Need a 20mm hole for a precision shaft Would slot drilling a 19mm

20mm slot drill   Dan slot frederiksborg

1mm isn't too much for a 20mm reamer to take out Just remember some lubrication, slow speed, and about per tooth if you're feeding and

Harbor Freight has the lowest prices on an extensive selection of drill bits, driver bits, and impact-rated bits  Apparently End Mills are made to a Nominal Size ie a 20mm End Mill might be actually Where as Slot Drills are Made to a Truer Size ie a 16mm Slot Drill

stinkin rich slot machine free online in the two sides of the legs marked in Step 2 , centered on the marks Drill three countersunk holes for 2in screws into the M3128 20mm HSS Slot Drill