The problem with string

 It is, of course, well known that everybody loves string, except when you are 3D printing. In the clocks that I've made recently, there is often a lot of stringing between gear teeth which are close together. It doesn't take much to clean it up: a few gentle swipes with a piece of sandpaper generally does the trick. However, there's always some residue left behind. The common advice is to lower the printing temperature, so I did a quick check to see if this helps. I selected a gear with 18 teeth, printed it at different temperatures and counted how many of the gaps between the teeth had significant stringing. "Significant" is a bit subjective here; roughly, I mean I would feel obliged to clean it up. Here's the results:

You probably can't make out too much in this picture. The counts of stringy teeth were:

• 210C: 10
• 205C: 10 or 11
• 200C: 4 to 6
• 195C: 3
• 190C: 3

So this validates that a lower temperature helps. 210C is the Prusa default for PLA and I think they use it to ensure a good flow. I'll certainly consider lower temperatures in future.