MIMF

I’ve been reading MIMF for a long time, but this is my first post. I wanted to share my latest creation because I did some unusual things that may or may not be of interest to MIMF readers. Let me say up front that I’m just a hobbyist and that this is only my third instrument. Also, I’m more focused on ergonomics, playability, and sound, so visually this is somewhat of a humble beast compared to many of the beautiful pieces I’ve seen posted on the forum.

This is a basic small body archtop with a laminated spruce top from Acme archtops. I have upper back problems that make straps problematic, so I like to play with a legrest (see photo). Because of this, I like fairly small bodies (this one is about 15-1/2” across the lower bout) and I care about the distance from the bridge to the heel, about 7” on this guitar, which is less than most archtops.

I used a Warmoth bolt-on neck. I stumbled on this neck design by accident when I built my first guitar, which was something of a cobbled together hack job (but I loved playing it). Although I originally used this neck design so I could cobble the neck off an old Les Paul, I found that I loved the increased access to the upper frets. On a normal cutaway, you can reach your hand under the guitar, but your hand runs into the block where the neck joins the body. With this design, my hand can slip into the hollow space in the back of the body. I find that this gives me about 5 extra frets worth of access. In other words, I can play at the 17th fret with about the same amount of ease that I can play at the 12th fret of more traditional designs. I’m totally spoiled by this design, and one of my motivations to build this guitar was to get the full access neck. Of course, this also let me buy a pre-made neck, which was good since I’m just a hobbyist builder with a small fairly limited shop.

I took the block that the neck attaches to and extended it through the body, creating double “tone bar,” to use the term I got from Jim English’s book. I wanted to take the stress off the strings away from the top because I was concerned that the size of the cutouts for the neck and pickup might weaken it structurally. The top is actually free floating around the base of the neck with about 1/16” clearance between the top and the neck.

The pickup is attached to the tone bars underneath and is totally free from the top. The trim ring around the pickup has 1/16”-1/8” clearance around the pickup. I did this for two reasons, 1) I felt that the top would be able to resonate more without the weight of the pickup 2) I felt that the pickup would have a little less “mud” if it wasn’t vibrating along with the top. I don’t really have much to compare it to, but I’m very happy with both the acoustic and electric tone of the guitar.

The leg rest and arm rest are things I’ve started using as my body has forced me to pay more attention to the ergonomics of the guitar. They attach with sticky Velcro, which might horrify some purists, but I built this thing to play it, not hang it in a museum. I’ve been using the leg rest-arm rest combo for decades and it works great, although I am working on a “new and improved” version of the leg rest.

Overall, I’m very pleased with the guitar. It’s very comfortable to hold and play, and I’m very pleased with both the electric and acoustic sounds. This is the first instrument I tried to get any acoustic sound out of (my first two were semi-hollow with a body block) and my goal was to get good enough sound that I could enjoy practicing without plugging in. I more than achieved that. It’s fairly quiet when compared to e.g. my wife’s Taylor, but it has a very sweet tone. And it’s not a showy guitar, but it looks decent.

Many thanks to all of you on the forum for helping me figure out this process. Although it is a bit of an addiction; I’ve already bent the sides for my next one.

Some of you might be interested in what it looks like inside.

Welcome Clark! I think it's very good clean work and I love it when someone works up a design that fits into their own personal needs! Well done.

Very impressive.
I was just watching a documentary on the Smith guitars that used to be produced here locally with their reduced heel that amounted to a glue on version of what you did. It really makes more sense to bolt on in that case. They were fighting 18 strings on a florentine cutaway flat top with tops so thick you couldn't hear much bottom. Most of their engineering went into fighting pull at the expense of sound and didn't look all that comfortable. Yours seems to be inviting.

That looks great!

Pretty darn cool Clark. Some good ideas and happy accidents.

Very interesting instrument and ideas. It also looks cool and apealing. Great job. Thanks for sharing.

Very cool. I have drawn numerous bad sketches for an ergonomic guitar, but nothing that I would want to build. This looks great. Thanks for sharing this.

