topic Fully constrained sketch needs dimensions in Inventor Forum

Fully constrained sketch needs dimensions

Vagulus — Fri, 30 Aug 2019 01:57:13 GMT

AI2018 shows this sketch in Blue which usually means that it is filly constrained

Needs dimensions

It also asks me for eight more dimensions!

🤔🤔🤔

Degrees of Freedom indicate that I need to dimension the centrelines bit AI still wants more dimensions.

🤔🤔🤔

How can a sketch be fully constrained and still need more dimensions?

Re: Fully constrained sketch needs dimensions

Pauli666 — Fri, 30 Aug 2019 03:35:56 GMT

you have 4 Centrelines, each has 2 ends, therefore 8 points = 8 dimensions required?

(without seeing the file Just guessing)

Re: Fully constrained sketch needs dimensions

JDMather — Fri, 30 Aug 2019 07:37:48 GMT

Inventor Sketching 101

Re: Fully constrained sketch needs dimensions

SBix26 — Fri, 30 Aug 2019 15:17:26 GMT

As @JDMather said in his video, those centerlines are extraneous. Eliminate three of them and constrain the fourth (if it is even needed) to the edge of the slot, and you're finished.

Notice that I changed the construction line between arc centers to a centerline, to maintain the look that you were trying for, I guess.

In sketching, I use construction geometry freely, knowing that for me, at least, it's easier to understand a constraint scheme by visible entities rather than by "hidden" constraints. But I absolutely avoid adding extra things. Seems as if you were trying to make your sketch look like a drawing-- don't yield to that temptation! A part sketch is only for geometry definition; communication is the sole function of a drawing. Confusing them is not helpful.

Sam B
Inventor Pro 2020.1 | Windows 7 SP1
LinkedIn

Re: Fully constrained sketch needs dimensions

el_jefe_de_steak — Fri, 30 Aug 2019 15:22:35 GMT

@Vagulus

I think it's asking for "dimensions" specifying the length of your center lines. A line will show up as fully constrained even if its length is not fixed. You can probably still move the end points of each line. If I were you, I would just ignore this... It really doesn't matter if your center lines vary in length since most likely you won't have geometry that is dependent on the end point of those lines.

Re: Fully constrained sketch needs dimensions

Vagulus — Sat, 31 Aug 2019 00:30:40 GMT

Thanks for taking the time and the trouble, JD.

Much appreciated

Re: Fully constrained sketch needs dimensions

Vagulus — Sat, 31 Aug 2019 00:33:59 GMT

Thanks Sam.

You wrote, "A part sketch is only for geometry definition; communication is the sole function of a drawing. Confusing them is not helpful." I'll chew that over, and over, and over ...🤔

Re: Fully constrained sketch needs dimensions

Vagulus — Sat, 31 Aug 2019 00:38:58 GMT

Thanks el_jefe_de_steak

You wrote, "I would just ignore this... It really doesn't matter if your center lines vary in length ..." That ties in with JD saying that he can't understand why anyone would draw in those centrelines anyway.

Someone else's experience is usually a pretty good guide. 🤗

Re: Fully constrained sketch needs dimensions

el_jefe_de_steak — Tue, 03 Sep 2019 11:00:53 GMT

@Vagulus

@Vagulus wrote:
Thanks el_jefe_de_steak
You wrote, "I would just ignore this... It really doesn't matter if your center lines vary in length ..." That ties in with JD saying that he can't understand why anyone would draw in those centrelines anyway.

Someone else's experience is usually a pretty good guide. 🤗

Yes, I agree with this statement.

I do see some value in drawing such center lines, but ONLY if you plan to use them to visualize some form of work feature that you plan to create based off of the sketch (like an axis or work plane). I know this may not be "proper", but it does make it a little more easy to "plan ahead" with work features as you can more easily visualize where they will be. I have personally used this method (although never on a slot). However, I would not recommend doing this a lot, especially if you collaborate with others that may not understand this and get annoyed/confused with your "messy" sketches.

Doing this is basically the opposite function of projecting work planes onto your sketch.