is a very snug fit around the brass. So much that I'll have to sand down the brass just a little bit to hopefully slide easier. The idea here is to glue or epoxy the tubing into the guitar to serve as bushings, and slide the brass rods in or out to make the neck removable. I anticipate tapping the ends of the rods for a small machine screw to serve as a removable handle for pulling the rods.
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A friend gave me two slabs of air dried Ash with the intent that I could use them for guitars. Once I got them to my shop, I realized there is a big difference between the Ash that can be found in Indiana and proper Swamp Ash. This stuff is HEAVY. Super heavy. I don't think it will ever make a nice Strat or Tele, but maybe I can use it for the thin back and internal structure of this guitar since it's going to be almost completely hollow.

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Some junk flamed maple I have laying around, that should work nicely and won't make me sad if the whole project is a bust. This board was never intended for guitars, but I've used a bunch of it for veneers on furniture. I have several other good flamed and quilt billets that I'm saving for better projects than this one.

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Possible fret boards...not sure what to go with yet. I also have some zebrawood that could be interesting, but I'm not sure if that would make a good fretboard. Has anyone around here ever tried it as a fretboard wood?
I hate to waste the ebony boards, but they're not that expensive, and the second one is already 24 frets and 12" radius, so that's looking like a winner.

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5 pieces ready to be laminated into a neck. The center is hard maple, the outside pieces are sugar maple that has a bit of flame to it, and I cut two 1/8" strips of paduak to go in between.

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Laminated neck in the clamps.

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p_baker

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This is a very interesting project. Hope it turns out well for you.
 

Ripthorn

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I'm loving this, Dave! For the amp, i would suggest putting a cross slot in the pot shafts and make them adjustable via pick tip, if st all possible.

As for the speaker grill, the holes look a little small. I'm an acoustic physicist by trade and do a lot with headphone design. Depending on how thick the top is, you could get some nasty resonant effects with those little holes. I would suggest larger holes near the center, and they can get smaller add they go out.

For the pickup, the Seymour Duncan custom/59 hybrid is supposed to split amazingly well, but I haven't tried it yet.

When you sand the brass rods, I recommend going lengthwise so that you aren't creating micro "teeth" which could make ros difficult to pull. I also put paste wax on the ros to make these sliding action smoother.

I'll make sure to follow along, but I'm happy to share my experience. Not that I'm an expert, but I did have many "learning opportunities" with the quark.
 

DaveR

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Thanks for all the advice Rip! You've been a huge help thus far. I've had ideas like this for years, but never even would have dreamed of trying this without seeing yours!

As for the speaker grill, the holes look a little small. I'm an acoustic physicist by trade and do a lot with headphone design. Depending on how thick the top is, you could get some nasty resonant effects with those little holes. I would suggest larger holes near the center, and they can get smaller add they go out.
This grille is probably the scariest part for me. I'm shooting for either 3/16 or 1/4" thickness of the wood there because I fear any thinner would crack if it had any impact. I'd hate to wreck the top with the drilling. I may work up a similar design with larger holes and post it back here, but I'm starting to wonder if I'd be better off just inlaying a proper metal speaker grille. As long as it don't wind up looking like one of these...

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Maybe I can find an appropriately sized shower drain... :laugh2: but I'm only half kidding.... maybe something like this. Surely that would interfere with the sound less, while offering solid protection?

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I'm a little limited on color selection because the bridge hardware is black and brass. So using black everywhere else. I suppose I could buy any color grille, scuff sand it and hit it with some black spray paint if I have to. I may even wind up going with a trans black finish on the maple top, because of all the other black hardware I'll be committed to.
 
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DaveR

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I've been rethinking the grille this morning. I think I might be better off drilling my own pattern in a disc of brass or steel to avoid that "shower drain" look. Brass would surely be easier to drill. I found some discs online in 16ga brass (.051"). As long as I could drill that without the whole thing deforming, I think I'd be in business. Or maybe I would need to use slightly thicker metal (something in the .1" ballpark?)

I worked up a new pattern, that I think would work out in metal, but not in wood. I don't like it as visually as much as the original spiral pattern, but this thing needs to sound decent or what's the point, right? The center hole is .5" and the outer circle is 4".

What do you think @Ripthorn ? Will the larger holes, combined with thinner material likely yield better acoustic properties?

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Ripthorn

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Dave, The larger holes will sound much better. One recommendation for materials is something that HD carries, called "smoked" acrylic. It is a transparent, dark gray material. You could buy a small sheet of that, drill (carefully!) and have enough material for several trials. In fact, you could make the discs the same size and try different patterns if you like, and listen to the difference. Having a thinner material with larger holes will sound a lot better. It is possible (my gut tells me not likely, and it doesn't usually lie when it comes to acoustics) that the spiral pattern will sound good with a thinner material such as metal or plastic. What I would do for the speaker mounting is leave the top wood fairly thick, and recess your drilled disc into it so it's flush with the top, and rear mount the speaker closely behind it.

