Learning another tool - FreeCAD

[What About The Bee]

Where to begin?

I can sketch parts with a pencil and paper and then make them. However, this becomes highly ineffective as the part complexity increases. If I am to make Planet, with oscillating handles, it will require CAD.

There are a few free CAD packages available. I selected FreeCAD 0.18.

After a few tutorials, I decided that Tiger's front buffer adapter would be an interesting first challenge. Generation 1 worked to propel chaldrons in the banking test. Yet the part was fragile.

On to generation 2.

I acquired some threaded rod and nuts in the 0000-160 persuasion, so as to make the part more robust. Instead of pine, I will use rosewood, a tropical hardwood scrap from an earlier project.

In FreeCAD, the rectangular blocks were fairly straightforward. The through holes and counter bores were slightly more challenging.

The threaded rods were a difficult challenge. These were not constructed from a library. Rather, a rod (0.021" diameter) was extruded and external threads applied via a helix of the correct threads per inch (160) and subtractive pipe.

The nuts were even more of a challenge. A hexagon was extruded. The chamfers on the top and bottom surfaces were applied, so as to relieve the corners. A thru hole, of the minor thread diameter (0.0128") was applied. Finally the internal threads were constructed using the helix process as above.

And the threaded parts, with my index finger, for a sense of scale

Bee

[96RAF]

Sketch up has a free version and supports 3-D printing output files. Plenty of tutorial videos and healthy support groups.

[What About The Bee]

Hi 96RAF

Thank you kindly for the suggestion.

I chose FreeCAD for lots of reasons, including the ones you mention. Lots of online tutorials. Rich community. It also has a vast array of real CAD tools and it it is parameter driven.

An example of this is the counter bore radius. I looked in my shop, and could only find a 0.104" flat bottom drill, nothing smaller. Instead of buying another flat bottom drill at the radius I designed, I dialed in the radius of the new drill. This was a problem, as the counterbores now intersected, a no no. So I changed the 2 parameters that represented the axes of the 4 holes....and all the parts, threaded rods, nuts, etc, all adjusted. I did not change the dimension on every part individually, I changed the parameter those dimensions were linked to. Viola!

I do suppose this is like Scarm v AnyRail, or any other track planning tool. Its a choice.

Bee

[What About The Bee]

Here is generation 2 of my buffer adapter.

The middle member has the wood grain running side to side, with the front plates and back plate grain running vertically. The metal threaded rod is installed and bolted. A bit of 242 Locktite to keep it secure. This is far and away more robust than generation 1.

I did have a problem with the #61 drill bits for the thru hole. My drill press could not grip the tiny diameter, so I was forced to use a hand drill. That's never as precise as a drill press, so the nuts aren't in a line, they are a bit wonky. Not noticeable at 3 feet.

The nuts, being a real three dimensional part, really pop on the buffer adapter. The rosewood grain really shows. I may add a touch of varnish to bring out the color

Bee