diff --git a/package.json b/package.json
index 07fd07ff..d36bea7c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "grid-apps",
-    "version": "2.9.5D",
+    "version": "2.9.6D",
     "description": "grid.space 3d slice & modeling tools",
     "author": "Stewart Allen <sa@grid.space>",
     "license": "MIT",
diff --git a/src/kiri.js b/src/kiri.js
index a4960432..744aa7ed 100644
--- a/src/kiri.js
+++ b/src/kiri.js
@@ -6,7 +6,7 @@
 
     if (!self.kiri) {
         self.kiri = {
-            beta: 2905,
+            beta: 2906,
             driver: {}, // driver modules
             loader: []  // module loading: array of functions
         };
diff --git a/src/license.js b/src/license.js
index b4922c82..884fd88c 100644
--- a/src/license.js
+++ b/src/license.js
@@ -3,7 +3,7 @@
     let terms = {
         COPYRIGHT: "Copyright (C) Stewart Allen <sa@grid.space> - All Rights Reserved",
         LICENSE: "See the license.md file included with the source distribution",
-        VERSION: "2.9.D5"
+        VERSION: "2.9.D6"
     };
 
     if (typeof(module) === 'object') {
diff --git a/src/mode/fdm/export.js b/src/mode/fdm/export.js
index 3cb4632d..9903a13d 100644
--- a/src/mode/fdm/export.js
+++ b/src/mode/fdm/export.js
@@ -7,7 +7,8 @@
     let KIRI = self.kiri,
         BASE = self.base,
         UTIL = BASE.util,
-        FDM = KIRI.driver.FDM;
+        FDM = KIRI.driver.FDM,
+        debug = false;
 
     /**
      * @returns {Array} gcode lines
@@ -97,7 +98,8 @@
             bcos = Math.cos(Math.PI/4),
             icos = 1 / bcos,
             inLoop,
-            arcQ = [];
+            arcQ = [],
+            minz = { x: Infinity, y: Infinity, z: Infinity };
 
         // smallish band-aid. refactor above to remove redundancy
         function updateParams(layer) {
@@ -295,6 +297,11 @@
             if (emit.x) o.append(" X").append(epos.x.toFixed(decimals));
             if (emit.y) o.append(" Y").append(epos.y.toFixed(decimals));
             if (emit.z) o.append(" Z").append(epos.z.toFixed(decimals));
+            if (debug) {
+                if (emit.x) minz.x = Math.min(minz.x, epos.x);
+                if (emit.y) minz.y = Math.min(minz.y, epos.y);
+                if (emit.z) minz.z = Math.min(minz.z, epos.z);
+            }
             if (typeof newpos.e === 'number') {
                 outputLength += newpos.e;
                 if (extrudeAbs) {
@@ -650,6 +657,10 @@
         print.lines = lines;
         print.bytes = bytes + lines - 1;
         print.time = time;
+
+        if (debug) {
+            console.log('minz', minz);
+        }
     };
 
 })();
diff --git a/src/mode/fdm/prepare.js b/src/mode/fdm/prepare.js
index f5a5e19b..905ecf29 100644
--- a/src/mode/fdm/prepare.js
+++ b/src/mode/fdm/prepare.js
@@ -11,7 +11,8 @@
         FDM = KIRI.driver.FDM,
         newPoint = BASE.newPoint,
         newPolygon = BASE.newPolygon,
-        getRangeParameters = FDM.getRangeParameters;
+        getRangeParameters = FDM.getRangeParameters,
+        debug = false;
 
     /**
      * DRIVER PRINT CONTRACT
@@ -47,8 +48,7 @@
             print = self.worker.print = KIRI.newPrint(settings, widgets),
             beltYoff = device.bedDepth / 2,
             beltfact = Math.cos(Math.PI/4),
-            invbfact = 1 / beltfact,
-            bfactor = invbfact * beltfact;
+            invbfact = 1 / beltfact;
 
         // compute bounds if missing
         if (!bounds) {
@@ -308,20 +308,6 @@
                     y: o,
                     z: o
                 };
-                // offset = { x:0, y:0, z:0 };
-                // locate the lowest point in slices and widget overall
-                let minby = Infinity;
-                for (let slice of widget.slices) {
-                    slice.minby = Infinity;
-                    for (let top of slice.tops) {
-                        let poly = top.poly;
-                        for (let point of poly.points) {
-                            let ypos = -point.y + point.z * bfactor;
-                            slice.minby = Math.min(slice.minby, ypos);
-                            minby = Math.min(minby, ypos);
-                        }
-                    }
-                }
             } else {
                 // when rafts used this is non-zero
                 offset.z = zoff;
@@ -472,26 +458,8 @@
 
         // post-process for base extrusions (touching the bed)
         if (isBelt) {
-            // find belt min y
-            let minby = Infinity;
-            let normout = output.filter(l => !l.anchor);
-            for (let layer of normout) {
-                for (let rec of layer) {
-                    let point = rec.point;
-                    if (rec.emit) {
-                        minby = Math.min(minby, -point.y + point.z * bfactor);
-                    }
-                }
-            }
-            // correct y offset to desired layer offset
+            // // correct y offset to desired layer offset
             let miny = process.firstLayerYOffset || 0;
-            let poff = minby - miny;
-            for (let layer of output) {
-                for (let rec of layer) {
-                    rec.point.y += poff;
-                }
-            }
-
             let thresh = firstLayerHeight * 0.25;
             let seqn = 0;
             // iterate over layers, find extrusion on belt and
@@ -511,7 +479,7 @@
 
                 for (let rec of layer) {
                     let point = rec.point;
-                    let belty = rec.belty = -point.y + point.z * bfactor;
+                    let belty = rec.belty = -point.y + point.z;
                     miny = Math.min(miny, belty);
                     if (rec.emit && belty <= thresh && lastout && Math.abs(lastout.belty - belty) < 0.005) {
                         // apply base speed to segments touching belt
diff --git a/src/mode/fdm/slice.js b/src/mode/fdm/slice.js
index 22b2a426..1d1e6e8f 100644
--- a/src/mode/fdm/slice.js
+++ b/src/mode/fdm/slice.js
@@ -27,7 +27,7 @@
         PROTO = Object.clone(COLOR),
         bwcomp = (1 / Math.cos(Math.PI/4)),
         getRangeParameters = FDM.getRangeParameters,
-        debug = true;
+        debug = false;
 
     let isThin = false; // force line rendering
     let isFlat = false; // force flat rendering
@@ -38,7 +38,7 @@
             if (isFlat) {
                 opt.flat = true;
                 opt.outline = true;
-                return opt
+                return opt;
             }
             if (isThin) return null;
         }
@@ -320,9 +320,9 @@
                 for (let slice of slices) {
                     let miny = Infinity;
                     for (let poly of slice.topPolys()) {
-                        let y = poly.bounds.maxy;
+                        let y = poly.bounds.miny;
                         let z = slice.z;
-                        let by = -y + z;
+                        let by = y + z;
                         if (by < miny) miny = by;
                         if (by < smin) smin = by;
                     }
@@ -345,7 +345,6 @@
                         if (!start) start = slice;
                     }
                 }
-                // console.log({smin: smin.round(4)});
                 let offset = spro.firstLayerBeltLead * beltfact;
                 // ensure we start against a layer with shells
                 while (start.up && start.topShells().length === 0) {