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FranzS
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- How to properly indicate dimensions on a 2D technical drawing?
Hi PF,
as in the company I work in we're updating all 2D technical drawings (production drawings) because of a software change, I'm now having some doubts about how to indicate dimensions correctly. By the way I'm not in charge of that job, I'm just discussing the possible options with the technical office in order to improve the current state of things.
So, until now, we have always indicated redundant dimensions (reference/auxiliary dimensions) without parentheses "( )". Actually, "my" guys from the technical office don't seem to have made up their minds about which really are the main dimensions and which are the reference/auxiliary ones... go figure. No issues in production though, just a bad old habit.
Now I'm suggesting to finally and formally decide which are the main dimensions and to use parentheses "( )" to indicate the redundant/reference/auxiliary dimensions (as in the sample drawing below).
Moreover, my concern is about formally respecting all tolerances. For instance, let's suppose that in the above drawing the dimensions are subject to a general tolerance of ##\pm 0.5## (whatever the units) and that the rightmost dimension "20" is not between parentheses.
In that case, I argued with my colleagues that the drawing is not technically correct because of the redundant dimensions and that the resulting tolerance on dimension "60" won't be clear (actually, you could think the same for each dimension).
They replied that they want to go on with their old method of redundant dimensions without parentheses and that, according to them, their way of indicating dimensions implies that, in this specific example, each single dimension will have to be within the general tolerance.
Now, their explanation actually makes sense to me as there's some kind of logic behind it (and it can indeed be applied to our machined parts without any issue) but I'm a bit skeptical about the conventionality / technical validity of such approach. I also think that their reasoning is equivalent to having a narrower tolerance on the three dimensions 20 / 20 / 20 (hope it makes sense).
Could you please advise me? Thanks guys.
as in the company I work in we're updating all 2D technical drawings (production drawings) because of a software change, I'm now having some doubts about how to indicate dimensions correctly. By the way I'm not in charge of that job, I'm just discussing the possible options with the technical office in order to improve the current state of things.
So, until now, we have always indicated redundant dimensions (reference/auxiliary dimensions) without parentheses "( )". Actually, "my" guys from the technical office don't seem to have made up their minds about which really are the main dimensions and which are the reference/auxiliary ones... go figure. No issues in production though, just a bad old habit.
Now I'm suggesting to finally and formally decide which are the main dimensions and to use parentheses "( )" to indicate the redundant/reference/auxiliary dimensions (as in the sample drawing below).
Moreover, my concern is about formally respecting all tolerances. For instance, let's suppose that in the above drawing the dimensions are subject to a general tolerance of ##\pm 0.5## (whatever the units) and that the rightmost dimension "20" is not between parentheses.
In that case, I argued with my colleagues that the drawing is not technically correct because of the redundant dimensions and that the resulting tolerance on dimension "60" won't be clear (actually, you could think the same for each dimension).
They replied that they want to go on with their old method of redundant dimensions without parentheses and that, according to them, their way of indicating dimensions implies that, in this specific example, each single dimension will have to be within the general tolerance.
Now, their explanation actually makes sense to me as there's some kind of logic behind it (and it can indeed be applied to our machined parts without any issue) but I'm a bit skeptical about the conventionality / technical validity of such approach. I also think that their reasoning is equivalent to having a narrower tolerance on the three dimensions 20 / 20 / 20 (hope it makes sense).
Could you please advise me? Thanks guys.
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