Overhaulin' the Trucks Part II

I worked some more on the design of the trucks this week.  I've added mounting points for the magnets and fine tuned the various dimensions over several generations.

Magnet mounting points in green.  Belt mounting points in orange

I'm glad I had the foresight to do this whole process in OpenSCAD.  It would have taken forever with traditional modeling techniques.   Also i now have a parametric design I can share with the community.

Added 'bumpers' at the ends of the axles to keep the wheels in place.

This is an early prototype.  I ended up with an asymetric design I call the BigWheel.  It has two small wheels on one side and one large wheel on the other.  You can see how the slit in the body panels creates a suspension system where the third wheel can pull away slightly, creating tension where it wants to pull back in.  This keeps the wheels firmly planted in their tracks.

Here you can see one of the wheels before I cut away the bridging layer of nylon.  This was necessary to print the ball bearing inside of the wheel.

Here is the whole truck/carriage assembled with magnets inserted into place.

Shot of the inside, assembled.

Shot of the outside.

I got this set of 12 tapped 10mm ball bearings and matching 12 mm magnets from eBay.  Two magnets go on each truck, and six on the effector.  Then one steel ball goes  on the end of each of the six pushrods. There is just one problem.  The magnets are very strong and everything, but one of the ball bearings isn't tapped, rendering the whole set useless.  I'll have to get this straightened out before I work on the push rods and the effector.

The purple material I've been using for all this is the new PLA+ from eSUN.  The good people at eSUN were awesome enough to send me a couple rolls of the stuff to play around with.  It prints like butter.  I haven't had a single failed print and I've gone through almost an entire roll.  Its really strong, yet precise, and probably my favorite material I've ever printed with.

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