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# 3D sketching and exhaust manifold design

Experimenter

I just installed my trial version of NX and decided to start with a coupld designs that would be higher priority for my needs for the software. One is designing intake and exhaust components.
I know NX doesn't have a 3D sketch environment but from some reading I was under the impression that without being in an actual sketch that you could add sketch lines, arcs etc that weren't constrained to a plane. For specific things like tubing I  know there are some other routing features and I am curious to see what all tools might best complete this goal but I would also like to know how much capability there is to have sketch features that aren't plane constrained.
I found a video of someone making a manifold and they used the bridge feature which is close to what I want to do but for tubular manifolds splines aren't really acceptable because I need to use dimensioned arcs to represent the tubing so I know we can reproduce it in real life as accurately and with as little modification as possible.
Since it can be hard to get from a fixed flange at one angle to another fixed flange at another angle using a couple arcs with a fixed radius it would be even better if one flange had some freedom of movement while you tried to sketch your tubing and then once your tubing routing was done you could position the flange within any range of movement that the constrained arcs allowed. I suspect this is a long shot but I also know NX is quite capable so I thought I would throw it out there.
I have attached a picture of one of our manifolds to give an idea of what I would be trying to design. This tubing is only available in straight sections and in bends with a 2.5" centerline radius so I would have to get from point a to point b using only straight lines and 2.5" radius arcs.

Step 2 is wondering if then it would be possible to make a flat cut pattern or drawing that showed me the length of the straight sections and the angles that I had to cut out of the U bends.

6 REPLIES

# Re: 3D sketching and exhaust manifold design

Siemens Phenom

A different suggestion from using sketch.

I would construct the path as a series of lines (without the blends) first.

For best flexibility of editing first start by creating dynamic Datum Coordinate Systems at the theoretical bend corner points of each straight section. Then connect the points between each CSYS with an associate  line (not sketch line). Then add the blend between each line using Circular Blend Curve. Finally use trim curve to shorten the lines to the start of the blends.

I would also recommend changing Preference-> Modeling->Edit - Double-click Action (Feature) to Edit Parameter so that when you select a coordinate system, to dynamically move it, the later geometry stays on the screen.

If you add additional sections, best to reorder the Datum CSYS to before the lines.

Steve V

# Re: 3D sketching and exhaust manifold design

Siemens Legend

One can use an assembly as a geometry solver.

Assembly constraints has the property of simultaneous solving, which in turn means that it can simultaneously change multiple conditions to find a solution.

As long as its only 2 bends the setup is pretty simple, and the solution is single. ( see green and yellow)

if the number of bends increase, there is no longer a single solution, and the constraints start getting "nervous". ( see blue pipes)

One can do this example in pure wireframe ,or as in the attached file solid bodies .
The constraints are applied on both the wireframe and some solid edges.

The components are not fully constrained. The "straight" is only tangent-tangent to the bends and can slide on that line. ( which is why the ends doesn't match perfectly)

Have a look at the attached example. Use BOTH the assembly constraints dialog AND the Move component dialog to move the pieces. the assembly constraints dialog allows you to drag any component ( press-drag-release), the move component is more regulated. Note also that you can turn off the option "Dynamic Position" to only move the selected component ( instead of all affected)

( One can move components with the spaceball,, but i don't remember how it's done at this moment.)

You should be able to modify the "engine" pretty freely.

The assembly only solves the geometry, the layout, but i think i could overlay a "true assembly" and there create the specific customer layout.

Regards,

Tomas

# Re: 3D sketching and exhaust manifold design

Experimenter

Thanks guys I will play with this more this weekend.

I am totally new to NX just checking out a trial right now. If there are any videos you know of that would help demonstrate this, any pages in the manual I should check out or any other learning resources that focus on this it would be greatly appreciated.

# Re: 3D sketching and exhaust manifold design

Siemens Phenom

Here is an example of using coordinate systems.

Steve V

# Re: 3D sketching and exhaust manifold design

Experimenter

Thanks for the file. That looks pretty simple and effective.

# Re: 3D sketching and exhaust manifold design

Siemens Phenom

Hi,

You can use "CIRCULAR BLEND CURVE" for creating arc transitions (specified radius) between two lines (in 3-d space).As far as your 3-D sketching is concerned please have a look at DIRECT SKETCH tools (probably that may help).

Best Regards

Kapil