Originally Posted by
the_tool_man
...As the holes get bigger, you remove material from the cross-section, which weakens the arm. Taken too far, the arm loses rigidity. Taken further, it breaks. However, as the holes get smaller, they cause stress concentrations which increase the liklihood of stress cracking. Aluminum is especially prone to this...
Please OP, read the above twice.
I'm a mechanical engineer, and from what I know about metals and stress distruibution, I will tell you that without actually testing your modifications, you'll likely see a very serious decline in the part's structural integrity which might give no clue to when a catastrophic failure will occur. Ask yourself, "how much do I know about the grain structure's orientation in this forging".
The bigger holes induce the very flex which can cause rapid failure, and the small holes create the highest stress concentrations.
Pick your poison!
This drillium activity should really be only for display parts, not riding.
This reminds me of the guys in the cities who ride their bikes with no brakes, and so I must question the definition of "cool".