Calibration woes

hey all.
have me printer running now, but not to pretty/accurate.
it seems on 20mm im around a half mm out for x/y(its a test hexagon im using) and out by .02 on the Z
is this acurate enough to print mendel parts as my cousin wants me to get him a set asap
also my shell seems to be a little blobby.(esp. on corners)
i use repsnapper(no opto's) and cant get replicator G to work for me(it doesnt read my temp and something called python crashes when i try to make G code..
anyone able to help me out.
been at it since bout the 23rd now.....
if someone could come on irc and talk me through what im doing that would be great. already asked in there but didnt get much response.

ah mendel
every steps a fight

cheers
brian

HI

After doing about 10 20mm tt blocks I just sick of wasting plasic. So I remove the extruder and put a pen in the hole, stuck a peice of paper on the bed and draw line in step of 10 and 100. At the same time I had the firmware open and after doing a test and mesuring the travel, I changed the setting in the fireware and uploaded, and reset the control board..
In the end I have the x a y to .01 of 20mm and the z down to .005.

To test the Z I stuck some paper to a tall block of wood and taped it down.

Hope this help as it does time but you will win in the end.

Auzze