Introduction: Making a Slide Whistle in 123D Design

     This Instructable will teach you how to model a functioning slide whistle, as well as how to use a number of tools in AutoCad's 123D Design software as you go.

Step 1: Create a Cylinder

     From the primitives menu, select cylinder. Enter the desired radius and height into the indicated spaces. The height and radius will affect the pitch of the finished project, and the height will effect the available range. Mine has a radius of 15 mm and a height of 200 mm.

Step 2: Extrude the Chamber

     From primitives, select circle. Position it at the center of the top of the cylinder you created in the last step. The radius should be slightly smaller than that of the cylinder. Mine has a radius of 12.5 mm. Next, select extrude from the construct menu. Click on the circle, and enter the height of the cylinder. Make sure that that resulting extrusion points down into the cylinder, and the cut function is selected before you finish the extrusion. This should leave you with a hollow tube.

Step 3: Cut the Fipple Hole

     Under the sketch menu, select circle and click on the sketch used in the extrusion in the last step. Position it so that it is co-centric with the tube and the previous sketch, and make the diameter the same as the outside edge of the tube. Next, select rectangle from the sketch menu and position the first corner at the center of the circle. the width should be about 1/6th of the diameter, and the height should extend past the outside of the tube. Mine has a width of 5mm and a height of 20 mm.
     Make an identical rectangle on the opposite side of the tube so that the two rectangles form a larger one centered on the sketch as shown. Using the trim tool, remove all geometry except the shape formed by the sides of the rectangle intersecting the circles as shown. Select extrude from the construct menu and click on the sketch you just made. select cut from the extrude modes. This is the hole that will form the fipple of the flute, which is what creates the tone. I my extrusion cuts 20 mm into the body. Finish the extrusion, and hide the leftover sketch.

Step 4: Make the Air Channel

     From the sketch menu, select project. Click on the end of the tube with the fipple hole in it, then roll over the surface until the edges of the tube are highlighted and then click. This should create a sketch that outlines the solid as shown. Next, from the sketch menu, select extend. Hover over one of the two straight lines in the sketch so that a red line appears on the inside of the circle as shown. Click to finish the extension, and then repeat for the second line. Next, use the polyline tool under the sketch menu to draw a line from the edge of the straight line you just created towards the inside of the circle. It should be around the width of the tube. Mine is 2 mm. Do the same to the second line.
     Draw a second pair of lines perpendicular to the endpoint of the small lines you just drew facing outward and extending past the outside edge of the tube as shown. Trim off the excess of these two lines so that a small triangular figure is created on each side with the tube and the perpendicular lines you have created. Make one more line on one side of the figure on the same long line used previously with the same dimensions as used to create the triangular figure. From the endpoint created by this line, draw a line perpendicular bridging the gap between the two parallel lines inside the tube. Select the extend tool from the sketch menu and use it to make the bridging line extend all the way through the inside of the tube as shown. Also extend the parallel edge of one of the triangular figures and the two circles so that all four are unbroken.
     Click extrude and select the two triangular figures. Extrude them as a "join" into the tube so that they terminate at the edge of the fipple hole. Finish the extrusion and select extrude again. this time select all geometry except the small rectangle on the inside of the tube, and extrude away from the tube. This will be the air channel into the body of the flute. Mine is 20 mm.

Step 5: Shaping the Fipple

Select a shape from the sketch for the previous step, click on the gear icon that appears and then click the eye icon to hide this sketch. Use the project tool to project the geometry of the wall of the fipple hole as shown. Sketch a line the same length as the width of the air channel onto the wall from the vertex that is next the the air channel. Draw another line from the endpoint of this line to the far corner of the fipple hole wall. Extrude the created triangle to the opposite edge of the fipple. When this is completed, hide the leftover sketch.

Step 6: Make the Mouthpiece

     Project all the geometry of the outside face of the air channel as shown. Extend both ends of the long side of the rectangle closest to the outside edge as shown. Trim off the larger arc. Create a line that divides the rectangle in half on its long edge. select the arc and hover over the gear icon. Click on the mirror icon that appears. When the mirror properties appear, select mirror line and click on the line that bisects the rectangle. A copy of the arc should appear on the opposite side of the rectangle. After this, finish the mirror. Next, draw a pair of line connecting the two arcs at their endpoints. Finally, extrude the resulting geometry to create the mouthpiece, mine is 20 mm long. Hide the leftover sketch.

Step 7: Create the Pitch Bender

     Create a circle on the face of the open end of the tube very slightly smaller than the inside radius of the tube. Mine has a diameter 1 mm less. How tight this circle can be to the tube depends on the modeling tolerance of the 3D printer you are going to use. Extrude this circle into the tube, this extrusion is 5 mm on my model. Zoom past this extrusion so you are viewing the inside of the tube. Project the geometry of the face formed by the back of the fipple hole as shown. Next, hide the tube solid to view just the fipple sketch and and solid created in this step. Move the cylindrical solid so that it is almost touching the fipple sketch, then hide the sketch and unhide the solids.
     Create a smaller circle centered on the cylinder, and extrude it to the end of the flute chamber, then hide the circle. Next, project the end face of the flute chamber and draw a line along the diameter of this sketch perpendicular to mouthpiece. Select split solid from the modify menu, select the long cylinder you just extruded, and select the line you just created as the intersecting entity. Delete the line and create another circle on the same sketch slightly larger than the inside cylinder. Extrude the geometry formed by this new circle and the inner edge of the flute into the chamber to enclose the chamber. Hide all leftover geometry.

Step 8: Create the Pitch Bender Arm

Hide one of the halves of the pitch bender and project the resultant exposed surface. Draw a small line from the center of the circular end of the geometry created in the last step on the same sketch perpendicular to the end of the pitch bender. Next, draw the path for the pitch bender arm. This can be any shape you  want as long as it does not end up intersecting with any other geometry, is a single continuous line and remains on the single sketch currently selected. Refer to the pictures for a guide. When you are done with this, unhide the second half of the pitch bender and select sweep from the construct menu. Unhide the solids, and select both halves of the end pitch bender, and then select the line you created previously as the path. Finish the sweep.

Step 9: All Done!

You now have a complete working slide whistle! Feel free to change the color and materials, or modify it however you may choose. The current revision of my finished model is available on my Autodesk profile at for download or just to view.

(The current revision is modified so that a gasket can be added to the plunger.)
Autodesk 123D Design Challenge

Runner Up in the
Autodesk 123D Design Challenge