Design Copilot NX vs ChatGPT vs Claude: The Short Version
Design Copilot NX is Siemens’ in-product help assistant, grounded in the docs for your NX version. ChatGPT (GPT-5.6 Sol) explains CAD concepts and often invents NXOpen APIs. Claude, via Claude Code plus an MCP index, is the stack inteliScience uses for DACH NX automation. Use Copilot for help, ChatGPT for concepts, Claude for code.
| Job | Design Copilot NX | ChatGPT (GPT-5.6 Sol) | Claude (claude-opus-5-5 + MCP) |
|---|---|---|---|
| Knows | Siemens docs for your NX release | Public CAD and coding knowledge, mixed across versions | The NXOpen API you indexed, plus your repos if you connect them |
| Sees the model on screen | Session context (active app, recent commands) | No | Only if an NX MCP server is driving a live session |
| Writes NXOpen that compiles | No. It answers “how do I”, it does not ship journals | Scaffolding. Signatures are frequently invented | Yes, when retrieval hits the real class and member |
| Runs inside NX | Yes, two stars next to Search in Designcenter X | Browser or API | Claude Code / Cursor on a workstation, or a custom chatbot |
| Your standards and macros | Invisible | Invisible | Only if you index them |
| Data path | Siemens copilot path, docs plus session commands | Leaves the company unless you are on a locked-down workspace | Local MCP index stays on the machine. The prompt still hits Anthropic unless you self-host |
| Use it for | “Where is this command?” | Whiteboard, generic CAD, first-pass English | NXOpen, journals, API debugging |
The Problem: “Siemens NX AI” Is Three Different Products
Search “Siemens NX AI” and you get a pile of unlike things. Siemens’ own page. A ChatGPT thread. A GitHub MCP repo. A vendor chatbot. They are not substitutes.
Design Copilot NX (Siemens now ships it as Designcenter Copilot) is a help system. ChatGPT is a general model. Claude is a coding model that becomes useful on NX only when you ground it.
Teams that treat them as one “AI for NX” buy the wrong one, paste a proprietary journal into a consumer chat, and then decide “AI doesn’t work for CAD.” The failure is the mismatch, not the models.
We would advise against a bake-off that scores all three on the same prompt. “Create a hole feature on this face” is a Copilot job if you mean the NX command, a ChatGPT job if you mean the concept, and a Claude job if you mean a journal that will run on NX 2606.
Comparison: Design Copilot NX vs ChatGPT vs Claude
Design Copilot NX shipped to NX CAD seats through Value Based Licensing with NX 2412 (December 2024). Siemens announced the natural-language interface in summer 2025. With the June 2026 release, version 2606, Siemens shortened the product name from Designcenter NX to Designcenter. The copilot is now the in-app assistant: answers grounded in Designcenter documentation, best practices, the active application, and conversation history you can resume later.
NX for Manufacturing 2606 shipped the same month. That CAM drop is a different AI story (Make Machining Suggestion, Chat Copilot in NX X Manufacturing). Do not mix it into this comparison. Teamcenter Copilot is another Siemens product again, for PLM, not for the NX graphics window.
ChatGPT in September 2026 is the GPT-5.6 family. Paid ChatGPT reasoning on eligible plans runs on gpt-5.6-sol. On the API, Sol is listed at $4 input and $20 output per million tokens (a promotional rate OpenAI has announced through November 2026). It will talk fluently about sketches, PMI, and “NX Open in Python.” It does not know which NX you actually run, and it has never seen your custom builder wrappers.
Claude’s current flagship on the API is claude-opus-5-5 at $4 / $20 per million tokens, with a 1M-token context window. That is the model we reach for when the job is NXOpen. Bare Claude still hallucinates proprietary CAD APIs. The difference is tooling: point Claude Code at a local NXOpen index and the invented class names drop.
