I will be making several different sized horns the biggest at about 500mm wide 400mm high and 500mm deep (roughly). As I said I am a total novice and my comments on machining in two halves are simply taken on face value from this e-mail,


  1. True 5 axis machining is complex and expensive, and should be avoided if possible
  2. Cutter lengths are limited. Your item in one piece exceeds this. The cutter length for optimum machining is 50mm.
  3. To accommodate 1. & 2. the machining solution is a hybrid 3 axis one. The first 48mm of material is positioned and bonded up. The surface is machined from 0 to 48mm in the height with a 12mm ball ended tool stepping over 1mm per pass, cutter orientated vertically. The next 48mm of material is bonded on, and machined from 48mm to 96mm in the height. Etc, etc, up to 216mm.
  4. The inside surface of your horn could be machined using this technique. The outside will be the edge in plan projected down to the same plane as the small hole (ie not 25mm thick). Is this an option?
  5. To cut the outer surface at 25mm thick the item need to be inverted. As it no longer has a flat bottom this way up it will require a male support jig, increasing the nominal cost by 50%. The item is now too deep for the 50mm cutter vertically, so has to be cut full 5 axis (expensive).
  6. Another option would be to split the model into 2 halves. Each half could be machined front and back using 3. above, as there are flat joint surfaces for support when inverted. The outer surface would require some limited cutting with a 100mm long 12mm ball ended cutter, run at a slower feed rate to avoid it snapping off.