diff --git a/resources/views/rd/fire-shutter-drawing/index.blade.php b/resources/views/rd/fire-shutter-drawing/index.blade.php
index d6f57f11..135f1e1d 100644
--- a/resources/views/rd/fire-shutter-drawing/index.blade.php
+++ b/resources/views/rd/fire-shutter-drawing/index.blade.php
@@ -84,7 +84,7 @@
                     <span>면적: <b id="calcArea" class="text-white">7.07</b>m²</span>
                     <span>중량: <b id="calcWeight" class="text-white">176.7</b>kg</span>
                     <span>모터: <b id="calcMotor" class="text-blue-400">300K</b></span>
-                    <span>레일: <b id="calcRailCombo" class="text-amber-400">3,305mm×2</b></span>
+                    <span>레일: <b id="calcRailCombo" class="text-amber-400">3,150mm × 2</b></span>
                 </div>
                 <button onclick="var d=document.getElementById('settingsDetail');d.classList.toggle('hidden');this.querySelector('span').textContent=d.classList.contains('hidden')?'▼':'▲';" class="text-[11px] text-slate-500 hover:text-slate-300 font-bold px-2 py-1 rounded hover:bg-slate-800 transition-colors shrink-0">
                     <span>▼</span>
@@ -487,13 +487,9 @@
         const weight = area * p.weightFactor;
         const motor = MOTORS.find(m => weight <= m.max) || MOTORS[MOTORS.length-1];
 
-        // Guide rail combo
-        let bestCombo = '';
-        const h = S.openHeight;
-        for (const r of RAIL_LENGTHS) {
-            if (r >= h) { bestCombo = `${r.toLocaleString()}mm × 2`; break; }
-        }
-        if (!bestCombo) bestCombo = `${RAIL_LENGTHS[RAIL_LENGTHS.length-1].toLocaleString()}mm × 2 (절단 조합)`;
+        // Guide rail height = 오픈H + 150mm (바닥~셔터박스 하단 결합부)
+        const guideRailH = S.openHeight + 150;
+        const bestCombo = `${guideRailH.toLocaleString()}mm × 2`;
 
         $('calcW1').textContent = W1.toLocaleString();
         $('calcH1').textContent = H1.toLocaleString();
@@ -1642,7 +1638,7 @@ function addPlate(w, h, d, x, y, z) {
 
         // === GUIDE RAILS (ExtrudeGeometry) ===
         const rw = g.width, rd = g.depth, rt = g.thickness;
-        const railHeight = H + 100; // 바닥(0)부터 셔터박스 밑면 +100mm까지 관통
+        const railHeight = H + 150; // 바닥(0)부터 셔터박스 하단 결합부 (+150mm)
         const railExtrude = { depth: railHeight > 0 ? railHeight : H, bevelEnabled: false };
         const railMat = new THREE.MeshStandardMaterial({ color: 0x64748b, metalness: 0.5, roughness: 0.4 });
         const railSusMat = new THREE.MeshStandardMaterial({ color: 0x9ca3af, metalness: 0.7, roughness: 0.25 });