Hi Amanda,
I grind my own rice for breads and sometimes find it is not quite fine enough, so I know what you mean about grinding it to a fine powder.
I agree with the link that Judy provided. Keep grinding on speed 9 in one minute intervals ensuring the bowl does not get too hot. However if it is just for me I'm not too fussy and one or two 60sec grinds usually does the trick
Many tmx owners do a similar process for making 10x icing sugar. Good luck!
*edited due to autocorrect
