Geometric positional tolerance is given of.1 mm with modifier M. The modifier has specific meaning, It add a bonus tolerance. When shaft is at MMC there will b . GD&T bonus tolerance is an important concept for design engineer. This article will explain the Geometric Dimensioning and Tolerancing concept with an. When geometric tolerance is applied to a feature of size and it contain a MMC modifier in the tolerance portion of the feature control frame.

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Just know that if you come across the circle S, take your pen and cross right through it and it has the same meaning.

Introduction to Bonus Tolerance

I hope this helps. Keep the information flowing guys! Here you would use the larger tolerance zone to locate your hole and your perpendicularity call-out to restrict the tilt of the whole to a tighter degree.

This does not work well when you are considering a pattern of holes that function together such as a bolt hole pattern. My original question If we have specified originally pos. There is no difference in what’s happening. Bonus tolerance is the additional tolerance available for a geometric control attached to gc&t feature of size with MMC maximum material condition and LMC least material condition modifier.

The tighter the tolerance zone the straighter the hole must be. So the difference in their sizes hole and pin is important, because the bigger the difference the more play they will have.

Figure 2 Figure 2 shows how to determine the amount of bonus tolerance permissible in an application.

Let’s assume, you have a positional callout for the hole with MMC. If the locating is not important, and the hole and shaft merely need to fit together, I would go for mmc on hole. Bonus tolerance in LMC mousepotato, I believe your confusion comes from a simple fact that you take the statement: The circle S is a now discontinued practice that just means that the tolerance or the datum is to be taken at regardless of feature size. The statement is true only if location of the hole is controlled by position tolerance defined at MMC basis.


That’s my question in first palce. In my opinion, R F S condition is applicable in case of critical fitments fitments involving critical demands like wear control, leakage prevention, smoothness at precision motion etc. Although a straightness control is used for the example in Figure 1, the bonus tolerance concept applies to any geometric control that uses the MMC or LMC modifier in the tolerance portion of the feature control frame.

Tips on Calculating Bonus Tolerance

But how is this possible with LMC of a hole See the attached excerpt? It is perfectly clear tolrance me how a Bonus tolerance gets added to the position tolerance of a hole, while it starts to “get bigger” from MMC towards LMC. The inclusion of the S or not just means that the datum references are to be considered at Regardless of Feature Size.

The problem for mmc is incorrect. I hope this helps, good luck.

Bonus Tolerance Calculation – GD&T

At MMC the maximum clearance available between the gauge and the hole is 0. Bonus tolerance in LMC greenimi: Which is actually visible if you look at the numbers given by me above.

It depends on what you are measuring for. What is Bonus Tolerance? It’s not the local size and it is not the actual mating envelope, it is the unrelated actual minimum material envelope.

If you really dig into what you said here, you have described the exact same thing for two different scenarios.


The goal here is functional assembly of your parts. Register now while it’s still free! I get annoyed when people just bury their heads in the sand.

Bonus Tolerance | eMachineShop

And before pmarc is pointing and question it and I realize it will confuse the OP I would say that: If locating is important for a hole and a shaft, then the “play” between them can be arrested by an Lmc modifier. Another example for a useage that benefits with the application of LMC is a precast hole intended for subsequent machining. The axis of the hole must lie entirely within the tolerance zone for your part to be accepted by inspection.

Bonus tolerance in LMC “the tolerance should get stricter”?? A functional gage does not provide a dimensional measurement; it only indicates if the part is or is not to the print specification. Our True position box looks like this. We do plan on circling back and adding valuable content to the website in the future though.

On Digital Transformation may be defined in a number of different ways by analysts or enterprise software vendors. Red Flag This Post Please let us know here why this post is inappropriate. When the actual mating size of the feature of size departs from MMC towards LMCan increase in the tolerrance tolerance— equal to the amount of the departure — is permitted.

This means contolling location of the hole by position at LMC tolerance is not the way to go when you mostly care about assembly.