Parallel mate

dr_hutchinson

I know I must be missing something here, but how does OS implement the parallel mate that you find in Solidworks? I cannot believe that it is not a question that has not been asked before so could someone show me how to find the answer from the existing resources?

philip_thomas

Here is a public document that shows several different mating strategies (including parallel) that I made for a chap looking to use Onshape for weldments. This document should give you a flying start. The trick is to think in terms of the degrees of freedom that you would like to either nail down, or leave free.

https://cad.onshape.com/documents/6ba1e39775d942b78b0c84f1/w/cdfcad3a3d7f4565ad4ffef4

andrew_troup

Onshape mates are quite different in intent and application from Solidworks:

I recommend that you check out some of the excellent training materials providd on the subject, but the short story is that Onshape mates are intended to provide different types of relative motion, rather than establishing static positions.

If you want to position parts at a given spacing, the optimum workflow is to model them in the same part studio, and simply use dimensions and constraints (including the parallel constraint) to arrive at the desired static relationship.

Then when those parts are brought into the assembly, fix one of them and "Group" them together, which maintains a live link between their positions in the Part Studio and in the assembly.

Onshape's mates can still be used to establish parallelism, but generally speaking they will also "lock down" one or more other degrees of freedom. So even if your situation does require you to establish parallelism using mates, there's no single answer to your question: often, for example, a part might be "fastened" using a mate in an assembly, which will preserve parallelism, but it can be moved away from, or towards, another part, by changing (in the Part Studio) the offset of a user-defined mate connector used in that "fastened" mate 

andrew_troup

The place to start is probably the second through fourth videos in this series:
https://www.onshape.com/learn/essential-training-series#!lesson-number=1&title=documents-ui

These, I think, do a good job of introducing the major conceptual differences between Onshape and other legacy 3D CAD modellers.

peter_hall

@dr_hutchinson
Thankfully I am not an old user of other 3D software like Solidworks, so I am not always looking for solidworks answers on Onshape software. Andrew has pointed out a big thing here for designing on Onshape. Use the Parts studio to create dimensional and constraint relationships between parts, then turn them into a group as soon as you insert them into the graphics area on your assembly document. It is a lovely feature and allows for modification and experimentation due to the live link as mentioned by @andrew_troup   The group command also decreases by a lot the amount of mates you need to use in the final assembly. When you click on the group command just use a window accross the newly imported parts to include all into the group. You do not need to fix one of them first unless you want to fix the whole group within the assembly environment. If you don't fix one of them, you can move the whole group as one using the mouse within the assembly area.

andrew_troup

Thanks for fleshing that out so clearly, @peter_hall
And of course you're right that fixing a part is optional:
The only time it's essential to do that is for the first group of parts in a given assembly
(things get too funky when you start applying mates, if everything is floating)

dr_hutchinson

Andrew,

Thank you for your reply. The key thing seems to be to try and sublimate all what you have done in the past and be prepared to accept a new way of working. Now I know I am changing the topic here, but what about Mold tools? SW has a whole raft of tools for molds, cores and cavities. Is ONSHAPE at this stage yet?

Barry.

andrew_troup

@dr_hutchinson

Not by a long stretch, Barry, but the basics are there, in a very coherent and wholesome way (it seems to me), to support a very simple and satisfactory workflow once we have good surface modelling tools, and a few essential dedicated mold-related operators (for part lines and such).
  
Onshape's boolean operations are very tightly integrated with the basic functions, and the Part Studio should be an excellent way of providing the rich inter-relations between all the components which make subsequent tweaks relatively safe and simple, without introducing the fishhooks which can sometimes trip up similar efforts in SW.  

philip_thomas

Here is a public document that shows several different mating strategies (including parallel) that I made for a chap looking to use Onshape for weldments. This document should give you a flying start. The trick is to think in terms of the degrees of freedom that you would like to either nail down, or leave free.

https://cad.onshape.com/documents/6ba1e39775d942b78b0c84f1/w/cdfcad3a3d7f4565ad4ffef4