What's wrong with my path?

[lemelman]

I've defined a spline in the shape of a teardrop - it was created by drawing one half and then mirroring it. I then created a sphere that I want to duplicate along the spline.

The attachments show the result. What have I done wrong, why does it not follow the the defined path?

[HughesTooling]

Can you export the f3d file and attach, I think one problem could be where the start and end of the path are set. It will be a lot easier to show you with your file.

Mark

[lemelman]

Hi Mark,

I've attached the file. I hope it's OK.

[HughesTooling]

Actually the problem is where the start of the path is, try moving it to the centre of the sphere like this.

You left it set at the start at the beginning of the path.

Mark

[lemelman]

Sorry Indy,

Choosing Path Direction makes the copies drift off to the right of the required path instead of to the left. I need it to place the sphere centres on the path.

[lemelman]

Mark, I see what you've done, but I don't know how to start the path at the centre of the sphere. I seem only to be able to specify a path - not where it starts. What's the secret?

[wilkhui]

@HughesTooling - nice catch, I'll edit my previous post in case it leads anyone else astray.

Indy

Edit - the edit has timed out...

[lemelman]

Mark, or anyone,

Please tell me how to move tghe start of the path to the centre of the sphere, I can't find any command to do it.

[HughesTooling]

There is no easy way to do this I just dragged the start point to where it looked about right. There are a couple of problems one you can't use snap in the pattern dialog to set a start point. Two the primitive shapes are not very useful for something like this, you are better off using sketches if you need accuracy in a situation like this.

If I get a chance I do a screencast later showing how to uses sketches.

Mark

[HughesTooling]

Here's a screencast with the best idea I have for doing what you're after.

Mark

[TheCADWhisperer]

Check the attached file.

[lemelman]

Thank you Mark,

Judging by the method you've used, it would appear that it's not generally possible to use a spline as the path for pattering a sphere.

I'd had success earlier (see attachment) when I placed the initial sphere at the bottom of the complete teardrop spline and used the symmetric pattern to arrange the 5 beads. I wanted to repeat the example with an even number (6) of beads, so decided to create a pattern of 3 beads on half of the teardrop spline, and mirror it. When it didn't work I assumed I'd done something wrong, but since you eschewed that method I can only assume there is a limitation that's preventing it. Am I wrong?

[lemelman]

 Hi TheCADWhisperer,

I got into a mess with your file. I clicked and opened it in Fusion, and since I already had Fusion open at the time was slightly surprised when it started another instance, which I watched OK, but then I did the wrong thing and closed it. I subsequently decided to watch it again, but this time the new instance gave an error saying that Opening of local files is not supported. I tried various things, none of which worked, so closed that instance and went back to the original instance, but now that is totally screwed and unresponsive. See screenshot.

I thought it would be simple to arrange the beads along the path, but appear to have entered unknown territory.

[TheCADWhisperer]

---

@lemelman wrote:

...it would appear that it's not generally possible to use a spline as the path for pattering a sphere.

... Am I wrong? 

---

It is possible to pattern sphere on spline path.

When I get a chance - I will demonstrate using your file.

[HughesTooling]

To import am f3d file use New Design From File on the file menu, you probably need to kill Fusion in the task manager if you can't close it.

Personally I never use the primitive shapes if you need to position bodies and resize etc. they are not worth bothering with, OK is you're building Lego! I've got another idea on how to make a parametric model I'll  do a screencast later. The real problem is there are no snaps to position the primitive sphere to start with then no snaps in the patter dialog to set the start point, you just have to eyeball it, again OK if you're building Lego.

I have found a couple of problems\bugs in the patter feature I'll put in another thread.

Mark

[TheCADWhisperer]

Turn on your sound.

[lemelman]

Wow, that's really good TheCADWhisperer, thankyou.

However, I still think there's a problem with pattern along a path. If you look at the jpg I attached to a previous post (Gallagher v1) you'll see why I'm still confused. The drawing is, in fact, a preliminary sketch for a pair of earrings made of pearls on palladium wire.

I started with a spline that caused me a few problems in that I couldn't get the top to be a sharp corner. I settled for a tighter curve that was hidden by a pearl. I first placed a sphere on the bottom om the teardrop spline and than formed a symmetric pattern of 5 spheres in opposite directions on the teardrop spline. This worked fine. The next sketch was to be the same, but with 6 pearls - 3 on each half which would then be mirrored.

As a result of feedback on why I couldn't create a spline with a sharp corners, I decided to do it by defining half of the spline and then mirror copying it. I then needed to create the 3 spheres on the half teardrop, which led me to the problem.

The question now is: why isn't it possible to pattern 3 spheres on a spline when it was posible to pattern 5 spheres on a spline?

Surely this implies that Fusion has a problem with spheres on a spline. If not, why did it work with the 5 spheres but doesn't with 3? In the case that worked, the initial sphere wasn't at the end of a path. This is a very obvious inconsistancy that smells very much like a bug.

[HughesTooling]

@lemelman See this thread for some ideas on drawing a spline\teardrop with a sharp corner.

The only reason you have a problem with 3 spheres per side is the start of the spline in not at the centre of the sphere, when you used 5 the sphere you based the pattern on was at the start of the path.

Mark

Edit I see the other post was you, sorry.

[lemelman]

The 5-sphere pattern was based on a spline consisting of a single path in the shape of a teardrop that started and ended at the top. There were 4 nodes in all. The initial sphere was placed in the centre of the path, at the bottom.  If a spline path is defined as the line between two nodes, then yes, the initial sphere was placed at the start of a path - namely the bottom node. It seems very odd that Fusion happily accepts the selected path and then ignores it. If it can't follow the path it should, at least, object to it rather than ignoring it.