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In the mean time I found a few extra boards and I was tempted to use them. But I did not, because I needed them for bracing. The front and the rear could be squared up and assembled while lying on the floor of my basement.
However, when I went to put the sides on, they had to stand up. And they had to be leveled. My son helped by holding things in place while I used the level, but at some point human arms grow tired and the attention wanders. If you've ever done anything like this you'll recognize my next step. I grabbed some clamps and extra boards and I clamped those boards in place. This gave me quick ways to engage and release these bracing boards and I was able to level and square everything.
Once things were leveled and squared, I could permanently affix the side boards to the framework. With a nice rigid framework I could mount the plywood top and I was nearly finished.
If you look closely at the two photos you'll see a discrepancy. The bracing boards in the first picture as well as the clamps are gone. Of course, after I'd mounted the side boards and gotten them perfect, the bracing boards were redundant. I released the clamps and put aside the bracing.
I've taken several pictures of my completed desk, and I've spread them around to my friends showing, "look what I did." And when friends come to the house, I show them the desk and I'm duly proud.
But I don't show the clamps and the bracing boards. When I worked in a factory, we had jigs that held parts together during assembly and welding. We never shipped those jigs to any customer.
I don't know how you write, but a lot of people have to work out a lot of backstory and details about
their characters before they can really "come alive." The trouble is that when an editor, or God forbid, a reader trips over this massive block of prose that does not directly advance the story, s/he may skip ahead, or worse, set aside your work.
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By all means you have to write these scenes if that's the way you work things out, but by NO means do you have to include them in your story. It's like those braces you see in the first picture that have been removed in the second. This means you should write like the wind, and then edit with a keen awareness of where your story starts, what parts belong in and out of the story, and when your story ends. The stuff that you cut out aren't necessarily bad, they may simply be bracing.