How to create points set on inner most curves in a pattern of curves & how to export those point

[sluzzer]

Requirement:
1. I want to make a profile, by creating a pattern of circles along a epicycloid curve and by selecting the radially inner most point of those circles.

What I did:
1. I created the epicycloid curve using expression (fig 1)
2. Then I created a circle at a point on the curve (fig 2) and made instances (pattern) along the curve (fig 3)

Problem:
1. Now I want create points along the innermost curves. How to create such points?
(I created those points by manually creating a line and then pattern it for 360 degree and then making intersection points at the innermost curves (fig 4). But it is very laborious. Is there any easy way by any inbuilt method or by GRIP or by Journaling)
(Mathematically those points are located, normal (towards centre) to the tangent at each point of base curve (epicycloid) curve and those are not simply radially innermost with respect to the pattern circle)
2. How to export those points to excel or text file?
(I searched this forum & got many GRIP or Journal files. But I don't know, which program to use for this specific problem.)

Thank You

Regards
shiva

 

[cowski]

I'm not sure I follow exactly; you refer to figures 1-4, but the only attachment is "4.jpg" (figure 4?)

Going by "4.jpg", it seems to me that if you offset the original epitrochoid curve by the distance of the radius of the circle, all your created points would lie on this offset curve. So, rather than creating all the points manually, you could offset the original curve and use a point set to (automatically and associatively) create any number of points along the curve.

www.nxjournaling.com

 

[sluzzer]

Thanks for the reply Cowski!

Sorry! I didnt notice that other figures are not attached!

Here I attach the part file which is created in nx8, in which I made the sketch.
Link


By offset, we will not get the same profile as required. Beacause while offsetting every point on the curve will move radially inwards. What I want is every point should move Normally to its own location.

Thank you

 

[cowski]

The offset curve command does move the curve normally (inwards or outwards); therefore, I maintain that offset curve will give you what you want. As proof for you, I've attached your part with an offset curve (in magenta to stand out against the blue circles). I've reduced the number of circles in the pattern to 50 so you can better see that each one is tangent to the offset curve (but this will still be true with any number in the pattern).

www.nxjournaling.com

 

[sluzzer]

Thank you so much Cowski!
So the offset curve works for this specific problem but it will not helps in selecting outer or inner boundary for other problems.

For example, if the same epitrochoid curve is rotated (circular pattern for 6 times) about an eccentricity (take 2 mm on x-axis), then how to select only the outermost curves! Here I attached the part for reference.

Link

Also please tell me how to export the point sets to excel or txt format.

Thank you

 

[cowski]

You can select the outermost curves in certain commands with the "single curve" filter and the "stop at intersection" option set. In the screenshot below, I'm creating an extrude feature from the outermost curves. To get the fully enclosed profile would take 6 curve selections.

www.nxjournaling.com

 

[sluzzer]

Thanks Cowski! It works!
But this also gets so tedious, when the pattern curves are more!
Is there any way by making window selection of all the curves, only the outer or inner boundaries will be selected?

Thank You

 

[cowski]

If all the curves are in the same sketch (project your law curve into a sketch and use pattern curve to make the copies) then you can use the "region boundary curves" to get the innermost curves in 1 selection, but I know of no easy way to get all the outermost curves...

www.nxjournaling.com

 

[sluzzer]

Ok.. Thank you very much! your answers helped me a lot