UPDATE OCTOBER 25th 2009

I have added the over voltage protection circuit and updated the Schematic and 3D board below. I ran the Capacitor charging circuit through some heavy testing and it performed better and faster than all calculations. I designed this PCB in such a way that I can easily add a new feature or change an existing one by just changing the programming on the microprocessor. I have some more tests to do and painstakingly go through every component and hole sizes to make sure everything is perfect before ordering some professionally made boards. 

I've spent a week reading through data sheets trying to find a suitable mosfet driver for this welder. The LTC driver that I selected is kind of an overkill but it works very good. I also changed the code to the Micro in such a way that when the capacitor is completely discharged or at a low voltage it will limit the current to protect the Mosfet and the transformer. I am busy designing an over voltage protection that will turn the mosfet off if the voltage goes over 20V and also a separate over voltage protection for the capacitor if the mosfet fails. The charging speed is fast enough for a dual pulse so I'm kind of throwing the contactor idea away at this moment(still have all the files) and working on making this a solid state welder that will be much cheaper than the $5000 price tag. Hang in there and don't build it yet until I give the go ahead.