The open-source server most teams try first is nxopen-mcp (a small project, around 10 GitHub stars as of September 2026). It builds the index from your licensed NX install. No Siemens XML is bundled in the repo.
| Prompt you actually type | Who should answer |
|---|---|
| “How do I start a synchronous sketch in this release?” | Design Copilot NX |
| “What is the difference between a wave link and a WAVE geometry linker?” | ChatGPT is fine. Copilot is better if you then want the command. |
| “Journal: list solid bodies and print volume in cm^3 on NX 2606.” | Claude + MCP, then a human run |
| “Why does our hole journal throw after the NX 2512 upgrade?” | Claude with your script in the repo, not Copilot, not ChatGPT |
| “Which AI should we buy for the department?” | None of them as a single purchase. See the checklist below. |
Siemens markets Copilot as a learning and productivity aid. Read that as “less time in Help,” not “less design time.” Copilot does not close an ECO.
Use Design Copilot NX for help, not for automation
Our recommendation: turn Design Copilot NX on for every seat that already has the license, and stop asking it to write production journals.
In Designcenter X it lives next to Search (two stars). It suggests prompts from recent commands, the same idea as Command Prediction. It cites sources at the bottom of a reply. Siemens says it does not read personal user data, it does read recent commands in the session. That is the right threat model for a help bot: context from the UI, not from Teamcenter items.
Siemens has described the Industrial Copilot behind Designcenter as powered by Microsoft Phi-3. Treat that as Siemens’ stack, not something you swap for claude-opus-5. You do not pick the model. You buy the license.
Designcenter ships twice a year, in June and December, and the 2612 release is already in early access. Copilot will keep moving. The job description will not: it is documentation plus context, inside NX.
If a reseller demo shows Copilot “writing NXOpen,” ask them to compile it against your author license and run it on a released part. We have not seen Copilot replace NX programming work. It points at commands. The automation still lives in NXOpen, Knowledge Fusion, or a signed add-in.
ChatGPT is a whiteboard, not an NX seat
ChatGPT is the tool engineers already have open. That is its real advantage. For a first explanation of synchronous vs history mode, or a sketch of a DFM argument you will rewrite anyway, gpt-5.6-sol is fast and cheap enough.
It is the wrong tool the moment the answer has to match a release. NX 2412, 2512, and 2606 do not share one API surface. ChatGPT blends them. A method that existed in 2212 and died in 2412 still shows up looking current.
The same failure mode hits NXOpen. Public models hallucinate package names even on PyPI and npm. One 2026 replication across five frontier code models put package-name hallucination between 4.62% and 6.10% over 199,845 prompts (arXiv:2605.17062). NXOpen is worse: sparse training data, vendor XML, versioned builders. ChatGPT will emit session.Parts.OpenPart(path) or NXOpen.Part.Open(path) when the real members are PartCollection.Open and PartCollection.OpenActiveDisplay. It reads well. It does not compile.
We have already written up why those NX answers go wrong. The short version: do not paste a production journal, a Teamcenter item id, or a customer part number into consumer ChatGPT. ChatGPT Business or Enterprise with training off is the minimum if the prompt must leave the building. Even then, you are paying for English, not for a compiler.
In practice this rarely works as the “AI CAD strategy.” It works as the engineer’s scratchpad. Keep it there.
Claude plus MCP is how NXOpen gets written
Claude wins the coding column, and only that column, once you ground it.
Claude Code on a workstation, claude-opus-5-5 as the model, MCP tools against an index built from the NX 2606 (or 2512) help that is already on disk. The agent calls search_api / get_class / get_member before it writes a builder. That is the loop. Without the loop you are back to ChatGPT with a different logo.
The first prompt should be a boring one. “Find CreateHoleFeatureBuilder for NX 2606 and show the constructor plus the license check.” If the tool returns a real member list, you can ask for a journal. If it does not, you do not have an NX assistant yet. You have a chatbot.
Hallucinations still happen on the seam: Teamcenter SOA, undocumented customer wrappers, KF rules the index never saw. That is why a headless run against a reference part is not optional. Copilot will not do that run. ChatGPT will not either.
A custom Siemens NX AI chatbot is the department-scale version of the same idea: retrieval over your journals, standards, and Teamcenter, with SSO and on-prem when the IP cannot leave. inteliScience builds that layer on NX Open for DACH engineering teams. Claude Code plus MCP is the developer laptop. The chatbot is what the rest of the team uses. Do not buy one and skip the other if both jobs exist.
Ready to implement? The retrieval-plus-headless-test path we use for journals is in our NX Open AI code generation guide.
Here is the class of bug the index is for. ChatGPT likes the first line. NX 2606 wants the second.
# WRONG: fluent, common, not a member of PartCollection
# part = session.Parts.OpenPart(r"C:\parts\bracket.prt")
# RIGHT: NXOpen.PartCollection.OpenActiveDisplay on NX 2606
# returns (BasePart, PartLoadStatus)
import NXOpen
session = NXOpen.Session.GetSession()
part, load_status = session.Parts.OpenActiveDisplay(
r"C:\parts\bracket.prt",
NXOpen.DisplayPartOption.AllowAdditional
)
load_status.Dispose()If your evaluation prompt cannot tell those two apart, you are scoring prose, not NX.
inteliScience’s position is blunt. For NXOpen, pick Claude and spend the week on the index and the test harness, not on prompt poetry. For NX help, use Design Copilot NX. For a slide, use ChatGPT. Mixing those three into one “AI CAD platform” is how POCs stall.
What to look for when choosing
Five checks. If a vendor cannot answer them in one sitting, keep walking.
- Which job? Help, concepts, or code. Design Copilot NX, ChatGPT, and Claude map 1:1. A pitch that covers all three with one SKU is a slide.
- Which NX version is the answer pinned to? 2412, 2512, 2606, or “whatever is in the weights.” Only the first three are usable.
- Where does the prompt go? Copilot stays in Siemens’ path. ChatGPT leaves unless you paid for a closed workspace. MCP can keep the API docs local. The LLM call still needs a destination you can name.
- Does it compile? Ask for a journal, sign it, run it. “Looks right” is not a test.
- Who maintains it after NX 2612? Designcenter 2612 lands in December. Journals break on upgrades. If the answer is “the intern who likes Claude,” you do not have a system.
Siemens NX consulting for us means the boring part after the bake-off: version pinning, retrieval, a test part, and someone who still owns the scripts in 2027.
Frequently Asked Questions
What is Design Copilot NX?
Design Copilot NX is Siemens’ in-product assistant for NX (Designcenter from the 2606 release). It answers natural-language questions from the documentation of the version you have open, with sources and links to commands. It is a help system. It is not an NXOpen compiler and it does not know your company standards.
Design Copilot NX vs ChatGPT: which should I use?
Use Design Copilot NX when the question is “how does NX do this in this release.” Use ChatGPT (gpt-5.6-sol) when you want a generic CAD explanation and you will not paste IP. If the output has to compile, neither is enough. That is Claude plus an NXOpen index.
Can Claude write NXOpen that actually runs?
Often, for read-only journals, once MCP is attached to your NX install. claude-opus-5 still invents members when the index misses. We run the result headless on a reference part before anyone else sees it. Bare Claude in a browser is ChatGPT with different manners.
How much does Design Copilot NX vs ChatGPT vs Claude cost?
Design Copilot NX is a Siemens Value Based Licensing add-on. Siemens does not publish a seat price on the marketing pages. ChatGPT is a subscription (Sol on paid plans); the API lists gpt-5.6-sol at $4 / $20 per million tokens as of September 2026. Claude API list price for claude-opus-5 is $5 input and $25 output per million tokens. A grounded departmental chatbot is a project. Price the senior hours it removes, not the tokens.
Does Design Copilot NX replace NXOpen automation?
No. Copilot tells you which command to click. NXOpen runs the work unattended, across an assembly, to your rules. They stack. If a demo claims Copilot replaces custom automation, ask for a signed library that still works after the next June release.
Next Step
Want this mapped onto your NX version and your actual journals? Book a free 60-minute strategy call. We will say Copilot, ChatGPT, Claude, or none, with reasons. Book a strategy call about Design Copilot NX vs ChatGPT vs Claude