Tuesday, March 21, 2017

Cutting down a dead tree in South Orange NJ 2017-03-18

I cut down a tree in my mother in-law's back yard!  It was about 12 feet tall and 24 inches in diameter at the base.  I mainly used a chainsaw (16" bar).  I did a hinge cut on the "downhill" side, and a thin back cut on the opposite side.  I then used a mallet to drive a wedge into the back cut to try to tip the tree over (towards the hinge), without any luck.  So I started cutting more away.  After cutting some away I would try to use the wedge again, without any success.  Eventually, it fell over spontaneously.  It was interesting that it didn't fall until it was cut down to about 3 inch diameter section in the center.  In the picture below you can see the small section in the middle that was left uncut right before it fell:

Here is a time lapse video of me cutting down the tree:

I realized it was going to take to long to cut into reasonable sized pieces, and I had to get it off the yard, so I decided to cut it in half and then attempt to roll each half.  (If I couldn't roll a half, I would cut those in half and try again).  I managed to get about 90% of the way through the log with the chain saw, but could not get the last 10% unless I rolled it over.  I was unable to budge it directly, so I tried using a large limb as a lever, but it broke.  So I used several limbs as levers simultaneously, and although they didn't break I was only able to lift it a small amount before they bent alarmingly.  So I decided to move it incrementally by first lifting a the lever-limbs a little, and then driving a shorter limb perpendicular under the levers with a mallet, and then repeating.  Here's a picture of the levers and the perpendicular limb after the fact:

This setup got the log high enough that I could then push it further by hand so it was on its side, allowing me to finish cutting through it.  The sawdust in the above picture nicely marks where the log was.

Luckily, the resulting halves were light enough that was able to roll them off the yard.  Here is a picture of where I rolled the logs to, from where they started, showing the path in the snow:

Here is a picture of the two logs:

Notes on making the time lapse video

  1. recorded on quicktime on macbook pro - original length ~3 hours 20 min.
  2. identified sections I wanted to keep
  3. installed ffmpeg using brew
  4. used ffmpeg to create time lapse (thank you stack exchange / super user):
    • ffmpeg -i 2017-03-18_chopping_down_tree_south_orange.mov -filter:v "setpts=PTS/60" -an -ss 177.2 -t 20 7.mp4
    • -i 2017-03-18_chopping_down_tree_south_orange.mov
      • indicates input file
    • -filter:v "setpts=PTS/60"
      • indicates sample 1/60th the original
    • -an
      • indicates remove audio
    • -ss 177.2
      • indicates seek to position 177.2, in seconds, but this is units of 60x the original, so it is really seeking to position 177.2 * 60 = 10632 s
    • -t 20
      • indicates run the conversion for a duration of 20 seconds, but again in units of 60x the original, so it is really running for 20 * 60 = 1200 s
    • 7.mp4
      • is the output file
  5. used ffmpeg to stitch the individuals together (thank you ffmpeg docs)
    1. created a file with 2 columns, first is the word "file", second is the path to the file, in order they should be stitched (myfiles.txt)
    2. ffmpeg -f concat -i myfiles.txt -c copy all.mp4
      1. -f concat
        1. indicates we want to concat things together
      2. -i myfiles.txt
        1. indicates the text file that is listing the files to be concat'd
      3. -c copy
        1. indicates that the original videos should just be copied
      4. all.mp4
        1. indicates the output file should be all.mp4

Update:  The Joys of a Chainsaw Manual

These images and phrases like "if necessary abandon the chainsaw", "have a retreat path"

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