I want to build some cabinets for my laundry room and the width inside of the cabinet will be 32.75, is that too wide a span for shelves with no center support? I was going to use shelf pins for the adjust-ability. Thanks
Search for the "Sagulator". It calculates deflection (sage) of a wide range of materials.
3/4" ply with solid edging on front & back. Every couple years flip em.
I have a wide cabinet (48") and used 3/4" ply with 1" x 1/8" angle iron, front and back, on full-width shelf supports. No problems as yet.
I agree with Glen, edge them with solid wood and you'll be fine.