mattharris75

I just realized I forgot to answer this question. Yes, that's the plan! Archtop guitars don't seem to be done that way, typically, but it's what is commonly seen in mandolin construction. At least with dovetail joints. I certainly have not followed many conventions with this build. Perhaps at times to my detriment. But hey, that's how I learn. Also, it will have a little macassar ebony and cherry sandwich glued to the heel, as an accent.

Hah! Too true. Actually, my second build, the 'goldfish' guitar for my godson, was completed, beginning to end, in three months. But that was before I had the responsibility of kids and got fat and sluggish. I've taken care of the fat and sluggish part, and apparently that has done the trick! Acoustics, especially carved tops, are quite a bit more involved than that little electric build though... I am actually already planning my next build though. Gathering all the information I can find (there's not much out there regarding specs) on the old Gibson L1's, the carved tops from the teens, before L1's became flat tops. Like this sheraton brown 1919 model. I want to do something like this, but maybe with a few tweaks:

I used a few known straight edged pieces of MDF to get everything aligned correctly, then just made a pencil mark around the neck tenon. I cut through the full depth of the neck block, so I was able to cut it with a bandsaw. I finessed the mortise and tenon with a small sanding block and some Japanese files until everything was kosher. Then I marked the side of the heel and strapped a metal ruler down to the neck, used an X-acto to make the initial scoring, then a fret saw and a small chisel to finish it off. I back cut around the tenon so there is a little play, so that the outside edges of the neck snug up nicely to the rim. Once the neck and the rim were good I removed the neck and aligned the top with the rim, traced the mortise on the bottom side of the top and cut it on the bandsaw then cleaned it up with the sanding block and Japanese files. Took a few hours of fiddling around, but it was easier than cutting a dovetail I'd say. I love the look of the instrument, it's a very unique design. I can't wait to see how it looks under finish! Of course that's probably a few months off yet, but I'm working as fast as I can!

Neck mortise cut and neck heel fit. I need to tinker with things a bit and get the bolt hardware installed, then the top can go on.

You know, I played five or six that were around $20K, and I have to say that, as cool as some were, I don't think any of them played or sounded better than my $3K Northfield NF-F5S. As far as how smooth the surface needs to be, I'm of the opinion that beyond a certain point it doesn't matter all that much. Some of the oldest, gnarliest looking instruments with the most mojo sound the best, even if their tops and backs are scratched and beat. The inside of the top is sanded to 220, and I'll probably sand the inside of the back to 400, because it will be visible through the F holes. I'll also be gluing a label to the inside of the back, and I need a nice surface to glue the parchment paper to.

Spent the last week carving the inside of the cherry back. It was a bit of slow going, I definitely need to get a bigger gouge if I do another carved top instrument. But it's more or less roughed out. I need to clean it up a bit, but it is graduated to my spec. It's 3mm in the recurve and 4.25mm at the thickest part of the back. Roughly Loar specs plus 15% to account for the slightly larger body and softer (than maple) wood. This week I'll get the mortise cut in the head block and work on getting the neck fit properly, then it will be time to get the top glued up. The wife and I spent the weekend in Nashville. Got my mind blown, once again, by the Punch Brothers at The Ryman. And got some inspiration at Carter Vintage Guitars: The average mandolin price on that wall was north of $10K, closer to 20 I'd imagine. Got to play a bunch of them. Didn't get the play the $175K Loar, but got my picture next to it.

She'll chew whatever she can get her teeth on! Strangely she always tries to chew on MDF, I'm constantly having to take it away from her. I gave her that piece of cherry that's lying not too far from her. That occupied her for a while, and she eventually fell asleep right there behind my chair, in the way of everything.

Tone bars are on and their initial carving is complete. The total weight of the top plate went from 214 grams (pre F-holes and tone bars) to 224 grams. The sound of the tap tone has become very drum-like. Lots more low 'pong' and less high 'ping'. But still quite alive and complex. I will probably shave a few more grams off and see what happens! Maybe get some high ping back, try to ensure there are no dead spots, etc. Here is the MP3 of what it sounds like currently: Harris 6 - Mandola - Tone Bar Tap 1 - 224g.mp3 Lucy the shop dog approves!

I am undecided on that. I've made a lot of design decisions here, including the relatively small area of the F holes, to help achieve a certain sound. Relatively small F holes should, theoretically, help with bass response. But, at the end of the day, I am a rookie to building acoustic archtop instruments and this is a rather oddball design, so... The option to tune them if necessary, after I string her up in the white, is always there. So, hopefully no, but possible yes.

Your work is always so clean. Great stuff.

That looks like a great, cost effective, dust extraction setup. My ten year old shop vac is dying on me, so I'm about to have to replace it. This gives me one more thing to think about...

F holes cut. The treble F hole has been cleaned up, the bass F hole still needs some work, I just ran out of time last night. I got to use my fathers day gift, a new scroll saw, so that was fun. Overall it went smoothly, but this redwood is incredibly splintery. There are a few very small areas of chip out, actually due to sanding, not the saw. It doesn't take much with this wood. It will get fixed in final sanding, but the more I work with redwood the less I like it... I'll clean up the other F hole and possibly get the first tone bar glued up tonight.

