concentricity callout. the concentricity callout limits the location of the of diameter "8in relation to datum axis "a" a axis b. concentricity callout

 
 the concentricity callout limits the location of the of diameter "8in relation to datum axis "a" a axis bconcentricity callout  Parallelism b

Concentricity is generally reserved for high-precision parts, and only when there is a need to control median points. Within the GDT panel: Oct 25, 2011. It should be used. 4. Many of the common symbols used in technical drawings make use of a graphical callout structure known in the ASME standard as a ‘feature control frame’ (FCF) and in the ISO GPS family of standards as a ‘tolerance frame’. Straightness, Flatness, Circularity, Cylindricity, Line profile, Surface profile, Perpendicularity, Angularity Parallelism, True position, and Concentricity callouts can be added to various created entities and shown in the report. Straightness can apply to either a flat feature such as the surface of a block, or it can apply to the surface of a cylinder along the axial direction. This scan must then be analyzed to determine the central axis points at each location along the cylinder, forming the true part axis. I know concentricity is obsolete, but I'm curious how you guys would handle this. ” This yielded five results, the first of which is in the Foreword section of the standard. Dont take it personal, we all screw up big at times, My favorite screw up is to be . Maximum Material Condition or for short, MMC, is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance. •The true geometric counterpart’s axis or center line or center plane is the datum. suckafree3000 • 3 yr. The intended meaning of the . In GD&T, Total Runout controls how much a feature or surface can vary with respect to a datum if the part is rotated 360 degrees around the datum axis. Lathe backbore - critical features - Pointer. Concentricity is a specific Geometric Control with fairly limited application as it relates to the theoretical axis rather than the 'real' surface of the cylindrical features. , it means that the median point(s) cannot be off centre over 0. Tubing OD/OD concentricity requirements can be indicated on a drawing in several different ways, including: GD&T. For example, injection-molded medical equipment uses a drastically different set of controls than a high RPM automotive component. Concentricity. It is a common symbol that references how flat a surface is regardless of any other datums or features. 5 up to 2009 (withdrawn 2018). It is often used in lieu of concentricity and symmetry which also belong to GD&T location controls group. to . Perpendicularity can reference a 2D line, but more commonly it. When applying concentricity as a bore attribute, consider that it does not control circularity. Question: In the following print Gd & T callout for the smaller hole is for a. Similar to break edges, deburr callouts are usually pretty loosey goosey. The first three characteristics (deviations) may be toleranced either together (in common) by the profile tolerance of the cone ( t in Fig. Two gears with the concentricity callout. Consider a cylinder whose purpose is to roll along a flat surface. ) has to "wrap" around the entire. 3. 4. Maximum Material Condition or for short, MMC, is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance. png. They could change this to a circular runout of 0. Datum A is a dashed line through the axis of the ring. In the drwaing below, A and B are the Datums used to establish the center of the hole using the Position Symbol and the. Chamfers do not have to be a 45 degree angle as shown in the picture above, but this is certainly the most common configuration. #2. Transforming CMM Metrology with PC-DMIS Pro, CAD and CAD++ software. From Old School conventional guys, to CNC Programmers, to the…When you call out parallelism, flatness is implied. However, for the first GTOL in the part, the GTOL frame is previewed with. Worst case scenario:hole for DR is . The Position tolerance is the GD&T symbol and tolerance of location. Flatness is the 3D equivalent of the surface straightness control. Concentricity: The rings on a bullseye are concentric, just as the wheels on your car are concentric to the axle. png. Concentricity b. The concentricity callout (provided it is an ASME Y14. Lathe backbore - critical features -Solution. Transforming CMM Metrology with PC-DMIS Pro, CAD and CAD++ software. Just echoing everyone else. Roundness, or circularity, is the 2D tolerance that controls how closely a cross-section of a cylinder, sphere, or cone is to a mathematically perfect circle. What I'm finding is that making the cylinder the datum I get bad results for the runout or concentricity. View Exam Notes ST01 2019MOW. Besides the removal of concentricity and symmetry, the changes in the ASME Y14. Lathe backbore - critical features - Challenge. (Reason: concentricity. Concentricity: ASME Y14. I just wanted to see how you might handle this concentricity callout in this cavity: Pic11. Search in titles only Search in PC-DMIS for CMMs only. Concentricity | GD&T Basics The datum, or master feature would be the shaft. Yeah I was thinking about using concentricity but from my understanding it is much more difficult to check than runout. The CMM operators decided they would look at the check with a concentricity function. 