Sears Spike tooth harrow
Sears Disk Harrow
I have seen people make drag harrows out of almost anything- even a section of chain link fence with cinde rblocks on it.
On the disc harrows, do the discs wear out? If so, can you find replacements? If there are replacement discs easily obtainable, then I don't think it should be too hard to build the harrow. My reason for wanting a disc harrow is that it seems that it is more capable at breaking up hard soil. The rural areas near where I live, from what I can tell, most, if not all farmers use disc harrows, that is why I'm quite interested in building one.
Growing up, my father used a wood crate with weight on it pulled behind a fourwheeler to level the dirt before planing grass. I think this fits the term "drag harrow." If he'd wanted deeper penetration, he could have driven large nails into it, correct?