Limit Tolerance Text Placement
Limit Tolerance Text Placement
(OP)
Howdy All,
I have a question about how Limit Tolerance type dimensions should be written. I have some old drawings with diameter dimensions to the Inside of a machined surface and diameter dimensions to the Outside of machined surfaces.
-When displaying a dimension for the inside diameter of a surface the smaller number is on top. Example 9.995/10.005
-When displaying a dimension for the outside diameter of a surface the larger number is on top. Example 10.005/9.995
The purpose seems to be:
1) When a machinist is machining an inside surface the first number he will machine too is the smaller number – so the smaller number is on top or first.
2) When a machinist is machining an outside surface the first number he will machine too is the larger number – so the larger is on top or first.
I've always put the larger number on top regardless of Inside or Outside machining, but can't explain way
.
My question is – Is this practice part of any current (or past) written "standard" that can be quoted from? ANSI, ASME, ISO, Global anything?
If not - Is there something in any of the Drafting Standards that defines the placement of the smaller and larger numbers when using Limit Tolerance type dimensioning?
Thanks
I have a question about how Limit Tolerance type dimensions should be written. I have some old drawings with diameter dimensions to the Inside of a machined surface and diameter dimensions to the Outside of machined surfaces.
-When displaying a dimension for the inside diameter of a surface the smaller number is on top. Example 9.995/10.005
-When displaying a dimension for the outside diameter of a surface the larger number is on top. Example 10.005/9.995
The purpose seems to be:
1) When a machinist is machining an inside surface the first number he will machine too is the smaller number – so the smaller number is on top or first.
2) When a machinist is machining an outside surface the first number he will machine too is the larger number – so the larger is on top or first.
I've always put the larger number on top regardless of Inside or Outside machining, but can't explain way
My question is – Is this practice part of any current (or past) written "standard" that can be quoted from? ANSI, ASME, ISO, Global anything?
If not - Is there something in any of the Drafting Standards that defines the placement of the smaller and larger numbers when using Limit Tolerance type dimensioning?
Thanks
Tobin Sparks
www.nov.com





RE: Limit Tolerance Text Placement
Not sure about historical use though.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently?
RE: Limit Tolerance Text Placement
ISO 406:1987 section 5 says:
The upper deviation or the upper limit of size shall be written in the upper position and the lower deviation or the lower limit of size in the lower position, irrespective of whether a hole or a shaft is toleranced.
RE: Limit Tolerance Text Placement
Thank you for your responses. Both ASME and ISO agree and now I know why I have been putting the larger number on top all along
Thanks Again
Tobin Sparks
www.nov.com