marking out centres for gates and railings

[brooker2006uk]

hello i am pretty new to the site and there is a thing in fabricating i cant get my head round. if i was making a gate or rail and had the flat bar cut ready for punching or drilling i am wondering how to mark it all out. i know the regulations is roughly to each bars should be roughly 4 and half inch centres but is there a method of working this out or a tutorial anywhere.

thanks

[MAC702]

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