diff --git a/blinky/src/main.rs b/blinky/src/main.rs
index b8c62fd..1acdbaa 100644
--- a/blinky/src/main.rs
+++ b/blinky/src/main.rs
@@ -21,6 +21,15 @@ use stm32f7xx_hal::{pac, prelude::*};
 
 use blinky::init_heap;
 
+const TICK_TIMER_HZ: u32 = 1_000_000;
+const RUN_COMMANDS_COUNT: usize = 6;
+const START_COMMANDS_COUNT: usize = 0;
+const STOP_COMMANDS_COUNT: usize = 0;
+const LEDS_COUNT: usize = 4;
+const AXES_COUNT: usize = 2;
+const SPINDLES_COUNT: usize = 2;
+const ACTIVE_COMMANDS_COUNT: usize = 1;
+
 pub fn get_run_commands<const TIMER_HZ: u32>() -> [Command<'static, TIMER_HZ>; 6] {
     [
         Command::Led(
@@ -83,7 +92,17 @@ fn main() -> ! {
     let user_button_timer = super_timer.sub();
     let mut user_button = SwitchDevice::new_active_high(user_button_pin, user_button_timer);
 
-    let mut robot_builder = RobotBuilder::new();
+    let mut robot_builder: RobotBuilder<
+        '_,
+        TICK_TIMER_HZ,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+        LEDS_COUNT,
+        AXES_COUNT,
+        SPINDLES_COUNT,
+        ACTIVE_COMMANDS_COUNT,
+    > = RobotBuilder::new();
 
     let green_led_pin = gpiob.pb0.into_push_pull_output();
     let green_led_timer = super_timer.sub();
diff --git a/gridbot-tahi/src/main.rs b/gridbot-tahi/src/main.rs
index 1320f0a..5bd4d22 100644
--- a/gridbot-tahi/src/main.rs
+++ b/gridbot-tahi/src/main.rs
@@ -36,6 +36,14 @@ use gridbot_tahi::{
     init_heap,
 };
 
+const RUN_COMMANDS_COUNT: usize = 32;
+const START_COMMANDS_COUNT: usize = 4;
+const STOP_COMMANDS_COUNT: usize = 4;
+const LEDS_COUNT: usize = 4;
+const AXES_COUNT: usize = 4;
+const SPINDLES_COUNT: usize = 4;
+const ACTIVE_COMMANDS_COUNT: usize = 8;
+
 const TICK_TIMER_MAX: u32 = u32::MAX;
 const TICK_TIMER_HZ: u32 = 1_000_000;
 type TickTimerDevice = Counter<pac::TIM5, TICK_TIMER_HZ>;
@@ -103,7 +111,17 @@ fn main() -> ! {
     let mut user_button: UserButton =
         SwitchDevice::new_active_high(user_button_pin, user_button_timer);
 
-    let mut robot_builder: RobotBuilder<TICK_TIMER_HZ> = RobotBuilder::new();
+    let mut robot_builder: RobotBuilder<
+        '_,
+        TICK_TIMER_HZ,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+        LEDS_COUNT,
+        AXES_COUNT,
+        SPINDLES_COUNT,
+        ACTIVE_COMMANDS_COUNT,
+    > = RobotBuilder::new();
 
     let green_led_pin: GreenLedPin = gpiob.pb0.into_push_pull_output();
     let green_led_timer: GreenLedTimer = super_timer.sub();
diff --git a/robokit/src/robot.rs b/robokit/src/robot.rs
index 99882ef..5f0bd1b 100644
--- a/robokit/src/robot.rs
+++ b/robokit/src/robot.rs
@@ -10,17 +10,43 @@ use crate::error::Error;
 use crate::runner::{Command, Runner};
 use crate::scheduler::Scheduler;
 
-pub struct RobotBuilder<'a, const LED_TIMER_HZ: u32> {
-    run_commands: Vec<Command<'a, LED_TIMER_HZ>, 32>,
-    start_commands: Vec<Command<'a, LED_TIMER_HZ>, 4>,
-    stop_commands: Vec<Command<'a, LED_TIMER_HZ>, 4>,
-    leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, 16>,
-    axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, 16>,
-    spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, 16>,
+pub struct RobotBuilder<
+    'a,
+    const LED_TIMER_HZ: u32,
+    const RUN_COMMANDS_COUNT: usize,
+    const START_COMMANDS_COUNT: usize,
+    const STOP_COMMANDS_COUNT: usize,
+    const LEDS_COUNT: usize,
+    const AXES_COUNT: usize,
+    const SPINDLES_COUNT: usize,
+    const ACTIVE_COMMANDS_COUNT: usize,
+> {
+    run_commands: Vec<Command<'a, LED_TIMER_HZ>, RUN_COMMANDS_COUNT>,
+    start_commands: Vec<Command<'a, LED_TIMER_HZ>, START_COMMANDS_COUNT>,
+    stop_commands: Vec<Command<'a, LED_TIMER_HZ>, STOP_COMMANDS_COUNT>,
+    leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, LEDS_COUNT>,
+    axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, AXES_COUNT>,
+    spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, SPINDLES_COUNT>,
 }
 
