Very cool to see, thanks. Very strange to see that the tire has such a strong effect. Would have never guessed. Such light weight on the outside can’t change the resonant frequencies?
It doesn't add much mass or change the stiffness, but it does add significant damping. Bicycle inner tubes are butyl rubber, which has a very high loss factor (high hysteresis losses) - see this Ansys chart: https://www.ansys.com/academic/educators/education-resources/chart-loss-coefficient-vs-youngs-modulus1
Relatedly, this why latex inner tubes for bike racing exist - they have lower rolling resistance than butyl (since latex has less damping than butyl), at the cost of losing pressure over time from the latex permeability.
Ok i see, the rubber gets streched and contracted in a cyclic manner on the outside of the motor somehow. This turns the vibration energy of the motor into heat and it stops vibrating. (Please correct me if wrong.) 😊
Hey Ben, this may be a dumb question, but could you please tell me why would you machine a 3D printed object? Is it for greater precision and lesser wastage of material? (won't that increase the cost though?) Or is it because it's easier to print just the basic structure?
For precision features (e.g. bearing bores, locating features), features that are too small to print directly (e.g. threads), or for a better surface finish (e.g. sealing surfaces). Aluminum printing tolerances are not great, in the +/.1 or .2mm range for small feature, worse for bigger stuff.
In this particular case, printing the basic structure allowed me to combine what would have been several machined parts into a singe part (there are enclosed water channels around the diameter), and worked out cheaper than sending out to get them machined (ignoring my own time machining on the printed parts)
Very cool to see, thanks. Very strange to see that the tire has such a strong effect. Would have never guessed. Such light weight on the outside can’t change the resonant frequencies?
ReplyDeleteIt doesn't add much mass or change the stiffness, but it does add significant damping. Bicycle inner tubes are butyl rubber, which has a very high loss factor (high hysteresis losses) - see this Ansys chart: https://www.ansys.com/academic/educators/education-resources/chart-loss-coefficient-vs-youngs-modulus1
DeleteRelatedly, this why latex inner tubes for bike racing exist - they have lower rolling resistance than butyl (since latex has less damping than butyl), at the cost of losing pressure over time from the latex permeability.
Ok i see, the rubber gets streched and contracted in a cyclic manner on the outside of the motor somehow. This turns the vibration energy of the motor into heat and it stops vibrating. (Please correct me if wrong.) 😊
DeleteHey Ben, this may be a dumb question, but could you please tell me why would you machine a 3D printed object? Is it for greater precision and lesser wastage of material? (won't that increase the cost though?) Or is it because it's easier to print just the basic structure?
ReplyDeleteFor precision features (e.g. bearing bores, locating features), features that are too small to print directly (e.g. threads), or for a better surface finish (e.g. sealing surfaces). Aluminum printing tolerances are not great, in the +/.1 or .2mm range for small feature, worse for bigger stuff.
DeleteIn this particular case, printing the basic structure allowed me to combine what would have been several machined parts into a singe part (there are enclosed water channels around the diameter), and worked out cheaper than sending out to get them machined (ignoring my own time machining on the printed parts)