Peter Coombe Mandolins and Guitars
Carving the back
This is how the back starts out. Plank of Myrtle. The Myrtle plank is the front piece of pink coloured timber on the left. Behind it is a nice figured piece of Rock Maple, but this mandolin is to have a Myrtle back.
So I take the plank down and measure it for fit against the A type mandolin template. It fits, so will do nicely.
Check the end grain. Quarter sawn. Not exactly on the quarter, but certainly good enough.
Mark the length.
And cut to length. The rest of the plank is put aside for the next mandolin.
Make sure that one edge is square. The best edge to be square is the one that is going to be on the outside. The square face is put on the bandsaw table when slicing it in half (next).
The other edge is than marked down the centre and the plank sliced down the centre with the bandsaw.
Here is the plank after slicing on the bandsaw showing the bookmatch. This is how it will be glued.
The centre join is prepared with my favorite plane with the blade very sharp and set to cut very thin shavings so the surfaces are perfectly flat and fit tight.
Ok, so the join is ready to glue. Apply glue to one surface. This time I am using LMI Luthiers glue.
Glue and clamp
After the glue has dried (at least 24hrs) the 2 pieces are flattened in the drum sander so one side is perfectly flat. I used to do this with a hand plane, but the drum sander is so much easier.
The back of the mandolin is marked out using the A type mandolin template and cut out with the bandsaw. The depth of the edge is marked with a marking gauge (see carving the top). Sorry, I forgot to photograph this for the back.
Rough carving the outside with my trusty rotary chisel. It takes off wood quickly, but needs a bit of practice because one slip can easily turn it all into firewood.
Here the rough carving has been finished. With the rotary chisel it usually takes no more than about 15 minutes.
The shape of the back is then formed by hand with finger planes.
Here I am sanding the back to smooth out the marks left by the fingerplanes.
Feel for bumps and any uneven curves and correct.
Check that the arch is nice and smooth with no bumps.
Check that the arch follows the template.
Everything now checks out ok so hand sand with medium and then fine sandpaper.
Finished the outside of the back. Here I usually give it one coat of blonde shellac. It is now ready for carving the inside.
Set up the drillpress before drilling depth holes into the underside of the back.
Holes are drilled to preset depths to guide the carving.
The perimeter is marked. This is an area I need to avoid carving because this is where the sides will be glued.
Rough carving the inside.
Finished rough carving.
The inner side of the back is now smoothed with finger planes so most of the marks from the rotary chisel are removed. The back is now put aside while I work on finishing the top. I will get back to the back once the top has been braced and tuned (see tuning).