Video of CNC machining a double sided part.

[Shinobiwan]

And a couple of pics






And the two dead cutters. HSS isn't really suited to this material as its even more abrasive than MDF but a combination of 4 flutes and a hefty 105mm cutter stick out meant you couldn't whack up the feedrates to anything like what they should have been without massive tool deflection or possibly even snapping the thing. My fault of course, tool was totally unsuitable for the job but I got them cheap so couldn't pass. A 14mm dia 160mm long cutter with 100mm flutes would normally set you back £50+. I expect doing a finish pass in alu would have suited them much better! lol

Check the carbide 2 flute on the left though. Not a scratch on it and it ended up doing most of the work. Yup. In my initial set of toolpaths I naively thought using the long cutting to get through the whole material was a great idea - save time changing bits, keeps the code simple and smaller. Wrong! You really only wanted to be doing the bare minimum with those massive cutters, just the parts where only they can reach. Anything else, use something smaller! In the end I broke it up into three tool lengths, one at 40mm another at 75mm and the 105mm. That worked but for the profile around each part there simply wasn't enough room to clear the chips when that valley got deep and it started burning cutters within minutes due to massive rubbing and recutting of chips. In the end I had to flip the part over and come at it with the 40mm carbide cutter from both sides leaving only 20mm right in the middle for the long cutter to get at.

In hindsight there would be a couple of things I'd do differently. First off is pick up a carbide 2 flute long cutter and the other being to size the stock to just over the size of the part and that'd do away with the deep profile problem I had.