The maderas barber spalted beech was the hardest wood to bend i've ever tried... And i can bend snakewood and padauk and granadillo...
I started at 2.7 cause the wood seemed too flabby already and beach should work at this thickness. Nope! Snap! A little thinner? Snap. Hotter? Snap. Wetter? SsssSnap. Dry? Snap snap. No warning.
1.7 and hot and wet. I didn't measure right on the second side and it started to brake. It was at 2 mm. I immediately started to bend it back straight, made it 1.7 and continued... Already weak so it continued to want to break in that spot.
Too difficult to change the shoulder bend position at this point so i thinned it down to something ridiculous like 1 mm and bent behind the wannabe crack.
Crisis averted. The sides were gonna get laminated/doubled anyway so it's all ok. The mahogany i will use for lamination is 1.2-1.4 mm. With wide solid linings and more reinforcing they will never break.
Heart attack avoided
The archtop is a lot of work but it's the most awesome thing ever. Nothing cooler than carving and tap tuning and bracing...