How can I create a “group” of lines and circles in a complex shape and lock them

[Anonymous]

For laser cutting, I’m drawing a shape that is a circle but with some outward protrusions like keyways.  I draw two circles and overlay rectangles, then delete all the line segments and circle arcs that aren’t needed and I quickly have the shape I need and at right dimensions.

but as a result of deleting the pieces I don’t need, everything turns blue again, and when I create copies or use constraints to position the figure, it loses all of its dimensional accuracy and opens the shape up.  Is there a way to constrain this finished group together so that it stays exactly as I drew it and allow copy paste and location by constraints?

[davebYYPCU]

No file, screencast or pictures, to explain the problem

Not sure why you are after 2d Cad from a 3d modeller, 

Copy pasting sketch articles is a performance drag.  

fusion does not have sketch blocks. 

You can use the fix constraint, will get you close, but copy paste is likely to bust that constraint again.

Might help....

[etfrench]

Put the sketch in a component. Copy/paste the component.  Use a master sketch with positions for each of the components. Use a joint to position each component at its place in the master sketch.

[Anonymous]

Why am I using a 3D program to do 2D work?  Because I have a 3D program and I need to do 2D work.  I use fusion for both 3D printing of parts and for laser cutting other parts that assemble together, so it makes sense to me to do it this way and choose what elements i print and which i cut.

I've attached a picture of the very simple design.  each rectangle is a laser cut section, and I now need to populate them with the cutouts shown (these are rocker switch cutouts in a plexiglass panel).  

I've tried to "FIX" constrain the cutout, but it seems to lock it down on the drawing and then I can't copy/paste it to other locations.  If i copy/paste before FIX, I still can't add constraints to fix their positions on the drawing in the right locations.   

It seems that the advice to create a separate component is good on the surface, but to laser cut the design, I think you can only pick one component to get a DXF from at a time, so I would lose the location of the cutout.  It seems that what I'm searching for is a FIX option that fixes the sketch items selected, but not FIXed to other objects?  Or, if I could:  Instead of deleting the line/arc segments I don't need, if I could convert those segments to construction, then I might not lose the constraints that were originally created.  

I realize the screencast may be needed to see how I drew this, but I don't have it loaded yet.  Basically, I drew two concentric circles, then two rectangles on top that defined the keyway widths and locations... then deleted all the lines I didn't want using TRIM.  Sadly (and I think this is bug or feature request as it happens to me frequently), the constraints are lost when I do the TRIMs... even though part of every line/arc still exists... its like Fusion360 locked to a point vs an entity and if the point is in the deleted segment, the constraint is erased.  This seems like a bug to me (But i readily admit that I am a total newbie to this kind of design and I probably think wrong)

[davebYYPCU]

You should be able to copy paste your object without the errors you have spoken of, 

works my end, as expected.  

Edit sketch, window select the articles, right click, select copy, 

deselect the highlighted articles, and right click menu, select paste, and move to new position, select ok.

https://autode.sk/2lUpBeY

Might help....

Screencast will be displayed here after you click Post.

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[ToddHarris7556 · Accepted solution]

A couple of thoughts shared in a screencast:

1) It sounds like your sketching workflow might not be as robust as it could be. There are a lot of ways to skin the cat, but take a look at what I've shown and see if it helps. One of the most fundamental sketching goals to keep in mind is to try to build sketches that are robust - i.e. hard to break. There are many aspects to this, but in general steps include:

• tie your sketches to origin planes where possible
• use parameters
• use sketch constraints instead of dimensions wherever possible, and don't be afraid to use construction geometry to accomplish this. 

 2) The end goal in your case is a 2d DXF, but I think the easiest way to get there is to use 3d geometry as shown. 

[jeff_strater]

@timmalia, I understand what you are trying to do.  What you really want here is "sketch blocks".  Here is the IdeaStation entry for that request:  block-in-a-sketch.  I encourage you to vote for that.

However, in the meantime, there are, as @ToddHarris7556 said, many ways to skin that cat.  I was able to create a fully-constrained version of your cutaway block.  See the screencast below.  With this constraint scheme, you can copy/paste "instances" of this unit of sketch geometry and place it precisely.  I will follow this response with another (we are limited to one screencast per post...) showing how I built that.

But, if it were me, I would follow @ToddHarris7556's suggestion of doing this as a solid.  Mainly the advantage of this is that you would not have to trim your sketch at all

first screencast:

[jeff_strater]

and here is how I created that sketch:

[Anonymous]

I took your advice to use Todd's approach ... great work you guys!