More Plowden Progress

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More Plowden Progress

Graduation

Graduating hard maple can be a tough, laborious job. Besides, there is always the possibility of carving too deeply and ruining the plate. So, I try to cut the risks by creating a “map” by marking the thickness every few centimeters, and then carving the “dots” until each “dot” is about the thickness I want. Finally, I connect the “dots”, using planes and scrapers, checking for thickness as I progress.

Creating the dots.

Creating the dots. The circled numbers are already the correct thicknesses.

 

Checking thickness.

Checking thickness. Pretty thin plate!

 

Connecting the dots.

Connecting the dots.

 

Getting there!

Getting there!

 

Grafted Scroll and Neck-Set

Once the graduations are complete, and the inside of the back plate has been scraped completely smooth, I install the label and I am almost ready to close the corpus. In this case, however, I also had decided to use the scroll I had carved, but graft a new neck to the scroll, as the original neck was too thin: so there was a good deal more work involved. Here is the grafted neck, partially shaped, with the completed back plate:

Completed back plate with neck-grafted scroll.

Completed back plate with neck-grafted scroll. The heel was still not shaped.

I had been anxious to complete the back plate, and had not yet set the neck. So I completed the neck and installed the fingerboard.

Fingerboard installed.

Fingerboard installed.

 

Next I set the neck, so that the angles were all correct.

Neck-set, front view.

Neck-set, front view. The mold is still in place.

 

Neck-set, side view

Neck-set, side view. Notice that the neck heel has not been trimmed flush, yet.

 

Closing the Corpus

Then I removed the mold, and installed the inside linings on the back edge of the ribs, shaped the linings and the blocks, flattened the back of the garland, and installed the back plate. I use spool clamps and a single large spring-clamp to close the corpus. My wife thinks the spool-clamps look like old-fashioned hair-curlers.

Closed corpus with spool clamps and a spring-clamp.

Closed corpus with spool clamps and a spring-clamp.

 

Trimming the Button and Neck Heel

Once the glue was dry, I removed all the clamps, cleaned off any glue that had squeezed out of the joint, and trimmed the button and heel. The dimension from the juncture of the top edge of the front plate and the side of the neck heel (from each side) to the very center of the curve of the heel, should be right at 26 mm. You can see the two marks I laid out with a compass, testing that distance: it was still a little too high in the center of the curve, so the neck needed to be trimmed a little more.

Ready to trim the button and heel.

Ready to trim the button and heel.

 

Purfling the Back Plate

Once the neck-heel and button were trimmed, I still had to perfect the outline of the back plate, making certain that the overhang was even all around, as much as possible. Then I laid out the purfling slot, using a purfling marker, and began incising the outlines of the slot.

Incised purfling slot.

Incised purfling slot. It will be corrected, and fine-tuned as I work, and look good with the purfling.

 

Next I cut the slot out, using a small knife and a purfling pick, then dry-fit the purfling, after bending it on the bending iron. Finally I glue it in place, using hot hide-glue.

Purfling installed, and glued in place.

Purfling installed, and glued in place.

 

Edge-Work

I marked a crest-line, about 1.6 mm in from the outer edge, then used a gouge and scrapers to carve the channel, and fair it into the plate surface. The edges were all still quite rough,and crude, so I began shaping them, using a small plane, and a half-round file, then sandpaper to get a smooth edge all around. I don’t use sandpaper much, but this is one place where it is appropriate.

Trimmed purfling, smoothed channel, and edges taking shape.

Trimmed purfling, smoothed channel, and edges taking shape.

 

The front edges have to be finalized as well.

The front edges have to be finalized as well.

 

Finishing Process Begun

Once all the varnish preparation is complete, I brush a coat of coffee all over the instrument, to tan the wood a little, and raise the grain. When that is dry, I sand off most of the raised grain, using 400-grit sandpaper. This ensures that the grain will not raise too much during application of the spirit varnish, later. Afterward, I rub in a coat of gypsum in a coffee suspension, to fill the pores of the wood with particles of the mineral. This keeps the varnish from saturating the wood, and possibly dampening the sound.

Mineral ground drying.

Mineral ground drying. See how it obscures the wood? that goes away when the sealer is applied.

 

Back with sealer.

The sealer renders the mineral ground transparent, and it will never be visible again.

 

I expect that, by tomorrow, the sealer will dry sufficiently that I can begin varnishing. I am getting anxious, as the show is a week from tomorrow, and I am far from completing this instrument.

 

Thanks for looking.

 

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