06-18-2009, 01:00 PM. Creating the GDT Call-out. If the operator on the mill measured 0. 16). Figure 5. In the crude diagram below, we are trying to mate the red blob into the blue hole. Perpendicularity is a fairly common symbol that requires the referenced surface or line to be perpendicular or 90° from a datum surface or line. After making several dozen of these parts, I have yet to fail to hit that tolerance with the fixture that I made. As already noted, a runout control on a drawing or CAD model always requires the axis of rotation to be indicated. Drawing Callout: Description: The circularity symbol is used to describe how close an object should be to a true circle. 033 bore to 16/16. While straightness has parallel lines representing its tolerance zone, the flatness tolerance zone is formed by two parallel planes. 2 mm. 5 might give you the envelope principle, but how would a reader interpret a concentricity callout, which has a very different meaning in the two systems? John-Paul Belanger Certified Sr. Concentricity: The rings on a bullseye are concentric, just as the wheels on your car are concentric to the axle. 5? As I understand the standard, it is looking for all of the median points of diametrically-opposed elements of the feature. Most often they're used incorrectly. Symmetry. GD&T, the abbreviation for Geometric Dimensioning and Tolerancing, is a set of standardized symbols and conventions that are used to describe parts in a way that makes it easier for customers, manufacturers, and other supply chain participants to successfully communicate. #6. Concentricity is generally reserved for high-precision parts, and only. ; For drawings, click Geometric Tolerance (Annotation toolbar) or Insert > Annotations > Geometric. We are quoting some parts with 1/4 -28 2A (male) threads and 8-36 2A Left hand male threads. Powerhound Production Supervisor Inventor 11 Mastercam X Smartcam 11. From the ribbon select Concentricity. This callout sets a standard on how straight a feature must be along its length. Both radial variation and axial variation are measured and held. Counterbores. Question: In the following print Gd & T callout for the smaller hole is for a. In GD&T, Total Runout controls how much a feature or surface can vary with respect to a datum if the part is rotated 360 degrees around the datum axis. San Pedro Street Ste 4 ♦ Gilbert, AZ 85233 USA (480)478-0041 ♦ (480) 478-0041 Fax ♦ An Introduction to Geometric Dimensioning and Tolerancing (GD&T) Michael Yount Proof Engineering Co. It says that each diameter much be concentric with each other and I was trying to avoid having 4 concentricity callouts for each diameter if at all possible. This control is used a lot in a variety of situations that involve coaxial relationships. If the case isn’t properly concentric and the bullet isn’t properly aligned down the center of the bore, the bullet will enter. ASME Y14. The centerline of your pattern must lie completely within a . Total runout controls both the amount of variation in the surface as the part is rotated, but the amount. ) in any combination have a common axis. 3. Concentricity in its true form is difficult to measure, and requires measuring size, roundness, and position of two surfaces. Total runout is measured by rotating the part 360 degrees around the datum axis and using a dial indicator to see the variation on the part surface. John Riggins. For the the complete list of the first 256 Windows ALT Codes, visit Windows ALT Codes for Special Characters & Symbols. GD&T Flatness is a common symbol that references how flat a surface is regardless of any other datum’s or features. 03. Search in titles only Search in PC-DMIS for CMMs only. FIG 5-50 OR SECTION 5. If anyone can give me a specific example, that would be greatly appreciated. Drag the tolerance to the existing dimension. 025" off and not notice. 005" with the holes that were cut by laser. Geometric Dimensioning and Tolerancing is supported in VXinspect if required. True position finds the centroid of the surfaces. 2 (front bore is datum, rear bore has concentricity callout). As long as the previous machine, and operator, is worth their salt then the concentricity, or ‘roundness’, should essentially be exactly zero. I would like to put a runout callout on my drawing, but have never called out runout on a gear before. Also there is no Diameter symbol in the control frame in front of the . Concentricity is, roughly speaking, what you want if you need a shaft to be balanced, but don't need it to be actually round. Use true position or runout/total runout instead. It's boundary and tolerances are relative to the physical edge of the circle, not the axis line. Cylindricity is a fairly common callout for shafts, pins and any critical cylindrical element. The GD&T symmetry callout ensures symmetry control by checking the distance. A countersink consists of a conical hole that is coaxial to a cylindrical hole, where the angle of the cone is. Concentricity. 