-pub struct Robot<'a, const LED_TIMER_HZ: u32> {
-    scheduler: Scheduler<Command<'a, LED_TIMER_HZ>, Runner<'a, LED_TIMER_HZ>>,
+pub struct Robot<
+    'a,
+    const LED_TIMER_HZ: u32,
+    const RUN_COMMANDS_COUNT: usize,
+    const START_COMMANDS_COUNT: usize,
+    const STOP_COMMANDS_COUNT: usize,
+    const LEDS_COUNT: usize,
+    const AXES_COUNT: usize,
+    const SPINDLES_COUNT: usize,
+    const ACTIVE_COMMANDS_COUNT: usize,
+> {
+    scheduler: Scheduler<
+        Command<'a, LED_TIMER_HZ>,
+        Runner<'a, LED_TIMER_HZ, LEDS_COUNT, AXES_COUNT, SPINDLES_COUNT, ACTIVE_COMMANDS_COUNT>,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+    >,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -33,7 +59,29 @@ pub enum RobotBuilderError {
     TooManyStopCommands,
 }
 
-impl<'a, const LED_TIMER_HZ: u32> RobotBuilder<'a, LED_TIMER_HZ> {
+impl<
+        'a,
+        const LED_TIMER_HZ: u32,
+        const RUN_COMMANDS_COUNT: usize,
+        const START_COMMANDS_COUNT: usize,
+        const STOP_COMMANDS_COUNT: usize,
+        const LEDS_COUNT: usize,
+        const AXES_COUNT: usize,
+        const SPINDLES_COUNT: usize,
+        const ACTIVE_COMMANDS_COUNT: usize,
+    >
+    RobotBuilder<
+        'a,
+        LED_TIMER_HZ,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+        LEDS_COUNT,
+        AXES_COUNT,
+        SPINDLES_COUNT,
+        ACTIVE_COMMANDS_COUNT,
+    >
+{
     pub fn new() -> Self {
         Self {
             run_commands: Vec::new(),
@@ -111,7 +159,19 @@ impl<'a, const LED_TIMER_HZ: u32> RobotBuilder<'a, LED_TIMER_HZ> {
         Ok(())
     }
 
-    pub fn build(self) -> Robot<'a, LED_TIMER_HZ> {
+    pub fn build(
+        self,
+    ) -> Robot<
+        'a,
+        LED_TIMER_HZ,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+        LEDS_COUNT,
+        AXES_COUNT,
+        SPINDLES_COUNT,
+        ACTIVE_COMMANDS_COUNT,
+    > {
         let runner = Runner::new(self.leds, self.axes, self.spindles);
         let scheduler = Scheduler::new(
             runner,
@@ -123,8 +183,38 @@ impl<'a, const LED_TIMER_HZ: u32> RobotBuilder<'a, LED_TIMER_HZ> {
     }
 }
 
-impl<'a, const LED_TIMER_HZ: u32> Robot<'a, LED_TIMER_HZ> {
-    pub fn new(scheduler: Scheduler<Command<'a, LED_TIMER_HZ>, Runner<'a, LED_TIMER_HZ>>) -> Self {
+impl<
+        'a,
+        const LED_TIMER_HZ: u32,
+        const RUN_COMMANDS_COUNT: usize,
+        const START_COMMANDS_COUNT: usize,
+        const STOP_COMMANDS_COUNT: usize,
+        const LEDS_COUNT: usize,
+        const AXES_COUNT: usize,
+        const SPINDLES_COUNT: usize,
+        const ACTIVE_COMMANDS_COUNT: usize,
+    >
+    Robot<
+        'a,
+        LED_TIMER_HZ,
+        RUN_COMMANDS_COUNT,
+        START_COMMANDS_COUNT,
+        STOP_COMMANDS_COUNT,
+        LEDS_COUNT,
+        AXES_COUNT,
+        SPINDLES_COUNT,
+        ACTIVE_COMMANDS_COUNT,
+    >
+{
+    pub fn new(
+        scheduler: Scheduler<
+            Command<'a, LED_TIMER_HZ>,
+            Runner<'a, LED_TIMER_HZ, LEDS_COUNT, AXES_COUNT, SPINDLES_COUNT, ACTIVE_COMMANDS_COUNT>,
+            RUN_COMMANDS_COUNT,
+            START_COMMANDS_COUNT,
+            STOP_COMMANDS_COUNT,
+        >,
+    ) -> Self {
         Self { scheduler }
     }
 
diff --git a/robokit/src/runner.rs b/robokit/src/runner.rs
index fae4132..46fa1ca 100644
--- a/robokit/src/runner.rs
+++ b/robokit/src/runner.rs
@@ -20,18 +20,33 @@ pub enum RunnerAction<Command> {
     Reset,
 }
 
