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Chris a great source of info on archtop building is Benedetto’s book and his video/dvd set. Here are some thoughts on arch height, plate thickness and bridge height. Hopefully Nelson Palen, Howard Klepper, Brad Goodman and others chime in.

Top Plate:

The centre of the plate is typically ?” thick, graduating to 3/16” at the edge and 1/8” at the recurve for a “X” braced archtop.   These dimensions very much depend on the stiffness of wood used so they are a guide only.

The height of the arch for a Benedetto style archtop is 7/8” measure from the “bottom” of the plate (not the top). Builders such as Steve Grimes shoots for about 5/8”.   The higher the arch the stiffer the plate becomes which will result in a more traditional “jazzier” sound and a louder guitar. This height comes at the expense of bottom end. A Grimes sounds more like a flattop – but tend not to be as loud as a Benedetto.

Another contributor is the steepness of the arch. The steeper the arch the stiffer the top plate. A more gradual arch – less stiff – greater bottom end and a more mellower sound.

Bridge Height:

The bridge height is also important. Benedetto shoots for about 1”, Ribbecke 7/8” and Grimes about 5/8”. The higher the bridge height, the more downward pressure on the top plate and the harder it is driven and the louder the guitar is. Over drive the top plate and the guitar losses its ability to produce a focused balance sound from low to high. The higher the bridge height the stiffer (or higher) the braces need to be to counteract the downward pressure and stop the plate from deforming too much.

I also took over an hour searching the MIMF forum and found one nugget of information that the shallower the arch to more forceful and edgy it'll be, I'm guessing that's what you meant by sounds more like a flat topped.

Chris -- I am not sure we are saying the same thing. I think the converse is true. The steeper the arch the stiffer the plate will be and yield a more "forceful and edgy" sound. A shallower arch will more approximate a flattop.

Steve Grimes is a great guy and builder. I met him at ASIA 2005 and had a chance to chat with him while playing his 30th Anniversary Koa back/side with Euro top archtop.

It's great that you are practicing on some pine to start. Nothing worse than messing up a $100+ top on your first go. Are you planning on making some arching templates?

I think you'll find that carving a plate isn't all that hard it you draw a contour map on the plate and then drill holes.

Good luck -- it's great to have another Archtop builder here!

Hi Chris,
All the archtops I have built have been 1" thick tops with a relatively gradual arch and a 1"+ bridge height.
I like the sound I get, so I have always worked to refine my carving whithin these parameters.
I use the drill press method and then the Lancelot carver to carve my plates.
Good luck,
Brad

[QUOTE=Anthony Z] The steeper the arch the stiffer the plate will be and yield a more "forceful and edgy" sound. A shallower arch will more approximate a flattop.
[/QUOTE]
Yep, 'cause the higher arch has shorter grain, and the lower arch has longer grain after carving.