In my opinion and in my experience Planes have been the best way to make mates inside a SW Assembly. When using a plane you don’t have the fear of losing a face ID. If your not aware of what a Face Id is I’ll try and explain it. SW uses what they call “Face ID’s” or “Edge ID’s” These ID’s are what control mates, colors, in-contexted relationships, Sketch relations, etc… If you remove a feature and add a new feature that takes precedence over the original face or edge then you have just replaced or removed the Face ID or Edge ID. When that happens you can and will get numerous errors in your model or assembly. So Face and Edge ID’s play a vital role in SW parts and assemblies. To get around that you can use Planes. Planes will always be there unlike a face or an edge (as you can see above how easy it is to lose face ID’s). Planes are infinite and are never ending so if you have lots of mates that are going to be on one face you should make a plane and use it. You should make planes for not only your parts, but also in the assembly itself. This process is not extremely fast, but the result is a good working assembly with fewer errors if made correctly.

Think ahead - Design Intent

Try and think about the Design Intent - what you’re going to do and how you’re going to use the part in the assembly. When making your parts, make them like you normally would with some exceptions. Example: A washer – If I was making a washer and I knew that I was going to be making a mate to both sides of the faces for a mate I would make it so the Default Front plane was located on one of the sides of the part. Then offset a plane from there at the Thickness I knew I wanted. Then build it using Boss extrusion up to surface. Pick the new plane you added at the beginning of part. Remember the start of the sketch is important too. When you use the boss extrusion I would start at the center of origin and drag the circle sketch line out. This away the default planes Top and Right will be in the center of the part. Those planes can be used to control the placement around a bolt, etc… You could use a DT to control the plane or just double click the plane and change the dimension from there.

Follow this example for all your parts.

Assembly Stage

Like listed above “Design Intent” cannot be forgotten when building the assembly. Just because your parts are ready for mating doesn’t mean the assembly is.

[u]Non-In-contexted[/u] - You can start adding the 1st component. The 1st component is crucial because this part will be the foundation for everything built on it. If you plan on starting the first component out at the origin you shouldn’t have any problems other that proper placement. If you plan on or are needing the 1st component to start out “X” distance away from the origin, say in the “Y” direction then you need to offset a plane in that direction using one of the Default planes (Front, Top, Right) It might take more than one plane to get the desired result, that’s ok. Offset as many planes, as is necessary to get the result your needing. Then slowly add a component at a time, while remembering to use the planes between each of the parts for mating.

[u]In-contexting[/u] – Before you add any components you should decide how you want to control this assembly. You should offset any and all planes, that you know you will use to control the parts in the assembly. Once you get those planes in, depending on the size of the assembly and the amount of control points, will determine how many planes you are going to have to use. A Design Table can control these planes. Which I highly recommend over any other means of control. A DT can utilize VBA programming plus you can use more than one sheet at a time when using a DT. I would add all the plane offsets in the assembly to the DT before adding a component. Make sure if you change an offset of a plane it works correctly. Set it back to your default choice and rebuild the model. After that you can add your 1st component. This component and all components that are to be in-contexted here after are crucial, because the planes in this assembly will control these parts. I mentioned above on how to setup your parts before putting them into an assembly. When you in-context a part, whether it is a feature, sketch geometry, or planes. You will lose a portion of control of the part at that’s part level. That’s because the assembly or another part plane is controlling it. You have to very careful when in-contexting. You don’t want to over in-context your parts and you don’t want to under in-context your parts.

Either way you choose the idea of mating to planes helps to alleviate future problems of errors in an assembly due to the loss of Face ID’s and Edge ID’s. There are all types of tweaks that can be performed once in the assembly and you start doing the in-contexting. Just watch what you do and be careful.

I have made an example of this - You can find this at - http://www.scottjbaugh.com/Design_Portfolio/In-contexted_Plane_mated_assembly.zip

Other rules to follow

Keep your Top level mates under 300.

With parts, sub-assemblies or both in an assembly. I figure about 2 at least, if not 3 mates to fully define (not always) per part or sub.

If you use more Sub-assemblies instead of parts, that will bring your number of top level mates down to a lower number.

By doing this and keeping that number down your performance should perform well. Anything over the 300 you might start seeing a degradation in performance.

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