Dimension between component instances?

[jeff.castle]

Modeling a simple wood bench. For the purposes of my question, let's just focus on the legs. Since I want the legs to show up as a single line item (with a QTY value of "4") in the BOM, I created one leg component and copied it to create 4 leg instances. No problems here.

But I really, really want to be able to dimension between the leg instances. This doesn't seem to be possible. All of the workarounds we've come up with at the moment are cumbersome and imperfect. In other words, if the width of the bench changes, I would like an easy way to adjust the leg instances. Right now we have to activate, select, move (and change pivot to face)... for each instance.

[HughesTooling]

Have you tried using a rigid joint?

Here's some help on assemblies and joints.

http://help.autodesk.com/view/NINVFUS/ENU/?guid=GUID-42E8723A-7032-4AE7-8F79-73D5675251C4

Mark

[ToddHarris7556]

@jeff.castle - 

This can be done using a skeletal modeling approach. It's a *little* cumbersome to set up in Fusion, but quite powerful and flexible once you've got it. 

I can post a walkthrough a little later, but have a look here.

It's a simple model with a tabletop and a leg. 

Change the parameters to adjust the model

Basically, you locate/model the master leg in position, then insert and position a copy of it using joints. (This is the *slightly* tedious part) It takes 3 joints to lock down the second leg - 

1. locks it to the bottom of the tabletop
2. offset the right distance in the X direction. (Note you have to pick the right faces to orient the leg)
3. offset the right distance in the Y direction. 

That gives you a pair of legs at one end of the table. Then use a rotate pattern to make a copy at 180º for the other end of the table. This preserves all the part names and gives you the BOM that you want : (1) top and (4) legs. If you tried to mirror the first leg, it'll create a new component with a new part number, which messes up your BOM.

[ToddHarris7556]

I should also add...

... it should be possible to do this with just joints and parameters, but it's probably/arguably less robust/easier to break.

[HughesTooling]

Todays update that allows a XY offset in a joint might make this a little easier using joints. See attached file and try changing the Parameters.

Mark

[TrippyLighting]

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@ToddHarris7556 wrote:

 It takes 3 joints to lock down the second leg

---

That should take exactly one rigid joint.

Could you create a screencast to show howyu are doing this ?

[ToddHarris7556]

@TrippyLighting It's entirely possible I've not learned everything there is to learn about rigid joints.

The issue I run into is that I don't know how to position as needed in 3 planes using a rigid joint - it requires three separate offsets from reference surfaces.

Please feel free to enlighten me if I've missed something!

HERE is my approach to this using multiple planar joints - 

Todd

[TrippyLighting]

He he, that game just changd with the update today. 2 weeks ago or so I had posted an iea in the idea station to add an X & y offset to the rigid joint. the update today does just that yto al joints. Pretty awesome!

In the past , yesterday , you still needed to first add a joint origin to the component you wanted to assemble somthing to, the table top in this case, then you were able to use a rigind joint to that betwen the table leg and the joint origin.

[ToddHarris7556]

Too funny - 

I thought I was going batty. I couldn't see it at all. Then I realized I've been modeling non-stop for 4 days. I haven't re-launched the Fusion app since Monday. 

Updates only download when you restart..... Go figure 🙂

[HughesTooling]

@ToddHarris7556 when you've updated try the file I attached to post #5, I set it up using the new XY offset in a rigid joint. I thought it was odd the XY offsets were not on your dialogs in the screencast.

Mark

[jeff.castle]

@HughesTooling@ToddHarris7556@TrippyLighting

Thanks fellas. Good ideas all around. I previously thought of using rigid joints, but it still seemed like a lot of clicks if I ever needed to modify the distance between component instances.

I just played around with the new X/Y offset feature + parameters. It's definitely helps, though I still need some help strategizing. It seems to work better if you have a single-piece top, since the DistanceToEdge parameter is relative to that component, right? The tops of our benches are made of slats in various orientations, so this is no single perimeter to reference.

@TrippyLighting wrote:

In the past , yesterday , you still needed to first add a joint origin to the component you wanted to assemble somthing to, the table top in this case, then you were able to use a rigind joint to that betwen the table leg and the joint origin.

I wonder if there is something fundamental that I'm not getting about rigid joints. Even with the new offset options, I'm still created 4 leg instances on top of each other, grounding one leg, then setting a joint origin and specifying and offset for each one of the remaining three legs. Is this a terrible idea?

[TrippyLighting]

It you could share a visual, a screenshot, hand sketch, or even your model that would really be helpful.

If you want to share a model, you can export it as .f3d and attaching to a post, or you can use the share function available in the Fusion 360 data panel.

[jeff.castle]

No problem. Attached.

A couple of notes. My sketches are not grouped with my components (I know, I know...). Beyond that, the browser tree is a mess for two reasons:

1) I still don't think it's possible to reset the numbering on component instances and/or rearrange them in the tree, which sucks when you are trying things out and delete stuff every once in a while.

2) If I group like-components into subassemblies, it messes up the BOM. For example, the BOM currently looks good for this model. But if I nest the bench slats inside of a master slat component in hopes of cleaning up the browser tree, the BOM just shows the master slat component and a quantity of 1.

And, of course, most relevant to this thread, there are no joints in this model, and only rough dimensioning between component instances.

[TrippyLighting]

I've started creating a model with the dimensions/parameters in your file.
See if by following the timeline and looking at the dimensions you can get how I did this.

There is nothing inherently wrong in your model. and there really are many ways to do this. What I show in this model is really only one.

Most parameters/dimensions are captured in the sketches you see. Only the table height is a User Parameter.

[jeff.castle]

Did you mean to attach the project file? I only see a screenshot.

[TrippyLighting]

Yes. 😉