Tolerence measurement +0.02 to + 0.05

[raynee]

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.

 

[timthereaper]

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.

 

[Bandit127]

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.

 

[PizzaWizza]

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.

 

[timthereaper]

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.

 

[Baluncore]

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.