diff --git a/Drive-Overview.md b/Drive-Overview.md
index 13d3e73..66d5558 100644
--- a/Drive-Overview.md
+++ b/Drive-Overview.md
@@ -1,2 +1,5 @@
 # 3 Axis Setup
 At purchase the CM-MiniCNC was setup for 3 axis with CW-5045 Stepper Drivers and [????]Motors.
+
+# Ball Screws
+TODO: measure ball screws
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