Invalid axis/origin on a sketch

[Anonymous]

On one of my extrusions on a part, sketch doctor is telling me that the sketch has an invalid axis/origin. The diagnosis says:

"Missing or invalid origin for defining the sketch coordinate system. Use Edit Sketch Coordinates to define the origin."

The sketch is fully constrained and looking at the sketch I don't understand how to fix it. The extrusion with this problem is extrusion 5

Attached is the part. Hope someone can help explain how to fix.

Thank you.

[rdyson · Accepted solution]

Right click on the sketch - Edit Coordinate System

Click the Blue Dot

Click any vertex

Right Click and OK

[JDMather]

I wonder if maybe the modeling technique could be simplified a bit (see attached).

[Anonymous]

Thanks so much

[Anonymous]

I'm a newbie so I really appreciate you putting in the time to show me how you would model this. I have not yet studied it but I will study your model technique. I have not yet used lofts. If I have any questions about how you modeled it can I follow up with more questions?

Thanks.

[JDMather]

I usually model a part 2 or 3 times before I am happy with the design.

Here is a (very) slightly different approach.

Make use of geometry constraints and avoid repeating dimensions.

Use symmetry (about the origin) as much as possible.

[Anonymous]

Hi again JD,

I've been studying the way you modeled my part and hope you can answer some questions I have. I'm an artist and I'm creating a series of sculptures called "Model Citizens". The parts are 3d printed and then assembled. Attached is a couple of images of this assembled project. The reason I'm telling you this is that my design process seems to dictate how I modeled this. I first drew a few hand drawn sketches. I then created a basic rectangular volume and began from there because I figured it out on the fly without any predetermined accurate dimensions. With this said, I'd like to hone my skills and begin using better practices to create my models. I like the economy of only needing 4 sketches and 5 extrusions in your model.

I see that 3 sketches establishes the parallel front and back faces with sketch 1 and 3, and perpendicular to these faces sketch 2, which is the 2" portion that gets carved out in the middle. I see that you established the center of the part along the YZ plane. The following are my questions:

Sketch 1:

1. Why is the convergence point of where angles meet established by dimension d1 (22") important? (this also pertains to 13" dimension d16 in sketch 3)
2. How did you determine where to place origin of x axis (4.25" from top)?

Sketch 2:

1. Is construction line on XZ plane used to locate origin for face of sketch 3? Also is this construction line what you used for the rail for the loft?

Circular Pattern 1:

1. Don't understand how you are able to use sketch 1 to make extrusion 4 on the back of the model defined by sketch 3. Why not make this extrusion from sketch 3?

Work Plane 1:

1. Don't understand what this is used for.

Work Axis 1:

1. Don't understand what this is used for.

What I'm asking here may be beyond what you are able to help explain to me as your time is very valuable so if you can't I understand.

Thanks so much. Also I'd like to give you Kudo's but don't know how.

[Anonymous]

I didn't see this message from you before I sent my message with questions. Look forward to looking at this approach.

[JDMather · Accepted solution]

---

@Anonymous wrote:

Sketch 1:

1. Why is the convergence point of where angles meet established by dimension d1 (22") important? (this also pertains to 13" dimension d16 in sketch 3)
2. How did you determine where to place origin of x axis (4.25" from top)?

Sketch 2:

3. Is construction line on XZ plane used to locate origin for face of sketch 3? Also is this construction line what you used for the rail for the loft?

Circular Pattern 1:

4.  Don't understand how you are able to use sketch 1 to make extrusion 4 on the back of the model defined by sketch 3. Why not make this extrusion from sketch 3?

Work Plane 1:

5. Don't understand what this is used for.

Work Axis 1:

6. Don't understand what this is used for. 

7. Thanks so much. Also I'd like to give you Kudo's but don't know how.

---

1.  The dimension comes out to a nice integer.  If I dimesion from bottom to top of part - the number is "strange".

2.  I would normally place it at the top or bottom of the part, or in the centroid of the part - but I needed a location for Revolution. (this probably was overkill and might actually have made editing harder depending on types of changes that might be anticipated)

3. I did not use any Rails in the Loft.  Construction line located the Workplane.

4. Now you have given me a idea of a better way (or at least another) way of modeling the part.  Back in a while with my new solution.

5. 2D sketches can only be made on workplanes or planar faces of geometry.

6. The Work Axis was used as the axis of revolution to Revolve the extrude from the front of the part to the back of the part.

7. Simply click on the Hand just below right in this response.

[JDMather · Accepted solution]

I was able to simplify the construction of the part.

[Anonymous]

Thanks JD. Have better understanding of how to model.

[Anonymous]

Thanks again JD. This is great to compare with previous.

[JDMather]

I forgot to mention - install Service Packs 1 and 2 for 2014.

And you might read this

http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

I might also point out - that in most of my parts you can delete every, or nearly every, feature and all of the sketches needed to complete the part will still be there and not sick.  I never get the error in my parts that prompted your initial post.

[Anonymous]

Thanks JD. Looking forward to reading all the tips.