diff --git a/apps/catalog/app/shared/fusion-library.test.ts b/apps/catalog/app/shared/fusion-library.test.ts
index ae5607d..8cc3f0c 100644
--- a/apps/catalog/app/shared/fusion-library.test.ts
+++ b/apps/catalog/app/shared/fusion-library.test.ts
@@ -19,14 +19,16 @@ const tool = (over: Partial<CatalogTool> = {}): CatalogTool =>
 const holder = {
   guid: '973eaa5d-4474-46c8-aaac-d89dcefcaa0f',
   brand: 'Kennametal',
-  catalogNumber: 'BT30ER16060M',
-  noseDiameter: 28,
-  noseLength: 20,
-  bodyDiameter: 34,
-  bodyLength: 15,
+  catalogNumber: 'BT 30 / PG 6 x 050',
+  // REGO-FIX's BT30 B4 gage length includes the 48.4 mm spindle-side taper.
+  // Fusion's holder gage is the sum of the below-spindle segments (B3).
+  gaugeLength: 98.4,
+  noseDiameter: 10,
+  noseLength: 10.55,
+  bodyDiameter: 12.02,
+  bodyLength: 9.6,
   flangeDiameter: 46,
-  projection: 60,
-  gaugeLength: 44,
+  projection: 50,
 } as unknown as Holder
 
 const ids = (): (() => string) => {
@@ -49,17 +51,17 @@ describe('the order list as a Fusion library', () => {
       CSP: false,
       HAND: true,
       LB: 31,
-      assemblyGaugeLength: 75,
+      assemblyGaugeLength: 81,
       'shoulder-length': 19,
       'shoulder-diameter': 8,
     })
     expect(first.holder).toMatchObject({
       type: 'holder',
-      gaugeLength: 44,
+      gaugeLength: 50,
       segments: [
-        { height: 20, 'lower-diameter': 28, 'upper-diameter': 28 },
-        { height: 15, 'lower-diameter': 34, 'upper-diameter': 34 },
-        { height: 25, 'lower-diameter': 46, 'upper-diameter': 46 },
+        { height: 10.55, 'lower-diameter': 10, 'upper-diameter': 10 },
+        { height: 9.6, 'lower-diameter': 12.02, 'upper-diameter': 12.02 },
+        { height: 29.85, 'lower-diameter': 46, 'upper-diameter': 46 },
       ],
     })
     expect(first['start-values'].presets).toHaveLength(3)
@@ -171,6 +173,7 @@ describe('the order list as a Fusion library', () => {
 
     expect(result.library.data).toHaveLength(1)
     expect(result.library.data[0]?.holder).toBeUndefined()
+    expect(result.library.data[0]?.geometry.assemblyGaugeLength).toBe(27)
     expect(result.holderWarnings[0]?.reason).toContain('no complete published Fusion shape')
   })
 })
diff --git a/apps/catalog/app/shared/fusion-library.ts b/apps/catalog/app/shared/fusion-library.ts
index daf5795..3728d58 100644
--- a/apps/catalog/app/shared/fusion-library.ts
+++ b/apps/catalog/app/shared/fusion-library.ts
@@ -131,7 +131,10 @@ const missingGeometry = (tool: CatalogTool): Array<string> => {
   return codes.filter((code) => !validNumber(tool.geometry[code]))
 }
 
-const geometryOf = (line: LibraryLine): Record<string, number | boolean> => {
+const geometryOf = (
+  line: LibraryLine,
+  holderGaugeLength: number,
+): Record<string, number | boolean> => {
   const { tool } = line
   const setout = line.stickout ?? tool.geometry.LBH
   const geometry: Record<string, number | boolean> = {
@@ -145,7 +148,7 @@ const geometryOf = (line: LibraryLine): Record<string, number | boolean> => {
     LB: setout!,
     'shoulder-length': tool.geometry['shoulder-length'] ?? tool.geometry.LCF!,
     'shoulder-diameter': tool.geometry['shoulder-diameter'] ?? tool.geometry.SFDM!,
-    assemblyGaugeLength: setout! + (line.holder?.gaugeLength ?? 0),
+    assemblyGaugeLength: setout! + holderGaugeLength,
   }
   for (const code of ['RE', 'SIG', 'TA', 'TP', 'TPX', 'TPN', 'NT', 'tip-diameter'] as const) {
     const value = tool.geometry[code]
@@ -161,9 +164,13 @@ const geometryOf = (line: LibraryLine): Record<string, number | boolean> => {
 
 const holderOf = (holder: Holder, nextGuid: () => string): FusionHolder | null => {
   const segments = segmentsOf(holder)
-  if (segments.length === 0 || !validNumber(holder.gaugeLength)) {
+  if (segments.length === 0) {
     return null
   }
+  // Fusion measures a holder from the sum of the geometry it receives. The
+  // catalog's gaugeLength can include the spindle-side taper (BT30 B4 does),
+  // which this deliberately below-spindle silhouette does not export.
+  const gaugeLength = segments.reduce((total, segment) => total + segment.height, 0)
   return {
     guid: nextGuid(),
     type: 'holder',
@@ -171,7 +178,7 @@ const holderOf = (holder: Holder, nextGuid: () => string): FusionHolder | null =
     description: `${holder.brand} ${holder.catalogNumber}`,
     vendor: holder.brand,
     'product-id': holder.catalogNumber,
-    gaugeLength: holder.gaugeLength,
+    gaugeLength,
     segments,
   }
 }
@@ -249,7 +256,7 @@ export const fusionLibrary = (
       'product-id': line.tool.catalogNumber,
       ...(line.tool.productLink === null ? {} : { 'product-link': line.tool.productLink }),
       description: `${line.tool.brand} ${line.tool.catalogNumber}`,
-      geometry: geometryOf(line),
+      geometry: geometryOf(line, holder?.gaugeLength ?? 0),
       ...(holder === null ? {} : { holder }),
       'post-process': {
         number: at,