Yes it's definitely 18mm. Cheapest way will probably buy another lathe with one and nicking the bits I want then moving it on again!!! I don't know enough about wood turning to know how long I can find a rest. As long as poss is the answer!
Richard
I don't know how much you can get another second hand lathe for but you could get a large thread faceplate and 18mm insert for around £50 new. A lot less if you have a pal with an engineering lathe :wink: .