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+Model for a thermostat dial. 
+
+The dial fits onto a pin with a flat side. The part which mates with the thermostat pin tends to break on the originals. I measured the pin diameter as 6.37 mm and the flat to opposite edge as 4.08
+
+I did some fit tests and found that 0.2 mm clearance (as measured after print) worked well with a tight fit that could still be removed without too much trouble.
+
+Calculations were done in fit-calculations.ods
+
+This was modelled with https://dune3d.org/