Assembly - Unusually large distances when mating parts

[jcowgar]

Good afternoon.

I created some complex parts, then decided to crate an assembly of those parts. I found that when using the distance mate, most of the time the distance was VERY large. To eliminate complexities in my parts and assembly, I decided to simplify everything.

I drew one part (2D) that is nothing but a 2"x2" square. I then created an assembly and placed 2 2x2 squares into my assembly. When I mate the edge of one 2x2 square to the other side of the 2x2 square and 0.5" distance creates a spacing that even at maximum zoom you can not see. If I, however, set it to 8" distance, then the distance seems to be what I am looking for, however, that distance is a small fraction of the overall square even, which is only 2"x2".

Originally I thought maybe my part was designed using a wrong scale, I double checked. Even in my Assembly, I added some Dimension markers and those markers verify that my squares are 2"x2"

Any thoughts? I've attached a screen shot of my example. Notice the Dimensions I added for the "Square Parts" and then the two highlighted lines, and the 8.00in in the "Distance" mate.



Thank you,

Jeremy

[Jeffrey Meyer]

Hi Jeremy,

This seems to be an unusually strange phenomenon, but I was able to recreate it albeit using (much-more-logical) metric units:

I suspect the problem is that your 8in distance is an assembly mating constraint, not a sketch dimension. You have constrained two lines to be parallel to each other in 3 dimensional space. When you look at the assembly in the 2D "Front" view, the two squares seem to be close together, but when you look at the 3D image they are indeed 8 in apart.

Hope this helps.

[jcowgar]

Jeffrey,

Thank you for this! This has been driving me nuts! I've been enjoying SolidWorks for a few months now and have made many 3D pieces for various projects (including my plane). I then ventured into Assemblies and couldn't get past this.

You are exactly right! When looking at the Front view of my 2D objects (laying out an instrument panel), everything looks great. When looking at the Isometric view, all the items are not on the same plane.

I am unsure how they got on a different plane, but that explains why some mate just fine with reasonable distances and other ones were 80" off! I guess when adding new components, I'll just make sure they are "Fixed" to the point of origin, then switch to the front plane, toggle the component to Float and then move it around. That seems to do the trick... unless you know a better way or more proper way.

Thank you again for helping with this. I have been struggling with it for a week now and it has brought panel design to a standstill.

Jeremy

[Jeffrey Meyer]

Hi Jeremy,

In assemblies try the following unless you have no other choice: Mate to planes and/or faces rather than wire-frame geometry.

Jeffrey

[jcowgar]

OK. In the case of the instrument panel layout, I have been mating bezel edges, for example, the Trig Com Radio edge is 0.5" from the PFD edge. Being able to think about the panel in edge distance is pretty nice.

[Jeffrey Meyer]

Perfectly legit to mate in terms of edges, but edges are usually only 2D and you might end up with the problem you had at the beginning of this topic.

[vondeliusc]

Jeremy:

OK. In the case of the instrument panel layout...Trig Com Radio

Here is the Trig TY91 (based on dimensions furnished by Trig)

The link for the solid model will be available for 1 month:
https://drive.google.com/file/d/1TBS...ew?usp=sharing
-Christian

[bigdog]

I find it easier to create the individual parts as separate files (.SLDPRT) and then pull them into an assembly (.SLDASM). The parts use 2D sketches and I've never been comfortable with the 3D sketches in the assembly. Editing the parts from within the assembly makes sense to me and helps me keep track of everything. The assembly just becomes a bunch of mates between parts.