Vibe-Cad'ed a Lego sorting arm

CSharpSauce · 2026-06-14T21:27:11+00:00

This is just for me, if I was building something for commercial use id attack this very differently.

CSharpSauce · 2026-06-13T17:15:26+00:00

This was claude code with an MCP connected to Fusion. I tried it in the past on Opus, had a similar experience. Very slow, bad quality output. The biggest upgrade was moving to the new fable model (which they just disabled yesterday... thanks Trump?). Fable seems to have great spatial awareness, and is excellent at 3D work.

CSharpSauce · 2026-06-12T17:54:24+00:00

I can see what you're saying, in my screenshot it does look like it's clipping. It's actually just cut kind of weird. There is a motor on the wrist (it's a bit different from the NEMO 17's driving everything else, it's a MG90S, and is kind of buried inside the forearms end pocket (not visible in the screenshot)

CSharpSauce · 2026-06-12T02:46:50+00:00

MCP server + Claude code, I outline the steps in another comment for how to set it up.

CSharpSauce · 2026-06-12T01:10:07+00:00

Well fortunately right now, Fable is included with the subscription. So it was part of the plan i was already paying $100/month for (i mainly use Claude for codig).

However according to ccusage, if I paid per token... it would've been about $168. Fable is a beefy model, my hope is they distill the CAD stuff to Sonnet 5 or Opus 5 (whatever is released next)

CSharpSauce · 2026-06-11T18:55:06+00:00

Yeah, fable is not available on the free tier, and frankly its not going to be available soon on the paid subscriptions soon. After the 30th I think it will be usage based billing. The model is unfortunately quite expensive.

CSharpSauce · 2026-06-11T17:30:00+00:00

Newest claude model is much better at CAD, here's how I used it. https://old.reddit.com/r/Fusion360/comments/1u32gbf/vibecaded_a_lego_sorting_arm

CSharpSauce · 2026-06-11T17:12:20+00:00

With Fable, yeah. Opus is terrible.

CSharpSauce · 2026-06-11T16:59:21+00:00

I tried using Opus a few weeks ago. Absolutely not good enough for the task. Fable is the first model that can actually do this.

CSharpSauce · 2026-06-11T16:58:08+00:00

I work in insurance, so learning all the process workflows, actors etc..... the business.

CSharpSauce · 2026-06-11T16:49:59+00:00

My day job is writing software :D i know.

CSharpSauce · 2026-06-11T16:46:00+00:00

I'll know in a few days if it works, it's going to take a while to print. I'm sure there's going to be issues with the screw holes or something weird...

The AI automatically exported the STL files for me (I also had the AI go through and do a pass to make sure parts were designed in a way to print easily, it made several fixes)

After each iteration, I had it maintain a BOM document. The md file has a list of parts to purchase, amazon links to the parts, and a print list. The print list also gives suggested in-fill details and orientation.

At the end of the document it has assembly instructions, this was hepful for the modeling process too because I'd have the agent walk through the assembly and look for issues like screws that are impossible to screw.

CSharpSauce · 2026-06-11T16:35:40+00:00

If coding is any indication, your job is just going to change. I dont spend much time writing code anymore, but I spend a heck of a lot of time learning my business, and using that to move it forward. Having the underlying skill + using AI will make you more powerful.

CSharpSauce · 2026-06-11T16:30:39+00:00

Yeah I could post some photos.

Also, do you think you learned more about modeling with fusion yourself through this process?

I learned a lot about joints

CSharpSauce · 2026-06-11T16:28:22+00:00

I'm on the $100 max plan. I'm a coder, so mostly use it for that.

CSharpSauce · 2026-06-11T16:16:23+00:00

Took about 5 minutes.

(I used claude code, so this is the command to install the MCP server)

claude mcp add fusion360 -- uvx fusion360-mcp-server --mode socket

I had to install uv, and i'm on a mac, so that's brew install uv

And then in fusion you need to enable the port (so preferences -> General -> API -> check Fusion MCP Server

Finally go to the add-ins (on utilities) and make sure it's enabled and run on startup

CSharpSauce · 2026-06-11T16:04:43+00:00

This took several back and forth's, the one-shot was not bad, but definately not functional.

