Joint vs. Constrain to Make an Assembly

[dfitzgerald2002]

Hello all,

I'm still a novice at Inventor and had to take an extended break but now I'm back and need to complete a simple assembly. If I may, I'd like to ask one quick question in order to minimize my review time as I get myself back up to speed.....

The attached picture is a hand-drawn sketch, of three cylindrical parts I created in Inventor. I want to assemble these three parts in order to create a single, solid part for 3D printing. I created three separate components because there were detailed features on Part #2 that would have made it too complex for me to manipulate & create the desired part in a single file. (NOTE: My sketch doesn't show all the details on Part #2.)

Part 1 will be inserted into Part 2 such that the bottom side of the flange on Part 1 will mate with the entire top surface of Part 2 as shown by the hash marks on the top of Part 2). The bottom surface of the legs on Part 2 will mate with a portion of the top surface of Part 2 as shown by hash marks on the top of Part 3.

Question: Knowing that I want to end up with a single solid part comprised of these three component parts, will it be any easier (or even matter) whether I create the assembly using the JOINT feature or the CONSTRAIN feature? (I'm asking because because the tutorials seem to imply that the JOINT feature does the same thing as the CONSTRAIN feature in less steps because the JOINT feature has many of the constraints built-in to  it.).

Any help or hints is greatly appreciated,

David

[chris]

@dfitzgerald2002 I would just use "insert" constrains for this, and maybe a few angle constrains to lock everything down. I don't think I've ever used a "Joint" before

[James_Willo]

Joint and constraint are just a matter of preference. They both have differences, but can mostly do the same things. 

For your design it appears you could easily use insert constraint. 
In all my years as a designer I never used joints unless I was constraining to a slot, but I also worked with people who only used joints. There are some advanced constraints that joint doesn't have, but like you say in the tutorials, Joints can restrict more than one degree of freedom where as constraints mostly only do one. 

[chris]

@James_Willo @dfitzgerald2002 

 Here's a quick look at advanced slots, (sorry the mic audio was a little low)

https://www.youtube.com/watch?v=4wa1r8m7UtQ

[James_Willo]

Nice video. 

With joints, just hold down ctrl and you can select the centre of the slot without any issue. 

[andrewiv]

I personally like joints most of the time because, as has been stated, they limit more than can limit more than one degree of freedom at a time.  In some cases you can get by with 1/3 of the joints compared to constraints.  But it really is just a personal preference, I still use constraints for a lot of things, just depends on the situation.

[andrewiv]

I've never thought of using an extra circle for cutting into a slot like that.  I like using joints now because they allow you to grab the center of a slot, but before joints I used do a circular surface extrusion in the center of my slot and then use that for insert constraints.  This allows for the same thing you are doing but doesn't have the extra lines on the geometry.

[dfitzgerald2002]

Chris,
Thanks for taking the time to respond to my post. Someone else said exactly
the same thing as you. Others said it didn't matter much.

I asked the question because I'm not trying to become an expert. I just
want to do what I need for this prototype part.

Thanks again, David

[johnsonshiue]

Hi! As James mentioned, it is a personal preference. Joints can be considered combo constraints. It helps lock down degree of freedom faster, because one joint can represent multiple constraints. Also joints are mostly loop aware. You may lock the component to a particular grip point of a face loop. It does have its limitation though. Joints only work for body geometry (face, edge, vertex). If you need to establish a relationship with a piece of construction geometry (sketch or work feature), you will need to use constraints. Joints don't support construction geometry.

Many thanks!