- be able to compress a 25mm spring down to 10mm
- not capable of pulling apart
- maintains it's x and y stability (keeps from bending)
- low friction
- easy to print
- easy to construct (minimal glue and clamping)
- easy to connect to the leg
|Parts drawn in OpenSCAD|
My attempts to build this pointed out a few more flaws. Conceptually, it should all work together, however the implementation is proving to be problematic - too many glue points where the glue will be the only thing keeping the pieces together. The resulting engineering is undesirable. It will not be very reliable and will have premature failure. Back to the drawing board!
This new design has only two parts and no glue! The design is based on the shock absorbers on my "Hello World" Rover. the two pieces slide together and 'click' into place. The spring will site between the two. It should provide the stability and motion needed, although friction will be a problem (especially true since the printing process leave horizontal ridges). For all the work put into this part this weekend, I think it will do. :)
After a few iterations on the printer and tweaking the design a bit, I have a working linkage with 7.5mm of compression. Now, I have to think if my servos can manage this. Good engineering would have worked out all the forces before hand. But, for this hobby round, I am just tinkering. The springs are from recycled printers, I have a few to choose from. On the enhanced round I might consider different characteristics such as the amount of travel vs the force. But, this will do for now - I have 3 more for a complete set.
Learnings this round: a lot of 3D Printing and 3D Part design thinking. Difficulties in getting a high importance but complex part to be built.
next up ... servos!