Tribulations of an Inventor neophyte

[Anonymous]

A couple of weeks ago I reached the forum for help with some revolved or sweep “solids” that did not have a surface.  Later on, I posted that I had solved my problem by creating a “tool” where I could place the offending parts and construct my paraboloid mirror.

One of you asked me why a newcomer choose such a difficult task.  I replied that was the problem that I needed solving. 

My experience has been frustrating.  While the first iteration worked:

• I could not replicate the pattern because it lacked an axis (later on I learned that I could create an axis at the intersection of two working planes);
• I had to redo the first iteration, and I wanted to have it fully constrained without relying on grounding pieces, and I spend days moving the parts and trying to constrained them, with thousands of “inconsistent” constraints;
• I ended up putting a ball and a half a sphere (at the two ends of the piece) but failed to remove the inconsistency, even when looking at the connections they seem to be OK and the measure of the distances of the axis was less than 0.5 mm (the part is about 1.5 m – so the tolerance was 0.0003) until it dawned to me that the ball/sphere leaves 2 degrees of freedom and by using a pair, I was removing all freedom (which is what I wanted), so the thing was inconsistent because I was using an expensive solution, so I accepted the inconsistency.  Nothing that in real life could not be solve with a light tap of a hammer, but I did not want to tap into the monitor!
• I am now creating the second set, and I am frustrated at the amount of time it takes to position the parts properly.

The books and the help can only teach you so much.  I have duplicated some examples and I have created simple parts to test hypothesis.  The forum is great, but searching on it takes a while to get something useful.

I am getting better, but I am also running out of patience.

[JDMather]

@Anonymous

Continuing the discussion - assembling parts is the trivial part of the problem - modeling the parts is where the difficulty in design lies.  We should consider Design for Manufacture and Assembly right up front, not tossed over the wall for someone else to figure out.

[Anonymous]

Hi JDMather,

Thanks for dedicating so much time to my problem.

Again, I repeat,  you have really opened my eyes.  Think before you star sketching (or assembling!).  Not because I can do a nice looking part (I was very impressed with my flat_box), it means that it is correct or will be easier to make.  Your solution of a weld part beats my extruded part in simplicity (and cost!). 

Hopefully, Circu1, Circu2 and para_bar are better.  Just two sketches.

Have a good weekend.

es223

. 

[JDMather]

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@es223 wrote:
...Hopefully, Circu1, Circu2 and para_bar are better.  Just two sketches.. 

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Avoid extra work - get lazy!  The BORN Technique will save you time and effort.

[JDMather]

Attach your new - fully defined part files that make logical use of the Origin Center Point and I will demonstrate how to complete the assembly.

[Anonymous · Accepted solution]

Hi JdMather

It is difficult to me to find words to express my gratitude for all the effort you have put in trying to solve my problem and I can see that a good part of my problems was due to my sloppiness. 

In my defense, I will state that creating an extra work plane for Circu1, Circu2 and Para_bar was using a work plane perpendicular to the point, which given the end chosen, happen to coincide with the XZ plane and therefore was duplicated and since Inventor created the plane at that point, I was not aware that it was floating.   Just that example shows me to pay more attention to details.  I usually was very satisfied when Doctor Sketch indicated that I was fully constrained, but I learned that clicking on DOF on a sketch can reveal inconsistencies.

I was aware of the problem of using straight line segments (the flat boxes or edge1) to hold curved parts, and the lazy solution I came with was to reduce the diameter of the curved part so that it will have some room of maneuvering so that I did not have to make many versions of flat boxes or edge1. 

I was also aware of the need to do the holes in the mirror following the angle of the mirror, but obviously failed to notice that some of them were not fully constrained. 

I am embarrassed that you have found so many mistakes.

Thank you. 

eduardo