Negative Dims with Ordinate Dimensioning

[jack.frahm]

When you dimension a part using ordinate dimensions, do you specify the dimensions in the negative, as negative?

I had a conversation with the mechanical engineer who was designing this part. His opinion was that we should not call out the negative dimensions as negative. I won the argument from the stand point that our "company policy" was to show the dims as negative for clarity to the machine shop.

I wasn't to happy with using that as my position, and was wondering if there is a standard out there one way or the other. I checked ASME Y14.5M-1994 and it did say one way or the other that i could understand. One of my designers in my group has the standard from 1976 and it seemed to talk about it in appendix A like you were suppose to call out negative dims as negative. Was that ever "adopted"? Is there another source that my fellow Augities know about?

Attached is a sample of what I am talking about.

[jaberwok]

FWIW, I've never seen a dimension labelled as negative.
AFAIK, our national standards BS308/BS8888, which are generally almost the same as yours, do not mention the idea.

[Ron Oldenbeuving]

In Australia, anyway, I have never seen ordinate dimensions shown with a negative. If some concern should arise due to the proximity of a point being very close to the datum, the normal practice we use is to have the dim line dogleg away from the datum, to signify which direction it is from zero.

My $0.0275 worth (allowed for currency exchange)