Ordinate dims have neg values - my machinist is melting


(Other Bruce) #1

For anything not dead clear, I ask my machinist where he would like his datum. Often he chooses a hole somewhere in the part. No problem until I give him the drawing. He freaks out because dims to the left or below the datum are shown as negative numbers. I don’t really care if they’re shown negative or not, but I have no idea how to show all of them as absolute values. Is there a way?

Many thanks!
OB


(Mary Ann Fugier) #2

Hi Bruce,

I am seeing some issues with ordinate dimensions, but I am not seeing the negative number issue.
Does he open the 3DM in Rhino, or are you sending him another file format to open?

No matter which way I go with the dimensions (up, down, left, right) I get positive numbers.

Could you please post a simple file that will show the issue?
I am also posting a feature request to update an existing dimension to the current datum.
Not sure what has changed or if there never was an update, but it need some attention.

Thanks for letting us know about this issue.
Sincerely,
Mary Ann Fugier


#3

I think I recall this being discussed earlier this year in an early release. What version of Rhino are you running?

IMHO ordinate dimensions should provide an option to show negative dimensions or not.

Traditional machinists running manual machines tend to think of negative offsets as pure fiction like imaginary numbers. After all, there’s no such thing as negative length, right?

CNC machines are designed to use negative numbers and will be totally confused by positive numbers on both sides of a datum. So will CNC machinists. They will laugh.

Which option a Rhino designer would chose would depend on his downstream environment and it’s preference.


(Other Bruce) #4

Thanks for the replies!
It’s Rhino 6 SR 4.
I am mildly enjoying that I moved his chosen datum to the corner of the part so its all in the positive direction now. Interestingly, I just opened the file to export the part that caused the fuss, and tried some dims to the negative side - they came out positive! Perhaps it was solved with the recent update (that also solved the ability to remember the base-point from the last time the command was invoked)