When drilling thin material, I would invest in a step drill bit. They are made for drilling thin metal and plastic. HF has them cheap if you need to keep the budget down. I like to drill a hole a little larger than my largest hole in scrap wood with a spade bit or something and then have that hole under the drill bit so that it supports the thin material well. I hope that description made sense. It minimizes deformation. So does some cutting fluid for metal and just letting the bit do the work. Pressing too hard will make the material deform and can make the bit clog faster (with metal it will get a built up edge).

One other thing I thought of was in regards to the steel bushings. I used CA and I am super glad I did, as I had to remove them once. That would have been impossible with epoxy. Plus, I installed them by putting them in, and applying super glue that wicked in. Then again, I was completely making it up as I went and had an issue with the string action that required changing the pin/bushing locations for a more playable instrument.

Hit me up with any questions, I'm pumped to see how this works out for you!
 

pbekkerh

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For the grill, you could try and find someone capable of lasercutting. It can be done in wood, plywood , acrylic or the very tough Lexan.
 

DaveR

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That's the first thing that came to mind when you suggested acrylic! :laugh2: I can't believe it never occurred to me to use plastic for the speaker grille. I'm already buying a huge sheet of .083" black pickguard material to make cavity covers out of (this guitar has 3 of them on the back side). I think that would work out nicely for what we're talking about.

I do own a few step drill bits from back in the day when I built some tube amps and guitar pedals and had to drill my own enclosures. Although I would imagine with something as soft as pickguard material that I'd have pretty good luck with brad point bits as well, and I have a large array of sizes to pick from in those. I'll give it a shot at least.

Good point about using CA for the bushings. Epoxy is very permanent.

Lasercutting is an interesting prospect, certainly for complex patterns. I also have a buddy who does a lot of things with a CNC, so that may be an option as well. If I inlay a circle, I could experiment with all different kinds of grilles down the road as long as the overall size and thickness is consistent.
 
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DaveR

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Not a whole lot of progress to report, and I am in the middle of multiple projects, the largest of which is getting my new table saw fully functional. This requires building a folding outfeed table, a router table and integrating dust collection. It's coming along slowly, but I"m back and forth between this project and the guitar build. I should probably do a New Tool Day post on this saw, because it is a fantastic piece of equipment!

I'm going to try to make some small measure of progress every day on both projects and post as often as I can to keep up my motivation and avoid distractions...

Here's the neck blank out of the clamps and after a light pass across the jointer. I'll true it up further with a hand plane. Don't want to go too far with the jointer and tear up the curly parts.

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Picked out my top section and broke out the 20" bandsaw to resaw it. It's such a pain to rig this saw up with my 1" resaw blade and this maple had some thickness to spare, so I did most of the resawing at the table saw, and just used the bandsaw to zip through the small portion in the middle that the table saw blade couldn't reach.

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That's it for the past couple of days. Next up will be thicknessing the body blank, resawing a slab off the back side of it, and making a crap-ton of MDF templates.
 

DaveR

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Not much to report. I've made a slight amount of progress. Still working on my table saw too and I'm starting to wonder if the bridge I ordered from China may be a lost cause. I expect it to take a very long time, but given the state of the world, it's possible that it won't ever come. I knew about passenger air travel from China being denied, but I had assumed that cargo was still moving. Unfortunately I designed this guitar around that style bridge, so if I can't get this one or find another like it, I may be up a creek. We'll cross that bridge later. Don't get me wrong, I'm not bent out of shape about it...I don't have any REAL problems, and so many people do right now.

Broke out the old router planing sled to plane down a pair of these ash slabs a little bit since the two slabs I have are over 3" thick and just slightly too wide to fit in my lunchbox planer.

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The last time I tried this, I used a 1/2" bit (all I had at the time) and it took forever since you can really only effectively take off about half the diameter of the bit. A brand new, flat bottom, 1.5" bit was much better for this and made short work of these slabs. It also did a number on my garage. I'm knee deep in chips. I brushed it all onto the floor intending to clean up later, when my five year old daughter came outside and started sweeping it all up without being asked. She did a pretty decent job too!

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Again, this Ash is super heavy. I don't think it'll ever work for a Strat, but I'll pick one of these to be the hollowed out body on this current guitar, and maybe use the other for a thinline Tele some day.... I only took about 3/4" off, still have quite a ways to go, but I'm not in a hurry and don't trust air dried lumber. I'm gonna let it sit for at least a few days to see if it moves any. Then I'll plane it down closer with this rig and true it up on my drum sander.

IMG_5350.jpg
 
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dspelman

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I'm getting ready to order a "travel" guitar, and it's headless, but the body is a LOT smaller behind the bridge. Overall length is about 31" for a 25.5" scale guitar with 24 frets fully accessible. Pretty much like a Kiesel. I really hadn't thought about a built-in amplifier. I have a Korg Pandora that's tiny and that operates pretty much as both a practice tool (metronome, tuner, phrase trainer, pitch shifter, aux inputs) and an amp/cab/FX device. It'll work with headphones, but there's no power amp, no speaker. The speaker provides most of the the weight and space issues. I'll be interested to see how yours comes out!
 

