Beginning the Plates

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Beginning the Plates

Bookmatching the Plates

When I last posted, I had the garland pretty much complete, and the materials were prepared for the neck and the front and back plates.  I had cut the back plate roughly to shape, in order to use as much of the “fall-off” material from the back plates, as possible, from which to make the neck.

I went ahead with the neck and scroll, just because I find it encouraging to have some of the “pretty” work done, as it makes me feel that I am making progress. You can see the neck progress, here.

But at some point, one has to go ahead with the task of bookmatching the plates and getting them ready to carve.

Sitka Spruce front plate halves for the five-string double bass.
Sitka Spruce front plate halves for the five-string double bass.
Rough shape of five-string double bass back plate, and template for the neck.
Rough shape of the five-string double bass back plate, with the template for the neck. The neck was cut out of the scrap from the back.

 

So, for the front and back plates, the next thing on the agenda was to plane the center-joints absolutely flat and straight and then glue them together. It took two tries on each of them, as it turned out that while they were technically “straight”, and if I put a try-square at any given point, they seemed to be square…in reality, there was a longitudinal twist to the surface I had planed, and the fit was not acceptable. (sigh…) No big deal… I just had to saw the joint back apart, and try again.

Finally, I got everything lined up correctly; then I glued and clamped the plate halves together, and produced the plate banks, ready to trace the actual shapes.

Sitka spruce front plate for five-string double bass, bookmatched and ready to glue.
Sitka spruce front plate for five-string double bass, bookmatched, and ready to glue.

 

Front and back plates for five-string double bass, bookmatched and ready to trace shapes.
Front and back plates, bookmatched, and ready to trace shapes.

Tracing the plates

Sitka spruce front plate for five-string double bass, ready to trace the shape.
Sitka spruce front plate, ready to trace the shape.

 

Ready to trace the shape of the front plate of the five-string double bass.
Ready to trace the shape of the garland onto the front plate.

 

Using a pipe spacer to trace the shape of the five-string double bass front plate.
Using a pipe spacer to trace the shape of the garland onto the Front plate.

 

Tracing the plate out with a pipe spacer like that enables me to establish a very even overhang of about 4.5 mm. The problem is, it also makes round corners, which I did not want. So I had to correct, the corners, using a long straightedge to “point” the corners toward the center of the plate at the far end, and then use circle templates to extend the curvature of the plate edge above and below the corner to meet the straight lines. (Incidentally, the reason I have stopped using a washer for a spacer, is that any washer small enough to have the right distance from outside to inside also is so thin that if there is the smallest change in the fit between the plate and the garland, the washer will slide under the garland, changing the overhang distance to zero. The thin slice of PVC pipe never does that.)

Cutting out the Front Plate

I used an old Craftsman “Auto-scroller” saber-saw (Hand-held jigsaw) to cut out the perimeter of the front plate. Ann, my beloved wife, bought me that saw 36 years ago, when we had been married for only about three years. That little saw has a lot of miles on it!

Cutting out the completed shape of the front plate for the five-string double bass.
Cutting out the completed shape of the front plate. I am not attempting to cut exactly to the lines. I will correct to the lines, after the arching has been completed.

 

Cutting is complete: the front plate for the five-string double bass is ready for arching.
Inside view: the cutting is complete: the front plate is ready for arching.

 

Outside view of the front plate for the 5-string double bass.
Outside view of the front plate.

Arching is Next:

Before I could begin arching, I needed to mark the intended plate thickness: I used a marking tool to scribe a line all the way around the plate at 6 mm. Before the plate is done, this will be reduced to 5 mm in most areas. I used a ballpoint pen to highlight the groove so that I could more easily see it when I am working, and not accidentally go past it.

Edge-thickness scribed into front plate for the 5-string double bass.
Edge-thickness scribed into front plate.

 

Then I secured the plate in a cradle especially made to fit this design, and secured it in place by affixing small squares of 1/4″ plywood around the perimeter so that the plate will not shift laterally, while I am working on it. The reason the little stop-blocks are so thin is that I do not want them to be in the way when I am planing the edges.

Front plate for the 5-string double bass secured in a work cradle.
Front plate secured in a work cradle.

 

Tools for arching the five-string double bass.
Tools for arching: cradle, gouges and planes.

 

Sculpting the front plate arch for a five-string double bass.
Sculpting the front plate arch.

 

five string double bass arching in progress.
Front plate arching in progress!

 

Planing the arching surface smooth on a 5-string double bass.
Planing the arching surface smooth.

 

Planes used to shape the 5-string double bass.
Some of the planes used to shape the bass.

 

Shadow line defining the longitudinal arching shape of the 5-string double bass.
Shadow line defining the longitudinal arching shape.

 

Transverse arching shape of the 5-string double bass.
Transverse arching shape.

 

Arching for the 5-string double bass nearing completion.
Arching nearing completion.

 

Arching and outline completed for the 5-string double bass.
Arching and outline completed.

 

Time to lay out the F-holes!

F-holes laid out for 5-string double bass.
F-holes laid out, incised, and inked.

When I build the smaller instruments, I inside the f-hole perimeters quite deeply, knowing that, without exception, I end up needing to correct the arching, using the f-hole side-profile as a guide. I want the “stem” portion of the f-holes to be essentially parallel to the plane of the garland-plate joint when viewed from the side. On the violins and violas I have built, I have universally found that, in spite of my best intentions, I have left too much “puffiness” in the area of the lower wings of the f-holes and I need to plane away more wood. If I have incised them deeply enough, I don’t lose the marks when I remove the wood.

I was quite pleased to find that, on this instrument, the side profile was exactly what I had hoped for, as soon as I laid it out.  So I incised them, but not very deeply, and then inked them with a ball-point pen, so that I could easily see them while perfecting the arching later, using a scraper.

So– the next step will be to complete the “graduation” of the plate– carving away the majority of the wood thickness from the inside of the plate, so that the plate is the correct thickness all over…ranging from 9mm at the center, all the way down to 5mm in the flanks.

Ready to carve the front plate graduations of the five-string double bass.
Ready to carve the front plate graduations.

But…I will leave that post for another day.

Thanks for looking.

 

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