purpose of setting the origin or chosing a new defined mate in a context design?

kees_bijker

So I use "in context design" a lot and it is a very powerful way to design something that works together with other parts.

I have noticed that nothing much changes when you choose the origin or when you make a self defined mate as origin for your in context design. I followed the "in context design" course till about 50% now, and I still am no wiser as to why you have to chose the origin opposed to it simply being the origin of the assembly?

I tried both and I cannot find any advantage of chosing your own mate, so please let somebody explain to me what is the difference and for what is it used normally?

I am sure I am missing something which could be really useful, so I want to add that to my tool box if I can.

Thanks in advance.

eric_pesty

The main reason why you would want to use a specific mate connector is that the origin of the in context part will follow that mate connector, and the front/right/top orientation of the in-context part can be set that way instead of following the assembly origin and orientation.

MichaelPascoe

The advantage of selecting a mate connector would be when you want the part studio's planes and origin to align with the center of a specific part. For example, maybe your creating a robotic arm and you have a cylinder that isn't at the assemblies origin. If you use a mate connector as the origin reference, your part studio can start with it's planes and origin correctly placed on that cylinders axis. This way you can immediately start using those planes to create sketches, instead of having to create another mate connector to reference the cylinder again.

eric_pesty

The main reason why you would want to use a specific mate connector is that the origin of the in context part will follow that mate connector, and the front/right/top orientation of the in-context part can be set that way instead of following the assembly origin and orientation.

MichaelPascoe

The advantage of selecting a mate connector would be when you want the part studio's planes and origin to align with the center of a specific part. For example, maybe your creating a robotic arm and you have a cylinder that isn't at the assemblies origin. If you use a mate connector as the origin reference, your part studio can start with it's planes and origin correctly placed on that cylinders axis. This way you can immediately start using those planes to create sketches, instead of having to create another mate connector to reference the cylinder again.

kees_bijker

Thank you eric_pesty and MichaelPascoe, Very clear and to the point.

I will have to try it from this point of view once and see what I can get done better and faster this way.

Kind regards,

Kees

bernard_lucas

As illustrated above, when moving the mate connector specified as the origin of the new "in context part", the part stays in place. Saying that "it will follow the mate connector" is not what I observe…

A second effect of moving (or any change to) the MC is that the part "looses" its references to the MC and fall back to the default assembly origin.

wayne_sauder

@bernard_lucas

Your part 2 is not connected to part 1. You created a new parts studio on a mate connecter that had certain coordinates at that time. Onshape will continue to use those coordinates unless you have a true-in-context loop and force an update.

Now, should onshape move the coordinates of the parts studio based on Part 1 is an entirely different and very controversial matter for which you could submit an improvement request if you feel it should be the default behavior.

bernard_lucas

Thank you, @wayne_sauder, for your response.

Since this discussion centers on the specific scenario of choosing between an assembly or an MC reference system, I wanted to share my thoughts on @eric_pesty's remark stating that "the origin of the in-context part will follow that mate connector."

Regarding your comment, "Your part 2 is not connected to part 1," I agree. If I wish to connect the parts, I can simply use a mate, so this isn't the issue.

Now, if I understand you correctly, you're suggesting that the situation changes when a context is established (for part 2) and updating that context will have an effect. You appear to imply that the effect would make part 2 follow the initial MC—but that’s not the case. For clarity, I initially reduced the issue to its simplest form. Here’s the "context" version of the same example. After updating the context, the reference system remained unaffected, and, as before, "part 2 did not follow the MC."

The primary question remains: why should one select an MC as a reference? Shouldn't it be explicitly stated that selecting an MC as the reference system is a "one-shot" choice, meaning it won't adapt to subsequent updates made to that MC? While this behavior isn't inherently an issue, it does challenge our natural expectations.