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Close Box. Log In Come Join Us! Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden. RE: Position vs Runout dgallup: "double hole movement", what do you mean by that?
RE: Position vs Runout Runout it's a surface control. RE: Position vs Runout Draw a circle with a radial offset corresponding to half the position tolerance; then figure out the runout that results from that. RE: Position vs Runout Yup - the hole moved 0. RE: Position vs Runout pmbov, Your runout zone is not shown properly. RE: Position vs Runout chez - it is a possible runout zone, just not one that corresponds to the offset shown by this particular feature.
RE: Position vs Runout Hum? RE: Position vs Runout A dial indicator at the 12 o'clock position will be down RE: Position vs Runout pmbov, The deviation you have shown actually results in 0. RE: Position vs Runout ok in conclusion, runout 0. See the article that greenimi posted earlier. Quote pmbov, 9 Apr 20 and are treated equally in a tolerance stack.
Total runout can allow form variation which would have a UAME with an axis outside of that allowed by the position tolerance. And the position tolerance can allow form variation in the surface which would not be allowed by total runout. If we're talking about circular runout which is the symbol you have shown in your examples that complicates the matter even further. RE: Position vs Runout ok hum, so position for location yes, but I thought it is also tilt of the centerline.
Resources Learn methods and guidelines for using stereolithography SLA 3D printed molds in the injection molding process to lower costs and lead time. Runout on a CMM is static. The part is not turned but is measured by points or scanned and these points make up the best-fit circle that will be use to check to the datum.
The datum is also made up of measured features that are fitted into an element. All dimensions are in mm. All GDandTBasics can provide is an understanding of the controls and how they work.
I can offer general advice regarding your situation. If your application is one shaft spinning within another then I would tend to agree that you need either a total runout or concentricity control as position would not be the best way to ensure fit. One word of caution would be to look long and hard at runout before using concentricity.
Concenricity is a more difficult requirement to machine and therefore inspect. I was confused how to fix the concentricity value for such a tolerance.
Is it possible to have a look and let me know your opinion of possible concentricity value. We have two dia in bolt. When we check concentricity of dia 8. I can not understand why it happened. Concentric should be same w. At first glance one would expect the concentricity between the two to be the same.
This would be the case in a perfect world, unfortunately reality sets in. What you are seeing is an issue with circularity.
How the part is fixtured from one diameter to the other is most likely what is causing the discrepancy. Your chuck may be grabbing the high points of one diameter in a different manner than it is the other diameter. Hi guys, I just want to know why we use diameter symbol for indicating concentricity two different O. D in same shaft….. JP — With concentricity controls you are required to have either the diameter symbol or the spherical diameter symbol precede the tolerance in the feature control frame.
As for why, it is because by its nature the tolerance zone for concentricity is either a cylinder or sphere. With that said, I would urge caution against using concentricity except in specific situations.
It is a difficult control to produce and measure, usually only required when a precise distribution of mass from the center axis is required. Normally, this is restricted to very close tolerance situations or where you are concerned about an imbalance such as for a rotating shaft.
Ok, I have an issue regarding inspecting for Concentricity on samples of extruded tubing. Since, if I am not on crack, this formula tells you nothing about how concentric the tubing is, what would you suggest as using for a physical determination of concentricity on an incoming goods inspection?
I would expect runout as being the easiest to physically measure. Opinions, thoughts? Second it sounds as though a more appropriate control for what you are describing would be position.
This often causes problems. To start things off, please understand that concentricity and symmetry are two often misunderstood and misused symbols. They are expensive to manufacture and inspect and can almost always be substituted by either runout, as you suggest, or position, depending on you application.
The instances where it should be used are where you care about the distribution of mass, i. As for how to inspect it, my immediate answer is to do it with a CMM. It requires two diametrically opposed measurements where the local radius from your datum can be determined. If the datum A of a gear is the center line of the gear should the datum A of the mating shaft also be the center line of the shaft?
If I assume that the drive shaft runs through the exact center of the gear, then I would agree with your assessment. However, there are always exceptions.
For instance, is there a big flange at the end of the shaft that has to mate to something else with fine precision? It really all depends on your specific application. Without knowing anything more about your part, my first inclination would be to make this your primary datum. Thanks for taking the time to help expand our community knowledge. Dear experts. I have an issue regarding on concentricity. The spec limit of concentricity between two holes is 0. The problem is, the after machine concentricity of these to holes is unstable out of 0.
Is there any other factor that may contribute to this condition? Your Position the coaxiality is one component of Concentricity, however it also controls the distribution of surface form. For example, a perfectly centered square part would be concentric because the part is coaxial and the form is even. However if you cut one of the corners of a square, the form would no longer be even. This would cause your Concentricity to go out even though your coaxiality is perfect.
Is it correct to use 0. Concentricity is a tolerance zone that locates a feature. The sizes do not matter. I have a text representation that calls for Maximum concentricity of 0. Seems like this should be maximum LACK of concentricity. What is the proper way to state this condition? The state to use and eccentrimeter to measure valve guide to valve seat concentricity in an engine head assembly. Optimum would be 0. Am I right? You are calculating the amount of concentric error in your part.
However, to measure concentricity according to the ASME standard is a much more complicated endeavor. You need to calculate if all of your derived median midpoints fall within your datum tolerance zone.
Question, Position on 2 cylindrical features, When inspecting with V-block and dial indicator and get. Thank you very much, Jay Gus. Tags: None. We had this discussion a while back. I'll try to locate the thread. Comment Post Cancel. Be careful. I couldn't find the thread. But I seem to recall, the conclusion reached agrees with Craig's post. Thanks Again Guys!
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