Joints and Assemblies

[Drewpan]

Hi All,

Quick advice on where Joints should fit into the Fusion Workflow.

Should I be putting Joints into the Top Level of my Model or with each Assembly?

I did a slightly more complicated Model recently and added Joints to individual Assemblies and then joined

each Assembly after to the Model. When I had a few minor issues I just had a bit of trouble "finding" some of

the Joints. Is there a Standard way to do this?

Picture supplied for @TheCADWhisperer 

(Model is quite cool and really good practice draw)

Cheers

Andrew

[TheCADWhisperer · Accepted solution]

@Drewpan 

No file Attached to diagnose?

Why are there multiple bodies in same 3D space?

I would place “joints” at the same level that they are in the real world.

Example: When I rebuild a car, the “joints” for the alternator sub-assembly exist in that assembly.  The joints mounting the alternator might be at the engine assembly level or at the top level car assembly level.

[Drewpan]

Hi,

I thought that was probably the case. I created the Wheel Sub-assembly with the Crank and Counterweight and

then Joined them at the Top Assembly. It got a bit confusing at times when there were Parts like the Steam

Pipe joining the Boiler and the Piston Assembly and exactly where I put that Joint.

No File because I have actually finished that one. The Picture was in lieu of a File because it showed what I

meant with Joints in different places.

Thought I had a lot of this worked out but what do YOU mean by "Why are there multiple bodies in same 3D space?"

The Picture is the finished Model with all of the Assemblies and Sub-assemblies. I am not quite sure what I did

wrong here.

Cheers

Andrew

[TheCADWhisperer]

---

@Drewpan wrote:

...

what do YOU mean by "Why are there multiple bodies in same 3D space?"

I am not quite sure what I did wrong here.

---

@Drewpan

No file Attached to illustrate?

[laughingcreek]

[Drewpan]

Hi,

Ok, I think I know what you mean now. I am not sure what that is or why it happens.

The Parts and Assemblies as joined don't overlap AFAIK. In the design there is empty space behind that piece

of sheet metal. I didn't think it necessary to check for interferences and now that I have there are no game

killers I can see except for a couple of Hex Nuts and simple stuff. There is nothing that should interfere unless

it treats the round Boiler like a square box and that overlaps. In which case how do I fix that or need to fix it?

Nobody has pointed this out before so it obviously wasn't a Problem I knew about.

Andrew

[davebYYPCU]

Another way to put it, - 2 bodies in the same space, 

One is a sheet metal, and the other a solid body, one eyeball turned on at a time, 

Not reviewed the file on how it was done, but I suggest you Remove this one.

Might help.....

[Drewpan]

Hi,

Think I remember how that happened. Now I know what it is.

Cheers

Andrew

[TheCADWhisperer]

@Drewpan 

Tip:  The tap-drill size of an M5 threaded hole is not 5mm.  I have seen this cause designers a lot of grief if not understood.

Tip: You can add the thread feature to the hole feature.

[TheCADWhisperer]

@Drewpan 

[TheCADWhisperer]

@Drewpan 

Axis of Spring is not constrained.

Tip: Because it is not easy to have a spring compress in Fusion - set one end to "disappear" into solid.

[TheCADWhisperer]

@Drewpan 

I doubt whether 1mm material thickness will hold up for very long...

Might even be difficult to machine - depending on the process - without blowing out the thin web.

[TheCADWhisperer]

@Drewpan 

Major interference - both ends...

Tip: For moving parts there must be clearance between the components for two reasons.

1. We cannot manufacture perfect parts.

2. Friction

So for a slot of 3mm the mating part must be less than 3mm (or other way around).  Must be clearance.

[TheCADWhisperer]

@Drewpan 

[TheCADWhisperer]

@Drewpan 

Imagine the friction between these components - even if we could manufacture "prefect" cylinders.

This cannot be assembled because of friction (without press fitting).

And if it didn't seize up immediately it would certainly heat up fast...

Same with all moving joints...

Imagine that we have two armies.

We'll call them the Red Atoms and the Blue Atoms.

Let's say the Blue Atoms occupy a circle of 24mm.

As the Red Atoms approach the Blue Atoms and attempt to occupy the same Ø24 space - somebodies Atom army has to move - they cannot occupy the same space.

[Drewpan]

Hi,

@TheCADWhisperer 

Thank you for the analysis. I should have taken more care with my drawing which was from a Plan from a magazine

on the Internet. I did not check the measurements and make allowances for things like clearances. I also made a

few small changes that created some problems - like making the Beam wider because I wanted pockets to make

it look nicer. A lot of the drawing was straight numbers from the Plans, not thinking.

Right now I am trying to do lots of drawing to get my head around the software and increase my speed. I should

be thinking like an engineer as I do it however. I need to take into account clearances and tolerances and model

them accordingly.

I do appreciate your time and effort to help me achieve all of this.

Regards

Andrew