Drilling 3/8" hole in an Arca-Swiss rail base?

[r.e.]

A box of Krispy Kremes for the local High School metal shop teacher?

Is it that easy? The 8cm base that I have has a 3/8" threaded insert in a drilled hole. Can't tell what keeps the insert in the hole, but it has tiny teeth all around the outside like gears. Is that because the hole for the insert also has teeth? And what holds it in? Glue of some kind?

[winterclock]

Without seeing it the threaded insert sounds like a PEMS insert, they require a specifically sized hole and are pressed in. A high school shop with a vertical mill should be able to do this. If the area where the hole is going to be is solid it might be easier to just drill and tap for a 3/8" keensert.