Top Down Assembly Modeling | Click by click

Top Down Assembly Modeling is what you'll want to understand right after Bottom-up assembly in whichever CAD program you're using.
WATCH NEXT: • Fusion 360 Appearance ...
Buy Me a Coffee buymeacoffee.com/arnoldrowntree
Patreon / arnoldteaching
This 5th intermediate tutorial shows you the basics of the Top-down method, otherwise known as "In-context design" one click after another and we're using Fusion 360 here.
You’ll want to work through the previous tutorials, especially the one before this - Bottom up Assembly. The bottom-up method is when you assemble separate parts that have been modeled at an earlier time. The top-down method is where you create or modify parts within the context of the existing assembly, or (as is the case in the example here in this video), just one existing part and everything else in the assembly is designed and created within the assembly while referencing its features.
If you haven't done the 16 Basic Tutorials you should start at the beginning:- Beginners Tutorial #1 of 16 • Learn Fusion 360 in a ...
See:- The Intermediate Playlist • Intermediate Fusion 36...
Chapters
0:00 Introduction
0:34 Review
1:13 Preparation
1:45 Initial component
2:47 Master sketch
6:35 2nd component
8:30 SMOKO
9:20 3rd - Shaft
10:28 4th - Drive wheel
12:16 Hand crank
13:46 5th - Key
14:53 Navigating the assembly
15:23 Joints
18:31 Contact sets
19:02 Animate model
19:25 Rename linked part

[@kiwinesss]

I like learning with you, your voice is the perfect teaching voice!

[@ArnoldRowntreeTeachesFusion360]

thanks Bob, but don't go to sleep on me now!

[@ArginLerit]

Thank you! The joint section of the lesson helped me a lot. :)

[@ArnoldRowntreeTeachesFusion360]

Great to hear!

[@spexr1106]

please never quit you have helped me out so much

[@ArnoldRowntreeTeachesFusion360]

Thankyou, that's encouraging.

[@jamesrayner8337]

Great tutorial, thanks

[@ArnoldRowntreeTeachesFusion360]

Thanks James, it looks like you've worked through a lot of stuff here, I'm looking forward to producing more. All the best for your journey from this point.

[@jwonderfulsuccess]

There go those Kangys again(:! Practicing the Geneva mech again AR, lots of valuable information here 🙏 Please more videos when you can AR, even if they are short n sweet!

[@ArnoldRowntreeTeachesFusion360]

That's the plan! I do need to get the revisions done but I've got some ideas queued.

[@espressoshot21]

Aww look at those cute kangaroos in your backyard!! Haha here in the US suburbs, we see sometimes see deer in our yard instead of kangaroos! 😂Anyways, another amazing series Prof Rowntree! I'm learning so much from you! Thank you again!

[@ArnoldRowntreeTeachesFusion360]

We have some feral deer nearby too but they are much more discreet - they need to be since they are known to be delicious. Thanks for your kind words, I'll keep going.

[@mrcarautomotive1157]

IT WAS VERY HELPFUL

[@ArnoldRowntreeTeachesFusion360]

Thanks Mr Car

[@jwonderfulsuccess]

Awesome, epic. Great video. Seemed overwhelming at first but step by step done 3 times over while understanding it. Its a sinch (; I'm not sure if I got the angle in between the 2 construction lines. My pin seems to be butting the Geneva mechanism and not revolving smoothly. Imagine, kangys in your backyard- the life😃

[@ArnoldRowntreeTeachesFusion360]

The kangaroos can be a bit of a distraction. If you've worked through this several time you've learned quite a lot. At least you understand the steps even if there's glitchy movement. The idea is that when you come to trying out your own designs or a modification of another Grabcad model, you know how things are supposed to work. That's a big step toward your goal. You may be needing help for a while yet but you're well on the way.

[@Bongkie1000]

great tutorial sir

[@ArnoldRowntreeTeachesFusion360]

Glad you liked it

[@kasper2lo]

Excellent video on joints. I think I even understood enough to ask a question. Is there an advantage to making the rigid joint between the indexing wheel and the shaft (17:30) over a rigid joint between the indexing wheel and the shaft-key joint?

[@ArnoldRowntreeTeachesFusion360]

Thanks Zachary, I did spend a few moments pondering that when I was making it and decided on the spur of the moment that I'd focus on the wheel to shaft joint because the function of the pin is only to stop slippage and reinforce the interference fit between those two main parts.

[@ArpanMukhopadhyay93]

very useful 2 videos!!

[@ArnoldRowntreeTeachesFusion360]

Glad you like them! This is where it begins to get really interesting. You can look at someone elses design or make something up, make a model and adjust it until it works, then you have a plan.

[@ArpanMukhopadhyay93]

@@ArnoldRowntreeTeachesFusion360 yess. The design I wanted to work on consusts of multiple parts. I was thinking how to do them. Then I came across top down and bottom up concept and now I have a clear idea how I am going to do

[@gordonmckenzie2982]

Very good delivery. Enjoyed learning from you. My only question during the development was how you knew 37 mm was the right distance to place the pin on the driving wheel. Seems that placing two construction circles for the two sides lobes of the slot entry and then averaging their radiuses would get you the proper distance. But perhaps there is an engineering design approach.

