neck set angle on high arched instruments

[nathan slobodkin]

Had a very nice instrument come into the shop with the fingerboard off which as near as I can tell had a pitch of about 23 mm. I am estimating the height of the belly at around 18 mm or even more. The bridge which was on it looks as if the pitch must have been quite a bit higher than it is now. Is it reasonable to set the pitch lower on a highly arched instrument? I have never set a pitch below 25 and in general would recommend  raising the pitch or resetting the neck. How does the high belly affect down pressure and is it reasonable to set the neck that low?

[Guido]

As long as you can close the case... 

It seems to be more common to encounter a lower projection on old high arch instruments, but I don't know if that makes it right.

One guess would be the higher arch is less resistant against sideway forces and bulges outward, probably in the area under the fingerboard as the projection drops.

[Andreas Preuss]

I usually follow the rule of ‘the weaker the top the lower the string angle’ 

Higher archings tend to be stronger but that depends also on the squareness of the arching and naturally the overall thickness. 
 

In your case I’d try to go back to the original bridge height by raising the pitch, probably a bit from the underside of the fingerboard and combined with a regular raise pitch aiming at a 1mm higher pitch so that it can sink in a little after stringing the instrument up. (Sometimes I glue the wedge between neck and top plate only after I know that it has settled.)