The AI Machinist in Claude
Is your part ready for a shop?
Ask Claude. With Millr, Claude works out how a shop would make your part and shows you the changes that make it cheaper to make, faster to get and less likely to come back wrong. Each one is highlighted on your own part with the exact fix for your CAD or drawing, and you decide which to make.
Free, on any Claude plan. For machined parts. Your part stays in your Claude account; Millr never receives it.
What a review finds.
Cheaper to make
Changes like a tolerance opened up to suit stock bar, an inside corner a standard cutter can reach, or one setup fewer.
Faster to get
Changes like a missing tolerance, datum or unit added, so a shop can quote the part without calling you.
Less likely to come back wrong
Changes like a fit, thread or keyway called out in full, so it isn't left to the shop's default.
How it works.
Add Millr to Claude.
You do this once. After that, Millr is ready in every new chat.
Attach your part and its drawing.
Export a STEP file from SolidWorks, Fusion, Onshape, Inventor, Creo or NX and attach it, with the drawing PDF if you have one. Using a CAD agent? Export a STEP from Zoo, or from the Onshape or Fusion model you built with Adam. CadQuery and build123d code work too.
Ask if it's ready for a shop.
Claude measures the part, reads the drawing and plans it the way a shop would run it. It then builds a review page you open from the chat, showing each change on a 3D view of your part. Choose Fix this or Ignore for each one. Each one shows how Claude worked it out, so you can check it before you touch your CAD. Then take the fix instructions to your CAD, have Claude make a PDF to keep or send, and attach the revised part to have it checked again.
Add Millr to Claude
claude.ai and Claude Desktop, any plan
- Check that Code execution and file creation is on in Settings › Capabilities.
- Download Millr.
Download millr.skill - In Customize › Skills, click +, then Create skill, then Upload a skill, and choose millr.skill.
- Check that Millr is switched on in your skills list.
Then start a new chat, attach your STEP file and drawing, and ask "Is this ready for a shop?"
Using Claude Code?
Millr added in claude.ai also loads in a recent version of Claude Code when you sign in with the same Claude account. Run /skills to check.
Or add the plugin in Claude Code. We recommend this one command, which needs a recent version of Claude Code:
/plugin install millr --marketplace millr-ai/millr-ai-machinistOn an older version, type these two instead:
/plugin marketplace add millr-ai/millr-ai-machinist/plugin install millr@millr-aiAnother way on paid plans: add Millr as a plugin
Skip this if you uploaded millr.skill above. On Pro, Max, Team and Enterprise you can add Millr from GitHub instead: in Customize › Plugins, click Add, then Add marketplace, then Add from a repository. Enter millr-ai/millr-ai-machinist and add Millr from it. Code execution and file creation must still be on.
On a company account (Team or Enterprise)?
Your company's Claude admin (Claude calls them the owner) decides whether you can upload skills. If you don't see Upload a skill, ask them to turn on user-created skills, or to add Millr for everyone. On Enterprise, the owner turns on Code execution and file creation and Skills in Organization settings › Plugins & skills, on the Policy tab.
To measure your part, Claude may need to download an open-source CAD library. If Millr says it can't measure your part, ask your admin to let code execution download packages from package managers such as PyPI.
Free. A review uses more of your plan's usage than a plain chat does.
Questions.
Can't Claude do this without Millr?
Claude can answer machining questions on its own. Millr gives it a senior machinist's review: Claude measures your part from the STEP file, checks the drawing against it, plans how a shop would make it, and only then lists the changes worth making, each with the exact value or note for your CAD or drawing. Millr also builds the review page that shows each change on a 3D view of your part, with fix instructions, and Claude can make a PDF of the review.
Does Millr see my part?
No. Millr never receives your part or your drawing. They go only to Claude, under your Claude plan's terms. On Team and Enterprise, Anthropic does not train on your chats by default. On Free, Pro and Max, whether it may is your choice in your Claude privacy settings. If your part is under NDA or export control, follow your company's rules for using Claude.
How do I know a change is right?
Each change shows how Claude worked it out: what it measured, what it looked up and what it judged. It also says what to check before you change it, or why it is safe to apply. Nothing changes in your CAD until you change it. AI can make mistakes, so check each change before you make it.
Does Millr edit my CAD?
Millr never changes your files on its own. You get fix instructions for your CAD or your CAD agent, and Claude can make a PDF to keep or send. When your part is code that Claude can edit, the review page also offers to have Claude make the changes you approved.
What does it cost?
Millr is free. A review runs in your Claude account and uses more of your plan's usage than a plain chat does.
Which files work?
Export a STEP file from SolidWorks, Fusion, Onshape, Inventor, Creo or NX and attach it, with the drawing PDF if you have one. Using a CAD agent? Export a STEP from Zoo, or from the Onshape or Fusion model you built with Adam. CadQuery and build123d code work too. IGES works best exported as a solid, but a STEP is better. Have a native file such as SLDPRT or IPT, or Zoo's KCL code? Export a STEP. A mesh such as STL gets a partial review, and Millr says what it could not judge.
Does it work on inch parts?
Yes. Millr writes each change in your part's units, inches first for an inch part. When your drawing leaves something out, such as the material, Millr says what it assumed so you can correct it.
Which Claude plan do I need?
Any plan. The skill works on Free, Pro, Max, Team and Enterprise with Code execution and file creation turned on. The plugin needs a paid plan. On Team and Enterprise, your owner controls skills and network access.
What is it not for?
Sheet metal, PCBs, CAM, feeds and speeds, G-code, and molded or 3D-printed parts with no machined features. Millr says so rather than guessing. It does cover the machined features of castings, forgings and weldments. In the chat, it also answers design questions about machined parts, such as a tolerance, a fit or a thread.
What am I installing?
millr.skill is a ZIP file of Millr's instructions, its scripts, the review page template and three.js, the open-source 3D library the page uses. To read every file before you upload it, open it with any ZIP tool or rename a copy to millr.zip.
Manufacturing feedback before the quote.
Add Millr once, then ask Claude about any machined part.
Free. For machined parts.