diff --git a/src/frames/pieces/front-or-back.scad b/src/frames/pieces/front-or-back.scad
index b37d9b2..02d4a0f 100644
--- a/src/frames/pieces/front-or-back.scad
+++ b/src/frames/pieces/front-or-back.scad
@@ -14,10 +14,8 @@ module front_or_back_frame_piece() {
 		left_frame();
 		difference() {
 			// include the whole bottom wall (including mount columns)
-			translate([0, -(frame_y/2)+(piece_width/2), 0]) cube([frame_x, piece_width, frame_z], center=true);
-			// ...minus the frame wall and lip on the left
-			translate([-frame_x/2+frame_wall/2, 0, 0])
-				cube([frame_wall, frame_y, frame_z], center=true);
+			translate([0, -(frame_y/2)+(piece_width/2), 0])
+				cube([frame_piece_x_x, piece_width, frame_z], center=true);
 			// ...minus a slot for the combining piece to go into
 			cube([frame_x, frame_y-(panel_support_width+frame_wall)*2, inner_frame_z/3], center=true);
 		}
diff --git a/src/parameters.scad b/src/parameters.scad
index 22bcda2..4463636 100644
--- a/src/parameters.scad
+++ b/src/parameters.scad
@@ -64,6 +64,9 @@ panel_x = frame_x - (frame_wall * 2);
 panel_y = frame_y - (frame_wall * 2);
 panel_z = 5;
 
+// some dimensions for frame pieces, useful in doing some intersections and chopping
+frame_piece_x_x = frame_x - (frame_wall * 2);	// essentially panel_x, yes
+
 // degree to which the extended frame pieces stick out from the end of the frame
 frame_extension_x = 25;
 frame_extension_y = 25;