F-18FMitutoyo reserves the right to change any or all aspects of any product specication, including prices, designs and service content, without notice.Fixture examplesOutside diameterBall diameterOutside radiusCountersink diameterExamples of measuring various features ItemD = Countersink diameter/Groove width; H = Countersink depth/Groove depthR = Outside radius of round objectR = Inside radius of round objectR = Outside radius of round objectFixture type*1Contact pointConeBallConeFlat or radius to suit featurex = Spindledisplacement from ORIGIN set position (retraction is the positive-going direction)θxDrθxHdDθxDθRXRrX2LRr2Lrx+dR2LCalculation (x’ = x + d)D = AxD = Ax' + BH = Ax' + BD = Ax'R = Ax'R = Ax' + B + C/x'R = A(x') + B + C/(x')CoefficientvaluesA－2tan θ－2－2tan θ－2－1－2tan θ－2sin θ－2 － 1－sin θ－2 1－2－ 1－2 1－2B0 2γ（ 1 cosθ－2 -tan θ－2 ） γ（ 1 sin θ－2 -1）- d 2tan θ－2 00－rr－rC00000L－22－ L－22L－22Origin offsetvalued00000000ORIGIN-set position of spindle *1dDisplayed measurement value at ORIGIN-set position of spindle0Value of coefficient B000Err 30*2(Overflow error of Display value)Depends on value of d*3*1 The spindle position at which the ORIGIN is set. This is when the contact point is touching either the reference plane or the calibrated artefact, as shown.*2 The ‘Err30’ message shown in the display is extinguished when the spindle is moved into the measurement range.*3 The value of d is chosen to suit the radius range to be measured, the stroke of the indicator and the best spindle position for the ORIGIN. Note that the value of x' should not be allowed to approach zero as this is a highly non-linear region of the equation and measurement accuracy will deteriorate rapidly. A spreadsheet simulation will aid selection of the best value of d for particular r, L and R values. Note 1: Fixtures suited to individual workpieces can be made to order.Note 2: Measuring accuracy is subject to fixture accuracy and workpiece form accuracy.