Grinding a Forstner bit to a custom size
I figured it should be possible to grind a 7/8" Forstner bit down by a tiny bit to make a hole just the right size for one of these bearings.
Then I held this up to my bench grinder, with the piece of wood pressed down on the tool rest to help steady it. With the drill spinning, I slowly pushed it against the wheel, then moved the drill forward and back to grind the sides of the Forstner bit in an even cylindrical manner.
Fortunately, the points on the edges were still ahead of the main cutting edges, so I didn't need to grind these back any.
I don't have a use for fidget spinners, so I figured I'd spin it with compressed air until it exploded. But I had to cut some slots into the sides of it to weaken enough. With the extra notches around it, it made a sound like a high-revving engine as the air was blowing against it.
On later analysis of the video, it's clear that the wood came off the bearing first, then probably broke apart when it hit the workbench. But it all happened so fast that, as far as I could tell, it just disappeared in an instant.
Cheap fortsner bits: Low quality but they drill ok (video only)
Making a drill index for Forstner bits (video only)
Drilling glass (video only)
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