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  1. Dan Thornton

    Another physics spinoff question - back leaning

    About 36" DBH. I'll set rope (5/8" Yale XTC) high in tree, pulling almost directly ahead, through block, to side, using a GRCS. Nothing wrong with the tree - a pine. Homeowner called it a yellow pine, but I haven't confirmed that, or discerned which kind of yellow it would be here in western...
  2. Dan Thornton

    Another physics spinoff question - back leaning

    It took me a while to follow your calculations. Looks good. To use this information requires some skills I'm still trying hard to develop: 1. estimating where is the Center of Gravity 2. estimating how heavy is the tree / piece / top I think it was one of Patrick's videos (Muggs) where he...
  3. Dan Thornton

    Brand New Husqvarna T540i XP Kit

    PM sent
  4. Dan Thornton

    Hello. Do you still have one of those Husky Battery saws left? I would love to have one of those...

    Hello. Do you still have one of those Husky Battery saws left? I would love to have one of those but can only swing $700 at this time. I understand if you need to wait for someone with the full $850 but let me know if you have one for me at the lower cost. Dan Thornton
  5. Dan Thornton

    Today....

    Wednesday, I took down an ailing pin oak, situated in a fenced school playground. What made it special was that I grew up on that property (before the church and school were built) and certainly played around that tree.
  6. Dan Thornton

    Best Rake

    I was wondering the same. Saw the Beaver Rake Head at arborist.com and liked the idea of using it on poles I already store, but have no idea how well it would work.
  7. Dan Thornton

    Milwaukee top handle is coming

    Yes, I did. Impressive vertical bury of the bar into the ground. Glad my grounds woman was not under the lift. I was using the sectional polesaw, not the extending version.
  8. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    I know - I was surprised by this as well! Here's Wikipedia: "Note that the radius of the cylinder has no influence on the force gain." (See "Capstan equation" in Wikipedia). BUT our intuition and objections are partly right ... friction can come from other places than just the rubbing between...
  9. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    Yes, the rope construction makes a difference in the amount of friction. Nylon is different from polyester which is different from amsteel. And for the same rope it makes a difference whether it is clean, wet, dirty, or sappy. Then for the porta-wrap the kind of metal makes a difference and...
  10. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    Then if your groundsman is a math geek like me, he'll probably object when he notices that a single wrap only touches the main part of the porta-wrap for 270 degrees, not 360 degrees. At that point you can thank him for noticing, compliment him that he has a promising future in tree work because...
  11. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    I probably should have left the "degrees" column off to avoid confusion. In figuring friction of a rope going around a bollard or cylinder (in our case, a porta-wrap) what matters is the number of degrees the rope is in contact with the cylinder. So a 'half-wrap' is when the rope contacts the...
  12. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    Bart said: "Still waiting for someone to calibrate a porty for tension ratio vs wraps. Its exponential." I have developed my own rule of thumb for porta-wrap friction. Maybe it will be helpful to someone. It obviously has to make many (too many) assumptions. But I still find it useful. Here...
  13. Dan Thornton

    Inversion Table

    Not necessarily. The point of an inversion table is to 'hang' your weight on the ankles or feet so that the head and shoulder weight stretches the joints - the opposite of the compression the joints get all day long. Laying on the ground won't do this if there is a lot of friction between the...
  14. Dan Thornton

    GRCS Storage

    I try to reuse things I already have and I like how this one turned out. Plus, it's in the right order for setup. A ratchet strap holds the GRCS frame on top of the Craftsman rolling case. 1) Remove ratchet strap and place it on the tree. 2) Hang the GRCS frame on the strap for easy attachment...
  15. Dan Thornton

    Today....

    Three of six trees felled, these leaning toward a work garage. Simple pulls with Maasdam rope puller.
  16. Dan Thornton

    Physics Question: Basal vs Canopy Anchor Forces

    For those who are still tempted to think that the rope going down from the natural crotch to the basal tie on the tree is contributing to the perpendicular pulling force, thus aiding the falling of the tree, try out this thought experiment for size ... Let's reverse the forces. Instead of...
  17. Dan Thornton

    Experience or Skill?

    In education, there is difference between Knowledge, Understanding, Attitude, and Skill. (In education, experience is simply one of the steps necessary to learn a skill.) Teaching methods are different depending on whether you are trying to teach for knowledge, understanding, attitude, or skill...
  18. Dan Thornton

    Experience or Skill?

    Great line! Is that yours, or who should I give credit to?
  19. Dan Thornton

    Pull Rope Height - what is optimal?

    Your intuition is again correct. If rope length is limiting factor, then 45 degrees produces the greatest torque. Over the last two days, during my vacation, I put down six trees for a retired missionary friend. Four were pulled against the lean with a rope and Maasdam rope puller. This...
  20. Dan Thornton

    Pull Rope Height - what is optimal?

    Bart's specific suggestion was eye-opening. How much does anchor distance from the tree matter? Not much!! If tree is 100' tall -- with TIP at 50' -- and anchor a minimum safe distance away of 100' -- moving the anchor back another 50' only increases the pulling torque 6%. In other works, get...

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