I want to create a mate that will speficy a distance along a specific dimension. Is this possible?
Depending on what entities you use for the mates (planes, edges, points etc.) you will get different results, mainly regarding rotaion constraint. I'll try to explain what kind of results you might get if you select different entities, but in general if you want to set a distance in one direction only then one of the mated entities will have to be a face or a plane that is perpendicular to that direction. For these examples let's say you have PartA which is fixed and PartB which you are trying to mate to PartA.
If you do a distance mate of a point in PartA to a point in PartB it will keep the distance between them but not in any particular direction, so its like PartB can orbit around PartA in a sphere with a radius of that distance. Also PartB can spin around the mated point so it will not constrain orientation of the two parts.
If you mate a plane or face of PartA to a point of PartB it will keep the distance of the point away from the face in a direction perpendicular to the face, so PartB can move around anywhere in a plane that distance away from the PartA face. But PartB can still spin around the mated point, so again it will not constrain orientation of the two parts.
If you mate a face or plane of PartA to a face or plane of PartB then it will keep those faces parallel and set the distance between them. Part B will still be able to move around in other directions and it can spin around an axis perpendicular to the mating planes if that makes sense. If this is the type of constaint you are looking for then you will need either a reference plane or a face on each part that is perpendicular to the distance direction.
Now that is all assuming one of the parts is fixed (or fully constrained) already. It gets weirder if neither of them are. Let's say you wanted both parts to be able to move around and spin and tumble and rotate around any axis, but you want to set the distance between their origins along the x axis. I don't think you can do that. Actually in that case you could make a dummy part with just a sketch of a line that is the distance you want. Then in your assembly mate one end of the line to the origin of PartA and the other end to the origin on PartB and make the line parallel to the direction you want the distance.
I am not exactly sure what you mean, but if you do a distance mate between two parallel faces it will only constrain them in the direction perpendicular to the faces, they could still move around parallel to each other. Is this what you mean?
Thanks - that is what I mean, but are the planes necessary? What about just two points?
As Jamil says, I'm not sure what you really want, but here goes. The answer is yes. Say you take two parts and make an assembly. Neither part has any geometry, and they both float in the assembly. Make a distance mate between their origins. There you go. You have specified a distance relation along a dimension. Both parts still rotate and revolve around each other freely, and they are free to translate together. Even the dimension rotates. Anything else?
Maybe I'm not reading you right, I don't see how this solves my problem. What do you mean that the "dimension rotates?" Maybe I can be a little more clear with an example. Say I have two parts, and I want the distance between two of the points along the X dimension to be 5cm. I don't care about the relationships along the Y or Z axes. I know that I can do that if I put reference planes normal to the X axis at those points and use a distance mate between those two planes, but my question is whether it's necessary to construct the reference planes at all. Thanks!
So I take it that the answer is "No, you can't explicitly mate along a single dimension." Very helpful explanation, thanks!
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