We learned many lessons from the collapse of our Snow Splitter v1.0. One is that a snow splitter is a Very Good Idea. The other is that is has to be not just strong but square. We put in the uprights by eye. Now John has a better eye than I will ever have, but even he is fallible. So I spent the weekend building batter boards.
These are devices probably known to the Ancient Egyptians:
Making these things was, however, not a walkover. The mosquitoes were ferocious. They tried to eat me. Fortunately I had a head net. I do not like being a buffet lunch for mosquitoes, and I wore long sleeves and pants. I roasted in the heat. But besides that, I found a willow tree that was impeding my lawnmowing. I cut 5 stakes out of it. Some scrap tree gave me the sixth. Work for a bowsaw. Then I pointed the stakes with the axe. Pounding the stakes in (with the maul) was difficult, because there is gravel on some of the area covered by the boards, and it had to be dug out. I placed the stakes by eye (my eye is far from perfect). But it doesen't matter much because the strings tell it all. String theory, they call it in Physics. I did level the boards. Then I strung up the harp of strings. All by eye. Again it does not matter. The next step is to get two people on the problem and start measuring diagonals. Takes two, one at each end of the tape. Then we adjust the strings until (a) the proper distance from the porch is met (3 meters) and (b) both diagonals are equal. Then we drop a plumb bob from the intersection; that's the center (or edge) of our post. At the end I was wet and very tired. Hard work, but worth it. And I can see that even with John's eagle eye, the posts are way out of place. No matter. They will be replaced.