topic Re: Constraints in 3D sketches, please help in Fusion Design, Validate & Document Forum

Constraints in 3D sketches, please help

maxxxw — Wed, 23 Feb 2022 20:02:27 GMT

I feel like I spend hours and hours clicking around just trying to get lines to turn black and it's so random and sometimes it's just soooooo unintuitive how it works. And then also Fusion 360 crashes regularly 😭

Anyway, I just want black lines, i.e. all constraints applied, but in 3D sketches it seems so hard.

My file is attached, my issues are with "Sketch36", questions:

Why can't I constrain that single line that divides the upper/smaller circle into 6 equal segments, like a pizza?
Why is nothing in the bottom 2 circles constrained?

I would love any help to explain where I'm going wrong 💖

Re: Constraints in 3D sketches, please help

laughingcreek — Wed, 23 Feb 2022 20:33:44 GMT

there are several answers.

1-3d sketches aren't really ready for prime time yet.

2-there is a bug associated with 3d sketches that sometimes prevent them from showing fully constrained no mater what you do

3-if a 3d sketch isn't necessary, it's better to avoid them regardless. in this case you have 3 planer profiles. If you break this into 3 sperate 2d sketches, you will have more control and a more stable model.

Re: Constraints in 3D sketches, please help

maxxxw — Thu, 24 Feb 2022 12:19:21 GMT

OK, thanks for the info laughingcreek, that's disappointing

Re: Constraints in 3D sketches, please help

TrippyLighting — Thu, 24 Feb 2022 13:18:33 GMT

There are 8 warnings and 2 errors in your timeline. You should address those as soon as the occur.

Also, your timeline indicates that you have yet to get more comfortable with parametric design basics.

Stick with 2D sketches and master those.

3D sketches should be limited to specific applications only, just as in any other CAD software.

Re: Constraints in 3D sketches, please help

maxxxw — Fri, 25 Feb 2022 18:52:45 GMT

Thanks for the reply @TrippyLighting

> There are 8 warnings and 2 errors in your timeline. You should address those as soon as the occur.

I agree but they are all for unrelated bodies. The sketch I am asking about here (Sketch36) is not connected to any bodies in in the design and has no warnings/errors.

> Stick with 2D sketches and master those.

I have no problems with 2D sketches, creating and constraining them gives me no issues.

> your timeline indicates that you have yet to get more comfortable with parametric design basics

Cool. Well that's why I'm asking for help!

Re: Constraints in 3D sketches, please help

maxxxw — Fri, 25 Feb 2022 19:27:31 GMT

I seem to have it all constrained now. I deleted many constraints and lines, recreated them multiple times and now it's all black, which is great, but I really want to know why I couldn't do it before. Otherwise I'm none the wiser!

Re: Constraints in 3D sketches, please help

TrippyLighting — Fri, 25 Feb 2022 19:38:42 GMT

@maxxxw wrote:

> your timeline indicates that you have yet to get more comfortable with parametric design basics

Cool. Well that's why I'm asking for help!

Ok, then lets start with the 1st 4 features in the timeline.

You imported 2 discrete pieces of geometry, the PSU and the base. both should be separate components, not bodies in a single component.

One of those components should have been grounded and the other one should have been assembled to it with one of the joints in the Assemble menu.

So the first thing I would recommend is to familiarize yourself with he difference between components and bodies.

Then read up on Fusion 360's R.U.L.E #1.

Re: Constraints in 3D sketches, please help

maxxxw — Sat, 26 Feb 2022 12:36:35 GMT

OK after a lot of trial and error, this is what I did to get my lines black:

Ensure "3D sketch" check box is enabled
Start to create a line
Click to set the starting point and click a second time at the end point
The length number field will be highlighted, the value doesn't matter, press enter once
The angle number field will be highlighted, the value doesn't matter, press enter again
Then both angle and length fields have yellow locks, press enter again
The line is created with 2 constraints but is still blue
Remove the constraints that were created for length and angle
Add your own constraints, line turns black 🙌

I think this is illogical and I'm perhaps making some other error here but it works for me.

Re: Constraints in 3D sketches, please help

maxxxw — Sat, 26 Feb 2022 12:39:59 GMT

> You imported 2 discrete pieces of geometry, the PSU and the base. both should be separate components, not bodies > in a single component.

> One of those components should have been grounded and the other one should have been assembled to it with one of the joints in the Assemble menu.

Thanks for the reply @TrippyLighting, I will read your links, but my issue is with Sketch36, which does not reference any of the bodies. We could simply delete all bodies from the file and it wouldn't help me with the 3D constraints. Or do I misunderstand?

Re: Constraints in 3D sketches, please help

maxxxw — Sat, 26 Feb 2022 12:44:15 GMT

A side note, why can't I constrain a line that:

Connects to both sides of an already constrained circle
The midpoint passes through the centre of the circle

See this photo, there is coincidence constraints at both ends of the blue line and a midpoint constraint to the centre of the circle. I would expect that to be enough?

