7 Replies Latest reply on Dec 6, 2013 11:24 AM by Glenn Schroeder

Finding Center-Point of Patterned Holes.

Hello!

I've got an interesting dilema: does anyone know of a simple way of finding the center-point of a hole that's a part of a curve driven pattern? I.e., something I can snap to to get dead-center? I've created a complex array of 3D holes that are on a non-uniform surface/part, but I can only grab the center-point of the original "seed" feature (via the underlying 3D sketch); the rest of the holes created by the pattern feature do not have any usable / "snapable" geometry (from what I can tell).

The seed hole was created via the Hole Wizard, the remaining holes were created via Curve Driven Pattern using a 3D sketch to define the curve, and uniform spacing value within the feature to uniformly space the holes. I know if this were a 2D sketch, it would be easy enough to just do a pattern of sketch points placed at the same distance along the spline as defined in the 3D pattern feature used to make the original holes. However, I'm unaware of any way to do this in 3D, short of actually creating a new 3D sketch and converting each hole perimeter into a sketch entity so I can then get the center-point from the newly derived sketch (come to think of it, I'm not even sure you get center-snaps when using "convert entities" on a 3D sketch)...

We're talking 100's of holes here, nothing small...  I'm surprised SW (seems to) ditch any snap-to geometry for the remainder of the pattern, when it obviously is retaining it somewhere for the sake of the pattern that's created? Seems like I'm missing something here.....

Hope somebody can help!

--Sloan

• Re: Finding Center-Point of Patterned Holes.

Sloan,

You could create a new 3d sketch, and sketch points should snap to the hole center, though you may need to hover your cursor on the edge of the hole first to "wake it up".  At least I assume so, I know that the end of lines will snap to the center of a hole in a 3d sketch; I don't know that I ever tried with sketch points.  But for hundreds of holes this could (will) get tedious, especially if it's something you'll need to do on more than just this one project.  Someone may be able to write a macro to do it, but I don't know enough about them to know.  If you think that's an option you might want to post the question in the API section.

Would you mind explaining more about what operation you need these center points for?  That might give someone an idea of something that will work.

• Re: Finding Center-Point of Patterned Holes.

That's the thing: in 3D Sketch mode, if I go to create a spline, the only thing it will snap to is edge geometry. Because the hole itself is void space, it won't allow me to snap to the center point of it. Yet, the seed hole has a nice, neat sketch point right in the center of the hole with an "on surface" relation. It's perfect, and it obviously had to make those same calculations for all future holes in the pattern, so it's a mystery to me why they suddenly would vanish for the patterned holes.

I'd *love* to avoid something like macros when this seems like something that should just "work" -- again, there's no logical reason I can see why SW would "ditch" the points it used on the back end to create the patterned holes; it even seems like that's something they'd have to go out of their way to do! Seems silly, yet that's probably exaclty the case, sadly..

To give you a clearer idea of what I'm trying to do: these holes are patterned on a non-uniform surface (cut all the way through, normal to the surface), and I need to neatly connect each hole with a "trench" of sorts-- a "connect the dots" scenario, using a swept cut / cut tool.

I could be lazy and instead connect the holes using the hole's edge/ring at the opening, but this would be eyeballing it. If I could connect the 3D sketched cut path from hole center to hole center, it would be flawless geometry.

Any ideas? This seems so silly to me that you can't snap to the center of these holes, when you can on a 2D sketch!

Thanks again.

• Re: Finding Center-Point of Patterned Holes.

I rarely use splines, but it you place sketch points concentric with the holes will the spline snap to these points?

• Re: Finding Center-Point of Patterned Holes.

Just realized I have this thread under 'Drawings & Detailing' - doh!

As far as I know (if I'm understanding your question correctly) there's no sketch relation in 3D that would allow me to make a point "concentric" to a circle, but the spline will snap to any point I create manually. The trick is creating points that have an On Surface relation to the master surface, even though the "suface" itself doesn't technically exist any longer now that the hole feature is parent to it, and the center of the hole is just dead air. But again, the main seed hole has this exact sketch point, right at the center of the hole, and perfectly flush with the surface that *used* to be there, ha..

I assume the primary reason you can't grab the center point of a circle on a 3D Sketch is that-- unless it was made via '3D Sketch on Plane'-- it's not technically a circle, which can only exist in 2D by nature. If it's a "circle" on a countoured / non-uniform surface, the shape would have a slight bow to it in the 3rd dimension, and thus no 2D center-snap would be available.  SW would just see it as an arbitrary shape / closed spline.

It's just insanely frustrating that SW would permanently hide sketch geometry that it's making on behalf of the Hole Wizard already! Unbeleivable... I have been reading and reading online, and have yet to see any information on this dilema...

• Re: Finding Center-Point of Patterned Holes.

I see your point.  I didn't think about the holes not being on a planar surface.  I hate to give up so here is one more idea.  Go ahead and place your spline on surface, placing the points close to the holes.  Turn on temporary axes and set coincident relations between the spline points and the temporary axes.  I just did a little bit of experimenting and it looks like this will work.  I know it will take longer than you had hoped but I think it's the best it's going to get.  It's about the time of day when the forum gets more active so maybe someone else will see this and have a better idea.

• Re: Finding Center-Point of Patterned Holes.

So I made a dummy file to tinker with vs. using the feature-heavy master file, and tried your suggestion. It actually works beautifully for finding the hole centers (great suggestion!), but it is verrrry labor intensive-- I'm curious if I did it the exact same way, however? I created my array of holes/fillets, un-hid the original seed curve, made a new 3D Sketch and started placing points along the trail, arbitrarily. Then turned on temporary axes, and one-by-one (i.e., hole by hole) selected each temporary axis at the center of each hole and made it coincident with each corresponding point I'd set nearby on the path. They snapped beautifully to the hole centers, but also would mean doing this 100+ times in a row to get all points locked into place... I'm wondering if there's a way to cheat that process somehow? Ha, probably a macro...

HOWEVER! A lightbulb went off when I reminded myself of a challenge I'd had a while back when trying to somehow get an absolute center-snap on a 3D curve. For whatever reason, the functionality is not there using Sketch tools, but IS there when making reference geometry/points (yet another odd SW quirk). So I un-hid my original seed curve, went to make a reference point (*not* sketch point) and it allows you to select your seed curve and do a number of things, like place a point anywhere along the path at a defined percentage, a certain distance from either end, OR ... drum roll ... evenly space a user-defined number of points along the path.  So I was able to match the spacing I had done using the Curve Driven Pattern and the points were perfectly at the center of each hole! Woohoo!

I feel like this is one of those stranger "double standards" SW has, where reference geometry has permissions that sketch geometry doesn't, and really for no logical reason, from what I can tell? Either way, alas, I can move on haha...

Glenn, I really appreciate all of your replies, it's easy to feel like you're on an island when nobody's chiming in and you've got a valid and time-sensitive problem at hand. I appreciate you throwing so many ideas into the mix!

--Sloan

• Re: Finding Center-Point of Patterned Holes.

I'm glad you got it to work.  I rarely use Reference Points, so it never occurred to me to try that, and I was at home last night and don't have SW there to experiment with anyway.