2.00mm EM reading 1.86mm?
Not sure what cutters you're measuring (3 or 4 flute), or what you're measuring with (calipers or mic), but one point I'll mention is that it is easy to overdo pressure on your measuring tool (ie pushing a caliper too far or tightening a mic too far) and giving a false reading. I have seen people (even in the trade) tighten mic's like g-clamps (not good, because it twists the frame).
If its a 4-flute, slide it until caliper jaws *just* touch, and rotate it until you get the highest reading - this is your actual size.
You say the cutters are from ebay - in which case they may be worn anyway (not knowing how they've been used / treated).
One other point of note: re-ground cutters can sometimes cut slightly oversize.
FOR SALE: Emco mill 50 cnc mill like Denford TriacBy gavztheouch in forum Items For SaleReplies: 0Last Post: 18-05-2014, 09:19 AM
By bmbaz in forum Machine DiscussionReplies: 2Last Post: 15-05-2014, 09:46 AM
By uitshguai in forum Items For SaleReplies: 3Last Post: 27-04-2014, 12:36 PM
By Tenson in forum Tool & Tooling TechnologyReplies: 19Last Post: 26-05-2012, 03:41 PM
By crimsonred in forum Probing, Digitizing & ScaningReplies: 4Last Post: 27-09-2010, 01:47 PM