E.M.C. PID Tuning - HELP !!!!

evening all,

i have a few questions and oddities that have arisen during a tuning
attempt of e.m.c. for my bridgeport series 2 retrofit project.the
first thing that i have set is the 'p' value, and a value of 150
seems to be the smallest reliable value that will work. i arrived at
this number by starting at 50 then trying to run an axis. when using
this number the axis operated very smoothly at feedrates of 1 to 5
i.p.m. which is very desirable for me, unfortunately when approaching
feedrates above this feed the motors lost counts and carried on which
is no good for me. in order to provide a realistic value for
feedrates and rapids i kept increasing the 'p' value and finally
attained reliable operation at the 150 value. i also noted that by
adding a value of 5 for the 'i' variable it seemed to help smooth out
the motors stepping. by setting up the software with the above values
the feedrates below 6 i.p.m have become very steppy. does anybody
know of a better approach to tuning in order to smooth the slower
feedrates while keeping the abilities of the higher 'p' variable?
i must add that i have altered the acceleration rates to values that
are conservative by most comparisons to other c.n.c. machines.what
would be ideal for me is to have a dynamically adjusting 'p' value
based on feedrates, is this possible? the oddity that i have
encountered happened when i added a backlash value into the axis.
when i added a value the motors kept on stepping after the command
was finished, they had no real direction or distance they were
wandering in , they just looked like an epileptic having an orgasm?
there are also variables such as
deadband,cycletime,bias,ff0,ff1,ff2,ferror, and min_ferror that i
cannot find an explaination for,can anybody tell me what these
variables do and how to implement them into tuning this motor?


thanks in advance

jeff