heres the low-tech, sorta low buck method
go out and buy a tap (i think its a 12 or 14 mm) kbc tools on annacis island is a good source, bout 20 bucks..
i like to tap the tie-rod first as deep as possible to make sure that once you cut off the end there are still some threads left to tap further.
take the tie-rod, and cut the required amount off (you can use a hack-saw, cut-off wheel, bandsaw, chop saw....whatever you have)
ask a parent to help if your not allowed to use tools
now if you have the style of tierod that has slits in the ends you have to elongate them , you can use the hacksaw, bandsaw, or a small cut off wheel
now, run the tap back through to clean up the threads and make sure the tie-rod can thread all the way in
rinse and repeat on the other tie-rod
it will take you about an hour, and you dont have to bother any more machine shops
try not to cut off your fingers!