Pattern on path - start point value

[harry.doldersum]

I’m now a bit puzzled on how to interpret the “Start point” value in the “Pattern on path” function?  As long as I keep it the Start point value on zero, the function works pretty much as one might expect… 

The other day, however, I couldn’t get my pattern right, no matter what I tried? Until I realized that the Start point value was not zero: when correcting that, everything was well again.

For example, moving the start point some 40mm to the right in the attached model, gives it a start point value of 0.016, but while the distance value remains constant (at 125mm) the actual holes are some 85mm apart (nowhere near 125mm).

And manually entering a start point value of, say “1”, places the holes in what looks like the next zip-code?  I’m totally missing the point on how to use this…?

I’d really appreciate it, if someone could help me understand how I should interpret the Start point value?  😊

[g-andresen]

Hi,

File is empty!

günther

[harry.doldersum]

Aw, let me try uploading that again....  🙂

Thanks for looking into it!

[g-andresen]

Hi,

the starting point should be as identical as possible to the position of the pattern feature.
If this is not the case, the starting point of the path must be moved.
The effect is particularly noticeable if the path is not straight.

Orientation = Path direction!

günther

[harry.doldersum]

Hi Günther, thanks for your response - I appreciate the effort of trying to help me understand this.  🙂

Maybe I'm misunderstanding the entire concept of the starting point? I'll try to explain better, sorry if I haven't been entirely successful in that.

When having the startpoint at the start of the path (value = 0), the distance between the pattern's objects is as entered in the dialog (= 125mm).  All's well & the function is responding as expected.

When moving the starting point to anywhere else than the start of the path (so, value NOT 0), the outcome is (or seems to be) unpredictable (?).

I agree, if the starting point is at the start of the path, the output is correct. I understand, that selecting "Path direction" for the orientation assures that the profile is correctly following/alignes to a path, should the path be curved.

My question is: what is the Start point value doing in this process? Moving it an exact 40mm along the path, gives the start point field a value of 0.016 - what does this value mean, where does it stand for? Obviously not a distance in mm: so if not that, what is it?

If I put a value of "1" in, the pattern appears to jump all over the place - why is that?

Where would you use the Start point value setting for? What does it do?  

Thanks! 🙂

[g-andresen]

Hi,

Watch the screencast.

1. The path starts at the object. Thus the starting point = 0.
2. Fusion recognises that the object is offset from the starting point and defines the starting point = 0.15. By moving the starting point minimally, one can then still optimise the alignment to the path.

günther

[laughingcreek]

---

@harry.doldersum wrote:

...My question is: what is the Start point value doing in this process? Moving it an exact 40mm along the path, gives the start point field a value of 0.016 - what does this value mean, where does it stand for? Obviously not a distance in mm: so if not that, what is it?

If I put a value of "1" in, the pattern appears to jump all over the place - why is that?

the startpoint here is being expressed as a percentage of the total distance of the path.

Where would you use the Start point value setting for? ...

---

if the profile is positioned along the path, but not at the beginning path , you can use the startpoint parameter to move it to where the profile is.

[harry.doldersum]

Hi Günther, 

Thanks for putting that together, I really appreciate that. It does help me to understand a bit better what the startpoint tries to do.  I think I do, at least... 🙂

However, I'll need a bit more explanation on this...

If Fusion sets the startpoint to "0.15" as you mentioned - what does that value stand for?  It's not a distance of any sort..., but what is it then?  I'd really like to understand that, as it appears to affect the result in spacing between the objects?

[  Edit: this portion of my question is now answered, thanks! The remainder is still open & any help on that is highly appreciated!  🙂  ]

I noticed, in your screencast (around 1.30 min. into it) you move the start point around...? 

I don't know why, but it appears we can move the startpoint around, which changes the distance between the pattern's objects, even though the distance parameter remains the same at the earlier value. 

So, when you make, say, a pattern where this distance dimension is important, the output result would not be consistent with the entered value?  In the screencast, at 1.30 min, you note a distance of 62.18mm: when moving the start point around, the actual distance between the objects changes, while the value in the Distance field remains constant at 62.18mm.

That's what I can't get my head around...  What is happening there?  I'm sure, there's a good explanation for it & I'd really like to understand that. 🙂

Thanks! 🙂

[harry.doldersum]

---

@laughingcreek wrote:the startpoint here is being expressed as a percentage of the total distance of the path.

Excellent: I took out the calculator & that matches exactly - so, that's very helpful, thanks! 🙂

---

if the profile is positioned along the path, but not at the beginning path , you can use the startpoint parameter to move it to where the profile is.

---

Yes, that's also what I understood from @g-andresen . So, that's also a good step forward for me... 

But this then brings me to the following: how is this value affecting the resulting distance between the objects? In my sample file, I had an entry of 125mm distance: when moving the start point around, the value remains constant, but the actual distance between the pattern's objects becomes considerably smaller. I see the same occurring in the screencast, around 1.30 mins. What is happening there, please?

Thanks! 

[g-andresen]

Hi,

---

@harry.doldersum  schrieb:

 when moving the start point around, the value remains constant, but the actual distance between the pattern's objects becomes considerably smaller. 

I agree with you, that can't be intentional.
Since I don't use pattern on Path for straight paths, I haven't noticed this before.

@jeff_strater 
I think this should be clarified.

günther

---

[zip70124]

I'm experiencing the same phenomenon with linear patterns.  I want to adjust the starting point but have the spacing stay as specified in the pattern dialog box.  Unfortunately, when the "Start Point"  is set to anything other than zero, the spacing distance changes also!   This makes the "Start Point" feature just about worthless !!  A bug in the software?  Inadequate documentation?  Both?

[g-andresen]

Hi,

please share the file for reply

File > export > save as f3d on local drive > attach to post

günther

[laughingcreek]

seems like a bug to me also.  I've always worked around this weirdness by creating a path at that starts at the intended location, which sometimes take a bit of extra work.  far as I know this has never been addressed.

[Josef_A_K_]

Hi,

Your file works for me.

I've tried it. And for me it is also not to understand.

Maybe that the Startpoint is a percent value as in other functions, but I don't understand what is going on with the distances. I made a video, my be I am wrong.