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First Acoustic. Not exactly a guitar...


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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. :) 

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Tone bars are on and their initial carving is complete.

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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!

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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. :)

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  • 2 weeks later...

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.

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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:

 

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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. :)

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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.

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11 hours ago, mattharris75 said:

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. 

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Now that is sweet! 

How did you go about cutting the mortise? 

I do like seeing a body that is proportionally bigger than a mando.

SR

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3 hours ago, ScottR said:

Now that is sweet! 

How did you go about cutting the mortise? 

I do like seeing a body that is proportionally bigger than a mando.

SR

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!

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12 minutes ago, ScottR said:

Hell, you're setting land speed records for a Matt Harris build!<_< 

So you cut the mortise all the way through the neck block and that will be covered by the back, correct?

SR

 

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:

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22 hours ago, ScottR said:

So you cut the mortise all the way through the neck block and that will be covered by the back, correct?

SR

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.

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I've mostly been taking a break from the build the last few days. Working on a few small things, such as the label, but mostly I've been doing some shop upgrades. Building a new secondary work/tool bench and a dust extraction system. Hopefully I'll have all that completed by the end of the week.

I'm still experimenting with finish. I like the overall colors that I've gotten with the shellac/dye/tru oil combo, but I'm not quite yet happy with the overall flatness or sheen of the finish.

This is the finish after 10 coats of Tru Oil, the first two using the slurry method, as it was applied over top of sprayed on shellac to seal the dye. I think I need to be more aggressive in the early coats with the sand back, as I carried some of that orange peel from the sprayed shellac all the way through. Not ideal. 

I also used Birchwood Casey's Stock Sheen & Conditioner and then Briwax on top of that. It may be slightly glossier than I want to end up with. I'm wondering if I use the stock sheen and then apply the wax with some 0000 steel wool I can achieve a slightly more satin finish.

I suppose further experimentation is in order!

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Thanks Andy! It's not quite up to the level of technical difficulty of your ultra-modern bass build, but it's pushed me in some new directions and allowed me to develop some new skills. I am absolutely smitten with building carved top acoustic instruments now.

So, the shop upgrades are nearing completion. The new work bench is in place and the dust deputy is more or less set up, I just need to do a little reorganizing and cleaning out, then I can get back on track.

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  • 2 weeks later...

You used to live on the gulf, Scott? Where exactly?

So, I established the inside of the binding ledge using a gramil to score it, then chipped out a good bit of it with a small chisel. 

Then I made a jig:

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This is definitely not my favorite part of the process, but it turned out well. I managed to get everywhere except the inside of the scroll:

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