Leading zero in dimensions

[jw48]

We've talked around this subject before, but I'm still puzzled.

The attachment shows a simple box. The longer side rightly gets a leading 1; the shorter side doesn't get its leading zero so gives an unbalanced appearance and is open to ambiguity. Of course, the zero can be edited in, but why is this necessary? Is it a standard drawing convention to start with the decimal point? As I now only draw for my own interest I'm out of touch with drawing conventions.

The Dimension tab gives options for .1 .01 .001 etc but a leading zero doesn't seem to be on offer anywhere, although a choice of point or comma is given for the decimal separator.

[Admin 1]

It's my understanding that the leading zero (0.00), as per decimal value standards, has always been a convention to indicate that it's a "less-than-one decimal value", as apposed to otherwise. (.5, or 1/2 -- Example: 0.5 will be noticed more so than .5 and 1/2 could be interpreted as '1 of two' in most cases.

I beleive "i44troll" will back me up here, it's not critical that a leading zero be used, but it's a good practice to have a leading "0" on most technical drawings/designs that require 'absolute-precision'. Typically a leading "0" will not be used on any dimension larger than "1" full unit, as defined on the drawing. (The 'true scale' as indicated on the printed sheet.)

How does one know if your printer is printing at (near) "True Scale"? See this "Hints and Tips" post.

Chris - "The Boss"

[jw48]

So a leading zero is preferred in best practice? It makes more sense. I wonder why the author of DeltaCad gives us only no leading zero?

[i44troll]

It's quite possible that a leading zero is included for that purpose, I don't really know, I always thought it was a matter of preference as with separators.
I choose not to use them because they can also be confusing to students who are not used to precision measurement. A tolerance of +/-0.005 can easily be misread by a novice as +/-.0005! Still, if it is (and it has been) a preference by many to use a leading zero to call out a dimension it should be an option included in Deltacad.

[jw48]

Thanks for the replies.

Perhaps the author might be able to include this option some time.

Regards
John

[Admin 1]

You can always add a leading zero, if desired, by editing the dimension text.

I guess the point I was making would mostly be shown as follows:

0.123

as apposed to

.123

However a value of

0.0123

could easily be misread and would best be displayed as

.0123

with no leading zero.

[jw48]

Yes, as mentioned in my first post, I edit the dimension to add the leading zero.

It's just surprising, especially bearing in mind the various opinions expressed here about possible ambiguities, that the author hasn't given us the option of 'leading zero/no leading zero'.

I live in hope!

[williamj]

I've just now read this thread, and it got me thinking.

I've read a large number of dimensioned drawings (mechanical), and as I recall, if a dimension (length, width, depth, diameter) was less than one, there was a leading zero.

But if a tolerance (+.000/-.000) was given, there was never a leading zero.

I have no idea if this is a standard convention or not.

John, thanks for shaking some cobwebs loose.

williamj

[jw48]

Interesting observation, Bill. Looking at your post, it becomes obvious why 'no leading zero' looks right when used for tolerances. It's because the + or - preceding the decimal point removes ambiguity and gives balance to the appearance, in a sense replacing a zero for that purpose. Seems to be a good convention then - preceding zeros for dimensions, no preceding zeros for tolerances.