diff --git a/notes.md b/notes.md
index 6b1ce320..12113044 100644
--- a/notes.md
+++ b/notes.md
@@ -51,7 +51,6 @@
 # FDM - BELT
 
 * `B` fix supports for belt printing
-* `F` hide layer lines under print
 
 # CAM
 
diff --git a/src/kiri/init.js b/src/kiri/init.js
index d0089f6f..5e382e9d 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -1603,13 +1603,13 @@
             firstLayerNozzleTemp:UC.newInput(LANG.fl_nozl_s, {title:LANG.fl_nozl_l, convert:UC.toInt, modes:FDM, show:isNotBelt}),
             firstLayerBedTemp:   UC.newInput(LANG.fl_bedd_s, {title:LANG.fl_bedd_l, convert:UC.toInt, modes:FDM, show:isNotBelt}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM, show:isNotBelt}),
+            firstLayerYOffset:   UC.newInput(LANG.fl_zoff_s, {title:LANG.fl_zoff_l, convert:UC.toFloat, modes:FDM, show:isBelt}),
             firstLayerRate:      UC.newInput(LANG.fl_rate_s, {title:LANG.fl_rate_l, convert:UC.toFloat, modes:FDM}),
             firstLayerFillRate:  UC.newInput(LANG.fl_frat_s, {title:LANG.fl_frat_l, convert:UC.toFloat, modes:FDM, show:isNotBelt}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM, show:isNotBelt}),
-            firstLayerLineMult: UC.newInput(LANG.fl_sfac_s, {title:LANG.fl_sfac_l, convert:UC.toFloat, bound:UC.bound(0.5,2), modes:FDM, show:isNotBelt}),
+            firstLayerLineMult:  UC.newInput(LANG.fl_sfac_s, {title:LANG.fl_sfac_l, convert:UC.toFloat, bound:UC.bound(0.5,2), modes:FDM, show:isNotBelt}),
             firstLayerPrintMult: UC.newInput(LANG.fl_mult_s, {title:LANG.fl_mult_l, convert:UC.toFloat, modes:FDM}),
-            firstLayerBrim:      UC.newInput(LANG.fl_sfac_s, {title:LANG.fl_brim_l, convert:UC.toFloat, modes:FDM, show:isBelt}),
-            firstLayerYOffset:   UC.newInput(LANG.fl_zoff_s, {title:LANG.fl_zoff_l, convert:UC.toFloat, modes:FDM, show:isBelt}),
+            firstLayerBrim:      UC.newInput(LANG.fl_brim_s, {title:LANG.fl_brim_l, convert:UC.toFloat, modes:FDM, show:isBelt}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM, show:isNotBelt}),
             outputBrimCount:     UC.newInput(LANG.fl_skrt_s, {title:LANG.fl_skrt_l, convert:UC.toInt, modes:FDM, show:isNotBelt}),
             outputBrimOffset:    UC.newInput(LANG.fl_skro_s, {title:LANG.fl_skro_l, convert:UC.toFloat, modes:FDM, show:isNotBelt}),
diff --git a/src/kiri/print.js b/src/kiri/print.js
index e32e924b..2145cd8c 100644
--- a/src/kiri/print.js
+++ b/src/kiri/print.js
@@ -749,9 +749,11 @@
                         break;
                 }
 
-                // optimize start point on belt for all tops
-                if (isBelt) {
+                // optimize start point on belt for tops touching belt
+                // and enforce optimal shell order (outer first)
+                if (isBelt && opt.onBelt) {
                     startPoint = startClone;
+                    shellOrder = 1;
                 }
 
                 // top object
diff --git a/src/mode/fdm/prepare.js b/src/mode/fdm/prepare.js
index f87c8cc0..a97fcdfc 100644
--- a/src/mode/fdm/prepare.js
+++ b/src/mode/fdm/prepare.js
@@ -292,8 +292,25 @@
             if (isBelt) {
                 offset.x = rotinfo.xpos;
                 offset.y = -belt.midy;
-                offset.y += rotinfo.ypos * beltfact;// - 0.5;
+                offset.y += rotinfo.ypos * beltfact;
                 offset.z = rotinfo.ypos * beltfact;
+                // 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);
+                        }
+                    }
+                }
+                // flag slices as being on or off the bed / belt
+                for (let slice of widget.slices) {
+                    slice.onbelt = Math.abs(minby - slice.minby) < 0.01;
+                }
             } else {
                 // when rafts used this is non-zero
                 offset.z = zoff;
@@ -382,7 +399,8 @@
                     tmpout, //layerout,
                     {
                         first: slice.index === 0,
-                        support: slice.widget.support
+                        support: slice.widget.support,
+                        onBelt: slice.onbelt
                     }
                 );
                 layerout.appendAll(tmpout);
@@ -431,8 +449,7 @@
                 }
             }
             // correct y offset to desired layer offset
-            let miny = process.firstLayerYOffset;
-            // console.log({minby, miny, firstLayerHeight});
+            let miny = process.firstLayerYOffset || 0;
             for (let layer of output) {
                 for (let rec of layer) {
                     let point = rec.point;
diff --git a/src/moto/space.js b/src/moto/space.js
index 4880c376..b1b1111c 100644
--- a/src/moto/space.js
+++ b/src/moto/space.js
@@ -645,6 +645,10 @@
                 Space.view.front();
                 cycleInd = 0;
                 break;
+            case cca('b'):
+                Space.view.back();
+                cycleInd = 2;
+                break;
             case cca('>'):
                 cycleInd = (++cycleInd % cycle.length);
                 cycle[cycleInd]();