Instance sketching??? Please Help. 3

[Willzville]

I know about instance feature, but I need to make copies (grids) of circles for a perforation IN SKETCH MODE. I don't want to use the instance feature because that keeps on saying that its completely out of the body.

How do I make copies of my circles (in a grid) in sketch mode?

Thanks in advance!

 

[JohnRBaker]

Please, what version of NX are you working in?

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Willzville]

nx5

 

[hudson888]

Will,

If you're on NX-5 or later you can take advantage of instancing bodies instead of features. However from your post I can see that you're looking to create booleans, either unite or subtract in all probability. But if you create an array which results in bodies that sit in space then you won't be able boolean them anyway. That is why you have this non-manifold or outside of body type error message.

There are a couple of possibilities that come to mind. To explain lets assume that you can test this using a number of holes in a rectangular plate to being with. You do yourself a favor by using small numbers and easy things to test with before attempting the real life example.

Try creating a mathematical expression for the number of holes that you would be able to have in a given plate size. You'll eventually need two expressions on for x and one for y if a rectangular array is your tool of choice. You could use an expression that calculates either the pitch or the number of holes. And you could also write the desired edge distance into your equations.

Another approach that works is to make another feature much larger than your likely requirements that you can use for a subtract later on. That is if we stick to the example of a plate with holes as our result. Then by making a plate with bosses you can subtract that to get holes. In this way if you have a plate 50 x 50 you can place above it a plate 100 x 100 with an array of 10x10 bosses, and then when you subtract it you get 5 x 5 holes plus any half holes that may cross over the edges. As long as your plate will never be bigger that 100 x 100 then it would always be covered by the hole pattern.

In general I would vastly prefer the first method as the geometry is far lighter to manage, but the second is there if you find no other workable alternative.

Best Regards

Hudson

 

[mmauldin]

Attached is a plate I created recently that demonstrates Hudson's first choice. It uses expressions to determine the number of holes based on the plate size and a maximum hole spacing. While it place the holes around the perimeter, a perforated sheet can be done in a similar fashion, only easier.

Just change either the length or width, or both, to see how it responds.

As a side benefit, creating a pattern of holes in this way, rather than in sketcher, allows the use of the component array ISET function when mating screws with all those holes if the part is used in an assembly.

 

[NXMold]

Couldn't you create the desired curve geometry outside of the sketcher but drawing arcs and using instance geometry?

 

[hudson888]

NXMold,

I can't check this right away so I want to encourage you to try it and let us know. I think anybody could easily test it and probably should. Try picking a sketch under the instance geometry function as well for that matter. My guess is that geometry for the purposes of that function may be restricted to bodies, (solids and sheets only). Please prove me wrong. .

On the other hand or in case it doesn't work; when you think about it, if you were going to use those curves and arcs to create solids or sheets then you could more readily just instance those to the same end.

Best regards

Hudson

 

[Xwheelguy]

Instance Geometry will instance any type of geometry, Datums, Points, Curves, Sketches, Sheets, Edges, Faces, Solids.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[hudson888]

Tim,

Thanks, instance geometry in NX-5 will allow you to select any of the features listed in the pull down selection filter. Strictly speaking it doesn't instance sketches as a whole, rather it duplicates any or all of the curves from within the sketch that you individually select. But because the instances are associative the effect is equivalent.

It also allows you to use groups as a selection method but does not propagate a group in the output.

Anyway thanks for helping us explore this something else has been learned as a result.

Cheers

Hudson