I don't know of any
free RIP that might work with your particular printer. There are a few RIPS that have a trial period, but I don't know if any of them will work on your Epson. A quick Google will find them. You might try to ask this question at a professional forum like the
B4Print Forums, though, obviously, they are more focused on commercial RIPs. Can we assume you are trying to output separations to your Epson?