Brian Ratliff

Bringing AI to mechanical engineering | Claude CAD

[Brian Ratliff @BrierRat]

So, Claude CAD built me a 15.6:1, 3-stage gearbox. I "sketched" a rough outline of what I wanted in Shapr3D with the general gear arrangement. Bearings and fasteners from McMaster. Claude did everything else. 139 part assembly. Involute teeth. Retaining rings. All of it.

[Brian Ratliff @BrierRat]

Did you guys know STEP supports colors?

20 years, I’ve never seen a STEP export in color from any CAD system. Or a STEP import, for that matter.

[Brian Ratliff @BrierRat]

It is so cool being able to just sit with Claude and make the software into exactly what I want

[Brian Ratliff @BrierRat]

Claude CAD, now in color!

[Brian Ratliff @BrierRat]

What do you guys think, should I add colors to my homebrewed CAD viewer? I feel like my profile might be looking a bit monochrome.

On one hand, basically every CAD design I've done in my career has been in this particular shade of gray. At some point it's tradition. I've built literally thousands of CAD parts--I've just never really cared about colors unless it's interfering with viewing the part. And sometimes, I'll admit, lots of colors seems a bit gaudy and not very useful except for presentation.

On the other hand, it seems all the new AI-CAD floating around has been splashed with color. Is this the trend now?

Cool thing about building your own AI-native viewer is you get to add the exact features you want. And only those features you need.

[Brian Ratliff @BrierRat]

@optomachina Did it. Glad I did. Good advice

[Brian Ratliff @BrierRat]

What do you guys think, should I add colors to my homebrewed CAD viewer? I feel like my profile might be looking a bit monochrome.

On one hand, basically every CAD design I've done in my career has been in this particular shade of gray. At some point it's tradition. I've built literally thousands of CAD parts--I've just never really cared about colors unless it's interfering with viewing the part. And sometimes, I'll admit, lots of colors seems a bit gaudy and not very useful except for presentation.

On the other hand, it seems all the new AI-CAD floating around has been splashed with color. Is this the trend now?

Cool thing about building your own AI-native viewer is you get to add the exact features you want. And only those features you need.

[Brian Ratliff @BrierRat]

I had a similar moment with Claude. I had a simple part, a block with an arced top which I put a slotted cut diagonally across the arced top. Asked Claude Code to read and manipulate the STEP code directly. It did that a few times, changing the slot angle and width by modifying vertex points, etc usi my greps. But at a point, I got bored and gave it a mod which I knew would break topology. Claude examined the request, saw it would break topology, went and coded the part up in Cadquery and made the change, regenerated the STEP, on its own, without my intervention.

Color me impressed. That’s when I started leaning hard to my Claude CAD system.

[Brian Ratliff @BrierRat]

@faraz_r_khan I would give build123d a try. I think the problem with python freecad is it might be one abstraction removed.

You are using a python script to operate freecad operating on the OCCT kernel. Using build123d or cadquery and you have a script operating directly on the OCCT kernel

[Brian Ratliff @BrierRat]

So, Claude CAD built me a 15.6:1, 3-stage gearbox. I "sketched" a rough outline of what I wanted in Shapr3D with the general gear arrangement. Bearings and fasteners from McMaster. Claude did everything else. 139 part assembly. Involute teeth. Retaining rings. All of it.

[Brian Ratliff @BrierRat]

This is a challenge in the AI-augmented CAD space. How do you get past dancing bear demos? Get to the point where people say, aha, this makes my life as a design engineer easier?

That’s why all the demos of Claude CAD I post here are buildable.

[kumikumi (Ankkala) @ankkala]

Dancing Bear is a good analogy I found for AI outputs.

Suppose there's a circus and people go there to see The Dancing Bear. People don't go because the dance is good. It isn't. It may actually be kind of terrible. What matters is that the bear dances at all.

[Brian Ratliff @BrierRat]

@BuildingDeeply My main problem is squaring cosmetic colors with the functional colors of labeling faces, since the face labeling is a big part of how the user communicates with Claude over the MCP

[Brian Ratliff @BrierRat]

@Peter__Ross You GTFO right now ;)

[Brian Ratliff @BrierRat]

@AndresMilioto I have had Claude suggest McMaster part numbers for screws it wants. But McMaster won’t let Claude download the models

[Brian Ratliff @BrierRat]

@ShabaniBetim That said, it’s a bit different than CAD. Many relationships are just handled in the code. Relationships are just reusing variables used to build the features

[Brian Ratliff @BrierRat]

@ShabaniBetim Not as such. This was built as solid bodies. Build123d and OCCT supports relationship constraints, but here I’m more testing geometric reasoning. With an agent, it’s a little unnecessary, since the agent can manually keep things together if parameters shift.

[Brian Ratliff @BrierRat]

Oh, there are a bunch of skill files behind this as well. And surprisingly, yes, Claude is pretty up on gear ratios and standards. The STEP sketch gave ratios, it asked what gear tooth ratio I’d prefer and built it to spec. It even assumes specifications—saw the shaft was in mm, built ISO standard keyways into the gears and shaft.

[Brian Ratliff @BrierRat]

@BrixActual Each gear/shaft has keyways and keys

[Brian Ratliff @BrierRat]

@faraz_r_khan I used a STEP file export from Shapr3d. It was just a bunch of extruded cylinders which Claude then interprets as gears and shafts. The build is in build123d, so fully parametric.

[Brian Ratliff @BrierRat]

@AndresMilioto McMaster Carr apparently doesn’t like Claude (or any AI) to browse its website, so I do it manually. This seems like something that’s automatable, but one thing at a time

[Brian Ratliff @BrierRat]

That’s the loose idea. I feel like the tight integration of my viewer with the MCP server and Claude is an advantage (rather than bolting on an MCP to normal CAD). This build went together particularly smoothly. Not sure if it’s Opus 4.8, the subject matter, or the skills making an impression, but it was smooth this time around.

[Brian Ratliff @BrierRat]

@ShirodkarKirtan @svankina13 There’s a bit of a method and a bunch of skills files involved, not a one-shot prompt