organic curves/beyond arcs and circles

[Kunkmiester]

I'm working on a project to build a model M1 Abrams, and will likely extend to doing numerous other tanks at points somewhere past actually getting a business started.

big problem is most tanks have curved surfaces that don't have fixed radii. I'm looking at the glacis plate(front armor on the hull) on the Abrams, and things like the turret on the M4 Sherman and a few other places. This has similarities to making fenders and car parts where spline type curves are used. While some parts of the curves don't necessarily need to be well defined, I do need decent models that can have some dimensions fixed(for defining attachment points and scale stuff etc.).

My Google-fu is failing me on getting a decent modern tutorial for this, most are like 10 years old, or not related. I'm also restricted in what material I can use to get data, since this is a commercial project, and can't always guarantee Ed Gruberman's model on Thingiverse is quite right, assuming Alibre can open it and let me turn it into a vacuformed part and accessories.

 

[bigseb]

Post a picture of exactly what you want to achieve.

 

[WillAdams]

How would one model organic shapes such as this?

H0011-L104564750

• WillAdams
• Nov 20, 2019

Or a flower? Or a tree?

 

[Lew_Merrick]

My argument is that we need a much richer set of curve entities available to us: 5-point conic curves, Wronskian curves, True Inolute curves, and the like.

 

[GIOV]

Alibre is lack in B-spline & loft and specially fall to have a feature Tangent constrain between B-Spline and line or curves so the surface remain with little discontinuity. Here is a little example:

 

[WillAdams]

Okay, I yield the point that this can be modeled in Alibre --- if I may revise my question:

>How does one draw the profile of such an organic shape directly using the spline tool?

(see my other post asking how one would draw the Alibre logo)

 

[idslk]

Hello WillAdams,

>How does one draw the profile of such an organic shape directly using the spline tool?

also the "organic"-tools are not state of the art in Alibre, why do you want o use a screwdriver to get a nail into a wooden plank?
Regards
Stefan

 

[NateLiquidGravity]

I've never tried it but a bunch of people on the forums have found MOI to be a great "organic" shape software that works well with Alibre. http://moi3d.com/

 

[WillAdams]

I've never tried it but a bunch of people on the forums have found MOI to be a great "organic" shape software that works well with Alibre. http://moi3d.com/

It's been on my radar to try for a long while --- I wound up with Alibre Atom3D since it's being bundled with Carbide 3D Nomads and Shapeokos in their Black Friday sale this year:

https://carbide3d.com/blog/2019/black-friday-2019/

(as opposed to the Alibre Black Friday sale)

https://www.alibre.com/black-friday-licenses/

​

So the consensus is that Alibre only does arcs, circles, and rectangles, and the spline tool is limited to the shapes which it will naturally/willingly make (which can then be rotated or extruded --- are there other options?) and if one wants free-form organic modeling, use a different tool.

See the specific question: https://www.alibreforum.com/forum/index.php?threads/drawing-with-splines.21363/​

 

[DavidJ]

At first glance the M1 Abrams hardly has a curve anywhere - nearly all angled flats. I would image that to keep manufacture fairly simple, complex curves would be avoided unless there was a very good reason.

As bigseb commented above - can you give us an example of the shape needed? or at least indicate which aspects are proving problematic...

 

[WillAdams]

As I noted, I simply want to be able to draw free-form things --- I haven't been able to access the 2D sketching at all in my copy of Atom3D --- is there a good tutorial on doing that? Step-by-step, with screengrabs?

 

[DavidJ]

Try the Atom3D training videos on the Alibre web site. Alibre Atom3D Training - Alibre, LLC

Try those in the 'Walkthroughs' sub section. 'Making our first Part' is a good one to look at initially - though it only uses regular shapes. You'll most likely need to use the Spline Tool if arcs / ellipses aren't 'free-form' enough.

 

[WillAdams]

Right. That's the problem --- I've gone through the videos insofar as I can and I haven't found a step-by-step set of instructions which works for me in my copy of Atom3D which will allow me to draw with the spline tool.

I need something which breaks down every interaction step-by-step showing screen state before/after and assuming nothing, describing each motion and each click and each interface element which one needs to interact with.

Why not do that as a tutorial for the Alibre logo at the link where I asked about that?

 

[DavidJ]

Can you get into 2D sketch mode ? If not we are wasting our time.

The Spline options are simplified in Atom3D. Select the spline tool to place spline points, click once in the workspace for each new point. To end the spline either hit Esc OR click twice in succession without moving mouse.

To adjust an existing spline - activate Select, then you can drag each node on the spline to a new location.

You can use dimensions or constraints to position the nodes too.

 

[WillAdams]

How do I get into 2D sketch mode? --- I suspect that's the point which is failing --- I managed to work through Atom3D well enough to do:

https://community.carbide3d.com/t/parametric-design-using-alibre-atom3d/17409

which references 2D Sketching --- is that what you mean?

 

[DavidJ]

Yes - that's why I referred you to the 'making first part' video, it shows step by step entering 2D sketch mode.

You can't do anything in Atom3D without being able to get into 2D sketch mode - you enter 2D sketch mode by clicking the 'Activate 2D Sketch' button - which is at extreme left of Ribbon, when you first open a part workspace.

 

[WillAdams]

Okay, I'm in 2D sketch mode, I can select the circle tool, click in the circle, plug in a dimension and get:



I've tried selecting the Spline tool, but no success with drawing --- how does one use the spline tool?

 

[HaroldL]

Treat the spline tool like a rubber line. Once it is selected click once to place the start of the spline. Click in other locations to place Reference points that the spline will pass thru. Double click to place the last point and end the spline.

There is a video on YouTube that cover using the spline tool but it is older and was created for Alibre Design so some of the content may not apply to Atom.

 

[WillAdams]

I'm clicking, and it's not working --- does Atom3D not work with a stylus or trackpad?

 

[DavidJ]

With spline tool active - click in the workspace, move cursor, click again, repeat.

If that isn't working, try re-setting user profile from link on Utilities Tab of Home Window.