Machine shop started for me today after missing the first two meetings for an engineering conference last week. Today we started in with the tools. If you'd told me last week that an hour long lecture on saws would be interesting, I might have rolled my eyes, but not anymore! We learned about a few different kinds of saws. Then, we learned that with the vast majority of saws in the States, you should always push the saw across the material and never pull. By pulling, you'll run the saw teeth over the material in their least reinforced direction and they'll break off, (picture 1).
It turns out there is one saw that you pull across the material, the Japanese dozuki saw.
We learned about the three tooth rule. Ideally, you want to select the pitch, (number of teeth per inch), of your saw blade so you can have no fewer than three teeth, and no less than nine in contact with the material at all times. Any fewer and the blade gets stuck, any more, and it becomes harder to push across the material and less efficient.
Oh, and we learned a new word: kerf. Kerf is the width across your saw teeth. The dozuki saw has teeth that are flush with the blade, so it makes a very good saw for trimming nubs off of parts. Most saws have teeth that extend out from the body of the blade, making for a wider kerf, (picture 2).
More of the pretty, yet oh so cool notes from machine shop!