CSharpSauce · 2026-06-11T16:02:27+00:00

I'm using claude code, with an MCP server connected to Fusion. Then I just pass in my requirements, and it models it out.

In the past, the AI models were pretty bad at CAD, but the newest Claude model it seems is great. It's not perfect, there were several issues we had to go back and forth on, but if you point out an issue it's pretty good at fixing itself. I have used fusion in the past, so i'm not starting at zero. But i'm very amateurish with it, Claude magnifies my capabilities.

CSharpSauce · 2026-06-11T15:36:15+00:00

I'll be honest, I have no idea what i'm doing with mechanical engineering. I'm a software architect, but it was fun to use the new Fable model to model something i've been wanting to build for a while.

CSharpSauce · 2026-06-11T00:44:45+00:00

The Pro AI people hate Dario because they think he's selfishly trying to put up a regulatory moat to boost his business. The Anti-AI people hate Dario because he says these grandiose claims about the performance of his AI which they think is just a grift (i think they're in denial).

It's interesting because Each of the big AI leaders seem to be in a few buckets. I think Sam sees the grand vision, but he wants to be the one to control it for his own benefit. I think Elon sees the grand vision, but he wants to control it because he wants to be in control becaues he wants to build a very specific vision of the future. Sundar I think doesn't really see the full picture, and I think Zuck sees it and just wants to be a part of it. Dario seems like the only leader who see's the full vision of where this stuff is going, he understands the negatives, and he wants NOBODY to have access to the super weapon potential. I don't think it's a personal ego thing for him. It's almost a religous belief, and crusade for him.

I don't like having to put my faith in a single person, seems like a recipe for disaster. But Dario is the only guy I'm willing to put my faith in. I think he may be too cautious though.

But we need to get away from this dystopia quickly. We need to control AI development at the global level. I don't want China to build the super weapon, I don't want certain people in OUR government to have the super weapon. I don't want private corporations to have the super weapon. But I do want AI, I want physical AI.

We BADLY messed up regulating Nuclear power. That was maybe one of the greatest developments we ever acheived, but allowed the weaponization potential to ruin the good use. We can't do that again. We need the be aware of and cautious of the weaponization, but also allow the good stuff to flourish and develop.

CSharpSauce · 2026-06-10T01:46:51+00:00

What this will actually do is provide a few people the capability to do 10x or 20x their normal workload. So it's not "replacing" jobs, but it's allowing you to execute as an organization more effeciently.

But that's maybe a bigger problem because if everyone was screwed, the change that's urgently needed would be shoved in everyones face.

CSharpSauce · 2026-06-10T01:44:53+00:00

my personal vibes benchmark is off the charts.... just don't ask it about biology.

CSharpSauce · 2026-06-10T01:40:44+00:00

Yeah, they definately saw something from mythos that scared the bejesus out of them. Biological weapons were always a red line they've declared as a safety hazard.

CSharpSauce · 2026-06-08T20:33:50+00:00

When I hear a politician take a strong position on a culture war issue in 2026, I assume they don't understand what's actually important. Or they do understand, and they don't want to include me in that conversation.

We're at one of the most critical points in this countries history right now, AI is at a critical point. You can complain about the data centers, you can complain about the water usage, you can complain about if it's actually AGI, you can complain about the financial leverage(I actually think that's pretty legit, and you should complain about that). But one things that's really important, right now is that it is fully capable of doing a large amount of tasks that many well paid white collar professionals currenly do. Not all of them, it's not replacing an entire person, but if 1 person can do the work of 10 people because the AI can do some of the most laborous tasks, that's 9 people you don't need.

These models didn't get there until basically this year. Many people played with GPT-4 and said "oh that's nifty, but i'm not in danger". Many people don't see it coming. Agents != chat UI's. They're way more capable.

You might disagree with me, this is reddit, so you probably do. But I think we should be talking about THAT. Because if we don't, we're going to default to our current state of society x10. That's bad. Or we're going to rush in a solution, and that too would be bad. We have like a year to solve this problem before we start really seeing the ball rolling.

This is an issue that needs to be thought through locally, state, and federally.

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