diff --git a/notes.md b/notes.md
index f0f6d97d..ce96bf83 100644
--- a/notes.md
+++ b/notes.md
@@ -12,6 +12,7 @@
 * `P` client/worker interface normalization
 * `P` explore widget vertex reloading / replacing (Onshape primarily)
 
+* `F` G2/G3 arc output / input
 * `F` expose grouping feature
 * `F` SVG import to 3D part like images
 * `F` bundle current profile into exported device
diff --git a/src/geo/base.js b/src/geo/base.js
index 213b8689..50a5bd46 100644
--- a/src/geo/base.js
+++ b/src/geo/base.js
@@ -316,6 +316,60 @@
         return (d2y * d1x) - (d2x * d1y);
     }
 
+    /**
+     * return circle center given three points
+     * from https://math.stackexchange.com/questions/1076177/3d-coordinates-of-circle-center-given-three-point-on-the-circle
+     */
+    function center3d(a,b,c) {
+        let ax = a.x,
+            ay = a.y,
+            az = a.z || 0,
+            bx = b.x,
+            by = b.y,
+            bz = b.z || 0,
+            cx = c.x,
+            cy = c.y,
+            cz = c.z || 0,
+            Cx = bx-ax,
+            Cy = by-ay,
+            Cz = bz-az,
+            Bx = cx-ax,
+            By = cy-ay,
+            Bz = cz-az,
+            B2 = (ax*ax)-(cx*cx)+(ay*ay)-(cy*cy)+(az*az)-(cz*cz),
+            C2 = (ax*ax)-(bx*bx)+(ay*ay)-(by*by)+(az*az)-(bz*bz),
+            CByz = Cy*Bz-Cz*By,
+            CBxz = Cx*Bz-Cz*Bx,
+            CBxy = Cx*By-Cy*Bx,
+            ZZ1 = -(Bz-Cz*Bx/Cx)/(By-Cy*Bx/Cx),
+            Z01 = -(B2-Bx/Cx*C2)/(2*(By-Cy*Bx/Cx)),
+            ZZ2 = -(ZZ1*Cy+Cz)/Cx,
+            Z02 = -(2*Z01*Cy+C2)/(2*Cx),
+            dz = -((Z02-ax)*CByz-(Z01-ay)*CBxz-az*CBxy)/(ZZ2*CByz-ZZ1*CBxz+CBxy),
+            dx = ZZ2*dz + Z02,
+            dy = ZZ1*dz + Z01;
+
+        return {x:dx, y:dy, z:dz};
+    }
+
+    /**
+     * return circle center given three points
+     * from https://stackoverflow.com/questions/4103405/what-is-the-algorithm-for-finding-the-center-of-a-circle-from-three-points
+     */
+    function center2d(A,B,C) {
+        let yDelta_a = B.y - A.y,
+            xDelta_a = B.x - A.x,
+            yDelta_b = C.y - B.y,
+            xDelta_b = C.x - B.x,
+            aSlope = yDelta_a/xDelta_a,
+            bSlope = yDelta_b/xDelta_b,
+            center = {x:0, y:0, z:0};
+        center.x = (aSlope*bSlope*(A.y - C.y) + bSlope*(A.x + B.x) - aSlope*(B.x+C.x) )/(2* (bSlope-aSlope) );
+        center.y = -1*(center.x - (A.x+B.x)/2)/aSlope +  (A.y+B.y)/2;
+
+        return center;
+    }
+
     /** ******************************************************************
      * Connect to base
      ******************************************************************* */
@@ -399,6 +453,8 @@
         time,
         round,
         area2,
+        center2d,
+        center3d,
         distSq : dist2,
         distSqv2 : dist2v2,
         inRange,
diff --git a/src/kiri/init.js b/src/kiri/init.js
index 5d66289c..da7b66db 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -1779,8 +1779,8 @@
             // outputWipeDistance: UC.newInput("wipe", {title:"non-printing move at\close of polygon\nin millimeters", bound:UC.bound(0.0,10), convert:UC.toFloat, modes:FDM}),
             sliceSolidMinArea:   UC.newInput(LANG.ad_msol_s, {title:LANG.ad_msol_l, convert:UC.toFloat, modes:FDM}),
             outputMinSpeed:      UC.newInput(LANG.ad_mins_s, {title:LANG.ad_mins_l, bound:UC.bound(5,200), convert:UC.toFloat, modes:FDM}),
-            outputCoastDist:     UC.newInput(LANG.ad_scst_s, {title:LANG.ad_scst_l, bound:UC.bound(0.0,10), convert:UC.toFloat, modes:FDM}),
             outputShortPoly:     UC.newInput(LANG.ad_spol_s, {title:LANG.ad_spol_l, bound:UC.bound(0,10000), convert:UC.toFloat, modes:FDM}),
+            outputCoastDist:     UC.newInput(LANG.ad_scst_s, {title:LANG.ad_scst_l, bound:UC.bound(0.0,10), convert:UC.toFloat, modes:FDM}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM}),
             zHopDistance:        UC.newInput(LANG.ad_zhop_s, {title:LANG.ad_zhop_l, bound:UC.bound(0,3.0), convert:UC.toFloat, modes:FDM}),
             antiBacklash:        UC.newInput(LANG.ad_abkl_s, {title:LANG.ad_abkl_l, bound:UC.bound(0,3), convert:UC.toInt, modes:FDM}),
diff --git a/web/kiri/lang/en.js b/web/kiri/lang/en.js
index d30028d2..4f8b06aa 100644
--- a/web/kiri/lang/en.js
+++ b/web/kiri/lang/en.js
@@ -481,7 +481,7 @@ kiri.lang['en-us'] = {
     ad_msol_l:      "minimum area (mm^2)\nrequired to keep solid\nmust be > 0.1",
     ad_mins_s:      "min speed",
     ad_mins_l:      "minimum speed\nfor short segments",
-    ad_spol_s:      "slow poly",
+    ad_spol_s:      "short path",
     ad_spol_l:      "polygons shorter than this\nwill have their print speed\nscaled down to min speed\nin millimeters",
     ad_zhop_s:      "z hop dist",
     ad_zhop_l:      "amount to raise z\non retraction moves\nin millimeters\n0 to disable",