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Electric Octave Mandolin Build

Posted: Sun Oct 21, 2018 2:02 am
by Perry Underwood
For several months, I've been building an electric octave mandolin. It's been and continues to be quite a challenge. I normally build electric guitars. Now I'm at the point where I need to start thinking about applying finish. Before beginning that, however, I'd like to share a few photos of where the build stands.

Here are some basic specifications. The body consists of mahogany on the top, spruce in the middle, and amargo on the bottom. The neck is maple with a rosewood fingerboard. The scale is approximately 19 3/4 inches, which is either on the high side of a mandola or the low side of an octave mandolin. Bubinga is used for the headplate, bridge, pickguard, and all cover plates. I made the bridge. For the tailpiece, I am using a 12 string guitar tailpiece similar to what is used on Gibson's EDS-1275. I haven't decided whether to remove the string slots on both far ends of the tailpiece. There will be one volume and one tone control.

This is a photo of the general layout of the body.
OM 8.jpg
On the back of the body the wood is amargo, which is also called bitter ash. The larger rout is for the electronics. The smaller rout is for me to tighten the nut on the barrel jack. The ground wire will also run from the tailpiece into this rout and then into the electronics cavitiy.
OM 5.jpg
These are photos of the bridge and tailpiece I am using. The bridge is my second attempt at making one. I still think it's rather bulky, so I might take more off of it.
OM 9.jpg
The first photo shows the tailpiece as it is now. The second photo shows what it would look like with the two outer pairs of string slots removed. I think the tailpiece would look better with the slots removed, but I am concerned about removing the material, which I believe is brass. Of course, one problem with removing the outer slots is that I would lose the two holes for screws. In addition to the one screw in the middle, I am thinking of using epoxy to glue the ends of the tailpiece once it is positioned correctly. The outer string spacing on the tailpiece the way I plan to use it is about 34mm, and the outer string spacing at the bridge will be around 44mm.
OM 6.jpg
OM 7.jpg
I'll add more photos later as the build progresses. I did photograph the headstock, but it turned out fuzzy. I take another photo of it soon. Comments and questions are welcomed.

Re: Electric Octave Mandolin Build

Posted: Fri Oct 26, 2018 3:35 am
by Perry Underwood
I've taken a few more photos. This is the headstock.
OM 11.jpg
This is the general mock-up. I've started to apply the finish. I will add a few photos of that process if there is interest.
This last photo shows the access to adjust the truss rod.
OM 12.jpg
Comments and questions welcomed.

Re: Electric Octave Mandolin Build

Posted: Fri Oct 26, 2018 9:13 am
by Bryan Bear
This should turn out pretty cool.

If you reshape the tailpiece, you could drill and countersink two new screw holes closer to the center one. Remember that if you start cutting into the tailpiece, you will have to deal with the plating. You will have two different surface appearances but the plating may also start flaking off.

Re: Electric Octave Mandolin Build

Posted: Tue Oct 30, 2018 9:49 am
by Perry Underwood
Bryan, thank you for your comment. I've decided not to cut the 12 string anchor tailpiece, mostly because I'm unfamiliar with how to cut and drill brass. I think for my first octave mandolin build, using the tailpiece the way it is should be OK.

I've begun to apply finish. I'm going for a kind of sunburst on top, but the colors will go from black to brown and then to red in the center. I've also notched the bridge and nut for the strings.

After I have more of the top finished, I'll add a few more photos. Thanks again for your comment.

Re: Electric Octave Mandolin Build

Posted: Wed Nov 07, 2018 9:35 am
by Andrew Porter
Working with brass is not that hard. Get a scrap piece and drill and counter sink a few holes.

What did you do for the fret board?

Re: Electric Octave Mandolin Build

Posted: Sun Nov 11, 2018 7:58 am
by Perry Underwood
Andrew, thank you for your suggestion. I feel that eventually I will replace the tailpiece I used with something smaller. The fretboard is rosewood. I can't remember the original scale that it had, but I removed the first three or four fret slots to arrive at a scale close to an octave mandolin.

I had to recut the bridge and nut for wider string spacings, and I have been working on applying finish to the body. Here are a few photos of where I am so far with that.

This is the front.
And the back.
I will soon begin to finish the neck. When I do, I'll add more photos.

Re: Electric Octave Mandolin Build

Posted: Sun Nov 11, 2018 9:48 am
by Brian Evans
I think I like the finish you've achieved, I would just gloss that up and polish. I like the tall bridge, but I might move the tailpiece farther towards the tail, to get a longer string extension behind the bridge. Reduce the break angle and longer strings will reduce compensation issues, make the strings feel a bit looser. I might need to experiment with string compensation a bit, finding the right string tension might need some experimentation, so finalizing the bridge saddle might be a last step.

Re: Electric Octave Mandolin Build

Posted: Thu Nov 22, 2018 12:41 am
by Perry Underwood
Brian, thank you for your suggestions. I am still working on applying the finish. Once everything is completed, I will spray lacquer to protect the finish and even out the gloss.

Since my last post, I have been working on applying finish to the neck/body join and the back of the headstock. This has proven to be more difficult than applying finish to the body. Today is the first time I have felt close to achieving what I want.

The body/neck join.
OM 18 resized.jpg
And the headstock.
OM 19 resized.jpg
This is still much to do.