Metal gate posts

[john4703]

I'm about to start making a new driveway for my car. I want nice looking wrought iron gates and the blacksmith said I should use 40mm square posts. If I fit these he will then weld on hinges and fit the gates he will make to fit.
I know very little about metalwork. Should the 40 x 40 posts be solid or hollow square tube?
I plan to have them 1700mm long with 500m buried and 1200mm above ground level.
The blacksmith was being really helpful by suggesting that I could buy the steel posts myself rather than get him to supply them. A 6m length will make all 3 posts

 

[Burnerman]

Your new posts should definitely be tubing, around 3mm thick material is about right.....however, I would have thought that 40mm square is on the small side for these.
If there's a Metals Supermarkets near you they can supply what you need.
John