Pattern tied to two paths?

[kevinwilcox46]

Hi, hoping someone may be able to give me a steer or stop me wasting time trying;

I'm trying to create a curved railing-type object. The top and bottom rails are arcs that form an arch and parallel to each other but the lower (inner) rail has a longer arc. They are connected by about 100 'balustrades', which have to be evenly spaced across the whole path of both top and bottom rails (i.e. revolve wouldn't work). This means their angles (tangents?) to the two arcs changes as you go along; which in turn means their length changes as the distance to be covered grows a little each time. Is this do-able in F360? Googling suggests not, but I thought I'd check here as this is very easily do-able in Tinkercad using the 'duplicate' facility, which copies whatever you did the first time you copied and moved the object. So, if you move it a step to the right, rotate by a few degrees, move it down to align with both rails and lengthen the whole balustrade it'll repeat that ad infinitum(-ish). And as Tinkercad is of the same family, maybe there's a way in F360?

[g-andresen]

Hi,

try:

1. pattern on path > Type: Features 

2. Orientation > path direction

3. Compute Option > adjust

4. Important : create a path that way the 1. Instance and the Start point of your path are identical

günther

[kevinwilcox46]

Thanks Gunther, gave that a try but it hasn't worked. whichever way I set or create a path, it does the logical thing and follows the (path) curve. What it needs to do is follow 2, perhaps 3 paths; one that controls what happens at the top of the balustrades and another for the bottom. It feels like I would have to specify parameters for it to do what I need and without a facility to specify there's nothing for it to work to.

I'll do a mock-up in Tinkercad and post a screengrab tomorrow eveniing, that might explain it better.

[jeff_strater]

no, it is not possible to do a pattern on path that uses two paths at once.  You can create a pattern one way, based on one path, then create a second pattern on path going along the second path, but I can't say for sure that the results will be identical to what you are expecting.

[davebYYPCU]

Not sure yet, 

Your two frame arcs are not concentric, should they be concentric?

your example setting out, does not allow for 11 items, not sure how you would fit 100, 

I have seen a move and rotate routine here before, but that was for a spiral pattern arrangement.

You have press pull to one end of the upright, is that how the "Stretch" has to be?

Do 50 one side and mirror the rest (unless you need a BOM)

Might help....

[kevinwilcox46]

Hi, no the arcs aren't concentric. I've attached a picture to show the real thing; for my purposes I'm treating them as having the same radius but with offset centres. The file upload was just a crude example to explain the issue. By the way, ignore that the railings would be convex to the body, the degree of curvature is so small that I'll treat them as flat, since a resin printed part will easily flex to the curve.

[shahriarsifat1802164]

Hi,
I think a pattern already having two paths is not possible in this case. Please try to use other ways.
Thank you.

[davebYYPCU]

Ok, that will likely be sheetmetal, Unfold, Add uprights, then pattern on path, and refold.  Will depend on actual geometry.

Humour me, is the whole face a loft or a tilted trimmed cylinder?

The  amount of stretch in that Photo can not be detected, and for resin printing you won’t see it anyway.

Might help....

[kevinwilcox46]

I don't think I have sheetmetal on the free version? I haven't even looked at making the main plate yet but if I do, I'd be looking at lofting. It's a very complex object that has to fit perfectly against 5 or 6 objects across the faces and edges and would be, as they say, a 'challenge'. What I'm doing is working on an injection-moulded 1:100 plastic model, made from moulds that are probably 40 or 50 years old, so the detail features are no longer that sharp. I'm going to be sanding all of these off and replacing with crisp 3D printed parts. Easier to paint this way as well. I promise you, you would notice inaccuracy in stretchiing or spacing the balustrades. They are 0.7mm wide reducing down to 0.3mm in places and if the chamfer lines at each end dont follow the arcs it will stand out like a sore thumb, as the variance effect is relative to their size, if you know what I mean. I'm finding, on this model, that it has to be accurate to 0.1mm for 'errors' to be invisible. Who'd have thunk that would be the case!

Anyway, seems there isn't a method in F360 so an evening of clunky copying, pasting, one by one awaits. Or a trip over to Tinkercad. Such a pity Tinkercad doesn't allow modelling by numbers, what I suppose is 'proper' parametric modelling; if it did, it'd be the bee's knee's.

[g-andresen]

Hi,

---

@kevinwilcox46 wrote:

I don't think I have sheetmetal on the free version?

---

Here it is

günther

[davebYYPCU]

We all have sheet metal.

We can make a flat pattern from cylinders and cones, but not compound curves.

If you can imagine that face flattened out then I think your pattern will work, but. 

All the windows are flat, you have the real thing to measure, will be quicker to scan in 3d.

Your original mock up accuracy has me wondering.

Good luck.

[kevinwilcox46]

Slaps forehead. In my defence I've only been using F360 for a week or two. I looked everywhere but there; sometimes it really is right in front of your eyes.

The original mockup wasn't intended to be at all accurate, just the electronic equivalent of a 'back of an envelope' sketch, using exaggeration to clarify the question. I didn't even bother to measure it. The snip below is an accurate pic of the real model rails, and in fact there will be 67 uprights. The difference in length between centre and ends is 0.8mm, i.e. twice the thickness of the rails, which are 7.5mm apart externally. The arc widths are 88.5mm and 91.5mm top and bottom respectively. Picture the difference between a shaped upright on the centreline and the same thing closing off each end and it'll make sense that I say corner-cutting will be clearly apparent. I'd end up with a visual 'curve' that didn't follow the line of the rails.

[davebYYPCU]

Then you have to start measuring 3d stuff.

translating linear measurements from 3d space will not work well on flat paper.

Demonstrating that the windows open and shut on straight tracks, that must be parallel.

my bet, stand way back from the ship, all those front view posts will be vertical, but laid out on a 3d face are not vertical in the side and top view.

start with the big face first, to see what you got....

not a beginners project but I think Fusion can get you there, but would need some actual geometry.

Might help....

[kevinwilcox46]

That's very much the case, which is why the big face is tricky. Aside from the centre post none of the uprights are vertical in any plane, both on the model and the real ship. I could see myself spending many hours plotting the various curves on the face which would undoubtedly be worthwhile if I ended up with a perfect object, but I'm conscious that my pattern is a piece of injection-moulded plastic that itself requires a little bit of encouragement to fit to profile. And, at the end of the day, I only want to improve on all the decoration. Some bits - the scrolls, figurines, lettering, toothed arch, have been simple and came out well. Others, like these rails do need a bit more geometryand trig, as will all the windows. The hard-ish part is learning enough F360 on the fly.... but I'm getting there.

The angle of the decorations to the face in the verticalal doesn't matter in this instance, resin prints are quite flexible enough to wrap to those curves. Until I print this first rail set I'm not certain there will be enough horizontal flex though, but I'll find out soon enough. And if there isn't, I'll tweak. The difference between arc width and length is only 0.2mm/0.3mm so I don't need much give. I know this is the lazy way, not what I'd have done in my trade, but symmetry and 'looks right' are more important here than absolute precision and a little bit of bodging will be fine if applied judiciously.