Why does this mounting hole have this shape?

Jul 01, 2010 1 Replies

I have a Fein "Multimaster". It's an electric hand tool with various "blades". For sawing, sanding, cutting. It works by vibrating very fast & with very small displacement.



The various blades have this mounting hole:

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The "points" on the hole do not engage anything on the tool - the blade is free to be rotated to any position & then fixed in place by tightening a screw. I.e., it's fixed by friction.



Why, then, does the hole have those points?



Thanks, Bob


Winston & Dave replies got me to take another look and I found nice sharp edges in the inside points. But the clamping washer is domed and only presses beyond the outside points. Hmmm?

Then Ned & Mike nailed with "other model compatibility". The new models do have star-shaped mount. Now I'm wondering if I need the adapter for my old model (I didn't know it was an old model!).

Thanks to all, Bob

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