17 inch carved archtop build about to begin

[Francis]

I'm just going through the planning stages at present for a 17 inch carved top and back archtop guitar based on the Georgia Luthier Supply plans and Robert Benedetto's book.
At present I'm locating materials and making formers etc., but would like any guidance some of the esteemed members of this forum may like to pass on before I jump in with two big feet
Cheers
Francis

[Francis]

Footnote:

I've been comparing more closely the plans, and sizing given in Benedetto's book (notably the sizing given on page 9 for the completed body mould) and the shape of the plan given at the back of the book - they're different. The book plan is smaller (for publication) and you are asked to copy it and re-size to suit, doing that however when the body is enlarged to give a lower bout of 17 inches produces a body that is short of the 20.75 inches quoted on page 9. If I overlay the plan with rectangles of 20.75 (body length) x 17 (Lower bout) and 12.75 (Upper bout) and 10.5 (Waist) and resize the Benedetto plan (i.e. stretch the length without changing the width) then the outline touches the rectangular box in the right places producing a good match.

So if you work from the Benedetto book be careful resizing the plans without checking the dimensions elsewhere.

The body on the Georgia plans is 0.147 inches (3.75 mm) longer than the Benedetto dimensions when the lower bouts are both at 17 inches - not enough to worry too much about.

Dimensions on the Georgia plans can be confusing as most seem to be made up by adding together smaller parts to find overall sizes.

Another roll of lining paper needed I think...

Read more: http://acousticsoundboard.co.uk/thread/ ... z4JPujYDMr

[dsgoen]

I had the same problem re-sizing the plans from the Benedetto book. I've had issues with every guitar book in this regard (not counting the ones with separate plans attached). Knowing what I know about printing from my career as a software support with Canon (big iron, like 1,500 pages per minute), there is little reliability in accurately printing diagrams. The only safe way is to use a good CAD plotter; those are the only machines where the techs take extraordinary car in making the X,Y dimensions completely accurate.

Have fun. The 17-inch that I built had a bad run-in (literally) and is no longer alive. I plan on making another soon. Do you also also have the Benedetto videos? They are tedious (relatively un-edited and therefore way too long), but informative. The rimmed building form is really a must.

[Francis]

Got round the re-scale and printing problems now - so happy with the layout. All transferred to a layout board and starting to make the body former and carving support.
Ordered Alpine spruce and flamed maple wedges plus F/M sides. Should get all the formers finished before the tonewoods arrive. Then the fun starts

[Francis]

Body former and carving support now complete:

[Francis]

Made a start on the carving - surprising how much 'litter' you can generate in a short space of time....



TBC

[seeaxe]

Epic. I like the little hole in the shavings where you were obviously standing!

[Francis]

After the bulk removal its time to start refining the curves - by no means finished yet but moving in the right direction...

[Francis]

Started to carve out the inside of the soundboard:


Tap tone dropped markedly once the interior material was removed. Will monitor this now as the top's thickness reduces.

[Jeremy D]

Looks great Francis, can't wait to see this build progress.

[kiwigeo]

Looks great Francis, can't wait to see this build progress.

+1

[Francis]

Forgot to show the final soundboard face:


Found the only way I could get and monitor the surface smoothness was to close my eyes and run the palm of my hand over the surface and 'feel' deviations.

One of the profile/thickness log images:


Number are in mm's minus the decimal place i.e. 81 is 8.1 mm

[Francis]

Taken the soundboard as far as I want to before cutting the 'f' holes and applying the parallel bracing. Tap tone and flexing are both good, slightly above the thickness' given in Robert's book. I expect to make adjustments to the top once the box is closed and bindings are fitted.
The inner face will have a flat planned around the outside for the sides and linings to bond to.

[demonx]

Looking great so far!

Please tell me it's going to be tobacco burst?

[kiwigeo]

The top looks great...I feel an uncontrollable urge to run my fingers over it!! Nice work

[kiwigeo]

After the bulk removal its time to start refining the curves - by no means finished yet but moving in the right direction...

Francis..I couldn't help but notice the small dark patches on that top....pencil marks or a little bit of mould?

[Francis]

Martin - First thanks for the comments.

The marks are pencil where I've rubbed a soft pencil along the edge of the template and lightly rubbed that on the soundboard looking for high spots. The upper one on the centre line is a reference point (there are two on the centre line) and shorter templates radiate out from the two reference points - there are 6 in all: one template shapes both the lower bout curves, another the two curves to the waist and one each for the upper bout non and cutaway sides.

Oh demonx - there is no sunburst of any kind or shade - this one is a clear finish, the fretboard head veneers, and tail block etc are all cocobolo, bindings are lacewood.

[johnparchem]

Thanks for the photos of the carving of top. It looks great. I will look forward to seeing the project move forward.

[kiwigeo]

Martin - First thanks for the comments.

The marks are pencil where I've rubbed a soft pencil along the edge of the template and lightly rubbed that on the soundboard looking for high spots. The upper one on the centre line is a reference point (there are two on the centre line) and shorter templates radiate out from the two reference points - there are 6 in all: one template shapes both the lower bout curves, another the two curves to the waist and one each for the upper bout non and cutaway sides.

Thanks for the explanation Francis....all interesting stuff.

[Francis]

Moved onto the back preps and started the external carving:

[Francis]

Chipping away....

[Francis]

Back plate taken a little further and beginning to start the process of blending the back's dome into the recurve areas:


Still in progress - seems a long way round. The blend above still needs tweaking as there's a small ridge developed and the recurve still needs to be lower...

[Francis]

Back plate with a coat of white polish to seal it. Few small indents remain from the drilling - these are all in the recurve areas and will be addressed once the box is closed.

[Francis]

Stared removing the bulk material from the back plate's inner surface with a forstner bit over a fixed post and depth stop circa 5.5 mm

[seeaxe]

Looks beautiful.