-pub struct Runner<'a, const LED_TIMER_HZ: u32> {
-    active_commands: Deque<Command<'a, LED_TIMER_HZ>, 8>,
-    leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, 16>,
-    axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, 16>,
-    spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, 16>,
+pub struct Runner<
+    'a,
+    const LED_TIMER_HZ: u32,
+    const LEDS_COUNT: usize,
+    const AXES_COUNT: usize,
+    const SPINDLES_COUNT: usize,
+    const ACTIVE_COMMMANDS_COUNT: usize,
+> {
+    active_commands: Deque<Command<'a, LED_TIMER_HZ>, ACTIVE_COMMMANDS_COUNT>,
+    leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, LEDS_COUNT>,
+    axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, AXES_COUNT>,
+    spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, SPINDLES_COUNT>,
 }
 
-impl<'a, const LED_TIMER_HZ: u32> Runner<'a, LED_TIMER_HZ> {
+impl<
+        'a,
+        const LED_TIMER_HZ: u32,
+        const LEDS_COUNT: usize,
+        const AXES_COUNT: usize,
+        const SPINDLES_COUNT: usize,
+        const ACTIVE_COMMMANDS_COUNT: usize,
+    > Runner<'a, LED_TIMER_HZ, LEDS_COUNT, AXES_COUNT, SPINDLES_COUNT, ACTIVE_COMMMANDS_COUNT>
+{
     pub fn new(
-        leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, 16>,
-        axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, 16>,
-        spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, 16>,
+        leds: FnvIndexMap<&'a str, BoxActuator<LedAction<LED_TIMER_HZ>>, LEDS_COUNT>,
+        axes: FnvIndexMap<&'a str, BoxActuator<AxisAction>, AXES_COUNT>,
+        spindles: FnvIndexMap<&'a str, BoxActuator<SpindleAction>, SPINDLES_COUNT>,
     ) -> Self {
         Self {
             active_commands: Deque::new(),
@@ -50,7 +65,16 @@ pub enum RunnerError<'a> {
 }
 */
 
-impl<'a, const LED_TIMER_HZ: u32> Actuator for Runner<'a, LED_TIMER_HZ> {
+impl<
+        'a,
+        const LED_TIMER_HZ: u32,
+        const LEDS_COUNT: usize,
+        const AXES_COUNT: usize,
+        const SPINDLES_COUNT: usize,
+        const ACTIVE_COMMMANDS_COUNT: usize,
+    > Actuator
+    for Runner<'a, LED_TIMER_HZ, LEDS_COUNT, AXES_COUNT, SPINDLES_COUNT, ACTIVE_COMMMANDS_COUNT>
+{
     type Action = RunnerAction<Command<'a, LED_TIMER_HZ>>;
     type Error = BoxError;
 
diff --git a/robokit/src/scheduler.rs b/robokit/src/scheduler.rs
index 52256b5..c35b373 100644
--- a/robokit/src/scheduler.rs
+++ b/robokit/src/scheduler.rs
@@ -17,18 +17,29 @@ pub enum SchedulerState {
     StopLoop,
 }
 
-pub struct Scheduler<Command, Runner>
-where
+pub struct Scheduler<
+    Command,
+    Runner,
+    const RUN_COMMANDS_COUNT: usize,
+    const START_COMMANDS_COUNT: usize,
+    const STOP_COMMANDS_COUNT: usize,
+> where
     Runner: Actuator<Action = RunnerAction<Command>>,
 {
     runner: Runner,
     state: SchedulerState,
-    run_commands: Vec<Command, 32>,
-    start_commands: Vec<Command, 4>,
-    stop_commands: Vec<Command, 4>,
+    run_commands: Vec<Command, RUN_COMMANDS_COUNT>,
+    start_commands: Vec<Command, START_COMMANDS_COUNT>,
+    stop_commands: Vec<Command, STOP_COMMANDS_COUNT>,
 }
 
-impl<Command, Runner> Scheduler<Command, Runner>
+impl<
+        Command,
+        Runner,
+        const RUN_COMMANDS_COUNT: usize,
+        const START_COMMANDS_COUNT: usize,
+        const STOP_COMMANDS_COUNT: usize,
+    > Scheduler<Command, Runner, RUN_COMMANDS_COUNT, START_COMMANDS_COUNT, STOP_COMMANDS_COUNT>
 where
     Command: Copy + Clone + Debug + Format,
     Runner: Actuator<Action = RunnerAction<Command>>,
@@ -36,9 +47,9 @@ where
 {
     pub fn new(
         runner: Runner,
-        run_commands: Vec<Command, 32>,
-        start_commands: Vec<Command, 4>,
-        stop_commands: Vec<Command, 4>,
+        run_commands: Vec<Command, RUN_COMMANDS_COUNT>,
+        start_commands: Vec<Command, START_COMMANDS_COUNT>,
+        stop_commands: Vec<Command, STOP_COMMANDS_COUNT>,
     ) -> Self {
         Self {
             runner,