On Monday, June 13, 2016 at 7:35:15 PM UTC-5, wrote:
is poplar a strong enough wood to support a large granite countertop? there would be 3 corbels ...each 8x145/32x3

I don't understand, comprehend, those corbel measurements. 145/32 = 4.53. With that, your figures are 8X4.5X3. That size corbel won't support much at all, no matter what wood it's made of.

Try this for some measuring assistance.
http://lib.store.yahoo.net/lib/iron-...-questions.pdf

Sonny