Mis-labeled dish

[Matt Atkinson]

So I have come back to making guitars after a long stretch. Long story short I had an old dish labeled 15’ back but it clearly is a 25’ dish. I sanded my assembled sides in it
I noticed it when I was sanding the curve into a brace and it just seemed wrong. I dug out the correct one and see that I will have to reduce my sides by about 3/32 in height if I sand on the correct form. I’m building a Martin style dreadnought. If I proceed will the sound and/or volume be compromised much? Would it be crazy to add material at the waist that will be covered by binding? Dang

[Aaron Helt]

Nothing to worry about.

[Clay Schaeffer]

Resand using the right dish and then install your linings "proud" of the sides and you won't have to lose any depth. I would install the linings about 5/32nds proud and then touch them up (1/16th) on the dish again. Have you added in the additional height the back adds to the side depth?
Even if you just proceed with what you have, as Aaron mentioned, 3/32nds won't make any difference in the overall scheme of things.

[Matt Atkinson]

Alas, the linings were already installed and sanded in the dish before I figured this out. Yes I have taken into account the top and back thicknesses and stopped sanding when the headblock and heel were at the calculated height. Nobody took a bite on adding material over the linings at the waist? I suppose it would be trouble if anyone ever had to pull the back off someday.

[Bryan Bear]

I wouldn't worry too much about either 1) the small loss of depth should you re-radius or 2) having a shallower dome in the back should you proceed without change. I would be a bit weary of adding material to the rim as that could turn into a mess for very little benefit. But if the linings were not already in, the advice to install them proud is good.

FWIW, I typically use the same radius for the back as I do for the top. I'm no expert and I don't make dreads but I have not found any issues with the shallower back radius. Perhaps others will post info on the cons and we will both learn something.