calibrating a spreader

Discussion in 'Pesticide & Herbicide Application' started by bababooie, Jan 31, 2001.

  1. bob

    bob LawnSite Platinum Member
    from DE
    Messages: 4,260

    I've got more than 1 lawn to fertilize, I think I'll stick with the Lesco for the same reason Ray said!
  2. Skookum

    Skookum LawnSite Senior Member
    Messages: 675

    If you just use the settings on the bag because your spreader is listed, you could still be over or under applying. Chances are it is close, but it still can be off. Bouncing around on trucks and trailers and just normal use will knock a spreader out of proper calibration.

    You should fill a hopper with a weighted amount of product, apply it to 5,000 sq ft plot, then weigh the product again to determine the actual amount applied to that plot. Check it against your spreader's manufactures settings. It might just be a simple matter of your walking speed, or you might have to use different settings when applying if your setting openings cannot be adjusted, but I would think all commercial units are adjustable.

    The bigger problem that most of us should check is the spread pattern of our spreaders. You can get kits from Lesco for this or you can make your own. All you need are some small 12"x12" boxes about 1-2" tall. The cardboard box trays that soda cans come in can work for this. Place them in a row and run your spreader over them at a 90 degree angle with just enough room between the middle few boxes for your spreader tires to pass through without hitting the boxes. You want the boxes out on each side as far as your spreader will throw. You might want to go over them, while operating the spreader, about 2-3 times in the same direction, not back and forth.

    You can look just at how much product was collected in each box, showing if it is heavy or light on any one side. The kits come with tubes, or you can make your own, that you can pour the product, from each box, into a coresponding tube that is in relationship to where each box was on the ground. Standing the filled tubes up, you can get a cross view of what your spreader's pattern looks like. The ideal pattern is one that tapers off evenly to each side and is more equal in the center. Using this test, you can then adjust the third hole to get the pattern right.

    Using the boxes, you also get the effective distance of your pattern. By using these two calibrations, you can know how far exactly you need to be from your last pass tire tracks to get the product applied to overlap the tapers of the ends of the pattern to get a even applied amount.

    I know that Lesco has a gauge or key kit for checking the pattern calibration, but the keys do get worn as well as everyone could push the key further than the next guy, so checking it in this manner makes sure it is correct despite the keys.

    Hope this was informative to some and not to redundant to others.
  3. KirbysLawn

    KirbysLawn Millenium Member
    Messages: 3,485

    The calabration gauge or "keys" got wore out? I've broke a couple but never wore one out, either way I have spares in the tool box. Since they are made in a stair-step manner, each step has a number, if the bag says calibrate to #14 to apply proper amount of product, #14 gets placed into the spreader and it's set.

    If someone pushes the gauge further in than instructed, well I don't know what to say, maybe they need a new profession, [​IMG]it can't get any easier than this. I would surly expect if someone could not get the simple calibration done correctly, how in the world could they get more difficult procedures as described above done?

    I agree the spreader can get out of calibration due to knocking around, I always try to monitor if the proper amount of product is be applied, so far no problems. If in doubt, take 15 seconds and check calibration

  4. GroundKprs

    GroundKprs LawnSite Bronze Member
    Messages: 1,969

    This description is the proper way to calibrate a spreader. Three years ago I helped a friend try to calibrate his new Lesco spreader using the proper technique described by Skookum. He had streaking problems in the little use the previous year. After trying to properly set the distribution for half a day, he gave up and never used the Lesco again. This spreader put out an extremely heavy band of fertilizer just right of center. Coincidentally, a golf magazine reported the same results four months later. Trusting the seller is an easy way to go, but you never know if he's telling you straight until you test it yourself.

    Even with this system of calibration, you cannot just say you are done. Each spreader must be calibrated at least once a year to correct for mechanical wear. Also, just because one model of one manufacturer has been calibrated, you cannot apply those settings to all like models. I have seen the settings for equal application of two units of the same model to be radically different, because of wear and manufacturing tolerances.

    Another concern in calibration is changing flow rate in areas of varying humidity. Increased humidity causes a reduction in product flow rate, especially with fertilizers. When we are fertilizing, since calibration has been done in dry air of winter, we actually calibrate on every job. Previously measured area of jobsite and current weight applied are used to determine application rate at that moment. Have seen days where we have had to open up settings significantly to apply proper rate of fertilizer.

    [Edited by GroundKprs on 02-02-2001 at 08:25 AM]
  5. bababooie

    bababooie LawnSite Member
    Messages: 134

    thanks for the replys.

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