Grazer — CNC Progress — Lukas


This week was spent with more time in the machine shop, working through issues, and arriving finally at yet more designs. Only time will tell if they remain permanent.

My process began with some fresh designs which offered around 67 degrees of rotation in each direction, a fraction of the rotation I need for the bends in the leg.

Screen Shot 2015-05-05 at 12.34.25 AMScreen Shot 2015-05-05 at 12.37.14 AM

Regardless, I went ahead and tried to cut the part, just to see what it would be like to mill something from such skinny material. Unfortunately, when I went generate mill paths in the “CAM” (Computer Aided Manufacturing) sub-program in Fusion 360, I always ran into warnings stating: Empty toolpath.

Screen Shot 2015-05-05 at 12.43.46 AM

I think the main problem arose with the size of the actual tools I could work with: limited basically to a 1/2 inch flat, a1/8 inch flat, and a 3/8 inch ball. Flat endmills are necessary for 90 degree angles in parts whereas ball or bull nose endmills are necessary (just about) for contoured/rounded faces. There are actually are ridiculous a ridiculous number of different endmills, all specialized for different applications. It was really quite a messy design: hard to mill, round in the wrong places, and probably frail in some places too.

To remedy this, I came up with a very simple joint designs. For all this time, I’ve been hung up on joints with a central flange sandwiched between two slices of aluminum. Each flange was not thicker than a tenth of an inch, something that probably compromises the structural integrity of the part. Instead, I changed it so that each side shakes hands with the other, two sides mating with each other.

Screen Shot 2015-05-05 at 12.40.38 AM

CAM tool path with simulated endmill (milling for just the notch)

CAM tool path with simulated endmill (milling for just the notch)

Toolpath for rounded features

Toolpath for rounded features

This makes it much easier to manufacture (I only have to mill one design), the design is probably much stronger (1/4 inch for each side), and gives the part part a much lower chance of binding, as there is now only one contacting surface between the two.

Unfortunately, I only got this far in the process:


However, I do have all the necessary scripts ready to go to finnish the part. Expect an update next week, Hopefully I’ll have a full joint!

In related news (additive vs. deductive), I found a really cool blog on 3D Printing, which details new technologies in an industry taking huge strides into the mainstream.

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