My friend Nelson has told me several times that "You can't push a file sitting down." Now I understand...
I spent about 20 minutes on the bolt, first watching the file cut and then watching the oil smear from the medium india stone. I eventually got the hang of positioning the tool on the work by feel, then locking my wrist and producing all the motion with my shoulder and elbow.
A commercial 'smith would have done this with a Cratex point on a Foredom tool in about 30 seconds because time is money. Learning how to use the tools was more important than how long it took.
It was also a good time to remind myself to keep cutting tools waaaaay over there. Nothing happened, but I
almost set the file down on the sideplate at one point.
Yes, I also moved the sideplate to a safer location.
The Zing! prevention device was used again to reinstall the bolt and this time it really did just pop back in.