I have been tasked with explaining some items concerning a program I inherited concerning Xactmeasure Profile. I have a two part question. Attached is a pic of the profile dimension results and the D datum results. First, the call out is |Profile|0.010|A|D(M)|B|. A is a plane, D is an intersect of a cylinder and plane (constructed circle for size) and B is a line. The attached results show the D Datum size at 0.4683 and the nominal at 0.472. I am trying to figure out the Bonus of 0.0113. Is it the bonus of the feature plus it's position tolerance, see second attachment? I have looked over 2.8, 4.11.5, 4.16.2, 4.16.4 & 4.17 and now my head hurts. This one I am confused as the standard shows the other way around, Datum is profile and feature is position.Second, if datum A is zplus and B is in the X direction, why whould I have a Y shift? Please let me know if you need more info. My previous job only used legacy reporting and this one has a lot of parts utilizing this boundary condition.
Go to your the profile dimension and turn GRAPH=ON then MULT=100. this will show you where the hits you are taking are showing up on the CAD model.
with a profile of .010 you have a +/-.005 on both sides of the imaginary "nominal" surface. if your max hit is -.0035 from nominal and your other MIN hit is .002 from nominal you have a total of .0055 profile but you never break out of your +/-.005 profile tolerance.
in your case your max/min values are .0027. combined that gives you a total profile of around .0055
since your D3 feature is MMC, nominal is .750 +/-.010 and the feature measure .7526 (a difference of .0026), you can add that the to true position tolerance of .010, effectively making it TP .0126. (the spec is ALLOWING you some extra BONUS room to play with since your .750 feature is not "MAXED" out on it's size.)
continue to apply the same thing to the other diameter feature, add them together and that's your total bonus tolerance.
Bigwig, this is incorrect information. When the "M" in a circle is applied to a datum it indicates in a material boundary condition not a maximum material condition. The 1994 standard confusingly used the term MMC to refer to both cases. The 2009 version attempts to clarify by using the term MMC for a feature and MMB for a Datum. The "Bonus" one obtains from MMB CANNOT just be added to the position or profile allowance like MMC can. Instead it allows the Datum to "shift" by up to that amount the actual Datum Feature varies from it's maximum size. This replicates wiggling a hard functional gage.
Russd, you cannot use MMB in Legacy and get the sort of results you are looking for. When you apply MMB in legacy it results in a go/no go result rather than a valid value returned for the GD&T tolerance. Somewhere years ago there was a document written by B&S/Wilcox/Hexagon explaining this.
I am very busy right now, but i will try to get back to this thread soon to clarify more.
Please post a sketch or relevant sections of the drawing that show the Datum Features, their spatial relationship to each other, the feature needing profile and the FCF(s) and Basic Dimensions.
Go to your the profile dimension and turn GRAPH=ON then MULT=100. this will show you where the hits you are taking are showing up on the CAD model.
with a profile of .010 you have a +/-.005 on both sides of the imaginary "nominal" surface. if your max hit is -.0035 from nominal and your other MIN hit is .002 from nominal you have a total of .0055 profile but you never break out of your +/-.005 profile tolerance.
in your case your max/min values are .0027. combined that gives you a total profile of around .0055
since your D3 feature is MMC, nominal is .750 +/-.010 and the feature measure .7526 (a difference of .0026), you can add that the to true position tolerance of .010, effectively making it TP .0126. (the spec is ALLOWING you some extra BONUS room to play with since your .750 feature is not "MAXED" out on it's size.)
continue to apply the same thing to the other diameter feature, add them together and that's your total bonus tolerance.
Bigwig, this is incorrect information. When the "M" in a circle is applied to a datum it indicates in a material boundary condition not a maximum material condition. The 1994 standard confusingly used the term MMC to refer to both cases. The 2009 version attempts to clarify by using the term MMC for a feature and MMB for a Datum. The "Bonus" one obtains from MMB CANNOT just be added to the position or profile allowance like MMC can. Instead it allows the Datum to "shift" by up to that amount the actual Datum Feature varies from it's maximum size. This replicates wiggling a hard functional gage.
Russd, you cannot use MMB in Legacy and get the sort of results you are looking for. When you apply MMB in legacy it results in a go/no go result rather than a valid value returned for the GD&T tolerance. Somewhere years ago there was a document written by B&S/Wilcox/Hexagon explaining this.
I am very busy right now, but i will try to get back to this thread soon to clarify more.
Please post a sketch or relevant sections of the drawing that show the Datum Features, their spatial relationship to each other, the feature needing profile and the FCF(s) and Basic Dimensions.
