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POST HOLES & TREE HOLE DIGGING - DRILLING |
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ABOUT MARKING YOUR HOLES Many times I have arrived to a job site prepared to drill post holes, and I have been unable to spot the hole markers from the top of the tractor and drilling rig. The holes need to be very easy to see, and must be functional. Blue, brown, yellow and green are not good colors to use in hole marking. The best color is glow orange. When using spray paint, it is best to spray an X on the spot, and the lines of the X should ideally be at least 24" long. The reason for the 24" mark is that after I begin to drill the hole, most of the mark will become covered with dirt and debris. Once this happens it is difficult to see your original mark, and if the auger gets kicked over a few inches from a large rock, we many not be able to tell. But, if your X is extended out to 24 inches, I will be able to tell if we get kicked over, and I can make an adjustment to ensure your post hole is as close to accurate as possible. Spray paint on the ground will not hold up well over long periods of time like weeks, but it does hold just fine for a matter of many days, or a week, even through a lite rain. So, if you are marking using paint it is best to wait to mark the holes at least fairly close to the time they will be drilled, and use orange, and do extend the X mark to 24" or more. There are other important things to think about with marking for holes. One of the most important things to consider is the proper linear alignment of the holes. If you were building a stretched wire style fence using all same size posts, just imagine a single one sided free standing stretched wire style fence being installed across the front of your property in a straight line. You have a corner post at the left corner, and a corner post at the right corner. Next to each corner post you would have a post set at appx. 8 ft. These will be your support post and there will be a post horizontally spanning the gap between the corner post and the support post. In between those, for the interior posts lets say you are using posts every 8 or 10 ft. If you set your corner posts first, and then stake out a string from center to center and mark your holes along that string, you could be surprised with fence posts that do not line up straight. Here's why, it is because the interior posts would end up being drilled in locations that would overhang your line by 4" on each side of the line. That won't line up with your corner posts that are already set. To correct this problem, you should mark interior posts so that the mark is set back from the line. Set the mark back half the size of the post that is going to be set there. If using a 6" post, set the mark back 2" or 3" from the line. If using 2" t-posts, mark the hole 1" inside the line, etc... Another way is to mark all the holes using a line, and do all the marking before the corner posts have been set. This will give you the ability to have holes that are very accurate in their alignment. I arrive at jobs all the time and when I stand at a vantage point and look at the line of holes that the owner has marked, so many times are quite a bit out of alignment. If it can be seen by the naked eye, just wait till your fence is built. It is going to look terrible. It's just like the old Accountant adage, garbage in, garbage out! If you don't take the time to mark your post holes so they are straight as an arrow, your fence will be a mess. Some of the factors that may cause a property owner to mark holes that are not straight may be placing your string line too high above ground level. 12" to 18" above ground is too high, unless you are using a plumb-bob from string to ground. If you are not using a plumb-bob, that distance allows for discrepancy in visual spotting of the mark under the string. Be sure and stretch your string 6" to 8" above ground level. Also, stretch the string very tightly, and don't try to spot the marks on a windy day as the string will bow. To spray your marks, walk along the string with one foot on each side of the string, straddling the string. And be careful to spray the mark exactly under the string. Another factor that may cause bad hole marking is not being aware of what may be interfering with your string line. If your line is being touched by plants, trees, rocks, branches, etc.. your holes will not be straight. Take the time to walk along your stretched line, and cut and clear all possible interference. Also, stretch those lines very tight!
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