Derek McCormick’s Violin Blog

Making a violin and other violin-related topics

Graduating the Back

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I have started the graduation process by drilling into the flat surface of the back. I put stops on the drill so that the bottom of the holes are about 6mm from the outer surface. This process allows me to carve away without constantly stopping to check the thickness - there is no danger of gouging too far. When my carving reaches the bottom of the holes its time to stop with the heavier gouges and to proceed more carefully with constant checks of thickness.

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This is the stage at which I stop using gouges and continue the process with small thumb planes.

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With the thumb planes I take the thickness down to within 1mm of the final measurement.

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This is the graduation pattern which I will use on this instrument - a maximum of 4.5mm in the centre decreasing progressively to 2.5 in the upper bouts and 2.6mm in the lower. The lines are for guidance and there is no sudden change at the boundaries - it is a very gradual transition.

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The final thickness has been reached using the shaped scrapers. The platforms at each end and at the corners are where the back will be glued to the blocks. The back now weighs 112gm which means that since cutting the outline 300gm of very expensive wood has ended up as shavings on my workshop floor!

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March 4, 2009 - Posted by | (08) Graduating the Back

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