How do I add an entity to a sketch pattern?

Maxpm

I've successfully created a circular sketch pattern and now I want to add a new entity to it.  However, short of deleting the pattern and starting over from scratch, I can't figure out how.  Creating a separate pattern for the new entity isn't acceptable to me; I want it to follow the repeat count of the original pattern.

NeilCooke

It can't be done because a sketch pattern is a constraint not a feature. That is why it is better to use feature patterns where possible. 

NeilCooke

It can't be done because a sketch pattern is a constraint not a feature. That is why it is better to use feature patterns where possible. 

hairy_kiwi

I ran into the same issue recently and as you describe, each time needed to redraw the circular pattern with the additional entities.

I also noticed the entity number and radial displacement parameter text-boxes could easily become obscured by other sketch entities, to the point where they were impossible to find. The only work-around I came up for this secondary issue was to start the pattern center 'off-site' and then use constraints it to bring it back to the desired location.

brian_brady

NeilCooke said:

It can't be done because a sketch pattern is a constraint not a feature. That is why it is better to use feature patterns where possible. 

@NeilCooke

I've read several times that we should use face patterns, not feature patterns for best performance for some unknown reason. This time you are proposing using feature patterns not sketch patterns (which I agree with wholeheartedly). Why not face patterns? I always use feature patterns because they are easier and make more sense to me that face patterns. What should we be using? Why can't feature patterns be as efficient as face patterns?

ilya_baran

Face and body patterns are more efficient than feature patterns.  Face and body are purely geometric operations and are done quickly.  Feature patterns actually reexecute all of the feature logic that many times -- and that's a lot more expensive.  Sketch patterns are a different beast altogether, making your sketch larger and slowing down constraint solving.

NeilCooke

@brian_brady sorry I was just being lazy but also wanted to clearly differentiate from a sketch pattern. What I should have written is part/feature/face pattern. Part and face patterns have their place but do not always work especially if the geometry they are patterning on to is different. Feature patterns are also easier to pick, but expensive in terms of part regeneration. 

brian_brady

ilya_baran said:

Face and body patterns are more efficient than feature patterns.  Face and body are purely geometric operations and are done quickly.  Feature patterns actually reexecute all of the feature logic that many times -- and that's a lot more expensive.  Sketch patterns are a different beast altogether, making your sketch larger and slowing down constraint solving.

Why don't feature patterns just perform like face patterns "under the hood" but allow you to select features while modeling (which is much easier)? My thoughts are that only the first item in the pattern should be editable anyway, unless there were some sort of switch that made each patterned feature a separately editable entity.

ilya_baran

@brian_brady
We could add the ability to select features to face pattern, but it would be a different behavior than feature pattern.  The issue is not what is editable (individual feature instances in a feature pattern are not editable) but rather, whether a feature instance can "adapt" to its situation.  For example, see the examples in the original video: https://forum.onshape.com/discussion/2675/improvements-to-onshape-february-11th-2016/p1 -- the geometry can actually be very different for each instance of a feature pattern; not so with a face pattern (or your "combined" proposal).

brian_brady

@ilya_baran,

Maybe a checkbox in the feature pattern dialog that says "Create as face pattern"? For geometry that does not need the adaptive nature described in the video you linked, such as large flat plates with many holes/patterns of holes, the adaptive nature would not be needed.

ilya_baran

@elif, what do you think?

elif

We have been considering a "lightweight" feature pattern that basically uses features only as selections. If it's not in the improvements list, please add it there and vote on it so that it can get prioritized accordingly.

john_kuyper

I often prefer to use Sketch Patterns because you can manage the parametrics better.  For example, suppose you have a shape to pattern.  The left side of the shape may need to be defined in instance "A" and the right side of the pattern may need to be defined in instance "B"  Of course, you can bend over backwards and do it outside the sketch, or just pattern the sketch and create your parametric relationships in one place.

Second, given Onshapes suggested workflow (sketched layouts that drive part geometery), it almost seems necessary to include patterns in layout sketches.  Right now, when you need to change your patterned shape in your layout, you will need to delete it and start over.  It seems odd to me that this is not already do-able.  
Under the hood, it should work much like mirror.  Each entity has it's own mirror constraint, making modifications easy.  In the same way, each entity could have it's own pattern constraint.
In both the mirror and pattern constraints, "adding" a sketch entity is really just copying existing constraints onto the new sketch entity.

karl_mochel

I am trying to use linear sketch pattern to setup a spline guide to create a uniform spline and need to add construction lines to the guide. Having to rebuild the pattern each time is a pain. I would like a capability, like Illustrator, where I can go into the pattern entity and edit it.