Dimensions Moving Themselves

[linkxsc]

Hi there, so I'm a college student learning how to use solidworks. And at my school (this isn't a problem only I have been having) we've been having a problem with dimensions, and parts within models and assembly moving on their own.

That sounds kinda vague but here's an example. So here we have an assembly... say we're doing like a basic DC brushless motor (the actual project us students were working on) we go model the armature, model some blob parts to be the "coils" , some magnets to go on the armature, make a housing for the outside and all. There's a base plate that the housing attaches to, and a few inches away from the housing on the base plate, theres a little control box.

So we get all that done, pretty simple project. The little control box is the important part. So now here we are on our winter break, and we've been told to use that same model to make a "newer" larger motor that uses the same base plate and control box. So several of us students go, try and use the old parts as much as we can cause we're lazy. I go, open up the old assembly to look at it, and the control box has moved.
I never touched it, all its mates for distancing itself from the edge of the base plate were still there, they changed the distances somehow. I go into the part during a "wth" moment. Start looking at it. I like to model things as much around the origin as possible, and i love my work-planes and axes. This part is now situated about 6inches away from the origin and though dimensionally the part is intact, the workplanes I used are all over the place.

So I'm wondering, what the heck is going on. This has also happened in numerous other models that I've gone back and checked.

 

[Mihail]

Hi, Linkxsc ! Well come to forum !
I am not sure that THIS is the answer to your question.

You say that you use part(s) and assembly(ies) of the old model in order to make a new one.
If in the newer model you change somehow this parts/assemblies in order to fit to your new requirements, you MODIFY it (parts/assembly) for ALL the models where use its.

My English is not very well but hope you understand the idea.
And is logic: if you take a part of an engine and you modify it in order to use in other engine, you can't use it anymore in the older engine. (I talk about real word; and SW simulate the real word)

Let me know if this is your situation in order to teach you how to handle it.

Good luck !

 

[linkxsc]

The problem isnt modifying the mates for the assembly, that
part is kinda obvious some changes might be made. But say
you made a part for your model, you just made a 1x1x1 box,
with the origin in the upper left corner on the back
surface of the box (so you extruded it up). Basically
what's been happening is that the parts have been moving
themselves from their origins and workplanes. The part
stays intact, but if when placing them in assemblies we
mated their origin or a work plane to something else, all
hell breaks loose.