[@ArnoldRowntreeTeachesFusion360]

Good question Gordon, my first attempt caused a glitch in the animation when the pin bumped its way into the slot. I looked a bit more closely and made one adjustment, didn't write down the details or the thought process and can't remember now. My purpose was simply to make a model that animated (nothing like an engineering approach).

[@Viper4tification]

Great tutorial! I like to follow along as you build. I did run into a problem with the animation. I followed you to the letter on the joints but for some reason the pin stops at the entrance to the slots periodically and the key loses it joint and then snaps back into place when rotating the drive wheel. Is there something I need to adjust to prevent this?

[@ArnoldRowntreeTeachesFusion360]

V4t, I wish I could be looking over your shoulder, there are many things that can cause the animation to fall over. Fusion is calculating large number of alternative scenarios with the geometry and angles within the contact set. What I'd be doing is checking the sketch and the extrusion extents, any variation in size can lead to an interference between the selected components. Since its good to repeat the exercises, its probably better to repeat it carefully than to check over all the details. Your call.

[@jwonderfulsuccess]

I liked seeing the kangys. It's a short, fun, laughable pause in between intense learning (:

[@ArnoldRowntreeTeachesFusion360]

You've been working hard JWS

[@harleyblanchard7275]

When are we gonna get intermediate 3D part modeling?

[@ArnoldRowntreeTeachesFusion360]

Hi Harley, the hand crank we made in this series probably looks far too basic for you now. It will be a while before I go in-depth on modelling, I want to cover more of the broad areas of Fusion 360 but we'll get there.

[@noweare1]

My biggest problem is some bodies are part of other bodies that should not be. I have to be more aware of "new componant" vs join etc.. I think that is where I am getting in trouble. Spent a lot of time trying to seperate bodies and combine with other bodies to come up with the same components as you. Learning is so frustrating sometimes.

[@ArnoldRowntreeTeachesFusion360]

I'm glad to see you're still going on with my tutorials Joseph. This is the intermediate series you're in now and there's a lot going on. Did you do the 'Bodies and Components' playlist before this one? I'm going to be building that out quite a bit when I've caught up on the revisions since its so foundational to these intermediate level tutorials. There is quite a bit of self discipline needed to keep the browser nice and tidy. Thankfully you can usually re-organise it as I demonstrate in the 'Bodies and Components' tutorials. kzbin.info/aero/PLFCTgdiT5-kKquu0V7q39r8aHb3e74xQA

[@OLLE3770]

If I use your method of creating a rigid joint between the BASE and "top level" the KEY does not rotate with the SHAFT during animation. If I instead "ground" the BASE, the KEY will rotate with the SHAFT. Is this a bug? Why are you not using "ground"? Other tutorials on joints uses "ground". I'm a bit confused.

[@ArnoldRowntreeTeachesFusion360]

I know that 'Ground' works OLLE, come to think of it, I can't remember who it was who said to use a rigid joint with the top level. It was someone at Autodesk in a live stream and I don't remember a reason why other than that he said this is the way they designed it to work. I'm sure a lot of others who use ground are re-living Solidworks days but on educational level projects like the one in this tutorial you can really get away with almost anything. Thanks for the question though, I'll see what I can find out.

[@jenspetersen5865]

Great advice - there is one thing though that I do not like in your process and that is that your are not tying things to the origio points - the Z azis really should be through the Geneva wheel, so that the Z axis was common for parts attached to that rotation. In larger assemblies it is invaluable to have common centerlines, and it is one of the things that are really cumbersome when you import from other sources.

[@ArnoldRowntreeTeachesFusion360]

Good point Jens, I'll take that on board from now on.

[@jenspetersen5865]

@@ArnoldRowntreeTeachesFusion360 Thanks - your videos here are insanely good!

[@jenspetersen5865]

@@ArnoldRowntreeTeachesFusion360 One other thing I would love for you to take up - a thing that I have a hard time figuring out in Fusion is constraining in the assembly space. In the sketch environment it looks totally like other CAD packages, but I am spending way too much time on doing the same with bodies - lets say an imported body that is designed at a 5 degree angle that you want to align to the x, y, z grid.

[@ArnoldRowntreeTeachesFusion360]

Thanks Jens

[@ArnoldRowntreeTeachesFusion360]

I'll be looking for a good place to include the answer to that question Jens, in the meantime, search for John Hackney's channel and find his video titled "Aligning imported model to Fusion 360 Origin".

[@printing3d722]

Right at 6:05 you say, "Make sure this circle is Concentric with the shaft of the indexing wheel." But you have the coincident tool selected. When I try this, it makes my Base too small. Here is what it's doing: kzbin.info/www/bejne/b3uaY4N_oa6FjqM

[@ArnoldRowntreeTeachesFusion360]

Yes P3D, I see that and well done so far! Thanks for your video, that makes it so easy to understand your question. I think you'll find that if you put a dimension on the radius of the curve or a dimension on the width of the base it won't behave like that. You'll be all over this in no time but please come back if you're still stuck.

[@billkellogg1403]

What’s with the smoko or whatever? Confusing, distracting.

[@ArnoldRowntreeTeachesFusion360]

Thanks for the feedback Bill, I'm going to be keeping my ear out for more reactions and then re-assess.

[@DellanaMetalArts]

@@ArnoldRowntreeTeachesFusion360 - I agree with Bill! 😊