05 A O O A O O O It is locating the 0100 cylinder's derived median points relative to the datum axis of the bore. 2 Concentricity -Concentricity tolerance drawing call out. If I construct an axis line from the cylinder and make that line the datum. 1528 W. none of the above The GD & T call out below is for a. 06-18-2009, 02:00 PM. I think the total runout callout of . The correct method would be to use the datum as the datum. 2. There's a concentricity callout for the deep bore (brown) called back to the small pilot (yellow). Turning Point Tutors cc Achieving academic excellence Exam Revision Notes MOW 217 Presenter 1: Benji Gwashavanhu Presenter 2:The thread is 1/2-28 if that matters. Concentricity r r Location Symmetry i i Circular Runout h h For Related Features Runout Total Runout t t . They also allow up to . See Figure 26. Sometimes called roundness, circularity is a 2-Dimensional tolerance that controls the overall form of a circle ensuring it is not too oblong, square, or out of round. powerhound (Mechanical) 27 Oct 15 16:52. Concentricity and symmetry are also types of location tolerances. 005" be within tolerance for your part?Straightness tolerance is a 2-dimensional GD&T callout that controls the straightness of part features. Post by Tom Oakes » Thu Sep 06, 2018 8:16 pm. 13. 5 2018 GD&T standard are relatively minor. Runout can also measure concentricity for a product. 005". Note that in the case of the 90° countersink, this callout is the same as a 45° chamfer because the countersink angle takes both sides into account, so it is twice the chamfer angle. A recommended datum. From Old School conventional guys, to CNC Programmers, to the…When you call out parallelism, flatness is implied. I just wanted to see how you might handle this concentricity callout in this cavity: Pic11. It says that each diameter much be concentric with each other and I was trying to avoid having 4 concentricity callouts for each diameter if at all possible. Drawing Callout: Description: Concentricity, (called coaxiality in the ISO Standard), is a tolerance that controls the central derived median points of the referenced feature, to a datum axis . I have Alig 1 for the main/piston bores and Alig 2 for the other 3 back bores. From the ribbon select Position. The shoulder diameter is the basis for the determination and callout of the screw size. Runout is what you measure by rotating a part clamped on one cylindrical surface with a dial indicator on another. • For workpieces with high concentricity callout • For radial readjustment of workpieces with big changes in weight during machining • To apply additional grip force to the workpiece by the adjustment screws • Readjustment of the centerline of the workpiece in process Technical features • Integrated fi ne adjustment to center the. 005" with the holes that were cut by laser. 1528 W. by Seth Elder on September 14, 2020. Introduction to Datums. The general rule of thumb is not to use threads for alignment. First, the journal would be measured to find out how much runout it had. Fluent with axial and radial stack ups as well as… In this thread, for example, you want to apply concentricity callout to the hole. You will be taken to the agent interface. . Here you can see that GD & T symbols are broadly categorized into the following categories based on their features. 020. Notice the difference in the picture above. Your challenge is to create a backbore operation in this part that has a tight concentricity callout. To optimally control and communicate these variations, engineers and manufacturers use a symbolic language called GD&T, short for Geometric Dimensioning and Tolerancing. Roundness, or circularity, is the 2D tolerance that controls how closely a cross-section of a cylinder, sphere, or cone is to a mathematically perfect circle. To specify geometric tolerance properties, do one of the following: For parts, click Geometric Tolerance (MBD Dimension toolbar) or Tools > MBD Dimension > Geometric Tolerance. 004 smaller than stock size. The ASME standard finally completely dropped concentricity as a callout altogether because everyone was misusing it so much. It’s a simple issue of uniformity. 2 width. For most else, other callouts are a better choice. Profile tolerances can be used to control location, but these are covered separately. OD/ID Concentricity Callouts Tubing OD/OD concentricity requirements can be indicated on a drawing in several different ways, including: GD&T concentricity symbol, which is a circle within a circle Eccentricity percentage TIR (Total Indicator Reading) Written statements such as “OD and ID must be concentric within 0. This scan must then be analyzed to determine the central axis points at each location along the cylinder, forming the true part axis. It says that each diameter much be concentric with each other and I was trying to avoid having 4 concentricity callouts for each diameter if at all possible. I ask because Y14. Concentricity is the measure of how true a geometric shape is to its ideal form. The size and alignment of each disc is taken into account. Concentricity is sometimes harder to measure, but it actually is more forgiving (because the bore could be oval-shaped yet still be concentric). If a drilled or reamed hole must run perfectly true to a coaxial counterbore or circular boss, a concentricity callout is the best way to assure this. In the case of axis parallelism, the zone’s shape is cylindrical which is represented by a diameter symbol in this block. I thought a concentricity callout was only used on a high speed rotating part application. 