AHG octave mando build

[AcornHouse]

Ah crap! Forgot you still needed to screw into something! D'oh!!!!!

<Swans>

It's always something.

<Loons>

 

[AcornHouse]

Time to cut into this ebony and get to work on the bridge.

 

[AcornHouse]

Getting the bridge bottom shaped close to the archtop. Once it's fitting close enough I can find tune it.

Not my favorite job. I'm still working at finding the best method. Right now the thick scraper (lower left on the bench) is the tool that's working best for me.

 

[AcornHouse]

Got a decent rough fit yesterday. Today I'll chalk up* some tape and refine the fit.


*(Rub chalk on a piece of tape in the bridge position and see where the high spots are. Rinse, lather, repeat until there is uniform chalk over the whole of the bridge base.)

 

[AcornHouse]

Not yet finished fitting the bridge (it seems to go glacially slow sometimes), but here's some procedural shots while I take a break.

A piece of low tack tape is laid at the bridge location and liberally covered with chalk.



The ebony is set carefully in position and, pressing firmly, is rubbed back and forth ever so slightly, no more than a couple of millimeters.



This leaves chalk marks at the high points.



The high points are brought down in small increments, using the thick scraper...



...or the fine riffler file. I'm finding the riffler (one of the more obscure villains from the Batman TV series, who got, unfortunately, cut out) works best at the end while the scraper is best in the middle parts.



Then repeat. The chalky high points should get bigger and bigger, until it's all chalk covered, at which time it's done.

 

[Stuball48]

Can you say, "DEEEE TAAAAIL?"

 

[AcornHouse]

So close. This is one of those intense activities, mentally. When I find myself starting to lose focus, it's break time.

It's all scraper now, which can take very precise, small, shavings. It's curved side can touch only where there's chalk.





Even without the chalk, now that it's getting down to the end, you can more easily see the bits that are still low. (Which I've circled for you in Patronizing Yellow.)



But I'll still continue with the chalk to hone the surface, avoiding any micro hollows.

 

[Default]

Patronizing Yellow is one of my favorite colors.

 

[AcornHouse]

I finished up with a little sticky backed (somewhat de-sticked) 400 grit sandpaper to get the final bottom surface. Now there's nice solid contact along the whole base for maximum vibration transference. (And now you see why most mass produced archtops use a bridge design with a gap in the middle. Far less labor intensive to fit.)



Now for the fun bit. Designing and carving the rest of it.

 

[The Guilds of Grot]

That seems to be a really large block of wood to start with! Can't wait to see it finished!

 

[AcornHouse]

That seems to be a really large block of wood to start with! Can't wait to see it finished!

 

[AcornHouse]

Working on bridge design ideas. A lot easier to erase pencil than put back wood.

 

[Opsimath]

Blink. Blink.

 

[GGJaguar]

The classic French curve. It's the only time I've ever seen one in real-world use.

 

[AcornHouse]

The classic French curve. It's the only time I've ever seen one in real-world use.

Indispensable. I use them regularly.

 

[Opsimath]

The classic French curve. It's the only time I've ever seen one in real-world use.

I have one in my sewing stash, and I've actually used it.

 

[AcornHouse]

The bridge has undergone a little weight reduction surgery. When you hit the right design, you just know it.
It'll get a bone saddle on top after I determine the string intonation. I won't rout the saddle slot until then. Then I can do the final contouring, getting things rounded and smooth.

 

[AcornHouse]

Sanding ebony is messy business. Got the the flat on top down to the desired level and the wings sanded down to 400 grit; smooth and flowing.

 

[AcornHouse]

Instrument making ain't always pretty.
The one thing I don't like about Rubner's tuners is that for the posts that hold the screws, they use a wedged tenon design that leaves tiny nibs sticking proud of the surface. A very traditional method that, when dealing with a softer wood like Spanish cedar or even mahogany, isn't too big of an issue.



But when you have a backplate of walnut, it's a problem. They don't seat all the way down. Which requires a little delicate, but ugly, chisel work, all hidden by the back plate.

 

[GAD]

Oh my!