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davehaigh13-Aquamarine
13-Aquamarine
October 30, 2012
Question

Dimension Rounding in Creo 2

  • October 30, 2012
  • 42 replies
  • 107375 views
I'm coming from Wildfire 4, so I guess I may have zoned out on previous discussions about this issue.

I've played around a bit in Creo 2, I'm not sure I would call what I'm seeing an enhancement. We work on some highly accurate parts, it not uncommon to use 4 digits in inches and 3 digits in millimeters.

I entered 3.9375 in the sketcher. The sketcher shows 3.938. Finish the feature and measure, it shows 3.9375. Double click on the feature to show the dimension and it shows 3.938. double click on the number to edit it and it shows 3.9375. The drawing shows 3.938. Edit properties on the dimension and it shows this.

[cid:image002.png@01CDB6A5.678682A0]

This is different behavior than in Wildfire 4.

What config options control this behavior?

* What settings make it like I see out of the box in Creo 2

* What settings restore it to traditional ProE behavior?

Why would I want the new behavior?

David Haigh
Phone: 925-424-3931
Fax: 925-423-7496
Lawrence Livermore National Lab
7000 East Ave, L-362
Livermore, CA 94550


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42 replies

T
tcooper1-Visitor
1-Visitor
October 30, 2012
Brings to question of what would the value be if you set the Dim Bounds
to Upper or Lower? I do stack up analysis this way, so wonder where the
boundaries will go.



Tim P. Cooper

Lead Designer

GE Oil & Gas

North American ATO



T +1 281 878 6168

M +1 281 796 9038

F +1 281 715 4116

- <">mailto:->

www.ge.com
B
23-Emerald III
BenLoosli23-Emerald III
23-Emerald III
October 30, 2012
It looks like it is doing what you are telling it to do.
Nominal value 3.9375 when displayed to 3 decimal places is 9.378.

What are you expecting to see?


Thank you,

Ben H. Loosli
USEC, INC.
D
davehaigh13-AquamarineAuthor
13-Aquamarine
October 30, 2012
Looking though the config options I think these all apply. Not really sure what all of these mean. Anyone have real world examples for these?

Round_displayed_dim_values = yes*, no
Set the default status of the Round Displayed Value checkbox for new and newly shown dimensions.

Round_prewf5_displayed_dim_val = calculated*, round all, round none
Rounds the displayed value

Default_ang_dec_places = 1*
Sets the default number of decimal places (0-13) to which to round newly created angular dimensions. Unrounded angular dimensions automatically determine the number of decimal places required to display their stored value.

Default_dec_places = 3*
Sets the default number of decimal places (0-13) to which to round newly created dimensions. Unrounded dimensions automatically determine the number of decimal places required to display their stored value.

Default_dim_num_digits_changes = yes*, no
Sets the default number of digits displayed in a dimension to the last entered value. No - The system defaults to the value specified for the configuration file option default_dec_places.

Tol_num_digits_default_driven = yes*, no
Yes - The Default check boxes in the number of digits area of the Dimension Properties dialog will be checked when a dimension is created or first shown. No - the check boxes will be unchecked when a dimension is created or first shown.

David Haigh
D
davehaigh13-AquamarineAuthor
13-Aquamarine
October 30, 2012
Found another config option

sketcher_strngthn_to_def_dec_pl = yes*, no
yes-Rounds<">http://localhost:60200/pma/sketcher/sketcher_strngthn_to_def_dec_pl.html?queryId=13ab3a8bcdd> off the values of new dimensions and of weak dimensions when they are converted to strong dimensions.
no-Does not round<">http://localhost:60200/pma/sketcher/sketcher_strngthn_to_def_dec_pl.html?queryId=13ab3a8bcdd> off the value of new dimensions and of weak dimensions when they are converted to strong dimensions.

