So there I was, doing a bit of back-yard carpentry work.
I decided that I needed some scaffolding to prune the apple trees at The Property. Careful measurements determined that I only needed four additional feet of elevation to do a dandy job trimming the lowest "whorls" of branches.
For those who haven't done this kind of thing. It would seem that an eight-foot tall step-ladder would be the cat's meow for this kind of thing, but you would be wrong.
Operating a chainsaw from a step-ladder has certain limitations. Among other things, you run out of arms and hands to hold onto the ladder, the branches you are trimming and the chainsaw, you don't have a bail-out option AND if a branch drops down and jumps back at you, it will knock you, the running saw and the ladder ass-over-teakettle before you can think, blink or fart.
A short platform offers more options. I can work from one end and remove most of the overhanging mass. Then I can shorten the horizontal to the length my pruning plan and the tree's natural branching dictate.
Fast-forward
My plan is to have a platform 4' square, 4' above the ground.
Unlike some of my other projects, I decided to cut the ends of the studs defining the perimeter of the platform's deck on 45 degree angles (i.e. picture-frame cuts). And therein lies the story. (At this point Roger is chuckling. He already knows what is going to happen)
Placing the 8' long 2-by-4 upon yon picnic table and carefully marking out my cuts, I proceeded to produce two, 4' long sticks with 45s on the ends. I then repeated the exercise with a second, 8' long 2-by-4.
Legs were cut. Diagonal bracing was added. Sub-assemblies were joined together. Another trip was made to the local lumber yard and 5/4" treated lumber was purchased in 8' lengths. The treating not only changes the color to gold but apparently adds to its value such that it IS gold.
Now for whatever reason, the picture in my head was that the exterior dimension was a skoosh less than 4'. Having seen decking that was nailed along the extreme, cut end and seen it splitting-out, I decided it would be extra-special-spiffy if I cut my planking 1.5" longer than the length they were spanning so the deck-screws would have some meat behind them rather than their gripping the ends of the planks by the fingernails, so to speak.
I pulled out the first 8' 5/4 treated and used the top of the platform and a scrap length of 2-by to measure the "length + 1-1/2"" and penciled my mark. I did not use my measuring tape because, like a ninny, I had laid it down instead of putting it into my pocket or clipping it to my belt. (Roger is cackling with glee. "Get the danged yo-yo" he is shouting at the computer.)
I went back to the picnic table and made the cut. Then, because I KNEW it was less than 4', I used the shorter piece to mark off the longer piece and I reduced it to the length of the shorter piece.
I repeated the same with the second piece of golden, Ponderosa Pine planking.
Lacking any better place to put them, I carried them over to the scaffolding and laid them on the framework that defined the top of the platform....
...and they were too short.
They weren't just 1.5" too short. They were 2" too short!
When you cut "picture-frame" corners, the outside dimensions grow.
Creating a word-picture of why-that-happens is difficult but I will give it a shot.
If you took two, 8' 2-by-4s and cut them into 4' lengths and them fastened them into a frame, you would create a rectangle with outside dimensions of 48"-by-51" because one dimension would grow by 2X the thickness of the wood (2-by-4s actually being 1.5"-by-3.5")
To make a true 48"-by-48" square frame, you would have to cut two of the sticks to 45", throwing away the equivalent of four, 1.5" SQUARES by 3.5" long prisms of wood.
When you cut "picture-frame" cuts, you end up throwing away 4 TRIANGULAR prisms measuring 1.5"-by-1.5" by 2.25" by 3.5" long. That is, if you aren't thinking ahead (like I wasn't).
It was painful (expensive) to mess-up the two 5/4 decking planks but I will surely find a use for them.
The fix is to scab a 2-by-4 inside of the frame. Buy two more 5/4 decking planks and cut them to 48" lengths and proceed as before. All "shortage" of decking will be chased to the scabbed end of the platform.
Just because I blog doesn't mean I don't make lots of mistakes. One of my reasons for remaining anonymous is because I have more latitude to share my opportunities-to-learn.