09-16-2008, 09:28 AM. Taking 3 points on a CMM using concentricity will construct the ideal circle and give you a better idea of how they will fit. Many people are confused by concentricity callouts. You can specify document-level drafting settings for hole callouts. 005 or so I’d rather bore these parts but they’re somewhat hard and there is a lot of deflection with the small boring bar that will fit the ID. I know concentricity is obsolete, but I'm curious how you guys would handle this. • So the Largest Axial Deviation is 0. Datum A is a plane. The feature must be concentric with the axis within 0. The concentricity value can be calculated by using two diameters — one for the hole and one for the shaft that goes through it. com readers get an exclusive discount on training! Get the Best GD&T Training Available. The shoulder is the ledge between threads and shaft. Circular Runout = Concentricity (axis offset) + total Circularity (out of round) Runout captures both of these in a single measurement when you are comparing the. Straightness, Flatness, Circularity, Cylindricity, Line profile, Surface profile, Perpendicularity, Angularity Parallelism, True position, and Concentricity callouts can be added to various created entities and shown in the report. See screen shot below from the machining program. A 3D scan of the entire surface, combined with expensive software to calculate every median point of every cross section is the only practical way to. png. Specified measurement position. This symbol specifies the depth of a feature. In ASME, you cannot have zone modifiers on a symmetry callout or a concentricity callout. 0 at the center. Or, can I just get away with using Calypso as is?Then make the end of the pin concentric allowing for maximum material condition based on the concentric call-out (and any other callouts such as perpendicularity and hole tolerance). Concentricity and symmetry are also types of location tolerances. The tolerance is 0. Straightness c. The symbol next to the datum is Maximum Material Boundary (MMB) and allows for datum shift as the datum feature moves away from its maximum material condition (for a cylinder, this is as it gets smaller). ASME: concentricity should be replaced with position. The following formula is used to calculate the concentricity: C =. Concentricity considers how a cylindrical shape is positioned on a theoretical axis. Definition of Total Runout. The graph expresses the annual evolution of the frequency of use of the. Concentricity. Despite the difference in name, both do broadly the same. A requirement that the centerline or axis of two features are located within a specified tolerance of each other. Both symbols focus on the theoretical center datum being. I’m making these parts that call for rough and finish reamers, but I’m having trouble holding to the concentricity callout of . 4. What I'm finding is that making the cylinder the datum I get bad results for the runout or concentricity. We can use the above setup and follow the following steps to measure cylindrical part concentricity. Total Runout. Note: If the GDT icon is ‘greyed-out’ this details that the selected feature does not support this call-out. I have multiple parts where a cylinder is called out as a datum and another cylinder has either a runout or concentricity callout back to the datum. If so, I would ask your customer for clarification on what feature they want you to use for datum -A-, because it is not clearly defined in the view shown. It is defined as the variance of the surface. I just wanted to see how you might handle this concentricity callout in this cavity: Pic11. Designers and engineers utilize this international language on their drawings to accurately describe part features on the basis of size, form, orientation and location. The 2 nd and 3 rd instances of the word “concentricity” in the 2018 Y14. 3 Surface profile: Surface profile tolerance is the allowed maximum deviation of an outline from the true one. Flatness d. The largest maximum and minimum difference is used as. The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions). In general, the combination of cylindrical run-out combined with balancing (as in balancing a crankshaft) can be performed which will result with the desired result. Concentricity and symmetry are also types of location tolerances. . My Notes Close. use cylindricity and concentricity items from the dimensions toolbar to report per the drawing. See Figure 26. To examine the differences in these concepts it is helpful to first review the Geometric Dimensioning and Tolerancing hierarchy of SLOF - Size, Location, Orientation, and Form. This instructional article by Bob Kohl explains the reasons brass can exhibit poor concentricity, and why high bullet run-out can be detrimental to