Using law curves, NX6.0

[fiddlinjd]

A couple of design projects have gone by, and every once in a while something comes up where i feel a curve driven by an function would be beneficial. i have played around with the law curve option, but for the life of me i clearly do not know the syntax for inputting.

the first dialogue box pops up, "enter parameter expression to define x", and in the box, there is a 't' already highlighted.

could someone help me define the limits t, and the input function(s)?

thanks a ton...

 

[JohnRBaker]

Perhaps a couple of examples might help you out (see attachment).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

UG/NX Museum:

http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.

 

[fiddlinjd]

well yes, but i am looking for the specific way to input them. what do i type in the first box??? originally i made expressions but when i typed them in, it just gave me and error saying "expression does not exist" - when it definitely did!!

because i am actually trying to make gear teeth a little faster, i opened your involute example first. i noticed you made expressions for angle1 and 2 - how do i tell it the 't' parameter is those expressions?

 

[JohnRBaker]

Have you reviewed the NX help files for Law Curves?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

UG/NX Museum:

http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.

 

[fiddlinjd]

i do not have access to them... is this a really complicated operation??

 

[JohnRBaker]

Well that's why we spend the time and money producing USER documentation. Why it is that you don't have access to the help files?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

UG/NX Museum:

http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.

 

[fiddlinjd]

i just don't.

all i need to know is, when i click curve->law curve->by equation, a box pops up with a highlighted 't', and it doesn't respond how i figure it would.

as in, i made a t parameter in my expressions list. i also made other parameters.

once i get to this box, it seems as if when i type in an equation or define t, it tells me it doesn't exist.

so clearly, i am missing something, all i am asking is, what is that something???

 

[JohnRBaker]

't' is set by the system and you have no real control over it. It's the 'parametric' value which gets evaluated from 0 to 1 as the equations are solved to define the shape of the curve. You supply the X and Y (and Z if it's a 3D curve) equations and you start with 't' equal to 0 (or 1 as it makes no difference since the system will take over anyway).

I would advise you to get access to the Help files since you've already paid for them and NX is too complicated and comprehensive to think that you can use it effectively by only reading the menus and dialogs. I suppose that you've never had any formal training either, eh?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

UG/NX Museum:

http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.

 

[mmauldin]

"t" is the NX default for the range to be evaluated and is evaluated between 0 and 1, while xt, yt and zt are default value for x,y and z, i.e. the function xt=t will return a set of values from 1 to 0 while yt=2t will return values from 0 to 2. In order to use it you will need to create an expression with the name "t" and assign any value and expressions for xt, yt, and zt as needed. If you are not using a function for any of these parameter, you do not need to create them.

If you create a law curve based on these functions for x and y and setting the z law curve to "constant" with a value of 0 you will get a line that runs from 0,0,0 to 1,2,0.

Attached is a file with a simple law curve.

t=0
xt=sin(t*360) (multiplying t by 360 returns values for 360 degrees)

yt= t*2

and zt is not defined (it will be constant).

So to create the curve:

Insert>curve>law curve

Select "by equation, accept "t" as the parameter and "xt" as the function.

Select "by equation, accept "t" as the parameter and "yt" as the function.

Select "Constant" and assign a value of 0.

Then accept the last dialogue box and the curve will be created.

 

[fiddlinjd]

ah, setting it to constant was definitely something i missed!!!

of course i've had formal training! though for those applications, nothing like law curves were ever covered!

thanks for the help! i knew i was missing something small...

 

[joycejo]

I have seen at many companies that the help doc's are not available. Your company paid lots of good money to have this information and because someone from the IT department is too lazy or ignorant to install them is not excuse. If they give you some lame excuse that they take up too much space then they can install them on the network where all the users can have access to them. Mention to you manager the cost of NX and the maintance fees they pay to keep up to date.

Would you buy a new car and never take a driving lesson?

John Joyce
N.C. Programming Supervisor
Barnes Aerospace, Windsor CT
NX6.0.5.3