3D sketch in an assembly?

[JD Mather]

What you are trying to do is trivially easy, but time to post an actual assembly here so that the process can be demonstrated with geomery rather the words.
If a picture is worth a thousand words, 3D geomety is worth ......

[Bunny]

I agree that it is time to post something that we can help you with. That being said, the solution is only "easy" if you know how to do it, and no problems are "trivial" especially when your livelihood depends upon being able to produce what your employer/client requires.

[jontym1360704]

Sorry guys I will get a model posted to illustrate when I get chance (being mega busy at the mo)

Also thanks to everyone for all your advice so far I really appreciate it and I hope none of my replies have read wrong.

[jontym1360704]

Here is a simplified version of what I am trying to do.

At present the stars and handrails are all the same part as I only seem to be able to produce a 3D sketch in a part file

I want to do a 3D sketch to produce the sweep rail for the banister as a sepatrate part within an existing assembly reason being I need to use the rake of the stair as a a guideline for the angle of the banister.

stairs.pdf

[JD Mather]

I am not familiar with editing pdf files in Inventor.
I would have to recreate this in Inventor to demonstrate the technique.
But seeing your picture it doesn't even look necessary.
Model as multi-body solids in one part file and then push out the assembly Manage>Make Components

[Pierre Marcotte]

You CAN create a 3D sketch in a part file, but only AFTER the part is created on a 2D sketch plane. Confused ? Me too.
Create your part in assembly mode, select whatever plane is convenient for you, it doesn't matter. Close the sketch, but stay in the part file. Save.
Your best bet at this point is to create a 3D sketch using the intersection method, i.e. using 2 2D sketches melded (molded ? melt ?) into one. Ergo, you will need to create 2 2D sketches representing each a view of the path you want your 3D path to follow.

In the attached screenshot, I created 2 sketches on different planes and can select the "Intersection curve" button. Pick both 2D sketches, click OK, and you have your 3D sketch. The beauty here is that if you change a 2D sketch, the 3D sketch will adapt (unless you delete and start over, in which case it's kaput).

3D sketch.JPG

Hope this helps.

Reminder : keep your corners and bends at a sufficient radius that your shape will be able to sweep properly. I've seen guys try to sweep Ø24" pipes at a 8'' radius. It ain't pretty.

And remember, drafters do it to a "T". Old guys will get this.

[jontym1360704]

Thanks a lot guys, I shall have a play around with both methods, really appreciated

[Bunny]

The pdf shows what appears to be a handrail made out of standard tubing, so either the Frame Generator or Tube & Pipe be the best tools to create the individual parts. A 3d Sweep will get the geometry, but a shop floor needs more than that to build it.

Have fun!!!

[Pierre Marcotte]

I agree ! But it's surprising to see what some shops can do with clever dimensioning and good tube bending machines. I like the "saw and weld" method, myself.