Mandocello - Projects - Audio Artillery

Mandocello

  1. Intro
  2. Design
  3. Top plate carving, exterior
  4. Top plate carving, interior
  5. Body construction
  6. Side bending
  7. Neck construction
  8. Headstock
  9. Body construction II
  10. Bracing
  11. Neck joint
  12. Back plate
  13. Body assembly
  14. Neck, meet body.
  15. Neck shaping
  16. Tailepiece
  17. French polishing
  18. Finished

1: Intro

You don't see a lot of mandocellos these days. Hopefully I can add one more into circulation.


 

2: Design

The first thing the aspiring mandocello builder finds is that nobody has plans for sale. The best source I found was from GAL's back issue archive #5 (which contains issue #56), from there I got the rough dimensions and shape. I'm winging everything else.


 

3: Top plate carving, exterior

I couldn't find any small amounts of spruce locally but I scrounged a cedar plank at a local decking supply that was roughly quartersawn. Here it is all joined up. The soundhole will be located where the large knot is.


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I'm using a fairly common small-shop technique usually termed "step routing." A topographic map is laid out on the plate and a router is used to remove the material from the outer/deeper edge inward. The steps will then be smoothed out to get the final contour.


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With part of the top routed close to final thickness it is now apparent that cedar is quite flexible. I think I will shoot for a minimum thickness of 3/16" and probably 1/4" or thicker in the center.


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Most people use thumb planes to smooth and shape the arches. I don't have thumb planes so I'm using a small round bottom spoke shave (Stanley #63). It works better than I expected.


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The soundhole could have been simply routed out, but I don't get to use power tools at night.


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A little touchup with a router and it is roughly the right shape.

One thing I'm doing that's odd here, I haven't cut the outline of the top out yet. Most people cut that out early on. The corners get in the way of the spokeshave, but they also allow me to flip it over and lay it flat for the interior carving.


 

4: Top plate carving, interior

With the convex shape of the outside surface shaped I can now use a drill press to drill pilot holes to a certain depth. But to do that on a mandocello you need a drill press with about 8" of reach. This is my ghetto long-reach drill press.


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It works surprisingly well. It helps that the benched it's mounted to is bolted to wall studs.


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I drilled to depths of 5/16", 1/4", and 3/16" for the center, middle, and outer regions, respectively. I used a 1/4" forstner bit. The area around the soundhole was left a little thicker since this is a high-stress area. It's a fairly vague question how thick the top should be but this seems to be a good starting point for a cedar top.


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The bulk of the material was then removed with a angle grinder. This goes really fast.


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Lacking the proper tools for final shaping of the inside (finger planes, scorps, scrapers, etc) I used a cheap rounded rasp/microplane from Harbor Freight. It works well enough for cedar at least.


 

5: Body construction

The body will be build using a positive form with slots for the neck and tail blocks. The blocks are made from layers of poplar with two dowels to center them while gluing. Poplar turned out to not be the best wood for this, it fractures easily when routing the shape. Now that they are made the poplar is a non-issue, it is plenty strong for this application.


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I may lightly stain these so they look nicer from the inside.


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The form is layers of plywood which are centered together with dowels.


 
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