SOLIDWORKS Design & Help

Hi Mateusz,

For complex assemblies with large number of components, plane mates are better since, if you make changes to the mating model geometry (edge, surface, point or line) errors are not generated into the assembly mates (as usually happens in geometry mating) .

Also starting a new 3D model by taking co-ordinates relative to the main assembly origin is basically a time saving technique. So that when you are assembling, you don't have to think much, just mate the planes and you good to go. Hence, this technique along with plane mating are meant to save time and improve accuracy of assembling.

The down side is that before commencing modelling, you have to be very sure of the co-ordinates and the orientation of the new model as you will not be able to play around with mating axes during assembly.

I've also heard that non origin start points for new 3D models are done for ease of exporting the code for CNC machining. But since I have never done this before I'm not sure of the veracity of it.

That's great. Let's do this. But for personal designs, tastes vary.

Thank you for your points of view.

I've also got an example from another board which shows some cons of this solution:

"For example, if you draw a wheelbolt (silly but obvious example) it could be in any of 5 locations, in the local coordinate system, and then if a different model (say the GT) is at a different ride height at design then it could be somewhere else."

Maybe the mixed approach would be suitable? As some parts have their specific positions and are always on the same place in every model so can be mated by planes and those which are in various positions could be mated using standard mates.

I used to work for a company that manufactured 10's of millions of fluid fittings per year for GM, Chrysler, Ford and some Toyota. We had 1,000's of part numbers that we sold. When we modeled our part, we used SW 0,0,0 for our models. This worked best for us for consistency of design at our end. It also made the CAM programmers life easier because the part was at a "true" 0,0,0 when imported in to the CAM software.

There was no way we could have modeled the fittings in vehicle 0,0,0 as the same part may have gone on 30 or 40 different types of vehicles across 4 different customers. This was never an issue when we worked with the Engineers at any of our customers.

Now very commonly they would send us the section of the model of the vehicle they were using our fittings on and it would be in vehicle 0,0,0. If we were using the model to communicate different options or something along those lines then we would continue working in vehicle 0,0,0 for that project.

All those words are to say it will HIGHLY depend on what you are selling and more importantly, what you customer wants.

Hope that helps!

Rob Stoll

in my previous company we do diecasting heatsink for zkw (supplier of led lights for automotives) they send us 3d drawing that have 0 origin floating out of nowhere in 3d file. problem is they require to reference in this position for cmm measurements. so we ask them how can we used this reference. it turns out the reference from the heatsink is on the assembly of the car. they instruct us to make our own origin point base on 3d heatsink file to measure the other points.

Thank you for your posts, they are all helpful.

I'll paste here an answer from another board which I think is the best one I've got so far:

"Standard modeling practice everywhere is to store files based off a standard universal coordinate system. When you're designing a part or assembly, you work parametrically using whatever mates/references are available in the given software package to ensure a good relationship between the new parts and surrounding existing parts. Once design is done however, everything within your new part/assembly needs to be referenced back to itself to ensure that when others change their parts yours do not change fit, form, or function due to existing mates/references. Your new parts can have their local UCS referenced back to a master company/vehicle/product UCS, typically the local and master UCS are simply made coincident to one another, however in the case of supplier parts its common simply to define the distance and orientation of planes vs the UCS bc suppliers typically don't have access to the vehicle/product model. In essence, that is what happens automatically when multiple instances of the same part are assembled."

Another thing I've learned is the fact that SolidWorks is not very commonly used in automotive industry as it is too simple and limited with huge assemblies and surface modelling. The Catia and Creo are the leaders in this branch.

Best Regards.

Mateusz