diff --git a/.gitignore b/.gitignore
index 95228f92..cafa4e3c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,4 +7,5 @@ embedded/dist
 *~
 .pio/
 .vscode/
-.history/
\ No newline at end of file
+.history/
+*.pyc
diff --git a/Grbl_Esp32/atari_1020.cpp b/Grbl_Esp32/Custom/atari_1020.cpp
similarity index 98%
rename from Grbl_Esp32/atari_1020.cpp
rename to Grbl_Esp32/Custom/atari_1020.cpp
index 342d73c6..a68080b0 100644
--- a/Grbl_Esp32/atari_1020.cpp
+++ b/Grbl_Esp32/Custom/atari_1020.cpp
@@ -23,9 +23,10 @@
  	This contains all the special features required to control an 
 	Atari 1010 Pen Plotter	
 */
-#include "grbl.h"
 
-#ifdef ATARI_1020
+// This file is enabled by defining CUSTOM_CODE_FILENAME "atari_1020.cpp"
+// in Machines/atari_1020.h, thus causing this file to be included
+// from ../custom_code.cpp
 
 #define HOMING_PHASE_FULL_APPROACH	0 // move to right end
 #define HOMING_PHASE_CHECK			1 // check reed switch
@@ -319,6 +320,3 @@ void user_m30() {
 	sprintf(gcode_line, "G90G0X%3.2f\r", ATARI_PAPER_WIDTH); // 
 	inputBuffer.push(gcode_line);
 }
-
-#endif
-
diff --git a/Grbl_Esp32/custom_code_template.cpp b/Grbl_Esp32/Custom/custom_code_template.cpp
similarity index 93%
rename from Grbl_Esp32/custom_code_template.cpp
rename to Grbl_Esp32/Custom/custom_code_template.cpp
index cd5b197f..89ae015d 100644
--- a/Grbl_Esp32/custom_code_template.cpp
+++ b/Grbl_Esp32/Custom/custom_code_template.cpp
@@ -30,7 +30,7 @@ Machines/template.h to a similar name.
 
 Example:
 Machines/my_machine.h
-my_machine.cpp
+Custom/my_machine.cpp
 
 Edit machine.h to include your Machines/my_machine.h file
 
@@ -43,14 +43,6 @@ enabled with USE_ defines in Machines/my_machine.h
 
 */
 
-// It is necessary to include grbl.h so that the machine definitions
-// will be loaded before the remainder of this file is processed.
-#include "grbl.h"
-
-// !!! Change this to the MACHINE_name you chose in Machines/my_machine.h
-// The compiler will skip the rest of this file unless that name is defined
-#ifdef MACHINE_CUSTOM
-
 #ifdef USE_MACHINE_INIT
 /*
 machine_init() is called when Grbl_ESP32 first starts. You can use it to do any
@@ -173,6 +165,3 @@ void machine_trinamic_setup() {
 // If you add any additional functions specific to your machine that
 // require calls from common code, guard their calls in the common code with
 // #ifdef USE_WHATEVER and add function prototypes (also guarded) to grbl.h
-
-
-#endif
diff --git a/Grbl_Esp32/polar_coaster.cpp b/Grbl_Esp32/Custom/polar_coaster.cpp
similarity index 97%
rename from Grbl_Esp32/polar_coaster.cpp
rename to Grbl_Esp32/Custom/polar_coaster.cpp
index f7aa3414..6387fbba 100644
--- a/Grbl_Esp32/polar_coaster.cpp
+++ b/Grbl_Esp32/Custom/polar_coaster.cpp
@@ -28,7 +28,7 @@
 	How it works...
 
 	If you tell it to go to X10 Y10 Z10 in Cartesian space, for example, the equations
-  will convert those values to the required joint values. In the case of a polar machine, X represents the radius,
+	will convert those values to the required joint values. In the case of a polar machine, X represents the radius,
 	Y represents the polar degrees and Z would be unchanged.
 
 	In most cases, a straight line in Cartesian space could cause a curve in the new system.
@@ -50,10 +50,9 @@
 
 */
 
-#include "grbl.h"
-
-#ifdef MACHINE_POLAR_COASTER
-#ifdef USE_KINEMATICS
+// This file is enabled by defining CUSTOM_CODE_FILENAME "polar_coaster.cpp"
+// in Machines/polar_coaster.h, thus causing this file to be included
+// from ../custom_code.cpp
 
 void calc_polar(float *target_xyz, float *polar, float last_angle);
 float abs_angle(float ang);
@@ -175,7 +174,6 @@ void inverse_kinematics(float *target, plan_line_data_t *pl_data, float *positio
 	// TO DO don't need a feedrate for rapids
 }
 
-
 /*
 Forward kinematics converts position back to the original cartesian system. It is
 typically used for reporting
@@ -264,8 +262,6 @@ float abs_angle(float ang) {
 	return ang;
 }
 
