Tuesday, December 27, 2016

SEA Cad files now available!

This is post 3 in the OpenSEA project, if you have missed part one and two see post one for some background.

I started this project with FreeCAD to design the parts, but now i am switching over to OpenSCAD, mainly because of the benefits of SolidPython. I have forked the SolidPython repository and will extend it to fit the needs of the OpenBiped project. One of the big benefits of SolidPython is the ability to auto-generate a Bill Of Materials (BOM) with cost and 3d printing time, i also plan to extend it with weight and filament usage.

Here is an example output: (not a complete SEA, nor real print time or cost for 3d printed parts)

Desc.CountUnit PriceTotal PricePrint Time
A22121RMB 31.28RMB 31.280
Fibre Glass Rod 4mm4RMB 2.78RMB 11.120
A2212 Attachment1RMB 0.20RMB 0.2032
ESC 40W1RMB 31.28RMB 31.280
3d Printed Spring1RMB 0.50RMB 0.5030
Shaft Adapter 3.17:41RMB 0.50RMB 0.508
SEA sled side bracket2RMB 0.50RMB 1.0032
Screw Rod m41RMB 2.00RMB 2.000
SEA Top Cap1RMB 0.50RMB 0.5030
Cost:RMB 78.37 (~ 10 Euro, ~ 10 USD)
Print time:132minutes
Part count:13

My goal for the OpenSEA project is to have a script where you specify what loads you want the system to handle, then the parts will be auto-generated and you will get a BOM with print time and weight and cost of the construction.

If you want the design files, they are available here. Note that this is very much a work in progress.

I have begun to test 3d printed springs in the (Finite Element Method) FEM workbench in FreeCAD. With some basic analysis i hope to decrease the number of parts needed to be printed and tested to get reliable results from the spring generator script. I will shortly release a post with a how-to/walkthrough.

And regarding the "HowTo re-flash a SimonK ESC" I wrote about in my last post, its coming, but i will dig a bit deeper then just reflashing ;)


  1. nice design but I think without using a highly flexible filament the parts will rather quickly desintegrate or lose strength. why not bend your own springs from spring steel rods or stripes? tey will by far outperform the printes springs and might in total add less weight to the part.

    1. Thanks, and of cause you are right. As i mentioned in my last post, 3d printed springs are only one of several possible solutions, I will also evaluate "normal springs".

      Its attractive to be able to 3d print springs to get the exact capability you want. I am sure it will work decently for some applications with the correct spring design and material choice.