topic Re: Two simple questions - I hope in Fusion Design, Validate & Document Forum

Two simple questions - I hope

lemelman — Sat, 04 Jun 2016 10:13:48 GMT

I'm an experienced TurboCAD user making the transition to Fusion. The first question is how can I draw a spline like a teardrop?

In TC I can specify that the curvature at a control point is equal, non-equal, or non-smooth, and can draw a shape as shown in the attachment. How can I do this in Fusion? I on't seem able to move the control handles independably.

Second question is: how can I change the size of a shere after I've drawn it? I can't find any way.

Re: Two simple questions - I hope

HughesTooling — Sat, 04 Jun 2016 10:30:46 GMT

Easy one first, there are a couple of ways to edit a sphere, one right click on it and select Press Pull or right click the feature in the time line.

Can you attach a DXF of the tear drop done in TuboCAD. @michallach81 did a nice screencast for someone a while ago to show how to do this I'll see if I can find it.

Mark

Re: Two simple questions - I hope

HughesTooling — Sat, 04 Jun 2016 10:37:58 GMT

Here's a link to the thread with the screencast.

Mark

Re: Two simple questions - I hope

jeff_strater — Sat, 04 Jun 2016 13:17:54 GMT

here is a quick video showing how I would draw a tear drop shape using splines. The key to getting the sharp point at the top is to initially draw the spline as not a closed spline, then later go back and join the points. The rest is just dealing with the curvature handles - making them vertical/horizontal, etc.

Hope this helps

Jeff

Re: Two simple questions - I hope

lemelman — Sat, 04 Jun 2016 16:42:57 GMT

Thanks guys, you answered both my queries in double quick time. I'm impressed and very thankful. Without this forum and your experience, Fusion, as it is without a good reference manual, would be very difficult to master. I'm very slowly getting there. Thanks again.

Re: Two simple questions - I hope

HughesTooling — Sat, 04 Jun 2016 16:58:36 GMT

Attached is a sample file using the method demonstrated by @michallach81 using 3 splines. It uses symmetry constraints on the handles and tangent constraints between the splines. If you mouse over the constraints the points\curves used by the constraint highlight.

To import the file use New Design From File on the file menu.

Mark

Re: Two simple questions - I hope

HughesTooling — Sat, 04 Jun 2016 17:15:16 GMT

Hey @jeff_strater any idea why the curvature Comb is not symmetrical on the teardrop I've attached to this thread, as far as I can tell I have everything symmetrical.

Mark

Re: Two simple questions - I hope

jeff_strater — Sat, 04 Jun 2016 22:40:36 GMT

Hi @HughesTooling, I'm not certain. It looks like a bug, probably with the solver. However, when I open that design, my curvature display looks different:

The bottom curve is symmetric, but the top ones are not.

I'll send this to the spline guys to check out. Thanks for posting it.

Jeff

Re: Two simple questions - I hope

HughesTooling — Sun, 05 Jun 2016 11:29:00 GMT

Hi Jeff, Part of the reason yours looks different is down to me adjusting the handles trying to make it more smooth. The other reason is I think you added the curvature comb one curve at a time and I selected all 3 and turned the comb on.

Here's an example on the left added one at a time, right comb added to all 3 in one go. I've attached the file with the setup.

Mark

Re: Two simple questions - I hope

jeff_strater — Sun, 05 Jun 2016 13:26:06 GMT

Thanks, @HughesTooling for pointing that out about the curvature display. I had forgotten that this command tries to pick a scale factor for you based on your selection.

As to why they are not symmetric, I'll have to ask the expert. But, I suspect that it has something to do with a bug that does not allow me to actually make the handle lines themselves symmetric. In your design, if I select on the the symmetric constraint, you can see that only the handle end points are marked symmetric:

And, I could not apply a symmetry constraint to the other endpoints. So, I tried to "fix" it by deleting that constraint, and applying to the handle lines, not just the points, and I get a solver error. Similarly, if I try to apply an equal length constraint, I get the same thing. So, there is something funky going on there.

I was able to get it work by just mirroring the spline:

which is probably an easier approach anyway.