On January 28, 2019 at 02:35, Ernie Gilman said...
Another thing just came to mind: We were building an A/V store and I watched one of the cabinet guys (who also did framing; that should have been a big red flag!) was marking off shelf mounting heights.
Ever listen to framers when they had one guy cutting and someone else nailing? The guy who's nailing will call out length in a few ways- might be "Eighty", "eighty strong" or "eighty short (or weak)". The total variation can be 1/4" but, since it's framing, it's close enough because they have shims. Doesn't mean the freaking wall is gonna be straight, though.
He was using some kind of marker to note the shelf marking heights. The marker was twice as wide as the height tolerance. I got him a pencil.
Unless the plan is to remove the whole line and it's the same width as the blade's thickness, yeah- a pencil is better and if possible, some kind of gauged pencil, like the ones used in drafting (not the super-thin ones, obviously). The 1mm Fine Line markers are OK, though- it's not the thick ones that can be mashed into a small mop.
We developed some car speaker boxes, about four feet wide by five feet high, with horizontal rails. To make them versatile, I had them install some steel rails with PEM nuts in them, installed in positions defined to within 0.005".
The first one didn't work too well. They said, quite correctly, that they couldn't put the rail supports exactly where I defined them to be. No problem! I went out there the next day with my new purchases: a three foot rule and a six foot rule, marked to 64ths of an inch on one side and hundredths of an inch on the other. That was about 200 bucks of ruler. They made them perfectly after that. Once they knew how serious I was, they stepped up. Those speaker displays were SO easy to use!
.005" is a bit fine for working with wood unless it was MDF. Any wood will move more than that unless the climate is controlled very closely but I understand wanting accuracy.
The carpenter on the job who yapped about how I should feed my cable saw the bow in the wall behind the desk when we placed the glass top on it and said "Wow!" as if he had never seen it before. I found that odd since he had installed the desk, mounted the top without scribing it and filled the gap with caulk.
