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View Full Version : Back carving..initial dimensions ?



sprucetop1
Nov-28-2007, 4:53am
I'm carving the back of an oval hole A model...and trying to follow as closely as I can the dimensions of a teens A that I have. The dimensions I have established on the back-in-progress are 0.600 in. maximum arching, circa 0.110 in. minimum thickness in the recurve area and circa 0.19 in. edge thickness. From these established areas, I'm well on with carving the back plate...which is old (and very hard) European maple...originally for a viola. Are these dimensions about right ? I would liked to have established a slightly greater arching height, at say 0.625 in. but the raw wood was so warped, I had to plane it a bit undersize. Do other builders agree with these dimensions?...thanks...John

buddyellis
Nov-28-2007, 8:13am
I go a little thicker on the edge (1/4 - 3/16) and you CAN (on the back-- esp with very dense wood) go a little thinner on the minimum, but looks good.

Mario Proulx
Nov-28-2007, 8:21am
Sounds good to me. You can go a bit lighter on the back, also, if you wish, but what you have there will work very well.

buddyellis
Nov-28-2007, 10:02am
P.S. I meant 5/16 not 3/16, but I shoot for right near 1/4 -- easier to remove wood than put it back. Reason being I don't use a safe-t-plane or anything for the edge thickness, but rather do it by hand, and I do not want the binding to get into the side at all. I leave the back/top a little proud of the binding, and after binding, bring the edge down level using the binding as a 'guide'.

Michael Lewis
Nov-29-2007, 12:37am
So you are wishing for another .025" height to your arch? Just glue a .025" veneer to the inside edge where the rim glues to the back. This makes a "doubled" edge, as they call it in the violin world. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/coffee.gif

sprucetop1
Nov-30-2007, 4:15am
Thanks to all for posts. I'm shooting for around 0.110 thickness (or a little less) at the minimum point of the recurve area...say around 3/4 in. in from the binding....but what should the final thickness be in the centre of the back? I have around 0.600 in. max. arching height at the centre of the back, and this is particularly hard European maple.
I also notice that in side profile, from heel to endpin, the modelling of my teens Gibson A is not a regular curve (as you would get by suspending a chain between two posts), but is quite angled at each end with a flatter central area. This profile tends to be a little different on each old Gibson A I see. Do current builders aim for a smoother curve?....John