Just finished building a scarifier and attaching it to the ole tractor.
The angle that the pins attach to is 3 x 3 x 3/8, main frame is 3 x 3 x 1/4 tubing, the pipes that go thru for the teeth to go thru is 1 1/2 sch40, teeth are 1 1/2 dia, diagonal brace is 2 x 2 x 1/4, flat bar is 3 x 3/8...