ok, so, here's the set up:

sugino messenger chainring
sugino R2 cranks
average shimano bb
izumi chain
phil wood cog

so why do i have this grinding sound - not to mention this grinding feel - when i'm pedalling? i'm at a loss. cleaned and greased / lubed everything, chainline - though not exactly perfect - is pretty damn close, and i've tried a bunch of different chain tensions. it's a mystery. anyone wanna try to solve it?

are they all new?

all bar the bb, which is only about 6 months old

Chainline not straight? Chain too tight? But you said they are fine. Stiff links?

if the chain is disengaging/engaging the ring or cog at even a slight angle you'll feel some roughness. Not sure if that qualifies as 'grinding' though.

happens to me when my chain is too tight.. play with chain tension mebbe?

Take the chain off. Spin the cranks. Spin the wheel. Any grinding? If not, then it's obviously a chain thing. As someone suggested, see if changing the tension helps. Also, did you make sure to apply lube to wear the rollers contact the plates? (Usually people just toss lube onto the chain and it ends up there, but the inside of the rollers is actually the place that needs the lubrication)