Assembly constaints in NX6 for first component in assembly?

[tonyjosephpaul]

Which is the best practice in assembly (more than one part) in NX6?
1) First part fixing in assembly origin using fix constraint or
2) Constraining the first part in assembly origin using three constraints
Why?


Thanks,

Tony Paul
Karayamparambu

 

[Toost]

- Fix it. It is faster.
You can always remove the fix and add other constraints later if that is needed.
Constraints in NX are not time stamp dependent.

Regards,
Tomas

 

[tonyjosephpaul]

You are right Tomas.but still traditionally everyone insist to use constraints instead of fix for first part.Is there any specific reason?

Thanks,

Tony Paul
Karayamparambu

 

[Toost]

I don't see any reason to use constraints for the first component, apart from the Fix constraint. I believe other systems automaticly puts a fix constraint on the first component.


Regards,
Tomas

 

[looslib]

The Fix constraint is new to some version of NX. It wasn't in UGII v1-18 or NX1.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[JonSelby]

I'd just Fix it.
If you constrain it, then future modifications to that part may cause some of those constraints to fail if the geometry changes. Fixing it just holds the part where it is.
Simples!

 

[JohnRBaker]

Actually 'fix' was in the old Mating Conditions, it's just that you had NO control over it as it was 'automatically' assigned to any free-standing component to which some other component was Mated. Once you assigned that first Mating Condition, it was set. We never really exposed that situation since there was nothing that users could do to overcome it, such as deleting or editing it.

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

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[DMiller01]

I am sure it is in part due to the 10 plus years I used ProE but I routinely constrain my first component to the assembly part's coordinate system planes. I often continue to use the assembly part planes to constrain additional components. If a component is to be centered in the assembly I will center it using an assembly plane.

If I have identical parts that are position in a pattern I will often choose one of them to be a leader and align the rest of them to that lead component where I can. If I change the location of the lead component the others follow.

When I am constraining a specific part I try to minizing spreading the constraints amoung multiple parts. Where it is practical I'll try to consolidate them to a single component.

Sometimes these rules of thumb which I have developed over the years work well and sometimes they don't work so well.

I would be very interested in what other experienced designers do.

I am using 7.5.2.5 NATIVE on Dell with windows XP OS

 

[JohnRBaker]

Of course, there is nothing preventing you from Mating/Constraining your initial Component to some reference object, be it a Datum CSYS or some body created in the Assembly file to act as an 'armature' or 'ground', just that with Mating Conditions, if you didn't do that, the initial Component will behave as if it had been 'fixed'.

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

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[fighterpilot]

I alway constrain mine to the three datums planes I put as the first features in my assembly. I always have three datum planes as first features in my parts as well. Old Pro/E habits.

--
Fighter Pilot
Manufacturing Engineer

 

[JohnRBaker]

I used to do that with Mating Conditions since this allowed me to in essence change how I wanted to locate my first component later on. However, with the advent of Assembly Constraints where the order in which components are positioned is no longer critical or that if I use a Fixed constraint that I can now change that at any time in the future, I no longer even include a Datum CSYS in my Assembly Template file since for me its just clutter 90% of the time.

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

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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