This is my holiday gift to the most awesome online community there is!
I was about to give a friend of mine an old hitch cover that was shaped like a small Railroad Knuckle coupler, when I realized I could probably make a much more realistic version. Thanks to the original work by Jeff Mauer (see remix ref) I was able to fairly quickly resize and chop and recombine parts to make four versions of this hitch cover, Knuckle Coupler.
The first two versions are made to be printed flat without any supports. One for a Type 1 and one for a Type3 Hitch.
Then for those of you (like me) that just want to take that 1 step further... I've included two more versions that are complete with top and bottom and includes a separate knuckle part (you'll need a bolt) for a more realistic look and feel. It prints from the flats on the hitch mount and the Coupler body up with supports that will have a nice slanted wall to support, so not too bad. The body and the hitch are separated to make printing easier. Two versions; one for Type 1 and one for Type 3. The knuckle file works for both versions.
Please VERIFY the tolerances of your 3D Printer before trying one of these 2 more complex versions. That is, print just a few layers of the bottoms of the hitch and the body and check that the rod fits the hole. If not you will need to adjust the hitch file accordingly.
I do NOT recommend this for someone who just got their first 3D Printer for Christmas and is looking for an awesome print to show off their new machine. Rather I suggest waiting until you have some smaller and easier to complete objects under your belt. Each of these can take 12-20 hours to print and fails can be discouraging to newbies!
I suggest printing it in ABS since it will be subjected to the elements, but I have no doubt PLA will work. The sample in the posted pic is spray painted with Flat Black Rustoleum.
Oh yeah! Here's another gift...
For more on how I made this thing listen my PODCAST!!! 3D Printing Today!
It's FREE and has no advertising! (at least not that I know of)
search for it in iTunes, Stitcher radio or Pandora as "3D Printing Today"
3 shells, 4 on the top 3 on the bottom.