-#endif
-
 // Polar coaster has macro buttons, this handles those button pushes.
 void user_defined_macro(uint8_t index)
 {	
@@ -298,6 +294,3 @@ void user_defined_macro(uint8_t index)
 void user_m30() {
 	inputBuffer.push("$H\r");
 }
-
-#endif
-
diff --git a/Grbl_Esp32/Machines/atari_1020.h b/Grbl_Esp32/Machines/atari_1020.h
index 328283b0..19bfa128 100644
--- a/Grbl_Esp32/Machines/atari_1020.h
+++ b/Grbl_Esp32/Machines/atari_1020.h
@@ -9,6 +9,8 @@
 
 #define MACHINE_NAME "MACHINE_ATARI_1020"
 
+#define CUSTOM_CODE_FILENAME "Custom/atari_1020.cpp"
+
 #ifdef USE_RMT_STEPS
         #undef USE_RMT_STEPS
 #endif
diff --git a/Grbl_Esp32/Machines/polar_coaster.h b/Grbl_Esp32/Machines/polar_coaster.h
index ad667100..b7485ac9 100644
--- a/Grbl_Esp32/Machines/polar_coaster.h
+++ b/Grbl_Esp32/Machines/polar_coaster.h
@@ -3,8 +3,9 @@
 
 #define MACHINE_NAME "MACHINE_POLAR_COASTER"
 
-// This must be defined so that polar_coaster.cpp is not skipped
-#define MACHINE_POLAR_COASTER
+// This causes the custom code file to be included in the build
+// via ../custom_code.cpp
+#define CUSTOM_CODE_FILENAME "Custom/polar_coaster.cpp"
 
 #define RADIUS_AXIS 0
 #define POLAR_AXIS 1
diff --git a/Grbl_Esp32/Machines/template.h b/Grbl_Esp32/Machines/template.h
index 11f8acf3..885c3d89 100644
--- a/Grbl_Esp32/Machines/template.h
+++ b/Grbl_Esp32/Machines/template.h
@@ -34,14 +34,16 @@
 // === Machine Name
 // Change TEMPLATE to some name of your own choosing.  That name
 // will be shown in a Grbl startup message to identify your
-// configuration.  If you need to implement custom code functions
-// as in custom_code_template.cpp, the beginning #ifdef in
-// your custom .cpp file must match your chosen MACHINE_name ,
-// so as to enable the compilation of your file and suppress
-// compilation of other custom .cpp files.
+// configuration.
 
 #define MACHINE_NAME            "MACHINE_TEMPLATE"
 
+// If your machine requires custom code as described below in
+// Special Features, you must copy Custom/custom_code_template.cpp
+// to a new name like Custom/my_custom_code.cpp, implement the
+// functions therein, and enable its use by defining:
+// #define CUSTOM_CODE_FILENAME "Custom/my_custom_code.cpp"
+
 // === Number of axes
 
 // You can set the number of axes that the machine supports
diff --git a/Grbl_Esp32/custom_code.cpp b/Grbl_Esp32/custom_code.cpp
new file mode 100644
index 00000000..1e400f9d
--- /dev/null
+++ b/Grbl_Esp32/custom_code.cpp
@@ -0,0 +1,8 @@
+// This file loads custom code from the Custom/ subdirectory if
+// CUSTOM_CODE_FILENAME is defined.
+
+#include "grbl.h"
+
+#ifdef CUSTOM_CODE_FILENAME
+   #include CUSTOM_CODE_FILENAME
+#endif
diff --git a/build-all.py b/build-all.py
index af19788d..502ed8d5 100644
--- a/build-all.py
+++ b/build-all.py
@@ -1,5 +1,10 @@
 #!/usr/bin/env python2
 
+# Note: If you experience random errors running this script within
+# VSCode, try running it from a regular terminal window.  Some VSCode
+# extensions seem to randomly interfere with the files that platformio
+# uses during compilation.
+
 # Compile Grbl_ESP32 for each of the machines defined in Machines/ .
 # Add-on files are built on top of a single base.
 # This is useful for automated testing, to make sure you haven't broken something
@@ -9,31 +14,16 @@
 # contain the word "error".  If you need to see everything, for example to
 # see the details of an errored build, include -v on the command line.
 
-from __future__ import print_function
-import os, subprocess, sys
+from builder import buildMachine
+import os, sys
+
+cmd = ['platformio','run']
 
-env = dict(os.environ)
 verbose = '-v' in sys.argv
 
-def buildMachine(baseName, addName=None):
-    displayName = baseName
-    flags = '-DMACHINE_FILENAME=' + baseName
-    if addName:
-        displayName += ' + ' + addName
-        flags += ' -DMACHINE_FILENAME2=' + addName
-    print('Building machine ' + displayName)
-    env['PLATFORMIO_BUILD_FLAGS'] = flags
-    app = subprocess.Popen(['platformio','run'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, bufsize=1, env=env)
-    for line in app.stdout:
-        if verbose or "Took" in line or "error" in line.lower():
-            print(line, end='')
-    print()
-
 adderBase = '3axis_v4.h'
 for name in os.listdir('Grbl_Esp32/Machines'):
     if name.startswith('add_'):
-        buildMachine(adderBase, name)
+        buildMachine(adderBase, addName=name, verbose=verbose)
     else:
-        buildMachine(name)
-
-
+        buildMachine(name, verbose=verbose)
diff --git a/build-machine.py b/build-machine.py
index 7e7d6e62..cb668d91 100644
--- a/build-machine.py
+++ b/build-machine.py
@@ -1,18 +1,20 @@
 #!/usr/bin/env python2
 
