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NX Routing - Flexible Pipe questions


Dear All,


hopefully somebody can help me to find a solution for my folowing issue Smiley Happy


At the moment my company using assemblies for flexible hoses (1 fitting + tube in the middle + 1 fitting) as deformable parts, having lines and bridge curves in the top assy level as a guide for the deformable tube.


When I insert this pipe assy in the main assy I add a constrain for 1 fitting and make the other fitting 'flexible' then I can constrain it where it needs to go, then select the bridge curve as a guise rail.


This method is not adaptive, so if I have to move the position of the fittings, I need to re attach the lines for the guide rail.


With this method I can have the same 'part nr' for many difffeent lookign flexible pipe (but with similar length) , and also I can produce a drawing, showing the original sub assy, with straight tube, so we can source it out from a supplier.



I have now a trial licence for the mechanical routing as the management is looking for a quicker way to do the piping



Is there any way I can achive the same principle for my pipe routes, such as:

-having only one assembly for the similar (same) length pipes, but using different guides (splines) in the main assy,

-have a drawing showing the straight pipe for manufacturing purposes.


I am using NX


thanks a lot,







Re: NX Routing - Flexible Pipe questions

Siemens Genius Siemens Genius
Siemens Genius

Hello Richard,


It sounds like you are new to routing, so I'll outline the whole process.  My apologies if you already know this.

Your fittings need to be 'Qualified' for routing.  Not strictly required but makes everything else easier.

Qualify Part, and create a fitting port.  Choices here, but usually put the port on the outside face of the hole for the stock.  Change the Engagement distance to a value where the stock will bottom out in the hole.  Extension for a default distance that you'd like to be straight before curving. Enter some small value so that the first direction will be in the direction of the port



Create an assembly and add the fittings.  Place anywhere, but it's helpful if they aren't in line.

Make a routing spline path using Spline Path.   Select the port of one fitting, a screen point somewhere in the middle, and select the port of the other fitting.  Change the shape mode to Locked Length, and set the length that you'd like.

You can add a stock or just a space reservation in the spline path dialog or separately.  Makes no difference.

Move the fittings if needed.

Create the deform definition.   You only need to select the stock feature.



Now add that to another assembly.  I usually just add by screen position and then move the fittings as needed.

NX will automatically create a new spline path at the assembly level for you and add the stock to it.  You can alter the spline as needed.  You'll always need one free point (that middle point) for the locked length constraint to work, but otherwise you can add new points and move or even associate to clamps as needed.

NX also adds a Position Override to the fittings automatically, and copies the constraints including the locked length to the assembly.


There's a lot of ways to make this act a bit differently.  If the length can change, e.g. you order the assembly of the same parts but difference lengths, leave out the Locked Length constraint.  If you'd prefer to create a spline path in the assembly beforehand, define the deform with Add Geometry.  And so on.


Good luck,


Re: NX Routing - Flexible Pipe questions


Hello Doug,


many thanks for your extensive explanation!

yes, I am a very newbie with pipe routing Smiley Happy


in the main time jsut found a youtube video explaning it, exactly how you described!


Really appreciate your time and help!


Al lthe best,



Re: NX Routing - Flexible Pipe questions

Siemens Genius Siemens Genius
Siemens Genius

That's a great video.  And it's a small world.  I know the person doing the demonstration.  And we live in the same city.  And the person who started AppliedCAX and I worked together at the same company before we both left for greener pastures.

Re: NX Routing - Flexible Pipe questions




I made a presentation and the management liked the routing licesnes potential, but they were asking if we can combine motion simulation with flexible pipe design.


They want to see for example if we have a cam lever with hoses and that motion...






Re: NX Routing - Flexible Pipe questions





I have a strange behavior wit the spline path for the routing.

I set it up to be locked but when I add extra points to the line it changes the length sometimes.

not a bit...could be 20+ mm

Is it a bug? 

please see attached screenshot



Also sometimes, when I insert a flexible pipe assembly (with fittings where 'fitting ports' been specified) into my main assembly the start of the spline jumps to the end of the fitting, instead of the specified port... very strange and dangerous, every tiem I have to check if it starts from the rigth point.



The splines have to have a middle point for using locked lenght, but when I move my assembly that middle point trying to stay in the same point ,so I have to re-definy every time.

For example, I have a swing lever, a conn rod and a sliding yoke.

We bought this routing license to check the length of the pipes at each end position of the movement.

Is there any way to solve this?



My colleauge wanted to use my routing pipe assemblies and he got many strange errors.

It turned out he had version and I had

I would not have thought that a not major release would cause issues like this, or at least could tell me why that is happening. 


We are a bit disappointed with NX and the routing license. 


many thanks,

please help meee Smiley Happy







Re: NX Routing - Flexible Pipe questions

Siemens Genius Siemens Genius
Siemens Genius

Hello Richard,


1. Check the Assembly Constraints.  Locked Length is controlled by an Assembly Constraint.  If included for the original spline, then on Deform in the assembly, you should see a new assembly constraint in that deform assembly that controls the length. 

Like any Assembly Constraint, the geometry of the objects may prevent the solution of that constraint.  So you can review the status of these constraints in the Constraint Navigator, or in the Assembly Navigator in the Constraints node.


2.  Need more details to comment.

3.  I don't understand.  Locked length requires at least one free point to move to meet the length constraint.  The position of the free points in space determine the plane of the extra length of the spline. If this point can't move, that may be your issue here.

4. Need more details.  NX fixes issues with every major release, maintenance release, and maintenance pack.

NX11.0.1 and .2 came out about 6 months apart. NX11.0.2 had about 1700 PRs fixed.  The MP's on top of NX11.0.1 and NX11.0.2 are fixes on top of the maintenance releases.

NX11.0.2 is about to have MP9 with the latest set of fixes.  NX11.0.1 is a MP8 and about to go out of maintenance.

I'd suggest going to the latest version if possible, and certainly going to a common version in any case.