Violin week 3 – the back and belly

Joining the violin plates

So to the task of joining the violin plates from the bookmatched back and belly sets. First I squared up the beautiful maple blanks and planed the two edges together to ensure a good fit.  This was so much easier to do compared with the cello as the pieces of wood are so much smaller/lighter and the join quite short.  I heated the pieces gently with the air gun and then glued them together with a rubbed joint which worked really well first time.

Gluing the back with a rubbed joint
Gluing the back with a rubbed joint

Next I planed the underside surface flat before tracing the outline from the ribs and using a washer to give the external dimension including 2.5mm overhang.

I cut out both belly and backs on the bandsaw leaving a bit of waste to be cleaned up after shaping the outside profile.

This was so quick I ran the same process for the belly.

Carving the outside profile

Next I created a set of templates for both back and belly based on the profile curves published by Sergei Muratov (the same source I used for the cellos).  I drew these up in solvespace and then stuck the full size printed drawings to a piece of perspex, cut out on the band saw and then finished on the vertical oscillating sander.  I finished by spraying these with a bright paint – different colours for front and back so they didn’t get mixed up.

profile templates for the belly
profile templates for the belly
Profile templates for the back
Profile templates for the back

Then to carving starting with a 3/4″ no 5 sweep chisel to get the rough shape. 

Rough shaping the belly and back
Rough shaping the belly and back

I cut a 10 mm wide platform at the edge with  the router using the same attachment I made for the cello work.  

Router attachment clamped to the bench
Router attachment clamped to the bench

These were cut at the finished edge thicknesses of 3.7 mm (back) and 4 mm (belly) and make it much easier to start the gouge cuts. 

Then I moved onto using thumb planes.

Here I am getting pretty close to the final profile.

008

I tack assembled the back and belly to the sides to cut the side overhangs down to final size – 2.75mm except for the c-bouts at 3mm. Started with the knife and finished with files with a piece of waste of the correct thickness taped to the middle of the file.

Also cut the corner shapes with a knife.

Just finished setting the edge overhangs with some simple tool/jigs
Just finished setting the edge overhangs with some simple tool/jigs

Purfling

Next job is to cut the purfling groove so I made up a simple holding jig for the body first.

Base made for holding the violin body when working on it
Base made for holding the violin body when working on it

Then I made up a laminate 1.4mm thick for the purfling of 0.3mm black (ebonised pear), 0.8mm white (sycamore) and another 0.3mm black. I sliced this up on the bandsaw into strips about 2.5mm wide.

Purfling after slicing up on the bandsaw
Purfling after slicing up on the bandsaw

Then I marked the purfling groove on the front and back with special gauge set in 4mm from the edge and deepened these faint marks with a scalpel lubricated with dry soap and carefully carved out the groove with a 1mm chisel.

Channel cut for the purfling
Groove cut for the purfling
Purfling fitted and channel roughly cut
Purfling fitted and channel roughly cut
Belly arching done
Belly arching done

Next I carefully fitted the purfling using the bending iron taking special care with the corners and glued up with hot glue.

Then trimmed back with a chisel when dry and gouged the channel round the edge about 1mm deep before fairing everything in with scrapers and checking the final arching.

Back arching done
Back arching done

There is a slight blemish in the maple on the back. I was hoping I would get through it with arching but there is a tiny thin bit left and I would rather keep the proper arching than keep on scraping away –  it looks like bark but it can’t be as it was not visible before carving.  Should dissappear when the back is coloured anyway.

Thicknessing

I started by marking out the thickness profile contours and then drilled on the bench press to a few millimeters thicker than this to make the rough thicknessing quick and safe.

Back drilled to rough depth for hogging out
Back drilled to rough depth for hogging out

Then I roughed out with a large gouge.

Belly inside roughed out
Belly inside roughed out

Now I have to build a caliper/nail tool for marking the finished thickness before plate tuning.

New tool for needle marking the thickness
New tool for needle marking the thickness

And it works really well – I have made it big enough so I can do a cello with it.

Back depth marked with the new tool
Back depth marked with the new tool

Nearly down to the initial thicknesses before plate tuning.

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