[Fix]: Weight fix for determine spoolers speed (#454)

Addresses a bug that caused spoolers to operate at super-fast speeds when the weight fell below the empty spool threshold and ensures that weight does not drop below zero during printing

Author: jimmyjon711

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [2025-06-16]
+### Fixed
+- Issue where espoolers would move way faster than normal when weight was below empty spool weight.
+
 ## [2025-06-15]
 ### Added
 - Added support for the AFC-Pro board in the installer to install an 8-Lane Boxturtle.

extras/AFC_lane.py

@@ -676,11 +676,11 @@ def calculate_rpm(self, feed_rate):
         :param feed_rate: Filament feed rate in mm/s
         :return: Calculated RPM for the assist motor
         """
-        if self.weight <= self.empty_spool_weight:
-            return self.empty_spool_weight  # No filament left to assist
+        # Figure in weight of empty spool
+        weight = self.weight + self.empty_spool_weight
 
         # Calculate the effective diameter
-        effective_diameter = self.calculate_effective_diameter(self.weight)
+        effective_diameter = self.calculate_effective_diameter(weight)
 
         # Calculate RPM
         rpm = (feed_rate * 60) / (math.pi * effective_diameter)
@@ -757,8 +757,9 @@ def update_remaining_weight(self, distance_moved):
         filament_weight_change = filament_volume_mm3 * self.filament_density / 1000  # Convert mm cubed to g
         self.weight -= filament_weight_change
 
-        if self.weight < self.empty_spool_weight:
-            self.weight = self.empty_spool_weight  # Ensure weight doesn't drop below empty spool weight
+        # Weight cannot be negative, force back to zero if it's below zero
+        if self.weight < 0:
+            self.weight = 0
 
     def set_loaded(self):
         """