Update: Purchased and used a Regofix high precision ER16 tool holder and collet. For the small feature, I first drilled as large a hole as would fit with .010 clearance per side, then used a .040" four flute end mill to clear out the pocket leaving .002, this was run at S4900 at 5ipm with a stepover and DOC of .008. This tool lasted through all 6 parts. To finish the sidewalls, I used a Harvey 886231-C6 in the Regofix tool holder at S6160 at F .9 taking .002" radially and .008 DOC. I used 3 radial passes each at .002 to cut the required feature. I was able to cut 2 parts with one tool before I was getting a small taper which blew out the required tolerance. Thanks for all of the help and suggestions. I would have updated sooner but I had caught the COVID, fortunately, it was a mild case. LeoC

The link is dead, would you re upload? Thanks.