topeak-mtx-tortec-expeditionrack-adapter: fix elevation

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/topeak-mtx-tortec-expeditionrack-adapter.scad b/topeak-mtx-tortec-expeditionrack-adapter.scad
index 6a4fc26d75ded92332100ce37623a5acfac38964..93f3ec1694c276c749fee1b755544264059a1716 100644 (file)
--- a/topeak-mtx-tortec-expeditionrack-adapter.scad
+++ b/topeak-mtx-tortec-expeditionrack-adapter.scad
@@ -92,7 +92,7 @@ brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
 
 function elevation_of_bolt_for(z) = rear_elevation_nominal
-  - (z - brk_block_z/2) * rack_shear_ratio;
+  + (z - brk_block_z/2) * rack_shear_ratio;
 
 function rack_rail_y_of_elevation(elevation_nominal) =
   brk_bottom_y - elevation_nominal - general_gap_y  - rack_rail_dia/2;