Placing mate connector on origin or on planes?

nick_papageorge073

Hi all, I'm getting used to mate connectors coming from ProE/Creo, if a Mate connector is where I want it. What I'm having a really hard time with is creating a mate connector either on the origin, or on the intersection of planes of my choosing. I can put a mate connector very easily on a tiny hole that is likely to move or go away, but I can't figure out how to put it on the most fundamental feature in CAD. I did a search on the forums for "mate connector on origin" and "mate connector on plane" and didn't find anything relevant. Same for the on-boarding tutorials I did. Is there a technique I'm missing to place the mate connector on origin/plane? Thank you.

nick_papageorge073

I found a workaround. Create a point inside of a sketch where I want the mate connector (tied to the origin or the planes in question). Then use that as the mate connector anchor. Is that the correct way in this scenario? Thanks.

tim_hess427

What are you using these mate connectors for? I agree that there are some quirks in how Onshape uses reference geometry that take some getting used to. I think, most of the time (there's always exceptions), there are ways to avoid having to put a mate connector on something like the origin or one of the Top/Left/Right planes. So, I'm wondering if there's an easier way to create the references you need. Having gotten used to Onshape now, I rarely create mate connectors explicitly in my models. The most recent example of where I actually needed one is when I modeled a spring and needed a mate connector at the center of the helix for the assembly model. 

Many features allow the use of "implicit" mate connectors, which allows you to create a mate connector within a feature. An example of this is using clicking the mate connector icon next to the plane input box when starting a new sketch. Mate Connector (onshape.com) These are really helpful and flexible. 

Also, there are some times when I need an axis or "direction" for a feature input. Sometimes, I'll do like you did and just create a sketch with a construction line to use as an axis later on. However, I recently realized that when a feature needs a "direction", you can select a plane and the plane's normal direction will be used. 

nick_papageorge073

tim_hess427 said:

What are you using these mate connectors for? I agree that there are some quirks in how Onshape uses reference geometry that take some getting used to. I think, most of the time (there's always exceptions), there are ways to avoid having to put a mate connector on something like the origin or one of the Top/Left/Right planes. So, I'm wondering if there's an easier way to create the references you need. Having gotten used to Onshape now, I rarely create mate connectors explicitly in my models. The most recent example of where I actually needed one is when I modeled a spring and needed a mate connector at the center of the helix for the assembly model. 

Many features allow the use of "implicit" mate connectors, which allows you to create a mate connector within a feature. An example of this is using clicking the mate connector icon next to the plane input box when starting a new sketch. Mate Connector (onshape.com) These are really helpful and flexible. 

Also, there are some times when I need an axis or "direction" for a feature input. Sometimes, I'll do like you did and just create a sketch with a construction line to use as an axis later on. However, I recently realized that when a feature needs a "direction", you can select a plane and the plane's normal direction will be used. 

The main use case is if you want to align parts by a "theoretical center-line" that might not necessary be in the center of the actual geometry. This theoretical centerline was designed explicitly to be at the origin. But for whatever design reasons, you didn't make the part geometry perfectly symmetrical about the origin.

Another use case is between subassemblies. You want to assemble one subassy to another subassy. But its early in the design process, there are no fasteners or even a fastening method thought of yet. All you know is that this subassy should align with the other subassy by their origins (or main default planes).

Another use case is for injection molded parts where nothing is at right angles due to draft, and every single edge has a round on it. And most injection molded parts have pretty surfaces on them. Using the default planes/origin in those cases can be very helpful.

It seems onshape is waiting for the small details of holes for fasteners to mate things, or using the edge or corner of a part, instead of using the 3 default planes which the whole design is built around.

shannon_freese733

I've been on the same journey with the origin planes. I'm coming from an Autodesk background where constraining origin planes is the preferred method.

I've opened assemblies made by coworkers in Onshape and found no mates whatsoever. All the parts are just sitting in an unconstrained "pile" so it seems that mates are simply not really a consideration in Onshape in the same way that it is in an Autodesk product.

In addition to all the points raised by @nick_papageorge073, it seems seriously risky to me to have an assembly just floating in space. 

S1mon

This is indeed one of the harder things to get used to in Onshape (coming from other CAD systems). If you’re dealing with a big group of imported parts (which don’t have any mechanisms/movements), the first thing to do is fix one key part, and group everything. That’s the bare minimum. Keep in mind that at the next assembly level the fix mate doesn’t mean anything. It’s good to have at least one functional mate reference or a good mate connector in one key part which can be used at the next higher level. 

If you’re designing complex parts (e.g. injection molded things that don’t have obvious functional mates) in a single part studio and putting them into an assembly, there are a couple of feature scripts which make it easy to add mate connectors to a bunch of parts in one step. I often create a mate connector at the origin in the assembly to make adding parts easier. You can then mate all the parts to that origin. 

roy_roffler

Sorry, I was in the wrong thread!