Summary:
Earlier today, a friend (Francesco) and I were looking for a short machining project to fill the evening and ran across this (click me) rather excellent video tutorial by Clickspring/Make detailing how one would create a metal scriber. Since neither of us had a metal scriber, and Francesco recently acquired a benchtop lathe, it seemed like a perfect fit. Machining on a bench-top lathe is a pretty different experience than machining on a larger machine and this project was not without its minor hiccups, but overall, I would say it was a lot of fun, and definitely educational.
Results:
We used size 18 sewing needles from Michael's for the scriber points, and turned the body of each scriber from 3/8th brass rod from the stockroom. In his video, Chris mentions that he thinks CA glue would work for holding in the needle, and I can confirm that the superglue we used worked just fine (though you've got to move fast with the cleanup tissue to avoid gluing it to the scriber). I went for a stocky design, and used a 5" scriber, with a 6 degree 0.4" tapper. Francesco took a slightly different approach with a 1.5" 4 degree tapper on a 6" body, which made for a nice sleek design.
Overall, both designs ended up working pretty well. We did run into a bit of trouble getting the surface finishes right, but a graduated sandpaper set would solve that problem pretty nicely (or at least make things a lot simpler). Failing that, we had a lot of luck with using worn 600 grit sand paper with WD40 as cutting fluid to get a nice brushed look. We did take a shot at using metal backed sandpaper to try to get a more consistent finish and remove our macheing marks, but the quality of our sandpaper was pretty low and we had more luck using finer grit scrap by hand.
Pictures:
Future Plans:
Francesco and I are hoping to use this as an intro machining project for the metalworking club. We also have plans to take a shot at a set-screw variant. With that in mind, I have included my notes on what went well and what went less well, along with some ideas for next steps in the "notes" section below. If you are planning on working through a similar project I would recommend taking a look at them before using anything on this page, though I am very happy with how my scriber turned out for a first run.
Notes:
- A #54 drill bit is just a bit too big for a size 18 needle.
- 0.5" - 0.8" seems like a good range for tip extension.
- Cut brass lengths 0.3" longer than needed and face down.
- Don't dwell at the bottom of a grip groove, creates chatter.
- Using a blueing compound on the scriber before the final sanding the surface could make the grooves darker and provide a nice contrast.
- Longer grip patches (1.0" and longer) make the scriber easier to use.