![]() ![]() ![]() Simulated datum axis established by inspection equipment Permission granted to reproduce for educational use only.ĭatum Feature Symbol Placement for a Datum Axis.Pitch cylinder for screw threads establishes datum axis unless otherwise specified – When not using pitch cylinder for screw threads, place note such as "MAJOR DIA" or "MINOR DIA" next to datum feature symbol.Represented in drawings with centerlines.Represents two theoretical planes intersecting at 90°.Specify number of surfaces with a note such as: "2 SURFACES" below related feature control frame.Used to establish coplanar surfaces as one datum plane.Surface is often placed 90° to the pin to create datum reference frame.Locating pins are cylindrical or knife-edged with datum target line along tangency where pins meet the part.Indicated by a target point on edge view of surface and a phantom line on surface view.Use datum target point at center location when area is too small to accurately or clearly display on drawing Permission granted to reproduce for educational use only.Top half of the datum target symbol identifies size of target area.Locating pins are flat end tooling pins with pin diameter equal to specified size of target area.Used to establish datums using areas of contact.Datum plane established by locating pins at datum target points.Location dimensions originate from datums.Dimension using baseline or chain dimensioning.Establish tertiary datum plane by locating at least one point on related tertiary datum surface.Establish secondary datum plane by locating at least two points on related secondary datum surface.Establish primary datum plane by locating at least three points on primary datum surface.Connect to datum target point, line, or area with a leader.Useful on parts with surface or contour irregularities.Place the note “2X INDIVIDUALLY” next to datum feature symbols of two separate datum features identified by same letter.Place a note next to datum feature symbols indicating how many datum features to consider separately.Datums L and M establish second datum reference frame.Datums X, Y, and Z establish one datum reference frame.Movement is either translational or rotationalĮstablishing Multiple Datum Reference Frames.All parts have six degrees of freedom.Assign precedence and datum reference order – Primary datum – Secondary datum – Tertiary datumĭatum Reference Frame Concept: Inspecting the Part.Select three perpendicular datum features based on their importance to part design.Datum plane measurements do not take variations in datum surface from datum plane into account.Can be controlled by geometric tolerance.Tangent planeĭatum Feature Symbol Placement for Surfaces.Surface of manufacturing or verification equipmentĭatum Feature Terms Use double letters when number of datums exceeds number of letters in alphabet.Use any letter to identify a datum feature except I, O, or Q.Do not apply to centerlines, center planes, or axes.Machine tables Surface plates Gauge surfaces Surface tables Specially designed rotation devices Permission granted to reproduce for educational use only. Two types: – Theoretical datum feature simulator – Physical datum feature simulator.Represent true geometric counterpart of a datum feature.Describe methods for representing datum center planes on drawings. ![]() Identify the degrees of freedom of a part Explain how to establish datum targets Identify datum target points, areas, and lines Describe methods for representing datum axes on drawings Permission granted to reproduce for educational use only.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |