Free (and nearly free) CNC machine monitoring for small shops

Option 1: A free software tier

CNC Monitor is software you point at your machine's controller IP address. Its free tier gives you real-time dashboards; the paid Full version is $30 per machine per month and adds ERP/MES integrations, APIs and an MCP server so you can ask an AI assistant about your machines. No extra hardware is required, according to the vendor. If your machines are networked, this is the fastest no-cost test.

Option 2: Read the data your machine already serves

Some controls already publish their status. Haas's service manual describes a built-in MTConnect agent on Next Gen Control machines that you can query over the network. MTConnect itself is an open, free standard, so if your machine has an adapter, you can read its state, program and part count with a browser or a small script. Be aware that many machine builders charge to enable these options, and some data (spindle load in particular) may be locked, as Practical Machinist members pointed out in a July 2026 thread.

Option 3: DIY sensors on older machines

For a machine with no usable network data, the cheapest trick is a clamp-on current sensor. Our ~$60 spindle load monitor on a 1998 Haas walks through one design. It's a write-up, not a measured deployment, but it shows how little hardware you need to see when a spindle is loaded.

If you want something sturdier than a hobby board:

• Arduino Opta is a DIN-rail micro PLC (listed at €206 on Arduino's EU store) with Wi-Fi, Ethernet and RS-485 that can run small machine-learning models.
• Edge Impulse lets you train small models on vibration, sound or temperature data for free on its developer plan and deploy them to devices like the Opta. Production deployment requires an Enterprise subscription.
• Our microcontroller listening for trouble case study shows that pattern in a print shop.

Option 4: Cheap cameras for counting and checks

A Raspberry Pi AI Camera / AI HAT+ ($70) runs vision models on the camera itself. It's prototype-grade, not an industrial inspection system, but it's enough to count parts or check that a part is present. LandingAI LandingLens has a free plan for training vision models in the browser, though models downloaded on the free plan are for non-commercial use only. See our Raspberry Pi vision case study.

Free doesn't mean zero cost

• Your time. DIY builds take tinkering and upkeep. A Practical Machinist member who wrote his own monitoring software for several control brands offered to help others, which tells you it's doable, but it's a project.
• Network security. Don't expose older machine controls to the internet. One forum member isolated his machines behind a small dual-port router so files can move internally without the controls ever touching the internet.
• Someone has to look. The value comes from acting on what the data shows: a long setup, an idle second shift, a machine waiting on material.

When to step up to paid

Once you know what you want to measure and on which machines, a paid system saves you the maintenance. Compare the paid options in our CNC machine monitoring software guide.

Bonus: free tools for program transfer

Monitoring often starts with a related headache: getting programs onto the machine. In the same July 2026 thread, members mentioned an open-source Raspberry Pi project (ChatterSync on GitHub) that lets an un-networked machine see a network folder as a USB drive. It's free and DIY, not a monitoring system, but it's a gentle first step into connecting your shop.

Sources

• CNC Monitor pricing
• MTConnect Institute
• Haas NGC machine data collection (service manual)
• Practical Machinist: Is connecting machines to the network worth it? (Jul 2026)
• Practical Machinist: Externally Monitoring (Jul 2026)
• ChatterSync on GitHub
• Edge Impulse pricing

Facts come from public vendor pages and the sources above, checked October 24, 2026. Prices change; confirm with the vendor. Forum comments are individual opinions. Spot an error? Tell us.