Router bit bearings become a precise guide for certain router bits providing they are top quality router bit bearings.  One of our manufacturers, Southeast Tool, uses these router bit bearings on all of their router bits requiring a bearing.  They understand how important a router bit bearing can be for a smooth, accurate cut.  The only CNC machine collets listed on the website are ER Precision collets.  However, Woodshopbits can supply you with most CNC machine collets and accessories.  Call 1-801-592-7835 for assistance.