Create shafts.md

Author: pingswept

content/notes/shafts.md

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+---
+title: "Shafts"
+draft: false
+---
+
+# Shafts
+
+## Rod vs. shaft
+
+In engineering parlance, a rod means a round stick and a shaft means a **really** round stick.
+
+If you look at [a 6 mm diameter steel rod like McMaster 8920K22](https://www.mcmaster.com/8920K22/), you'll find it costs around $9 per meter, can be undersized up to 0.05 mm, and has no straightness specification.
+
+Compare that to [a 6 mm steel shaft like Mcmaster 1482K64](https://www.mcmaster.com/1482K64/). The shaft costs around $40 per meter, can only be undersized by 0.01 mm, and has a straightness specification of 0.03 mm per 300 mm of length.
+
+Generally, we buy rods unless we need to make something spin. For spinning stuff, we use shafts.
+
+## How to attach stuff to shafts
+
+### 1. Press fit
+
+### 2. Set screws
+
+### 3. D-shafts
+
+### 4. Keys and keyways
+
+### 5. Tapered hubs
+
+### 6. Clamping shaft couplings