Instance Feature vs Instance Geometry vs Pattern Face? 2

[azonic3d]

Could someone give me a quick run down on what the major differences between these 3 functions are, and what they're best suited for?

I've actually used all three, mainly just when one method didn't work, but I'm trying to actually understand which one would be better suited for which type of situation.

We work with a lot of plate that has holes drilled in them. These are usually for bolts to pass through. Normally, I create one hole, and do a rectangular/circular array using the Instance Feature feature. My understanding is that by doing it this way, I can then use that to drive the pattern/arrays for the bolts at the assembly level.

However, since this particular part I'm working on has its hole pattern on the XC-ZC plain, I can't use the Rectangular array option (will only allow you to do an array on the XC-YC plane?), so I use the Pattern Face option under Instance Feature. What's the difference in doing this, and will I not be able to use these patterned holes to drive the component array when I go to put the bolts in at the assembly level?

Other times, we have parts that have holes to accommodate oval head bolts. Since the hole geometry has to be created manually, I usually do so as a separate body, then use the Instance Geometry command to make the hole pattern. Sometimes the orientation of the oval head needs to be varied/changed, so using this command allows me to do that.

Any other insight into using these options?

 

[joycejo]

I think the major diference between Instance Feature and Pattern is the ability to recognize the feature array when adding components. You can have an instance array in any direction you need if you move your work coordinated prior to creating the array.

Pattern Face will work with unparameterized geometry (No Features)so you can create a pattern of faces. I think that's why it is part of Synchronous Modeling in NX6

Instance geometry can instance non-feature geometry like curves for example.

John Joyce
Tata Technologies
1675 Larimer St.
Denver, CO

http://www.myigetit.com

 

[BOPdesigner]

I to am interested in a summary of these three. However, for your rectangular array in a different plane, just change the orientation of your WCS and then you can create that array you want.

 

[azonic3d]

Wow, I feel dumb now. Thanks BOPdesigner. Guess I shouldn't have brushed over Lesson 3 so quickly.

So let me see if I get this straight. If I change the orientation of the WCS to define a rectangular array, and later change the orientation to something different, like back to match the absolute coordinate system, NX will still "remember" what the WCS's orientation was to define that rectangular array?

 

[hudson888]

azonic3d,

Instance feature generally works regardless of whether the feature is first booleaned (united or subtracted), from other features. It supports move geometry types including curves, sheets, solids and sketches etc... Iike arrays it respects a range of vectors including re-orienting the WCS as BOPdesigner mentioned. It is probably the most powerful and flexible of the instancing tools.

Pattern face is fairly lightweight way of instancing pads or pockets including holes and other similar features. You could for example patch a set of sewn sheets onto the face of a solid and then instance that or simply model something parametric including a range of blends, draft and chamfers. If the features are parametric then the patterned one will be too. It does require the faces of a base solid to be arrayed and booleaned onto that same solid rather than multiplying geometry in fresh air so to speak as can the instanced feature, but this is generally an appropriate use for such functionality.

Feature arrays can be the most processor intensive method of multiplying holes or other features. In very large numbers they'll be heavier on your memory usage than patterned faces. They're the oldest of the array methods but still the only one to support automated component arrays in assemblies, (we're told this may be added elsewhere in NX-7 or NX-7.5 'ish timeframe). You can also manipulate you're WCS to chnage3 the direction in which the X and Y patterns are propogated, but this function will only do one feature within the boundaries of the solid it is booleaned with. You can apply blends, drafts or chamfers later on with the "all instances" setting applied so that if you want an array of holes with chamfers on each you can select one edge and to infer all of the holes in the array.

What you'll find is that you'll use feature arrays where the geometry is simple and you want to mate arrays if other components (typically fasteners) to it later on. Once the geometry becomes more complex it is generally appropriate to use pattern face where possible, and if you need to create separate features in space or to work with more kinds of geometry then the instance geometry will be your tool of choice.



Best Regards

Hudson

www.jamb.com.au

Nil Desperandum illegitimi non carborundum

 

[SiW979]

azonic

NX will remember the location of the WCS when you create feature such as a rectangular array, this is known as an FCS or Feature Coordinate System. Lots of features behave this way.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...