Coordinates
Tool Frame
A tool frame is the coordinate system attached to the robot's faceplate that defines the tool center point's location and orientation relative to that mounting flange.
What it is
The tool frame is the coordinate system the robot uses to describe where its tool actually works. It's fixed to the faceplate (the mechanical flange at the end of the wrist) and offset from it to sit at the working point of whatever end-effector is bolted on: the tip of a welding torch, the center of a gripper's grasp, the nozzle of a dispenser.
Its origin is the tool center point (TCP), and its orientation defines which way the tool points and how its axes line up. Once a tool frame is defined, jog and motion commands in tool coordinates move the TCP directly, so the robot's position readout means the position of the working point rather than the position of the bare flange.
How it actually works
A tool frame is stored as a six-value offset from the faceplate: X, Y, Z translation plus W, P, R rotation. A straight welding torch sticking 200 mm out from the flange along the flange's Z axis gets an approximate tool frame of X0 Y0 Z200 with no rotation. Angle that torch, and the W/P/R values capture the tilt so the TCP still lands at the wire tip and points the right way.
Values can be entered numerically when the tool geometry is known, or taught. The six-point method drives the TCP to a single fixed reference point from several different wrist orientations; the controller solves for the offset that keeps that one point stationary across all of them. Once the frame is active, a tool-Z jog runs the tool straight in or out along its own axis regardless of how the wrist is twisted, which is what lets you plunge a drill or retract a torch cleanly.
How it differs
- User Frame · A tool frame is attached to the robot's faceplate and moves with the wrist; a user frame is attached to a fixture or workpiece and stays put in the cell. One describes where the tool works from, the other describes where the work happens. You typically set both, then jog the tool frame relative to the user frame.
- World Frame · The world frame is the fixed reference tied to the robot base and never moves. The tool frame rides along with the wrist and reorients every time the robot moves. Position readouts differ depending on which is active: world coordinates report the flange in cell space, tool coordinates report motion along the tool's own axes.
- Tool Center Point · The TCP is a single point, the working tip. The tool frame is the full coordinate system whose origin sits at that point and adds orientation. Defining a tool frame is how you tell the controller where the TCP is; the TCP alone carries no direction information.
Where you meet it in the field
- 3-point user frame setup · User frames are taught with the same touch-a-reference-point technique used to teach a tool frame; the two work as a pair and the tool frame defines the TCP that traces the taught points.
- FANUC CRX-10iA · A collaborative arm where the tool frame gets set for whatever end-effector is mounted, so hand-guided teaching and jogging move the actual working point.
Common questions
- Do I have to define a tool frame, or will the robot work without one?
- The robot always uses a tool frame; if you never set one, it defaults to the faceplate itself (all zeros), so the TCP sits at the center of the flange. That's fine for rough jogging, but any real tool works some distance out from the flange, so positions and tool-coordinate moves won't reflect the actual working point until you define the offset.
- Why does my robot reorient around a point in mid-air instead of the tool tip?
- That's the classic sign of a wrong or default tool frame. When you rotate in tool coordinates, the arm pivots around the TCP. If the tool frame offset is zero or inaccurate, the pivot point sits at the flange or somewhere off the tip, and the tool swings instead of rotating in place. Re-teach the frame so the TCP lands on the real working point.
- Can I keep several tool frames and switch between them?
- Yes. Controllers store multiple numbered tool frames, so a robot that changes grippers or runs a multi-tool end-effector can hold a separate frame per tool and select the active one in the program. Each carries its own offset and orientation.
- Is the tool frame the same thing as the TCP?
- No, though they're tightly linked. The TCP is the single point at the working tip. The tool frame is the coordinate system built at that point, adding orientation (which way the tool points). You define a tool frame in order to place the TCP.