pic: Spectrum 3847 Public CAD Repository 2015



We are opening up our CAD repository this year GrabCAD Workbench makes it easy enough to do it and no one on the team could really think of a good reason not to share it.

Head over to our blog to see a few caveats with the release and for the link to GrabCAD Workbench file repository.

Once Again you guys never cease to amaze me! Great job guys and thanks for uploading your CAD during build season!

Thanks for releasing the CAD, it’s amazing!
I was checking out your can grabber gearbo and saw you had a 12:42 reduction from the cim to a 2.5" wheel that drives the mechanism. Why did you opt for such a high reduction?
EDIT: Did you figure out the strength of the tape measure spring?

We haven’t figured anything out about spring force, but I just a did the numbers quickly and at full speed I think that’s ~18.7 fps. I don’t think we will actually be able to use it at that speed. We’ll probably have to slow the motor down more. Plus we have to pull the RC some what with that motor so we need the torque. Again as we stated none of this works (yet). We happen to have a bunch of the 42t pulleys so we figured we’d use them. The 12t is 3D printed. Hopefully we will be testing it this weekend.

Ok. I put the numbers in JVN calc and it spat out 16.5fps free, 11.7fps loaded, but it loads at 37 amps at 8lb force. I guess it really depends on the load, as some measures will fall under their own weight even.

My guess is you were using the free speed of a CIM (~5,300) instead of a MiniCIM (~6,000).

  • Allen

Ah, I see! Whoops.