great i can just see it now, i roll into work on Monday and i'm no longer fitting a boiler, im going to be trimming hopper necks. d'ya think i can charge the same hourly rate.....?if you know a plumber or gas engineer copper pipe cutters are perfect for the job.Use them on the hard shell and then a decent hacksaw on the blue raceway.
http://www.plumbworld.co.uk/pipe-cutters-616-0000
oh and yeah you can use a junior hacksaw but take it slowly or you could cut at an angle, and as was said sand off the burs afterwards