[kevan]

When you're grinding there's significant metal and abrasive dust thrown into the air. Given the airflow they generate and how fine the radioactive powder is even a small nick in the capsule could end up with a lot of material in the air without you noticing it.

A jig to limit grinder motion sounds like really cheap insurance to prevent this failure mode.

[ethbro]

I'm curious if the capsules like this are standardized or one-off. The description of the tungsten plug makes it sound like the latter.

In which case a more sane procedure would probably mandate some examination of the capsule, formulation of a plan off-site, then implementation of said plan.