From 3252d53c5574ba261d44abbff10ddc1c7f024c35 Mon Sep 17 00:00:00 2001
From: Sam Hadow <sam.hadow@inbox.lv>
Date: Thu, 22 Jan 2026 22:28:52 +0100
Subject: [PATCH] BTT belter

---
 README.md                    |  5 ++++-
 belter_tension_calculator.sh | 42 ++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100755 belter_tension_calculator.sh

diff --git a/README.md b/README.md
index 6a7caaa..28e72dc 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,9 @@
 
 My collection of useful shell scripts.
 
+### belter_tension_calculator.sh
+script to calculate the tension with the readings from [BigTreeTech belter tool](https://bttwiki.com/belter.html) in mm, formula from the xlsx on their [git](https://github.com/bigtreetech/Belter-belt-tension-Tool).
+
 ### randint.sh 
 usage: randint \<positive integer\>   
 print in the terminal a random integer x with $` 0 \leq x \leq \$1`$
@@ -42,4 +45,4 @@ Automatically toggle DNS leak protection for wireguard connections with nftables
 Adds tcp/udp rules to block outgoing traffic to dns port (53) if the outgoing interface isn't the wireguard connection.   
 It assumes wireguard connection names start with "wg-"  
   
-  You can check for DNS leaks with [this website](https://www.dnsleaktest.com/)
\ No newline at end of file
+  You can check for DNS leaks with [this website](https://www.dnsleaktest.com/)
diff --git a/belter_tension_calculator.sh b/belter_tension_calculator.sh
new file mode 100755
index 0000000..72c3fa1
--- /dev/null
+++ b/belter_tension_calculator.sh
@@ -0,0 +1,42 @@
+#!/bin/bash
+if ! [[ "$1" =~ ^-?[0-9](\.[0-9]+)?+$ ]]; then
+    echo "Usage: $0 <Belter display value (mm)>"
+    exit 1
+fi
+
+echo "Belter display value: $1mm"
+
+tension=$(awk -v x="$1" 'BEGIN {
+    if (x < 0) x = -x
+    printf "%.3f", 7.673640167 * x - 33.7167364
+}')
+
+echo "Belt tension: $tension N"
+echo ""
+
+ESC=$'\033'
+GREEN="${ESC}[32m"
+RED="${ESC}[31m"
+RESET="${ESC}[0m"
+
+check_range() {
+    local label="$1"
+    local min="$2"
+    local max="$3"
+
+    awk -v t="$tension" -v min="$min" -v max="$max" \
+        -v label="$label" -v G="$GREEN" -v R="$RED" -v Z="$RESET" '
+    BEGIN {
+        if (t >= min && t <= max)
+            printf "%s 🟩  %s[%.1f, %.1f] N%s\n", label, G, min, max, Z
+        else
+            printf "%s 🟥  %s[%.1f, %.1f] N%s\n", label, R, min, max, Z
+    }'
+}
+
+echo "Reference tensions:"
+check_range "Voron A/B belts    :" 7.8 15
+check_range "Voron 2.4 Z belts  :" 20.4 25.8
+check_range "V350/250 belts     :" 12 20
+check_range "GT2 belts          :" 20 30
+