defined sketches produce undefined sketches after array or mirror

kees_bijker

I have been asking myself this question several times now and I cannot understand what it is I need to do to make a sketch remain totally constraint even when you circular array, mirror or rectangular array a part of that sketch?

I have a fully constraint sketch, https://cad.onshape.com/documents/846012bb8ff605db05d26360/w/73253eebda7a07c4e761a8bc/e/b806c256b869db951a4dbc8e,

and I use circular array to create 3 more corner pieces. Now you end up with 1 constraint (the original) and 3 non constraint pieces of the sketch. But by definition of the fact that my original was constraint AND I use the origin to rotate around with a known number of copies equally spaced, the results should also be constraint, or not?

What am I missing?

I have noticed the same in rectangular patterns and with mirrors.

S1mon

The origin of the pattern needs to be constrained. In some cases it may be hard to see because it's on top of the origin, but if you drag the pattern instances around you should see a blue dot move off the origin. Just make that coincident with the origin (or whatever you need). With rectangular patterns, the axis (or axes for 2D patterns) need to be constrained as well.

kees_bijker

S1mon said:

The origin of the pattern needs to be constrained. In some cases it may be hard to see because it's on top of the origin, but if you drag the pattern instances around you should see a blue dot move off the origin. Just make that coincident with the origin (or whatever you need). With rectangular patterns, the axis (or axes for 2D patterns) need to be constrained as well.

Hi S1mon,

Thank you for your tip, it kind of works but....

It only works while I do it from scratch and I deliberately move the center of the rotate away from the origin and complete the rotation pattern. Then to constrain it with origin and voila, everything is black after that.

However, for the life of me I cannot get this accomplished when the center of the rotate is already on the origin in the first place. It simply will not select the correct dot to coincide with the origin. How to do this or is this something that must be done during the rotate pattern?

matthew_stacy

@kees_bijker, in order of descending preference mirror/pattern:

1. Parts (select "new" or "add" depending on your design intent and relative location of the parts)
   
2. Feature
3. Sketch Elements

Applying mirror/pattern to sketches is the last resort.

S1mon

kees_bijker said:

However, for the life of me I cannot get this accomplished when the center of the rotate is already on the origin in the first place. It simply will not select the correct dot to coincide with the origin. How to do this or is this something that must be done during the rotate pattern?

If you hide the origin, you should be able to select the center of pattern, and then unhide the origin, and select it, then hit coincident. Not ideal and you should be able to box select the two points, but you can't.