Simulation mode lets you see a mechanism move: drag it by hand, or run its motors and servos. Nothing you do here changes the project: leave the mode, or choose Reset, and every part goes back where it was.

Choose Simulation in the mode box in the top bar. It opens once every part has finished building.

What is on screen

• The Outliner, Scene and Environment on the left.
• The Simulation panel on the right, with Stop, Reset, and a row for each motor and servo in the project.
• No tool bar: you select and drag with the pointer.

Drag a mechanism

Press on a part and drag. The parts joined to it follow through their joints: a crank turns, a slider slides, a four-bar linkage moves as a loop.

• Let go to keep the pose. Esc while dragging puts it back.
• Select one part to see rings and arrows for the joints it can move, and drag one to move just that joint.
• A part that is grounded, or joined to nothing, does not move. The panel says why.
• On a touch screen, one finger drags, and two fingers turn and zoom the view.

Run motors and servos

Each motor and servo has its own row:

• Target: type a position, or use + and −. The motor moves there at its own speed.
• Max speed and Max acceleration: how fast it gets there. These two are saved with the project.
• Position, Speed and Acceleration show where it is now.

Press Space, or choose Stop, to brake every motor. Reset puts every part back at its saved pose.

What moves with what

• Gears you coupled in Assembly Mode turn each other at their tooth ratio.
• A nut on a lead screw runs along it as the screw turns.
• A joint with a range, set with Set Joint Ranges in Assembly mode, stops at its ends, and the panel says so.

What it does not do

• Parts pass through each other: there is no collision, gravity or physics.
• Targets and poses are not saved; only each motor's speed and acceleration are.
• Undo, delete and the other editing commands do nothing here. Switch to Assembly mode to change the project.