Braun Satin Hair 7 replacement fan (parameterized press fit)

thingiverse

CAUTION: press fit alone doesn't seem to solve the problem. My fan was pulled off the shaft even with a very strong press fit of 0.13mm! In the picture of the broken fan you can see that the connector was OK. It just disassembled from the shaft. So the recommendation is to glue the fan to the shaft as described here: https://www.thingiverse.com/thing:3791353 -- this lasted several months until it got separated. This is a parameterized press fit replacement fan which I designed for the Braun Satin Hair 7. I simplified the design a bit compared to the original part. First print the test print pieces (yellow cylinders in the picture). Each test piece has the inner diameter printed on it. In my case the 2.4 diameter fitted smoothly on the shaft, the 2.35 and 2.30 were strong, 2.25 too strong. So I chose 2.27 in my case. As a good rule of thumb you can chose 0.13 less than the bore diameter which still fits without much effort. Then you have a good press fit. The diameter you have elaborated with the test is then filled in as bore diameter in the design. I had then to press the fan on with both hand's thumbs -- after dissassembling the front air guide piece and putting the fan on the floor with the front side. Note: please use fine resolution (say 0.1mm layer height or less) both for the test prints and for the fan. Otherwise the press fit might be too inexact and might not be durable. With version 0.3 there comes an optional gluing gap such that you can glue the fan, if you want. Also I made the blade edges round for better air flow. I now glued the fan (variant with gluing gap) with some installation glue (Montagekleber) to the shaft. Let's see how long it will last. Edit August 2020: with installation glue and gluing gap 0.1mm it lasted only 3 months. Glue was still on the shaft, but fan was pulled over the glue. Now I increased the gluing gap to 0.7mm and hope that this lasts longer.