I've been vacillating on the design of the knuckles that support the front wheel axles for a while now. First, it was a series of flat aluminum plates that would be welded together into a bracket. Then, I redesigned it to use rectangular tubing to avoid having to weld plates together. I knew I'd have to machine all 4 sides of the rectangle, but it seemed easier than the first scheme. I was confident enough that I ran some stress analysis on the rectangular bracket. Everything seemed doable.
But as we've gotten closer to actually making these parts I've changed my mind again. The way it was designed, the parts would require both CAM (computer-aided machining) and considerable manual machining to complete, including a lot of tricky alignments between the faces. Making the knuckles suddenly seemed harder than I originally thought. So I altered the plan one more time.
Instead of making it out of rectangular tubing, I went back to the idea of multiple pieces but with a twist. The piece that holds the wheel axle is again a flat plate, but, instead of welding, it will be bolted to two brackets.
The brackets are thicker than the plates that preceded them, so they can better support the forces going through them without needing an inside wall. I also added ledges to the brackets to reduce the forces going through the bolts that hold the face plate in place. And I designed them so 90% of the machining can be done by computer. I still have to drill and tap mounting holes on each of the brackets, but that should be easy to do manually after the CAM jobs are complete.
So yes, it still requires both automated and manual machining, but I think it's much less work to complete than before.
It took all day Sunday and Monday evening, but I was able to run the CAM jobs on the Tormach with the help and supervision of our machine shop Captain. The parts came out great and now they are made, so I can't alter this any further.
I just have the manual bits to complete. I have to flip the plates over and remove the extra material in a facing operation (looks like the plates are in Carbonite! 🤣) and I have to drill and thread mounting holes on the brackets.
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