Tolerence measurement +0.02 to + 0.05

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Discussion Overview

The discussion revolves around the interpretation of tolerance measurements, specifically the range of +0.02 to +0.05 in fabrication drawings. Participants explore how to apply these tolerances in manufacturing processes, particularly in the context of fitting parts together.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks clarification on whether to fabricate within the range of +0.02 to +0.05 or to follow the maximum value.
  • Another participant suggests that there should be a nominal value associated with the tolerance, which should be targeted, while the tolerance indicates the acceptable range for inspection.
  • A different participant proposes aiming for the middle of the tolerance range, providing an example with a nominal value of 10.00 and suggesting a target of 10.035 with a tolerance of ±0.015.
  • One participant explains that tolerances ensure parts fit correctly, illustrating with an example of a bore hole and a shaft, where specific tolerances are applied to both to ensure compatibility.
  • A participant acknowledges previous advice may have been misleading, indicating uncertainty about double plus tolerances and expressing a preference for targeting the middle of the tolerance zone.
  • Another participant discusses the requirements for different types of fits, such as press fits and non-interference fits, emphasizing the importance of specifying tolerances appropriately for each scenario.

Areas of Agreement / Disagreement

Participants express varying interpretations of how to apply the tolerance measurements, with some proposing specific approaches while others indicate uncertainty or differing practices. No consensus is reached on a single method for applying the tolerances.

Contextual Notes

There are limitations in the discussion regarding the assumptions about nominal values and the specific contexts in which different tolerances apply. The discussion does not resolve how to handle double plus tolerances definitively.

raynee
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Hi,

I am new here. I would like to know if anyone can explain to me the meaning of +0.02 to +0.05 in a fabrication drawing.Does this part needs to be fabricated in this range of tolerence or,i should follow the maximum value.

Appreciate your replies.

Thanks.
 
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There should be a nominal value associated with the tolerance. That's the value you should try to hit, but the tolerance just gives the acceptable range for inspection not to reject the part.
 
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You should aim for the middle of the tolerance, or size +0.035. That then gives you a tolerance of ±0.015.

So if the nominal is 10.00, aim for 10.035 and that comes with a tolerance of ±0.015.

Shaft and hole diameters are commonly specified like this. Specifying (e.g) 10.00 as the nominal maintains the design intent, while the shaft will normally a be negative tolerance and the hole a positive one, and that makes it work in the real world.
 
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Tolerances can be used to ensure parts mate correctly.

For example, if you have a machined bore hole which is designed to accept a shaft through it, you could put a tolerance on both items. The Bore hole say 100mm diameter, you could put a tolerance on of your +0.02 +0.05.
For the shaft, you could say 100mm diameter - 0.02 -0.05. What this is doing is to ensure that the shaft will fit in the bore. If you had no tolerance, the bore & the shaft could have an identical diameter, and wouldn't fit.
 
Yeah, I think I gave some bad advice there. I don't deal much with double plus tolerances like that, so I guess I would make try to build it to the middle of the tolerance zone.
 
A "press fit" requires the shaft be specified oversize compared with the nominal bore size.
A non-interference or a lubricated fit, requires the bore be specified oversize compared with the nominal shaft size.
 

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