Page History

...

1. Obtain necessary supplies
   • Medium-density fiberboard (MDF)
   • Layup supplies (squeegees, acetone + shop towels for cleaning)
   • Clamps
   • Sharpie
   • End mill for router
   • Sandpaper + spray bottle of water
   • Mold release wax
   • PVA film (from Fibreglast)
   • Fine-haired brush
   • Bearings or dowels for alignment holes
2. Get access to necessary technology
   • Router: like a giant mill, drills and moves laterally to route out mold. There's one in the Hobby Shop (which you have to become a member to access) and in Gelb. 
   • Horizontal bandsaw or tablesaw to cut MDF

   Notes about Gelb router:

   • CAM program is called "Cut3D" and is a dedicated toolpath for CNC machining
   • Make sure to orient part correctly, paying attention to the axis along which you want to cut it. There is usually more than one way to orient the part, just make you set it up on the router according to how you defined it in the software
   • Cut3D gives you the ability to scale parts if you need
   • The "roughing cut" removes most of the material. For this mold Cut3D says it takes 23 minutes (will vary depending on what you're routing)
   • The "smoothing cut" finishes the mold by smoothing the surface. Cut3D says it takes 56 minutes for this mold.
   • Make sure you select the proper "feed rate" and "plunge rate." This depends on the material you're using.
   • Make sure that the toolpath is correct and save it. Give the file time to download onto the USB
   • When routing, make sure that the tool does NOT intersect the table 
   • Put a foam block under the tool when you turn the power off or it will crash into the table. 
   • You can either use the vacuum attachment while routing or vacuum periodically while it's routing.
3. CAD mold using CAD of nose cone
   • Check out Solidworks mold-making tutorials for help
   • If you want a linear section at the base, determine how long (you want at least 2" for enough engagement with the coupler or things will be bendy/not rigid)
   • Include holes for alignment pins (around three on each side of the mold). Half-spheres work even better because you can put a bearing inside and alignment will be easier/more accurate.
4. Prepare Mold Material (MDF)
   1. Measure: The amount of MDF you need depends on the thickness of MDF you're using, and the dimensions of the nose cone you want to make a mold for. 
      1. For 6" OD nose cone, use 5 layers for each half of the nose cone of 3/4" MDF (total thickness: 3.75"). Since the radius of the nose cone is 3", this gives us an extra 0.75" on the bottom
      2. Account for space on either side of the nose cone (top view) so you have room for pry slits and alignment holes
   2. Mark the cut lines in Sharpie, accounting for the thickness of the blade that you're using to cut the material.
   1. Cut: Using a bandsaw works, but a table saw might be better. Basically you want the lines to be as straight as possible and the pieces you're cutting might be pretty large, so plan on how you're cutting in advance. 
      1. Have more than one person helping you, because cutting large pieces of MDF by yourself is difficult.
      2. Either cut slots in the side so that you have something that you can use to clamp, or attach brackets after the layers are glued together (described below)
   2. Epoxy layers together

1. Route mold (roughing pass + finishing pass)
   When using a router, you first make a roughing pass that removes most of the material in rough steps, then goes over and smooths it with a finishing pass (because starting with a finishing pass would take way too long)
   • Prepare CAM and tool
     • Set finishing passes (the step size for the roughing cut should be no greater than 1/2 the diameter of the tool you're using)
     • Verify that the tool head would not run into the wall of the nose cone while routing (this can happen if you're cutting too steep of an angle: see images below)
     • Insert tool into the router 
   
   
   • Attach mold to router bed. You want this to be secure because if the mold moves around while you're routing, your mold will be ruined. (if you didn't cut slots into the MDF layers before epoxying them together, add brackets so you can attach securely to the routing table)
   • Zero the router (zero for router and CAM file will be different so make sure you're zeroing correctly)
   
   
   • Route!
     • Don't wear clothes you care about. Have vacuum ready because lots of sawdust will be generated. 
     • Make sure to wear safety goggles and earmuffs. It's going to be pretty noisy. Also offer earmuffs to anyone in the vicinity. Protect everyone's ears!
     • Ground yourself by touching the router (but make sure not to be in the way of any moving parts) or you'll probably get shocked.
     • Do a test pass offset above the mold
     • MAKE SURE THE ROUTING TOOL DOES NOT CUT INTO THE ROUTER BED
     • If anything goes wrong, pause if necessary (instead of stopping the router altogether, set the speed to 1% so you don't have to re-zero everything after. It won't technically be "stopped" but it will be moving very slowly so you're effectively pausing it). Or if you're panicking and don't have time to set the speed to 1%, you can also just press the E-stop button.
       

...