Reading about Bitter's CAD/CAM success is making me happy, I am genuinely happy for you.

As much as I love the "old fashioned" skills of creating something yourself you can't help but love what can be done with CNC machining.
Ironically I have had a very challenging couple of months which finally resulted in some personal triumphs (after considerable tribulations) and I've been busting to tell people but a confidentiality contract severely limits what I can say!
Fuck it though I have to let get some of this out somewhere, it might as well be here in the world forgotten...
I have been through an exhaustive and stressful process of developing a new product which was commissioned by a powerful organisation headed by an individual I will refer to as Barbossa, as for the product I cannot tell you what it is though you may end up guessing - I will refer to the finished products as "Roy's" since this is the nickname I gave them early on in the ordeal.
So, we had to cast hundreds of these "Roy's" within a few months (the deadline was not negotiable) and a very talented sculptor was the creator of the final Roy design (the sculptor was guided by Barbossa's brief outline of what he wanted) and this particular sculptor really took on the responsibility for something quite daunting that tested the mettle of everyone involved - it would be fair to say he bit off more than he could chew.
The tooling we manufactured involved 3D laser scanning of the original sculpture, 3D printing of a "pattern" for prototyping (green-sand casting) which then resulted in some slight design changes (this was a delay we could do without). Finally everyone signed off on the "winning" design and we very quickly set about manufacturing the tooling (for die-casting) and in no time we began production - only to hit a massive (almost fatal) flaw in the process, which had myself & the sculptor at a very real risk of being torn apart by Barbossa and his henchman (lawyers).
I am the manufacturer of the casting but the sculptor chose to use a Toolmaker of his own choice and due to the number of chiefs on the project (in different States & Countries no less) I was not given the opportunity to put forward my opinion on what might go wrong (we can't all be fucking blind optimists!) and before I knew it I was looking at the finished die with a sinking feeling - I could see immediately they had put the in-gates and risers in the wrong places.
Too late, the tooling had been made at great expense (on a much bigger CNC machine to Bitters) and could not be remade, but it could be modified if necessary and it would prove very necessary. On the face of it, the problem we had with our castings was this: They were the right size and shape but they looked crap! The surface finish was not good enough, there was a rash of porosity on one side and ugly laminations (folds in the metal) on the other side. We had tried moving the in-gates and risers (Basically this is how the metal gets into the cavity and feeds molten metal into the casting as it cools) but the real problem was not where we fed the metal into the cavity, it was the shape of the damn product! It had too many dimensional changes (from thick sections to thin sections and back again) and very limited options for where we could get the metal into the cavity. We had modified the design of the tooling 3 times and got closer to achieving success each time but it still eluded us and we were about to run out of time - we couldn't give up...
I was literally lying awake in bed at 3am on a Tuesday night and this nagging idea had been bouncing around the outer edges of my thoughts and it finally presented itself centre stage in my sleep deprived mind - it was obvious what I had to do to fix this thing and get back on track.
The solution? A filter!
The real problem had not been just the shape of the cavity but the turbulence in the molten metal as it flowed through the thinner sections of the casting causing it to "squirt" and thereby draw in gasses which caused the porosity, the thicker sections then stayed molten for longer and caused the appearance of laminations. By using a simple silicon carbide ceramic foam filter (these are used in sand casting but to my knowledge this is the first time they've been used in a permanent mold or Die-cast design) we were able to slow the flow of metal to a more manageable rate without chilling too soon and EUREKA!
Mr Barbossa has his shiny minions, Mr Sculptor has his fame and I have less hair, bags under my eyes and a nice warm feeling deep down inside rather than that cold knotted ache I had when things were looking grim a few weeks back.
Happy