And that may well have been Lloyd Loar's thinking as well. I'm not sure anybody really knows. I think the science of the matter indicates that it's really a whole lot more complex than that. It's just one component in a complex system. In my research most mandolin luthiers seemed honest in saying that they placed them, at least initially, based on Loar's specs, and it works. And since people want to buy mandolins that sound like his, well, that's where the market is. So, pragmatism rules the day. Even guys that have experimented with tone bar placement don't seem to be able to articulate any particular quantifiable difference. So, I tried not to overthink it...

Yeah, on an electric it won't really matter either way. If you were to do F holes you could always just thin the area around the F holes and leave a thicker section down the middle. Even carved top mandolins are thicker 'along the string line', as they call it, for the sake of extra structure.

Scott, when I was roughing out the fit I was able to slide them back and forth a bit, but once I got close they really wouldn't move, due to the shape of the top they pretty well locked in place. But yeah, using chalk/carbon paper and a scraper was an exercise in futility for me. Just a lack of skill on my part I suppose. So, integrated tone bars have been done, but they don't generally appear to be highly thought of in the mandolin or violin worlds. Presumably something to do with the grain direction of the bars vs integrated ones having a lot of run out because of the angles. Another one of those areas where I have a hard time finding concrete answers, and tradition reigns. Another one of those fuzzy tone voo doo areas is how the tone bars are positioned. You can see that the treble bar is closer to the center line than the bass bar. Why? At the end of the day I really don't know. Some people will give you their ideas, but ultimately it's because Lloyd Loar did it that way back in the 1920's. Archtop guitars often use symmetrical tone bars, and I nearly did that, but ultimately decided to stick with mandolin tradition.

So, the tone bars are fit. And man, that was a much bigger pain than I expected. In the end I managed to get it quite close, not 100%, but very close... I tried using chalk to mark the high spots and it didn't work. So I tried carbon paper, and it was marginally better, but I didn't seem to be making much progress. I ended up holding them in place and sliding strips of sandpaper under them over and over and over and over... Next up, cutting the F holes and then gluing in and carving the tone bars.

Mic placement was the same, roughly. I was astounded how little wood had to be removed to make such a big difference. I've never seen the tuning fork trick either. I might have to see if I can't dig up a tuning fork...

In the same vein as Prostheta, shellac is typically used on acoustic instrument tops (soft wood) as a sealer to prevent any finish from soaking into the grain. Not exactly the same application, but a similar concept that supports what he's saying.

Thanks Scott! I spent a little time tuning the top last night. It's right at 4mm in the recurve and 6.5mm at the thickest part of the top. I was at 7mm initially before one of the luthiers I consulted said to take it down another .5mm in the middle, and it's really interesting to hear how dramatic a difference that .5mm and 8 grams of total weight can make: The top @ 7: Harris 6 - Mandola - Top Tap 1 - 222g.mp3 A high tap tone. It's tight, there's not a lot going on. The top @ 6.5: Harris 6 - Mandola - Top Tap 2 - 214g.mp3 A lower tap tone. Much more resonant, more bell and drum-like. I will also tune, trying to make sure there are no dead spots, after the tone bars are attached and the F holes are cut.

Top graduated. I'm still tweaking a bit. Taking tap tone sound files and exchanging them with a couple of good acoustic luthiers I know to incorporate their feedback.

With fear and trepidation I began carving out the inside of the soundboard this weekend. I decided on some base numbers for my profile based on reading, asking luthiers questions, and some total guess work. I used my drill press jig to cut holes at those various depths around the top, and then spent a couple of hours with a gouge and finger plane getting it to where it is. It's maybe halfway done at this point, not including the fine tuning, but I'm definitely getting more comfortable with the process as I go, and it's starting to go a little faster. The reason that there are large uncarved sections in the middle is that I want to manually carve a slight hump that runs the length of the top along the string line in order to provide a little extra structure. So far, so good...

Thanks! I think it's shaping up well. So I figured out one thing that I won't be doing again. Using .020 binding as the outside most piece of binding. Too easy to sand through. I haven't...Yet. But I definitely sanded off about half of it on one side of the neck while finishing up some rough shaping. Going to have to be careful. So, finishing experimentation. After a few weeks the cherry back under the garnet shellac darkened up enough to look muddy. So this time around I went with a lighter orange shellac seal coat. And this time I used dark vintage maple, red mahogany, and brown mahogany to shade the cherry. I like this much better! Also has a couple of coats of Tru Oil on it. Should have a nice shading effect without looking like a traditional burst. Also, 8000 lumens of LED light has totally revolutionized my shop! No more headlamp for me!

This is similar to what I tell friends and family when they say something like, "Oh, you're so talented". I'll say that it's not talent, it's primarily a combination of patience and stubbornness combined with a little bit of planning.

Me too, Norris. Working with scrapers is great. Not much progress in the last few days, a little time here and there continuing to refine the top and bottom plates before I cut/carve the insides of them. I made this little jig for my drill press to help me hog out the material to the appropriate thicknesses: I'm also working on replacing my shop lighting. I ditched the old fluorescent fixture for an LED fixture, and am adding a second one out over the main shop area. Should finish that up tonight. It will be nice not to have to wear my headlamp all the time.

Just do it manually, no worries. Pretty common.