Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

NX4 Sketcher: How to control "Arc Length"?

Status
Not open for further replies.
tooldeziner

tooldeziner

Aerospace
Joined
Oct 14, 2005
Messages
98
Location
US
Looking through the available functions, it appears that the closest thing to Arc Length dimensional constraint is Perimeter. However, when I set the Perimeter value to 40mm, for instance, then measure the actual length of the resulting arc using "Analysis > Arc Length", the length is 13.33mm.
1. What does the Perimeter constraint actually do?
2. How can I control an arc length in sketcher?

Thanks,
'ziner
 
Sort by date Sort by votes
It seems to work OK for me (I'm running UGS NX 4.0.4.2). One thing that you need to be careful of is that the 'Perimeter' constraint can be applied to a string of curves as well as just one. Make sure that when you applied the Perimeter constraint that you didn't select more curves than just the single arc.


John R. Baker, P.E.
Product 'Evangelist'
UGS NX Product Line
SIEMENS
UGS PLM Software
Cypress, CA
 
Upvote 0 Downvote
As far as I know, it does relate to the curve length. Perimeter "should" work, it does in NX3 (kind of) and NX5. That obviously doesn't guarantee it works in NX4 however. Unfortunately I don't have NX4 (at the moment) to test.

Specialty Engineered Automation
 
Upvote 0 Downvote
Thanks for your interest, guys.
Here is what I am doing:
The goal is to drive a sweep along an arc, controlling the arc length using an expression "S".
The geometry for the sweep extrusion and the arc is in separate sketches. The arc sketch was created solely for this purpose, no other geometry in there to cause conflict. The sweep is a trianglular shape, only 3 lines in the sketch, with one corner anchored coincident with the start point of the arc. The sketch plane of the sweep geometry is normal to the sketch plane of the arc. In the arc sketch I applied the Perimeter constraint. (Is it typical for that constraint not to show anywhere except in the "Tools > Expressions" list? Can't see it in the sketch.) I also added constraints to anchor the arc center and the start point, and a radius dimension on the arc. Fully constrained.
In the Expressions list, I created an expression "S", for arc length. The value of S is 20mm. Still in the expressions list, I edited the p value for Perimeter to become "p=S". The extrusion changed immediately. Eureka! I thought. However, when I analyze the actual length of the edge of the arc (Analysis > arc length) it is 6.66mm. This is the same length as the edge of the sweep that was driven by the arc. When I change the expression "S" to 40mm, both the arc sketch and the sweep update to reflect the change, but the true length is 13.33. I'm confused.
If you got this far, thanks again for your interest.
'ziner
 
Upvote 0 Downvote
The arc radius is 28mm. I have also tried starting a new sketch for the arc, same result.
As for the constraint value of the Perimeter, I can't see any reference to the value or even the existence of the constraint while in the sketch. It doesn't appear in "Show/Remove Constraints". I have to leave the sketch altogether and go to "Tools>Expression" to see it. That could be very perplexing to anyone else trying to edit my sketch at a later date.

Thanks,
'ziner
 
Upvote 0 Downvote
Actually, just select the 'Inferred Dimensions' icon and then the 'Sketch Dimensions Dialog' option and you will see all the dimensional constraints in the sketch including the perimeter constraints.

Note that I tried, from your description and values, recreating your sketch with the single arc and everything works OK for me. How are you measuring the length of the arc? Are you using Analysis -> Arc length...?


John R. Baker, P.E.
Product 'Evangelist'
UGS NX Product Line
SIEMENS
UGS PLM Software
Cypress, CA
 
Upvote 0 Downvote
Exactly what version of NX are you running? My testing was done using UGS NX 4.0.4.2, which is the latest maintanence release which will be available later this week.


John R. Baker, P.E.
Product 'Evangelist'
UGS NX Product Line
SIEMENS
UGS PLM Software
Cypress, CA
 
Upvote 0 Downvote
NX 4.0.4.2 was made available for download from GTAC on 17MAY07.

Tim Flater
Senior Designer
Enkei America, Inc.

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.
 
Upvote 0 Downvote
I think the version is NX 4.0.3. How can I confirm that?
Thanks,
'ziner
 
Upvote 0 Downvote
I opened a new file and recreated the sketch, and it is ok. So I will just dump this one and say "oh well".

'ziner
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Anton Liubimov
  • Locked
  • Question Question
NxOpen, How to programmatically open a dialog box "Extrude"
Replies
2
Views
832
Anton Liubimov
Anton Liubimov
SDETERS
  • Locked
  • Poll Poll
New Sketcher vs the old Sketcher
Replies
5
Views
6K
Toost
Toost
MANox
  • Locked
  • Question Question
Change tabs bar posiotion to "centered"
Replies
2
Views
466
MANox
MANox
Asieros
  • Locked
  • Question Question
Siemens NX Drafting - Reset the "Border to Arrow Distance"
Replies
0
Views
727
Asieros
Asieros
DDerek
  • Locked
  • Question Question
How to make "Balloon" Result in only the number for the callout
Replies
3
Views
620
SDETERS
SDETERS

Part and Inventory Search

Sponsor

Back
Top