DaveR

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I'm getting ready to order a "travel" guitar, and it's headless, but the body is a LOT smaller behind the bridge. Overall length is about 31" for a 25.5" scale guitar with 24 frets fully accessible. Pretty much like a Kiesel. I really hadn't thought about a built-in amplifier. I have a Korg Pandora that's tiny and that operates pretty much as both a practice tool (metronome, tuner, phrase trainer, pitch shifter, aux inputs) and an amp/cab/FX device. It'll work with headphones, but there's no power amp, no speaker. The speaker provides most of the the weight and space issues. I'll be interested to see how yours comes out!
Yeah, I'm starting to doubt the size of this thing I'm cooking up. Not so much the shape of the body but the near 2.5" thickness. Which I'm kinda stuck with because the depth of the circuit board. I'm trying to avoid permanently modifying the katana, in case this project is a total flop, I can at least put it back the way it was and have a nice little travel amp. If I were to hack the shafts off all the pots and slot the ends for adjustment, I could get the total thickness well under 2", which is really tempting. I'm also still working out the geometry of body contours and bevels to make it only full thickness in the areas that it HAS to be. This is really really hard in 2-D design software.

That Pandora sounds very full featured, and I've built a number of SS amps in the past that will drive a 4x12 at conversational volume with a 9V battery. They can be tiny, and I suppose one could use whatever speaker you wanted. None of them ever sounded really great, just okay. After your post I started down the rabbit hole of finding a different onboard processing device like that Korg and making my own tiny power amp, but discarded it because I'm so far down this path already. What I liked about the Katana is that it sounds awesome (at least in it's original configuration). Also, what appealed to me the most about this project is the gimmick of no cables or separate components to deal with, everything is self-contained.
 

Ripthorn

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Dave, a few thoughts:

1. Cargo is still moving, I've been getting things here and there that I have ordered.
2. I have 1:1 scale drawings that I made of the bridge in SVG format. I can send them your way if you like.
3. If your Katana won't work, I have left over PCB's from my onboard amp. It is a zendrive, clean preamp, cab sim, and headphone power out. Measures 1.65x2.75" and is mostly SMD, though all controls are board mounted trimmers. I haven't built one up to test yet, but if it works, you are more than welcome to one of the spare boards. Total mounting depth is about 1/2", and certainly no more than 5/8".
4. I recommend thinning out the body as much as possible wherever possible, but that's kind of a given.
5. I like a modified Ruby amplifier for those times when I have to drive an external cab. I built a mini head a little while ago with a box of Rock, cab sim, and modified Ruby. Sounds great and gets my 1x12 much louder than my wife would ever like :)

I'm enjoying watching this come along!
 

DaveR

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Thanks @Ripthorn! That’s generous of you and as always I appreciate the advice.

I’d love to see those drawings if you can send them my way. I’ve been trying to figure out the string spacing based on a low res drawing I found online. It almost looks like a trembucker matches up better, but I have a line on the perfect regular humbucker and need to make a decision pretty quickly.

As for the amp, I really dig the way the katana sounds, but it winds up making this body thick. If I knew more about the circuit I think there are some components I could remove and buy myself some space, but I fear that I might “let out the magic smoke” and ruin the amp. I’m great at through hole soldering of full size components, but lack the tools for micro SMD stuff.

I’m unfamiliar with the zen drive but would love to hear how yours turns out. I have built a ruby amp before and others like it. They’re fun!

Here’s some shots of the board...
My plan to mount it is to attach all the pots through a piece of pickguard plastic and recess that into a deep cavity cover route in the backside of the guitar.
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It’s right at 2” thick without knobs. By the time I recess the knobs a tiny bit into the back of the body and have a 1/4” maple top on the guitar itself I’m sitting around 2.5” total thickness

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This tall metal bracket is just a mounting point for the wall wart power adapter that I don’t have and will never use. It’s soldered on, but could come off super easy. However I’m not sure what the copper wound circle behind it is. I’m guessing a transformer of some type for the power adapter, but don’t think I can just remove it and leave a hole in the circuit.

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I think I’m going to wind up cutting all the pot shafts down to tiny nubs. That would buy me close to 3/8”. I didn’t really want to be destructive to the Katana because it’s a sweet little amp, but I bought it specifically for this project and it was cheap. If I remove the metal bracket and the pot shafts I’m down to a 2” guitar body and I can totally live with that. If I can lose the copper winding that gets another .25” at least. It’s funny how we can agonize over the tiniest of measurements, but .25” across the entire guitar body is a lot of material.

I also considered mounting all the controls on a separate board and connecting to the main board by wires, but that’s a whole lot of points of failure I’d rather not mess with.
 

Ripthorn

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That wire coil is likely a choke inductor for power supply filtering. It can't go, unfortunately. With the pots, I would entertain the idea of clipping off the legs and wiring off to pots in a separate location using the cut off legs as solder lugs. That could help reduce a lot of body thickness and give more flexibility to placement of both board and controls.

I'll dig up my drawing. PM me your email address and I'll send it along. I'll also stick some calipers on the bridge for string spacing.
 


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