I'm using 20mm conduit (Again for free) and have just done my bends today, what I did was cut 4 pieces about 1m long then where it says in the book the measurement BEFORE the bend add a bit extra.
I now have 4 90 degree bends which I intend to join by means of an insert into the pipe and weld fully ensuring I grind the galv off and use a mask when welding.
alternatively buy the ones on ebay
