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

6: Side bending

I threw together this bending iron setup very quickly. It works ok. More mass on the iron would make for a more steady temperature. I suspect this gets hotter than the 350 F people recommend for bending wood; the solder in the copper joint melts if you turn the flame up too high. One detail not shown: there is a small hole near the end of the copper pipe (which is otherwise sealed). Without this the flame didn't have enough oxygen flow to stay lit.


(click for full size)

My procedure is something like, squirt water on the wood, heat it up on the iron and bend, lay it next to the form to judge the bend, and repeat. The wood I am using is on the thin side (.070") and bends easily enough, but bends near the ends are difficult.


(click for full size)

There is the test piece on the form. It's not bad for the first one. There are a couple burn marks that will be sanded out.


 

7: Neck construction

The neck is two 5/4 mahogany pieces with a 3/16" wenge "microboard" sheet inbetween. I like wenge because it's got some wild side grain if you cut it just right. I have chosen a piece and oriented it just right to exploit the grain; it should result in a zebra stripe for most of the neck.


(click for full size)


(click for full size)

Two slots are cut on either side of the wenge to house some carbon fiber rods that will serve as a fixed truss rod.


(click for full size)


(click for full size)


(click for full size)


(click for full size)

That's the scarf joint where the headstock joins the neck, all planed smooth.


(click for full size)

And there's where the 12" CF rods will lay, roughly.


 

8: Headstock

A quick note about drilling the concentric holes for the tuning pegs. I used a printed template and marked the centers with the tip of a 1/4" forstner bit. I then drilled the 1/4" holes. Then I used a trick where I used a 1/4" drill bit in my drill press to align the hole, clamped the piece down, and then swapped the bit out for an 11/32" to drill the counter-bore for the tuner bushings. Seems to work ok but the counterbores are off center a schmidge here and there. Will probably be fine, but off-center holes can affect the tuners ability to turn freely and hold a stable tuning.


(click for full size)


(click for full size)


 

9: Body construction II


(click for full size)

And there are the sides glued to the blocks and the kerfing glued on. I used a plane and a spokeshave to (hopefully) flatten the edge after assembly. The sides were trued on that edge before bending and glue-up but there is bound to be some change in the edge. This is the top edge.


 

10: Bracing

I'm using the same cedar plank for braces as I did for the top. Because the braces are thin strips of wood I was able to cut the plank at an angle to harvest some vertical grain pieces. This makes the braces a little stiffer than otherwise.

I used a spokeshave to get the rough shape and then turned to the chalk trick shown below. You apply chalk to the top, place the braces where they go and rub them around slightly. The chalk sticks to the high spots, which can then be removed and the process repeated. It's tedious but it works.


(click for full size)


(click for full size)

Once they fit perfectly (err... close enough) I slapped on a ton of hide glue (I masked off the X on the top, not shown) and clamped with a couple paint cans.


(click for full size)

At this point the middle of the X was about 5/8" high. After playing with the top a bit it seemed pretty stiff, so I planed the braces down to 1/2" in the middle.


(click for full size)

I thinned the braces slightly and rounded off the corners just before body assembly. The tapped response seemed to improve slightly, but really hard to say. The top is quite stiff; I'm not concerned it will cave in but I am concerned it may be too stiff.


(click for full size)


 
< previous page | next page >