One of the key steps in successfully constructing a good looking farm fence (or any fence – for that matter) is installing a guide wire to use for putting in line posts. Without a guide wire (or one that is installed too quickly) your fence posts will not be in a straight line.
I feel sure that we would all like to build fences that are true and straight. One, where you can sight down the fence line when you are done and everything lines up to your satisfaction. But, I would also feel sure that most of us have at one time or another NOT spent enough time on the guide wire.
The guide wire will also help in lining up your brace posts and gateways. Technically, the guide wire should be stretched immediately after the corner or end posts are secure and before any other posts or bracing are installed.
With high tensile fencing, you can use the bottom strand of your fence as your guide wire. Simply install your end insulators and attach the guide wire. Install a wire strainer or tensioner at about the midway point and tighten it up good and snug, so that you can snap it up and down like a chalk line.
If you are going over hills and thru dips, then you will need to physically walk out to all the high spots and assure that the guide wire is in a straight line without any obstructions, horizontally. [Note: a 6” to 12” variance, out of true line, is not very distinguishable to the naked eye, but after the wire is tensioned up it will be trying to bend the line post towards the true line.]
After your guide wire is installed, straightened and established, you can now install your brace posts, gate posts and any line bosses that you want to incorporate into your fence line. I do recommend using line bosses periodically and especially at ridge tops or rises. They just add a little extra stiffness to the fence where you need it.
Now you can go ahead and attach the guide wire to the brace, gate and boss posts. After this is done, you are now ready to begin installing your actual line posts.