There’s a few items that most every car guy or gal have in arms reach at all times when working in their shop. For me one of those is Sharpie marker. They work great to write notes on things as I work or to mark out measurements, trace lines for bead rolling, etc, etc. These work great when sharp, but they tend to wear out and get dull quickly. The more dull they get the wider the mark will be that it leaves.
Above I’ve drew a line with three of the same brand/style markers just each are worn differently. Starting from the top you can see the new Sharpie will make crisp lines that measure approximately 1/32″ thick. Next below the new marker is a partially worn Sharpie that leaves a line about twice as thick that measures about 1/16″. Finally the last line is a heavily worn marker tip that could leave a mark as thick as 1/8″ wide !!
What does this mean to you? If you’re making a cut or bend line you could be up to 1/8″ off depending on which side of the wide line you are! I like to keep my worn out markers in the drawer for marking junk metal or just writing measurements or notes on something and my fresh, sharp markers for making cut and bend lines and anything more precise. If you need to make an extremely precise mark I ditch the Sharpie all together and use an ultra-sharp scribe, but remember it does scratch the surface of the metal and needs to be sanded to be removed. Keeping an eye on your marker wear can save a potential bad measurement that could mess up an entire project!