-# Compile Grbl_ESP32 for the machine listed on the command line, as in
-#  ./build-machine.py 3xis_v4.h
+# Compile Grbl_ESP32 for each of the machines defined in Machines/ .
+# Add-on files are built on top of a single base.
+# This is useful for automated testing, to make sure you haven't broken something
 
-# Add-ons can be built by listing both the base name and the adder, as in
-#   ./build-machine.py 3axis_v4.h add_esc_spindle.h
-
-#  -q suppresses most messages
-#  -u uploads the firmware to the target machine
+# The output is filtered so that the only lines you see are a single
+# success or failure line for each build, plus any preceding lines that
+# contain the word "error".  If you need to see everything, for example to
+# see the details of an errored build, include -v on the command line.
 
 from __future__ import print_function
-import os, subprocess, sys
+from builder import buildMachine
+import os, sys
+
+extraArgs=None
 
-cmd=['platformio','run']
 verbose = '-v' in sys.argv or '-q' not in sys.argv
 if '-v' in sys.argv:
     sys.argv.remove('-v')
@@ -20,32 +22,14 @@ if '-q' in sys.argv:
     sys.argv.remove('-q')
 if '-u' in sys.argv:
     sys.argv.remove('-u')
-    cmd.append('--target=upload')
-
-env = dict(os.environ)
-
-def buildMachine(baseName, addName=None):
-    displayName = baseName
-    flags = '-DMACHINE_FILENAME=' + baseName
-    if addName:
-        displayName += ' + ' + addName
-        flags += ' -DMACHINE_FILENAME2=' + addName
-    print('Building machine ' + displayName)
-    env['PLATFORMIO_BUILD_FLAGS'] = flags
-    if verbose:
-        subprocess.Popen(cmd, env=env).wait()
-    else:
-        app = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, bufsize=1, env=env)
-        for line in app.stdout:
-            if "Took" in line or 'Uploading' in line or "error" in line.lower():
-                print(line, end='')
+    extraArgs = '--target=upload'
 
 if len(sys.argv) == 2:
-    buildMachine(sys.argv[1], None)
+    buildMachine(sys.argv[1], addName=None, verbose=verbose, extraArgs=extraArgs)
 elif len(sys.argv) == 3:
-    buildMachine(sys.argv[1], sys.argv[2])
+    buildMachine(sys.argv[1], addName=sys.argv[2], verbose=verbose, extraArgs=extraArgs)
 else:
     print("Usage: ./build-machine.py [-q] [-u] machine_name.h [add_name.h]")
     print(' Build for the given machine and optional add-on regardless of machine.h')
     print('  -q suppresses most messages')
-    print('  -u uploads to the target after compilation')
\ No newline at end of file
+    print('  -u uploads to the target after compilation')
diff --git a/builder.py b/builder.py
new file mode 100644
index 00000000..d9b09780
--- /dev/null
+++ b/builder.py
@@ -0,0 +1,32 @@
+# This script is imported by build-machine.py and build-all.py
+# It performs a platformio build with a given base machine file
+# and an optional add-on file.  The verbose argument controls
+# whether the full output is displayed, or filtered to show
+# only summary information.  extraArgs can be used to perform
+# uploading after compilation.
+
+from __future__ import print_function
+import subprocess, os
+
+env = dict(os.environ)
+
+def buildMachine(baseName, addName=None, verbose=True, extraArgs=None):
+    cmd = ['platformio','run']
+    if extraArgs:
+        cmd.append(extraArgs)
+    displayName = baseName
+    flags = '-DMACHINE_FILENAME=' + baseName
+    if addName:
+        displayName += ' + ' + addName
+        flags += ' -DMACHINE_FILENAME2=' + addName
+    print('Building machine ' + displayName)
+    env['PLATFORMIO_BUILD_FLAGS'] = flags
+    if verbose:
+        app = subprocess.Popen(cmd, env=env)
+    else:
+        app = subprocess.Popen(cmd, env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, bufsize=1)
+        for line in app.stdout:
+            if "Took" in line or 'Uploading' in line or "error" in line.lower():
+                print(line, end='')
+    app.wait()
+    print()
diff --git a/platformio.ini b/platformio.ini
index 2ec4ff08..8b638982 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -28,4 +28,5 @@ framework = arduino
 upload_speed = 512000
 board_build.partitions = min_spiffs.csv
 monitor_speed = 115200
-build_flags = -DCORE_DEBUG_LEVEL=0
+build_flags = -DCORE_DEBUG_LEVEL=0 -Wno-unused-variable -Wno-unused-function
+src_filter = +<*.h> +<*.s> +<*.S> +<*.cpp> +<*.c> +<*.ino> +<src/> -<.git/> -<data/> -<test/> -<tests/> -<Custom/>