[PSUBS-MAILIST] Finishing O-ring groove

[Alan via Personal_Submersibles]

I have been finishing some internal O-ring grooves in aluminium on the lathe, 
with sandpaper.
The grooves are small; 3.4mm x 2mm. There was a bit of chatter after machining.
I am wondering if there is a better way to finish them rather than folding up small
bits of varying grades of sand paper & sticking my hand in the work. ( am being careful)
Maybe an abrasive paste & a bent piece of wire of a similar diameter to the groove?
The hole diameter is 60mm & the groove is only 4mm in from the face, but difficult
to get a straight stick with sandpaper in to it on the correct angle. I have a few to do.
Any suggestions thanks.
Alan

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