Rounding off dimensions
Rounding off dimensions
(OP)
Trying to find a setting to make SW round off a .125 dimension to .12 instead of .13. I checked in the GD&T forum and they said that rounding off is specified by an ANSI or ASME standard, but my options are already set to ANSI. We have this same problem with Autocad but have never been able to fix it.
Thanks
Thanks






RE: Rounding off dimensions
RE: Rounding off dimensions
RE: Rounding off dimensions
BTW solidworks rounds up to .13 because of the 5 in the thousandths digit. You may be able to find a setting where the dimensions are truncated. This essentially cuts off the remaining digits after the place that you indicate.
RE: Rounding off dimensions
Most everything I do is drawn at the 2 place dimension unless I want 3 or 4. So much of our work is derived from old designs that use fractions, so I just round them off to 2 place decimals before putting them in. Also, it is convenient because our default tolerances are for 2 places. We have one guy who uses fractions but enters them in 4 places or more, and then tries to make the dimensions round off to 2 places. Kind of backwards I think.
I had one that I designed at .125 and then later decided not to hold it that tight, so I tried the lazy way of using a 2 place dimension but it came out to .13 instead of the .12 that I wanted. No big deal. I just went back and changed the model.
RE: Rounding off dimensions
Be careful with that. You would be breaking a norm of rounding digits 0 through 4 down and 5 through 9 up. To round a digit of 5 down would be wrong according to scientific rules of rounding--so I don't recommend doing so or your dimensions will be misunderstood by all who read them. So your dimension of .13 is somewhat common for a two-digit representation of 1/8.
Jeff Mowry
www.industrialdesignhaus.com
Reality is no respecter of good intentions.
RE: Rounding off dimensions
There is an old tradition that if the 5 is preceded by an even number you round it down and if an odd number you round it up (we're only talking about the case where the last digit is 5). Most people would round upward regardless. I checked at the GD&T forum and apparently there is an ANSI standard for this, although I have not seen it. Those guys called it "rounding toward the even number" which I never heard of but it means the same thing.
RE: Rounding off dimensions
Jeff Mowry
www.industrialdesignhaus.com
Reality is no respecter of good intentions.
RE: Rounding off dimensions
This seems more applicable to numbers from an outside source (recorded data) than numbers that you are making up (dimensional specifications).
For more info see:
h
RE: Rounding off dimensions
1.3, 2.5, 3.6, 5.5 with the average of 3.225
Rounded using the simple method of .5 always rounds up:
1, 3, 4, 6 with average of 3.5
Rounded using even/odd rule:
1, 2, 4, 6 with average of 3.25
So you can see how that method of rounding helps prevent overall skewing of a set of numbers to a larger average.
Jonathan Anderson
RE: Rounding off dimensions
Now, how do we make SW work this way?
RE: Rounding off dimensions
I suggest do not change the settings. Make the models per whatever decimal places you want them, dimension on the dwg with tolerances how you need them. Let the software round the way it's suppose to. Whoever is working with fractions, learn decimal equiv per print.
Chris
Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
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