David Haigh
D
dgschaefer21-Topaz II
21-Topaz II
October 31, 2012
It's rounding the value but not changing the nominal. This is a change
from long standing behavior in Pro/E. In the past, changing the number
of decimal places of a dimension actually changed the value. As a
comparison:



Past behavior:

Entered value - .28125

Rounded value - .3

Measured value - .3



New behavior:

Entered value - .28125

Rounded value - .3

Measured value - .28125



The idea in the past was that if are saying that you can allow the part
to be made at 0.3 +/- 0.1 (the likely tolerance on a 1 place dim), that
gives a different acceptable range (0.2-0.4) compared to a nominal value
of .28125 +/- 0.1 (0.18125 - 0.38125) and the model should reflect that.




Over the years, many wanted to simply round the display leaving the
nominal alone and didn't understand why their models were changing
simply by rounding dimensions. The default behavior was flipped,
starting I think in WF5.



--
B
23-Emerald III
BenLoosli23-Emerald III
23-Emerald III
October 31, 2012
The old behavior has also lead to many parts being scrapped in manufacturing by producing parts outside the limits of what the engineer envisioned.
The drawing display of decimal places should NEVER change the model.
If I want to change the modeled dimension, change the model itself. The drawing may not even change, depending on the round off selected.

Companies need to decide what is the master for dimensioning and manufacturing. It can be the model or the drawing, but NOT both!
At one of my prior companies, we made the model the master since manufacturing used the engineering models for all CNC operations.
This company and my last still use the drawing as the master for production.

Thank you,

Ben H. Loosli
USEC, INC.
T
tcooper1-Visitor
1-Visitor
October 31, 2012
When I pick the feature and then edit and it says the value is 3.0, and
I show the dimension of the feature on a drawing to place the dimension
and it says 3.0, yet when I measure the feature and it measures 3.04.
That is a problem!



Tim P. Cooper

Lead Designer

GE Oil & Gas

North American ATO



T +1 281 878 6168

M +1 281 796 9038

F +1 281 715 4116

- <">mailto:->

www.ge.com
B
23-Emerald III
BenLoosli23-Emerald III
23-Emerald III
October 31, 2012
That is a problem, but the original poster stated that when he edits the dimension in either sketcher or in the model, it shows the full 4 decimal places.
This is what it should show. The drawing display and the measured display are being rounded. They are DISPLAY values only.

Thank you,

Ben H. Loosli
USEC, INC.

From: Cooper, Tim P (GE Oil & Gas) [
C
cpipe1-Visitor
1-Visitor
October 31, 2012
Based on my experience, there are many cases from a tool manufacturing standpoint, where the rounding is beneficial when used with a tolerance block. For example, screw clearances are often fractional size drilled holes that can have a value of 3 or more decimal places. To keep the print clear these hole sizes are shown with 2 places to match the appropriate block tolerance, but the model should still reflect the fractional size hole so the machinist/programmer can easily select the correct tool. The print is then easy to scan for critical (usually toleranced dims) and non-critical (usually 1 or 2 place non-toleranced dims) features. If the print shows a 4 place dimension and a wide open tolerance, it is confusing and requires more time to interogate. And if the model shows a non-standard, 2 place, hole size, the cost could increase because the hole might be made with a more expensive process than needed (ie machined instead of drilled).

PTC gives you both options with checkbox and the default choice can be set with your config.pro per David's post:

Round_displayed_dim_values = yes*, no
Set the default status of the Round Displayed Value checkbox for new and newly shown dimensions.

Chris Pipe<">mailto:->
Eng. Sys. Analyst
trans-matic


From: Loosli, Ben H [
T
tcooper1-Visitor
1-Visitor
October 31, 2012
So you're saying the drawing or the model dimensions do not need to
reflect the geometry because they are for display purpose only? If so
what do I not understand about parametric concept between models,
drawings and geometry?



Yes if I pick on the dimension in the model to actually edit it, it
shows the 3.01. But when just picking the feature then edit to see the
dimension it shows 3.0. With your approach I need to pick the feature,
then edit then double click the dimension to see what the actual value
is!?



Tim P. Cooper

Lead Designer

GE Oil & Gas

North American ATO



T +1 281 878 6168

M +1 281 796 9038

F +1 281 715 4116

- <">mailto:->

www.ge.com
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