Help with a delta 3d printer

Hi,

I just finished the build of a kossel xl 3d printer and i have done the paper test and adjusted the bed so that its level and calibrated to the center of the bed, so that the point 0,0,0 is a piece of papers width from the center of the bed. All the electronics work on the printer work as far as i can tell, i can move each axis, heat the hotend and bed, and move the extruder accurately (calibrated).

I tried my first couple of prints but i couldn't get it to work.

Im using repetier host and i load up my solidworks builds (stl) and slice it, but when i then start printing, the bed lowers to 0,0,0 and then starts moving straight towards an edge of my plate and goes past it (although my bed size limits for x and y are set correctly in marlin firmware).

Also, weirdly, the effector moves the first 90mm fine in the x and y axis when i tell it to move, but after that, the effector just keeps on moving past that point and then i have to stop it manually to stop it from damaging itself, despite the max x and y positions being set to +125mm and the min x and y positions being set to -125 (i have a 250mm diameter build plate).

Please help!!!!!!!!!!!!

Thanks

OK, stupidly I had my rod lengths set wrong, I have altered it to the correct value and now it almost works, but each cm I tell the hotend to move, the hotend moves just over a cm, so do you think I should keep altering this value to make it move the correct amount, or is there another value to change.
Sorry about my poor terminology.