$100 Challenge- Apple bowl back Octave Mandolin

[Josh Humphrey]

Well, I think I may just be able to pull this off! It will be tight but it's worth a try!

This is the apple billet I sliced to 3/32" for the ribs of the bowl. I harvested the apple in my backyard five years ago, so it is VERY local. I paid $1000 for about the same number of board feet slab sawn and kiln dried, so I'll say at 1.5 * 6 * 22" its around 3 board feet or $3.

Sliced apple billet

A shot of the sequence.

Rib blanks in sequence

[Josh Humphrey]

I am planning to have a modified bowl- not the common half-round radius, but a more flattened back shape so the instrument is not as bulky. It involves a bit of guesswork and various radii, but I've been wanting to try this for a while!

Plan

First step is to create the assembly that holds neck and tailblock in place for gluing up the ribs. Neck block is marked.

Neck block marked

Then is rough cut.

Rough cut neck block

[Josh Humphrey]

Then the neck block is shaped to match the profile of the body, and attached to a long holding block.

Neck block attached

Similarly, the tailblock is shaped and attached to the holding block.
The tailblock is usually half round, but since the bowl will be the flattened irregular style, it is elongated and looks odd...

Completed holding block

Now it is time to sand the ribs to thickness and start bending!

[Josh Humphrey]

Sanded the ribs to thickness. Then, made a profile rib by bending one to shape, fitting it, and flattening it back into a template.

Here are the ribs rough cut (the center 7 have altered bottom shapes to fit the flattened back)

The ribs rough cut

Then in trying to fit the first rib I realized both the tailblock and neck block needed to be reshaped to more closely fit the outline.

Tailblock take 2

Finally, I got the first rib fit and glued in place.

Rib 1 in place (actually rib 8)

[Josh Humphrey]

Got a bit of work done- now 4 ribs. Time is tight this week, so I hope I can squeeze in enough time to get caught up...

4 ribs

[Andrew Porter]

Looking good. I can't wait to see the finished product. I admire your adlib on the back. Did you cut the neck block on a bandsaw?

[Josh Humphrey]

Thanks Andrew! In that regard, the ad lib is working out OK; there is something off with the geometry for sure which is making it end up overall about 3/4" narrower than the plan!! Once I get this one built, I can have a closer look and better idea how to get the next one right.

Yes, the neckblock was cut on the bandsaw.

Here is the latest bottom view:

Bottom of bowl

And a front view. I am liking this improvised clamp situation.

Front

Finally- a close up of the new flexible clamp idea. Just add more rubber to get more power; it flexes to any part of the curve, and it pulls up towards the next rib each time.

Rubber band clamp

[Josh Humphrey]

Wow- only a week left! Better get busy...

[Josh Humphrey]

The bowl, pretty much complete

Apple bowl

[Josh Humphrey]

Now time for the soundboard. I have this piano soundboard given in trade by a local friend- I don't know if the spruce is local but I think it's been here long enough- he had it in his garage for 40+ years!

Piano Soundboard

I cut it up into manageable parts, and saved one for this instrument. Here it is, sanded to thickness. It ain't pretty, but it sounds excellent- a very rich tap tone. I think it will have "nice character..."

Thicknessed soundboard

[Josh Humphrey]

Now for the rosette- I have been developing this idea for the last dozen or so instruments. This one is spruce and walnut (shop made purflings leftover from another project!)

Soundboard rosette

And the bracing.

Bracing

Solid linings for the bowl; hopefully I can get the top glued on tonight and have half a chance of finishing...

Gluing in solid linings

[Jason Rodgers]

I'm not familiar with the variety of staved back construction techniques, but I like the seemingly simple (is it?) three-section method you're using. Not all the staves converge on the same point at the tail, but so what. This is going to look really cool!

[Josh Humphrey]

Got soundboard glued on this morning' very interesting to clamp! Then bindings- some leftover shopmade walnut with fir striping

Binding taped

The bridge was an incorrectly sized one from previous project, that I think will work swell for this! It uses about $1 of madagascar rosewood.

[Josh Humphrey]

Now for the fingerboard: I saved a chunk of nicely figured walnut for this purpose, and resawed today. I got 6 boards out of an $8 piece; so that's $1.50. Here is the blank

FB blank

I slotted it, radiused, and glued on some ebony bindings (scrap offcuts of a previous fingerboard) with strips of maple veneer for a contrasting stripe on the sides.

FB bound

I will TRY to get the position markers inlaid tonight

[Josh Humphrey]

I got the neck blank glued up, and the peghead overlay glued on tonight- if I can get the neck shaped, frets in, some other odds and ends done tomorrow, I have a prayer of putting some finish on on Saturday and assembling Sunday. I'm not giving up yet!

Gluing peghead overlay