Just had a chance to measure TIR on my spindle. My best dial gauge only reads down to 0.01mm, and as far as I can judge, TIR on my spindle is slightly over 0.01mm. Difficult to be very accurate as the CNC router is built from MDF and there's a lot of play and bend in the structure, so every time you touch the spindle collet to rotate it, you see more movement than that! I measured using the shank of a solid carbide cutter in a 6mm ER20 collet just below the collet face, so runout further down could be more. The collet was from Arc Euro Trade, not the 1/4" collet supplied with the spindle, and I can't see any figures quoted for collet accuracy.