Re: Constraints in 3D sketches, please help

laughingcreek — Sat, 26 Feb 2022 18:20:50 GMT

what's controlling the angle?

Re: Constraints in 3D sketches, please help

TrippyLighting — Sat, 26 Feb 2022 19:36:38 GMT

@maxxxw wrote:

> You imported 2 discrete pieces of geometry, the PSU and the base. both should be separate components, not bodies > in a single component.

> One of those components should have been grounded and the other one should have been assembled to it with one of the joints in the Assemble menu.

Thanks for the reply @TrippyLighting, I will read your links, but my issue is with Sketch36, which does not reference any of the bodies. We could simply delete all bodies from the file and it wouldn't help me with the 3D constraints. Or do I misunderstand?

Your workflow is broken starting with the first feature in the timeline. Start from scratch and do it properly this time. Once done, we can discuss your sketch or perhaps a better more stable workflow not including 3D sketches.

Re: Constraints in 3D sketches, please help

maxxxw — Sun, 27 Feb 2022 19:39:31 GMT

You're right, I'm an idiot!

Although I've designed loads of wonderful parts for 3D printing and CNC machining, I think it's clear from this thread I'm still an absolute amateur at Fusion 360 😅

Thanks for taking the time to reply @laughingcreek @TrippyLighting

Re: Constraints in 3D sketches, please help

TrippyLighting — Mon, 28 Feb 2022 12:30:33 GMT

@maxxxw wrote:

You're right, I'm an idiot!

No one said that! But you seem strangely reluctant to heed advice from folks that have much more experience in the CAD /Modeling/Assembly side of Fusion 360 than you. This design does not require 3D sketches. It already has the basic framework to create 2 planes @ angle. Then you can create 2 D sketches on those two planes. This is much quicker to perform and creates a more robust design.

@maxxxw wrote:

I think it's clear from this thread I'm still an absolute amateur at Fusion 360 😅

I don't know much about the CAM side of Fusion 360, but I do have over 309 years of professional experience CAD/Modeling/Assembly and rendering side. The timeline in your design contains conceptual and workflow mistakes, which really aren't that difficult to address.

If you read the 2 links I provided that will provide you with a good indication what can be improved.

I had started doing that with your design but ran out of time last night.

Re: Constraints in 3D sketches, please help

TheCADWhisperer — Tue, 01 Mar 2022 16:06:34 GMT

@TrippyLighting wrote:
... but I do have over 309 years of professional experience

...and I thought I was getting old???

Re: Constraints in 3D sketches, please help

maxxxw — Wed, 02 Mar 2022 12:25:33 GMT

But you seem strangely reluctant to heed advice from folks that have much more experience in the CAD

I'm not reluctant! I was just not aware of how fixing errors with unconnected bodies will affect me constraining a 3D sketch. Also, aside from my errors, I really want to learn why in many situations I can't constrain 3D sketches.

I don't know much about the CAM side of Fusion 360, but I do have over 309 years of professional experience

Wow, that's a long time ha

The timeline in your design contains conceptual and workflow mistakes, which really aren't that difficult to address.

I will start fresh with this project and in the future pay closer attention to any errors or warnings.

This design does not require 3D sketches. It already has the basic framework to create 2 planes @ angle

I am trying to create a 3D wireframe body. Like a lampshade but without the paper. I want the "wires" to be about 0.8mm. I was going to create a 3D sketch and then use the "Pipe" tool to turn the sketch lines into wires that make up a 3D frame. Is there a better way to do this?

Here's a photo for reference:

Re: Constraints in 3D sketches, please help

TheCADWhisperer — Wed, 02 Mar 2022 12:40:26 GMT

@maxxxw wrote:
I was just not aware of how fixing errors with unconnected bodies will affect me constraining a 3D sketch.
I really want to learn why in many situations I can't constrain 3D
I am trying to create a 3D wireframe body.

@maxxxw
I examine the totality of someone’s work before I attempt to help them solve a problem - especially the foundational techniques. If I see issues with foundation techniques I insist on setting their current issue aside for a moment and first address the foundations. There is little point in building a house of cards on a foundation of quicksand. Maybe it can be done, but why? How robust and predictable will the “solution” be?

I almost always use 2D sketches to create and control my 3D sketches.

My 3D sketches are actually simply intersection Projections of the 2D.

Easier to create.

Easier to change the dimensions.

More robust and predictable.

Re: Constraints in 3D sketches, please help

TrippyLighting — Wed, 02 Mar 2022 16:38:51 GMT

5 simple fully defined sketches get this done.

The larger amount of sketches seems like more work, but they are much simpler and easier to control.

I've not done that in this design, but I would control pipe dimeters and perhaps a couple of other dimensions with user parameters.

Re: Constraints in 3D sketches, please help

maxxxw — Thu, 03 Mar 2022 09:58:23 GMT

Thank you @TrippyLighting, this is very helpful. I've added it into my project and will try and copy it. I've also started recreating my whole design from scratch, nice and clean, and will pay attention to errors/warning.