accuracy. In this case, the concentricity callout would be referenced to the journal measurement slice (red band). Figure 5. I know concentricity is obsolete, but I'm curious how you guys would handle this. So ideally, both features should share the same true central datum plane. How to Use True Position. Perpendicularity can reference a 2D line, but more commonly it describes the orientation of one surface plane perpendicular to another datum plane. We can explain the working of the cylindricity callout by means of a disc stack. In the ISO standard, it's more or less a position callout, vs the ASME definition which is that the center of all opposing points is within the tolerance zone which is the part that's difficult to measure. A Reddit for Machinists of all varieties. The groove can be dimensioned for total runout to datum A. Step-2: Plot the controlled surface outer profile using CMM or other measurement instruments. These measurements would then need to be compared to. And MachinistGuides. There's a concentricity callout for the deep bore (brown) called back to the small pilot (yellow). The geometric dimensioning and tolerancing (GD&T) standards in ASME Y14. Your drawing uses 2 surfaces only. 05 20 0. Concentricity tolerance is a condition in which the axes of all cross-section elements of a feature’s surface of revolution are common to the axis of a datum feature. The GD&T is telling you what the datum is. First, you will have to establish and identify where would the point of the datum plane, surface, or axis lies. it needs to point to an actual feature of size. It is locating the 0100 cylinder's axis relative to the datum axis of the bore. Most often they're used incorrectly. Advanced Search We may lose more than 36% of the tolerance zone by using the callout in this manner. Transforming CMM Metrology with PC-DMIS Pro, CAD and CAD++ software. Select the GDT tab. Measure the inside diameter datum A as a cylinder then level and origin to it and then measure the grieve and dimension the total runout of it to Datum A The basic. You can apply positional tolerances to the individual holes. Question 9 of 92 SELECT THE TWO CORRECT ANSWERS: What specifically is this Concentricity callout controlling? O O O +0. The tolerance is 0. We would like to show you a description here but the site won’t allow us. Concentricity by definition requires a mathematical analysis of the surface to determine "median points. Concentricity is a special case of coaxiality where multiple features exist on the same plane. Figure 5 shows the recommended definition using SOLIDWORKS MBD. 4(k) of the 2009 edition, we can assume the hole is coaxial with the spherical surface, hence datum E is. The reason shooters work with tools and gauges to measure and control concentricity is simple: to make sure the bullet starts down the bore consistently in line with the bore. We can use the above setup and follow the following steps to measure cylindrical part concentricity. The purpose of a countersink is to allow a fastener, typically a flathead screw, to sit slightly below the surface of the part. Concentricity. The tolerance zone consists of two concentric circles that lie on a plane that. Concentricity, is a tolerance that controls the central derived median points of the referenced feature, to a datum axis. For the the complete list of the first 256 Windows ALT Codes, visit Windows ALT Codes for Special Characters & Symbols. Concentricity: . However, in GD&T, the meaning of concentricity differs slightly from its literal definition commonly understood by engineers. Tubing OD/OD concentricity requirements can be indicated on a drawing in several different ways, including: GD&T concentricity symbol, which is a circle within a circle; Eccentricity percentage; TIR (Total Indicator Reading) Written statements such as “OD and ID must be concentric within 0. This callout sets a standard on how straight a feature must be along its length. 3. I'm inspecting a manifold with a custom bore. 5-2018 define five main types of controls for various part features. You really don't even need a tapered shoulder. When you project a datum along the axis line, the projected deviation grows. It can be out of round by more than the concentricity callout, but still pass if the out or roundness is symmetrical. As outlined above, the concentricity value relies on two points 180 degrees apart on the same cross-section, while the runout value is comparing the most extreme. This tolerance is similar to concentricity, and the verification of symmetry tolerance is also time-consuming and difficult. ground on the outside diameter (OD) and also ground on the inside diameter (ID) the difference from dead zero on an indicator is your concentricity deviation from perfect. 