diff --git a/src/kiri-mode/cam/ops.js b/src/kiri-mode/cam/ops.js
index ac518af4..0246986e 100644
--- a/src/kiri-mode/cam/ops.js
+++ b/src/kiri-mode/cam/ops.js
@@ -14,7 +14,7 @@ gapp.register("kiri-mode.cam.ops", (root, exports) => {
 
 const { base, kiri } = root;
 const { paths, polygons, newPoint, newPolygon, sliceConnect } = base;
-const { poly2polyEmit, tip2tipEmit, segmentNormal, vertexNormal } = paths;
+const { poly2polyEmit, tip2tipEmit, segmentNormal, vertexNormal, arcToPath } = paths;
 const { driver, newSlice } = kiri;
 const { CAM } = driver;
 
@@ -1733,28 +1733,121 @@ class OpHelical extends CamOp {
 
     async slice(progress){
         let { op, state } = this;
-        let { settings, addSlices, widget, updateToolDiams } = state;
+        let { settings, addSlices, widget, updateToolDiams, slicer } = state;
         let { zBottom, zThru, thruHoles, color } = state;
-        let { drills, drillThrough} = op
-
-        let drillTool = new CAM.Tool(settings, op.tool),
-            drillToolDiam = drillTool.fluteDiameter(),
-            sliceOut = this.sliceOut = [];
-
-        updateToolDiams(drillToolDiam);
-
-
+        let { cylinders, forceStartAng, startAng, fromTop,offOver,offset, down, thru } = op
 
         
-        let slice = newSlice(0);
 
-        let poly = newPolygon();
+        let tool = new CAM.Tool(settings, op.tool),
+            toolDiam = tool.fluteDiameter(),
+            sliceOut = this.sliceOut = [],
+            startAngle = forceStartAng? startAng : 0;
+
+        updateToolDiams(toolDiam);
+
+
+        console.log(cylinders,cylinders[widget.id] )
+        let faces = cylinders[widget.id] 
+
+        if(faces.faces) faces = faces.faces
+        console.log(faces)
+
+        let polys = [];
+
+        //iterate over selected faces
+        for(let face of faces){
+        
+            //get poly info for the cylinder
+            let {zmin, zmax, diam, center,interior,faces} = CAM.cylinder_poly_find(widget, face)
+
+            console.log({zmin, zmax, diam, center,interior})
+
+            let radius = diam >> 1;
+
+            let radAdd,
+                zBottom = zmin-thru,
+                clockwise = true,
+                numSegs = faces.length/ 2,
+                poly = newPolygon().setOpen();
+
+
+            if(offOver){ //apply offset override
+                if(offset == "auto"){
+                    radAdd = (interior? -offOver : offOver) * 2
+                }else if(offset == "inside"){
+                    radAdd = -offOver * 2
+                }else if(offset == "outside"){
+                    radAdd = offOver * 2
+                }
+            }else{ //otherwise, calculate based on offset type
+                if(offset == "auto"){
+                    radAdd = (interior? -toolDiam : toolDiam) * 2
+                }else if(offset == "inside"){
+                    radAdd = - toolDiam * 2
+                }else if(offset == "outside"){
+                    radAdd = toolDiam * 2
+                }
+            }
+            console.log({radius,radAdd})
+            radius += radAdd
+            
+            let startPoint = center.clone().setZ(zmax).add(newPoint(Math.cos(startAngle) * radius, Math.sin(startAngle) * radius,0));
+
+            let currentZ = zmax
+            for(;;){
+                let bottom = currentZ - down
+                if(bottom > zBottom ){
+                    //if not at the bottom, do a whole helix
+                    
+                    let start = startPoint.setZ(currentZ),
+                    end = startPoint.clone().setZ(bottom);
+                    console.log(currentZ,bottom,[start.z,end.z])
+
+                    let path = arcToPath(start, end,numSegs,{
+                        clockwise,
+                        radius,
+                        center,
+                    })
+                    console.log({path,start, end, radius,center})
+                    poly.addPoints(path);
+                }else{
+                    //if at the bottom, do a partial helix
+
+                    let toBottom = currentZ-zBottom,
+                        ofFull = toBottom/down, 
+                        ofCircle = ofFull * (2*Math.PI),
+                        finalAngle = startAngle + ofCircle,
+                        finalEnd= center.clone().setZ(zBottom).add(newPoint(Math.cos(finalAngle) * radius, Math.sin(finalAngle) * radius,0))
+                    
+                    //circle down to final point
+                    poly.addPoints(arcToPath(
+                        startPoint.setZ(currentZ),
+                        finalEnd,numSegs*ofFull,
+                        {
+                            clockwise:!clockwise,
+                            radius,
+                            center
+                        }
+                    ))
+
+                    //do a full circle at the bottom
+                    poly.addPoints(arcToPath(finalEnd,finalEnd,numSegs,{clockwise,radius,center}))
+
+                    break
+                }
+                currentZ = bottom
+            }
+
+            polys.push(poly)
+        }
 
 
 
+        let slice = newSlice(0)
 
         slice.camTrace = { tool: op.tool, rate: op.feed, plunge: op.rate };
-            slice.camLines = [poly];
+            slice.camLines = polys;
 
             slice.output()
                 .setLayer("Helical", {face: color, line: color})