Badass Lawnmower Blades

[Tritium]

Thurmond, those "teeth" actually stick up away from the grass, and are to provide upwards airflow / "suction". (Supposedly, they also blow air / clippings back towards the center of the blade, for subsequent repeat cutting / mulching and a more even clipping distribution.)

I should have looked at the full sized picture. I see it is a mulching blade now. No lawnmower blade I have ever had would drill easily. Use lots of cutting fluid and very good bits and you may get it done.

Thurmond

[jakeru]

I got it done! I didn't end up needing any fancy bits either (just quality-made, old school high speed steel. The crappy harbor freight "high speed steel" bit was clearly lacking metallurgy, or good heat treatment, (or both) because it dulled before any WD-40 even started smoking (so didn't appear to even get that hot before it dulled.)

I used a 3/16" split point (which I had sharped on my drill doctor! And made nice long curled shavings) followed by 3/8" (which wasn't as sharp, but was sharp enough), both at 400 RPM (the lowest setting my drill press allowed.)
Attachment 2007
I learned by the sound what a good feed rate was. (Nice "shhh" sound was best, shrieking / squealing like a pig = not as good.)

The holes needed just a touch of tuning with a rat-tail hand file, and then when it went together, I found it doesn't seem to sit too low in my mower either. Although it is slightly lower than the original blade, it's still comfortably recessed from the deck at the rear and sides.
Attachment 2009

Here are some comparative shots of the new vs original blade:
Attachment 2010

Can't wait until the next chance to mow my lawn and try this out! (Shouldn't be too long, this time of year.)