0002 so you would have as little taper as possible. It looks like a callout exist for that. I have multiple parts where a cylinder is called out as a datum and another cylinder has either a runout or concentricity callout back to the datum. in the figure above. I know concentricity is obsolete, but I'm curious how you guys would handle this. ASME Y14. I would have recommended calling the profile of the hex concentric to the shaft, however seeing as most others here seem to be settled on "profile of a surface" I'll have to re-evaluate my understanding of the concentricity callout. Drawing Callout: Description: Angularity is the symbol that describes the specific orientation of one feature to another at a referenced angle. jdm2008 said: I have the following call out on a drawing. To Insert a Geometric Tolerance into a Part. 0025 from the center axis of the part as defined. Then measure the other diameter and note the location of its center. It says that each diameter much be concentric with each other and I was trying to avoid having 4 concentricity callouts for each diameter if at all possible. A true position of . Relation to Other GD&T Symbols: A great way to relate this symbol to others is through this equation: Circular Runout = Concentricity (axis offset) + total Circularity (out of round) Runout captures both of these in a single measurement when you are comparing the surface to another datum. So if your center is 0. 3. I know concentricity is obsolete, but I'm curious how you guys would handle this. Surface perpendicularity does not directly control the angle between the surfaces. Channel: PC-DMIS for CMMs. In other words, the GD&T "Position" Tolerance is how far your feature's location can vary from its "True Position". It can reference a 2D line referenced to another 2D element, but more commonly it relates the orientation of one surface plane relative to another datum plane in a 3-Dimensional tolerance zone. What is concentricity in GD&T and how is it measured and calculated? Let’s get into some details and the difference between concentricity and runout. Cyclindricity c. For more ALT codes for various signs and symbols, see ALT Codes for Miscellaneous Symbols. This passage reads “However, two past practices, use of concentricity and use of symmetry symbols, are no longer supported. The standard form of straightness is a 2-Dimensional tolerance that is used to ensure that a part is uniform across a surface or feature. Tweet. The measurement setup requires two indicators at 180° to each other, from which the median. cylindricity e none of the above 50 in a concentricity callout. •The true geometric counterpart’s axis or center line or center plane is the datum. Available for all document types. The GDT panel will open in the lower LH corner of the UI. 2 mm. To make an assessment of whether the part conforms to our concentricity callout we must make a representative check of the surface of our controlled cylinder as it compares, by our definition, to the datum axis. Post by Tom Oakes » Thu Sep 06, 2018 8:16 pm. RE: ISO Standards Not Recodnizing Rule #1. Definition: The countersink symbol is used to indicate that a countersink hole feature is required. What they are doing in QA is the best they can do. This 2D callout needs us to assign it a datum axis to check these features. 05mm and we were getting numbers around. As shown from the table, the Straig htness Tolerance remains the same regardless the change on the FOS of the diameter . I would have recommended calling the profile of the hex concentric to the shaft, however seeing as most others here seem to be settled on "profile of a surface" I'll have to re-evaluate my understanding of the concentricity callout. Many people are confused by concentricity callouts. Q: Can a datum callout be attached to a feature axis, center line, or center plane? A: No. In GD&T(Geometric Dimensioning and Tolerance), concentricity is a 3D callout that ensures one or more part features are concentric around a datum axis. Level and origin to that 3D line. 005 however it meets the diameter call out (at all points) which is less strict. Straightness can control two very different types of functions. Fri, Mar 13 2020. If I construct an axis line from the cylinder and make that line the datum. Straightness c. Both concentricity and coaxiality are difficult to measure but coaxiality is much more difficult to measure between the two of them. To create a feature control frame: Click on the “Annotation” tab. Total runout controls both the amount of variation in the surface as the part is rotated, but the amount of variation in the axial dimension. 4 mm. Concentricity Tolerance Zone. The goal is to ensure it is straight enough for the application. Total runout controls everything that circular runout controls + tapering of the. Symmetry. 005" be within tolerance for your part?Straightness tolerance is a 2-dimensional GD&T callout that controls the straightness of part features. Default file types. You could check the plate hole first screw it in then check the cylinder. , GD&T stands for:, The often misused concentricity callout means: and more. Symmetry is a three-dimensional tolerance that defines two features on a part that are uniform across a datum plane. The concentricity tolerance can be evaluated or measured in four basic steps. concentricity callout. Concentricity is concerned with the centre, and the control is associated with a feature of size to indicate it is applied to the axis. Determine if the free state modifier should be specified. This looks like an ISO print so I'm not sure, but this may also be.