About 8 years ago, I developed a severe rotator cuff strain, and eventually realized it was in large part from playing a standard archtop for many hours each week. It took a year of PT to recover, and now I do arm and shoulder stretches during breaks and after a gig.

Clark, now that you have it in playing order, if you were going to do it again what if anything would you change?

I wouldn't change much. As far as the ergonomics and comfort of playing it, I'm very pleased but I've been working with this design for a while. Perhaps trying to get the bridge to tail distance down to 6", but I'd worry about losing sound. I played an Eastman El Rey in a shop that had 6" bridge to tail and I liked the feel of it a lot. But it had almost no acoustic sound for a variety of reasons.

Also, the sound port in the top side of the upper bout is too big. I got this idea from an "Outdoor Guitar" (the ultimate travel guitar) that I owned for a while. I think it does give better acoustic sound to the player, but I've read some stuff online (some classical builders are playing with this a lot) that indicates it could be much smaller.

Internally, if you look very close at the drawing, the pickup mounts to a plywood plate that is attached with screws that go through a slot to allow adjustment. This allows the pickup to be adjusted slightly so the strings can be centered exactly on the pickup. I had some issues with this string centering when working with semi-hollow guitars in the past but after building this "real archtop" I realized that it's a piece of cake to slide the bridge side to side an eighth or so and deal with that (duh). So I'd just mount the pickup directly to the center bar (or whatever you call it).

Also, on my next guitar, I'm going to try a modified florentine cutaway. Bending that tight radius for the cutaway has always been a challenge and bending the sides for the guitar I'm working on now, I turned a beautiful set of walnut sides into scrap by getting a little too aggressive. I use a pretty funky homemade pipe-and-propane-torch bender. But that's more just a recognition of my limits as a bender.

Also, I tried using Tru-Oil Filler Sealer as my only grain filler and then Tru-Oil as my finish. The true oil filler sealer took about 20 coats to fill the grain and then shrank back over time so the surface of the finish has ripples over the pores in the mahogany and the Tru-Oil finish scratches pretty easily. Neither one is a big deal, but next time I'm going to try Z-Poxy as a filler with KTM-SV as a topcoat).

My next guitar (I've bent the sides and bought the neck, but that's about it) is going to be an almost direct copy of this one as far as the neck, back, and sides, but internally, a tricone resonator. I've been playing around with modifying cheap production resos for years, and they can do some interesting things other than delta blues. I'll post something in the reso thread when it's built; I'm hoping to finish it this summer.

So those are my "lessons learned" from this one.

Perhaps trying to get the bridge to tail distance down to 6", but I'd worry about losing sound. I played an Eastman El Rey in a shop that had 6" bridge to tail and I liked the feel of it a lot. But it had almost no acoustic sound for a variety of reasons.

Don't be afraid of that. Strings afterlengths can change the guitar feel, but that's it. won't kill or suck tone. Personally I prefer them short (or long tailpieces) in most cases. But for certain particular guitars I prefer long afterlengths (short tailpieces). You'd probably noticed that some makers like to slant the stop bar, some like them straigh and some even reversed (bass strings shorter than the treble ones) Erich Solomon as an example. This also changes the feel and response of the guitar somewhat. Also some makers have them adjustable, like Ken Parker. Players can change the afterlenghts at will or taste in these guitars. Just try by yourself and choose you preference.

Personally I prefer straight stopbars in most cases. Hardly ever like slanted bars on any guitars (never liked the Epi Frequensator as an clear example of way longer bass strings than trebles), and for some guitars, specially for short scaled ones, I totally favor reversed slanted stopbars a la Solomon or... Otwin. but that last one is a different approach for the same results. In certain way the Otwin system is an old fixed version of the Parker approach. The idea is having different breakover angles for the treble and bass strings more than altering the strings afterlengths. The results are basically the same.

Clark,
Great job. I like your concept and love the dark natural color.
I'm on the look out for #2...

Hans

This design looks like what I had in mind. There is a very strong connection from the neck all the way to the tailpiece, you could even say that the neck extends to the tailpiece? I presume the archtop soundboard has no rigid mid-bracing and is free to vibrate under the bridge?