[[AgustinOrtu]]

Mas pruebas:

Código Delphi [-]
unit Unit1;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants, FMX.Types, FMX.Controls, FMX.Forms3D,
  FMX.Types3D, FMX.Forms, FMX.Graphics, FMX.Dialogs, System.Math.Vectors, FMX.Ani, FMX.Controls3D, FMX.Objects3D;

type
  TForm1 = class(TForm3D)
    Cube1: TCube;
    FloatAnimation1: TFloatAnimation;
    procedure Form3DKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
    procedure Form3DKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
    procedure Form3DCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

procedure TForm1.Form3DCreate(Sender: TObject);
begin
  FloatAnimation1.Enabled := False;
  FloatAnimation1.AnimationType := TAnimationType.In;
  FloatAnimation1.AutoReverse := FalsE;
  FloatAnimation1.Delay := 0;
  FloatAnimation1.Duration := 0.1;
  FloatAnimation1.Interpolation := TInterpolationType.Linear;
  FloatAnimation1.Inverse := FalsE;
  FloatAnimation1.Loop := False;
  FloatAnimation1.PropertyName := 'RotationAngle.Y';
  FloatAnimation1.StartFromCurrent := True;
  FloatAnimation1.StartValue := 0;
  FloatAnimation1.StopValue := 360;
end;

procedure TForm1.Form3DKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
begin
  if FloatAnimation1.Running then
    Exit;

  if Key in [vkLeft, vkRight] then
  begin
    FloatAnimation1.AnimateFloat(FloatAnimation1.PropertyName, FloatAnimation1.CurrentTime);
    case Key of
      vkLeft: FloatAnimation1.StopValue := Cube1.RotationAngle.Y + 10;
      vkRight: FloatAnimation1.StopValue := Cube1.RotationAngle.Y - 10;
    end;

    FloatAnimation1.Start;
  end;
end;

procedure TForm1.Form3DKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
begin
  if (Key in [vkLeft, vkRight]) and (FloatAnimation1.Running) then
    FloatAnimation1.StopAtCurrent;
end;

end.

En este caso al presionar las teclas izquierda/derecha el cubo rota en la direccion indicada. Al soltar la tecla el cubo se detiene. No hace falta usar timer, de hecho las animaciones crean su propio thread para animar el objeto