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One Robot Tending Two CNC Machines?

one robot two machine tools



Published on

Feb 21, 2023

We sometimes get a request to have one robot tend two machine tools. The question is, what makes that a good idea?

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Key Takeaway: What makes one robot tending two CNC machines a valid idea?

More than fifteen years ago, a small European machine shop was struggling with competition from low-wage countries. They knew they needed a paradigm shift if they had any hope of being competitive. European countries are not known for having a low-wage or low-cost-of-doing business advantage.

As they pondered the options, they thought a robot tending a CNC machine as the paradigm shift that could once again make them competitive. The problem was no one was making machine-tending robots. So they did it themselves.

Nearly two decades later, they are the international leaders in purpose-built, CNC machine-tending robots. Today, more than 1,400 RoboJob robots are installed and working at more than 400 companies spread over more than 500 locations.

We’ve seen our share of CNC tending robot installations. We know what works and what doesn’t. We know why it works, or it doesn’t and the reasons behind it.

The robot loads and unloads the CNC machine. As the CNC machine cycles, the robot sits in the home position because there isn’t anything for that robot to do.

We sometimes get asked the question, “Can you make me one robot to tend to two CNC machines at once?”

That is both an obvious question and a great question. Because it makes so much sense, the answer may surprise you.

Can we do it? Absolutely! Do we recommend it? Absolutely NOT!

If we can do it, what prevents us from recommending that approach? Here are some of the elements that go into consideration.

Compact Design

We make our work table as large and yet as compact as possible. This allows you to maximize your jobs and run as many parts as possible while giving your machinist full access to the work envelope. Your machinist can still get in and change a cutting tool or a collet with no physical hindrance. They won’t have to avoid uncomfortable positions to get the job done.

They can even run a part or a job if needed, and the robot would not be in the way.

If you are trying to make, one robot tend two machines, the compact design and the positioning all go out the window.

Plus, you’ll be loading and unloading the parts table more frequently.


The robot's movements seem simple. Entering job instructions into the robot simply enters the raw and finished parts dimensions. That lays out the positions for the parts on the parts table.

We’ve made this process as simple as possible.

Imagine having to keep the dimensions of the parts separately for each job and CNC. That can add unwanted complexity to the process.

Programming the robot for two jobs at once more than doubles the complexity.

Complexity adds expense.


Our software tells you the gripper settings when you enter the raw and finished parts dimensions. If you are trying to run two CNC machines simultaneously, you’d need to keep the parts remarkably similar. Otherwise, you may need two separate gripper settings.

That would seem to give away some advantages you might gain when simultaneously tending to two CNC machines.


The robot location is important because we look at the weight of the parts and the distance from the robot parts table to the work-holding device in the CNC. That is all measured, pre-programmed, and calibrated to +/- 0.03mm.

While we make the robot’s movements seem simple, its programming is complex. Imagine having to do that twice.

Can it be done? Of course, it can. Should it be done? Unlikely.


Machine shop floor space is always valuable and expensive. Even if you own the building, every inch of floor space is valuable. You may be carting pallets on a pallet jack between machines, and in the tight squeeze that can be machine shop life, an inch here or an inch there can be the difference between getting the pallet through or not.

There is also the robot's location relative to the work envelope. If we created one robot to tend to two machines simultaneously, the location would have to be different and likely take up space, so your machinist would have to give up easy access to the work envelope and have their tool cart close by.

Robot Size

We work to make the robot size as compact as possible and still handle the part's weight and the distance from the end of the parts table to the work-holding device. To tend to two CNC machines at once, the robot length will probably increase.

Adding size adds to the cost. But it also can create space issues in other ways. A longer robotic arm would increase the size of the safety zones.

What If?

What happens if the robot is placed between two CNC machines and has it programmed to tend to both machines at once if something prevents one machine from operating? Let’s say a cutting tool breaks, and your machinist has to get in and replace it.

Because of safety issues, neither machine can operate. You don’t want a moving robot and a human that close together. That means you are giving up production on machines that would otherwise be turning out parts.

While that scenario may not happen frequently, you can probably count on Murphy’s Law to apply.

Can We Make a Robot To Tend Two CNC Machines Simultaneously?

We can do this. So why don’t we do it?

We don’t recommend it because of the drawbacks mentioned in this blog post. Some of those key points included:

  • Limitations on access to CNC machines.
  • Robot arm length.
  • Limits on grippers.
  • Smaller job capacity per run because of feeding two machine tools
  • Slower job change over
  • Loss of access to the CNC work envelope
  • Added complexity to the programming.

We also don’t recommend it because of all the technical issues involved. There is another reason. The cost would be more than buying two robots and deploying them in our one CNC/one robot match. We strive to make robots cost-effective, not cost prohibitive.

Despite the warnings, some insist on moving ahead with a DIY project to have one robot and two machine tools. We always want to be respectful of our customers and those who are not our customers.

Ready to move to start your journey to automation? Call us at 866-952-9020 and press 1 to start the conversation.

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