Tuesday, May 18, 2010

The Great Deer Park Chainsaw Death Fiasco Debacle

I almost killed my chainsaw three weeks ago, though to be fair it tried to kill me back.

Mrs Stevie1 had expressed a desire to have the enormous Arbor Vitae bushtree growing between the King Crimson Maple we planted in the corner of the property and the struggling-back-to-life stump of the Intolerable Berry Menace - already subjected to chainsaw justice two years running - pruned tootsweet, so I dug out the 20-inch Poulan Pro and went at it.

I'd done most of the cutting, and turned the bushtree into a sort of vertical green poodle, it being several feet taller than me, when the chainsaw let out an almighty bang and tried to leap out of my hands.

Regular reader2 of this blog will know that I'm long accustomed to power tools attempting wily bids for freedom, so it didn't manage to free itself from my vise-like manly grip.

Which was a pity really, I realized when I came to think about it later, because a spinning chainsaw blade has a lot of energy that has to go somewhere in the event the engine comes to an abrupt stop, and that was why the blade - which had decided to make an independent bid for freedom and jumped off the guide bar in anticipation of getting a head start while I chased the saw around the garden but had hung up on the drive cog - swished around in impressive, razor sharp circles, threatening now my crotch, now my face.

Mindful of the hazard posed to others in the vicinity I warned them of the danger by emitting a series of loud, falsetto shrieks as I desperately dodged the whirling blade of unpleasant and embarrasing cuts should it score a palpable hit. It was all very trying.

Eventually the blade was done with its anti-handyman jiggery-pokery and I kicked aside the sawn-off bits of bushtree and sat on the lawn to assess the damage.

I thought at first that maybe the chain had broken, but it seemed whole, though hopelessly tangled. It took me several minutes to puzzle out the series of events that it had gone through to achieve the knotted mess it had become, and restore the more usual circular arrangement.

Next I figured I'd check out the cog, but first I should remount the chain on the chainbar. This required me to get covered in oil and gasoline, not sure why, but the saw was feeling mischevious that day as events had so ably demonstrated. I was checking the gas levels as a possible reason for the motor stalling and the saw rolled over in my lap and gave me a refreshing dousing in unleaded gasoline. The oil was from just touching the saw's guide bar, which was about as oily as the Gulf of Texas right now.

Since I was already covered in odiforous flammables I decided to check the oil levels as a possible reason for the failure. The chain needs constant oiling otherwise it overheats and might seize in the guide or break or expand so much it jumps out of the guide. This sort of failure is usually signified with lots of blue smoke from the workpiece3 but the branches I'd been cutting were thin so maybe they didn't get time to overheat. No, there was plenty of oil.

I then decided to remount the chain on the guide bar. The chainsaw blade has sharp, hook-shaped, horizontal teeth on the cutting side, forming a never-ending chain of miniature planes that shave the wood away, and vertical teeth remeniscent of those on the backs of T34 tank tracks4, which engage in the drive cog and in a slot in the guide bar, which keeps everything pointing the right way5. When the engine is turning, a centrifugal clutch, formed from whirling pivoted weights in a bell-shaped housing which is attached to the cog, allow the drive to slip and the chain is motionless. Rev the engine by pulling on the trigger in the handle and the engine speeds up and the weights fly outward and catch on the bell housing causing it to spin and drive the cog which in turn makes the chain move. Where was I?

Oh yes. Well I checked the guide bar for damage and, finding none I could see, attempted to get all those vertical teeth back in the slot in the guide bar, but they wouldn't go. It turned out that some of them had suffered damage that knocked up spurs of metal on them, widening them quite a bit. Well, that was that then, a new chain would have to be bought . I surmised that he damage occurred at the drive cog.

I didn't have time to find out though because at that point I accidentally let the little finger of my left hand brush up lovingly against the engine's muffler, still very hot after all the sawing, and as a result spent some time explaining how very unpleasant that was to the neighbors, then even more time attempting to stave off the inevitable agony with ice cubes and cold water.

Why I do this I don't know since it never works. As soon as the cold is removed, typically because I've run out of ice, the pain reasserts itself, building to a crescendo that, once passed, dies down to something only moderately intolerable.

Overcome by ennui and agony I refused to work any more that day.

A week later I managed to track down a new chain and reengaged the saw in single combat for mastery in a World Gone Mad.

First I stripped the chain guide off the saw completely and checked that the motor would in fact start. The "clonk" it had emitted had sounded like a piston breaking, and this motor only has the one. It started with only eight to ten minutes of pulling on the starting cord and yelling the Magic Start Words, which not only removed one item off the "possibly busted up good" list but removed the gaggle of jeering neighbors and their children from the vicinity too. Bonus.

I checked out the drive cog for damage while I was at it. There were some marks on the teeth, but the wear seemed even, such as might be suffered during normal wear and tear rather than a ding caused by the chain attempting a break for it.

The new chain came out of its packaging tangled, so once again I was obliged to become a master of improvised topology before I could start the Main Attraction - fitting the chain to the guide.

First I ran a few of the teeth along the guide bar to check that the slot really was undamaged and clean out some of the gunk a year and a bit of sawing had left in it - a lotion made of pulverised tree in chain oil is what it was. Then came the fitting together of all the bits.

The correct proceedure is:

  1. Hook the chain over the sprocket, allowing a couple of tangles to form in the chain
  2. Untangle chain, cutting exposed skin on teeth of chain
  3. Fit bar on bolt-and-peg seating. Tangle chain again.
  4. Untangle chain and hold in one hand, while keeping guide bar aligned with other hand.
  5. With other other hand fit combination cover/guide lock/guide extender and attempt to locate the extender wheel indexing pin in the matching hole in the guide bar
  6. Fail spectacularly
  7. Turn saw over in an ultimately futile attempt to see the pin and the hole in order to match them up, spilling the chain in a tangled heap into your lap
  8. Untangle Chain
  9. Repeat from step 1 until utterly overcome with the desire for death
  10. By dismantling the saw and adjusting the bar extender to wind the indexing pin as far back as possible, figure out the position at which the guide bar will properly engage the index pin
  11. Untangle the chain again
  12. Reassemble the saw, guide bar, chain and cover, finally engaging the hole in the guide bar on the adjustment pin
  13. Untangle chain
  14. Gradually lengthen the guide bar by turning the thumbscrew downward
  15. Or was that upward?
  16. Before the guide bar gets too long, hook the chain over the length of it
  17. The end, the bit with the cog inside, is tricky so mind you don't...
  18. The band-aids are in the bathroom
  19. Well, you should have bought some more last week while you were in the pharmacy!
  20. Once the bleeding stops, refit the chain and wind out the guide bar using the thumbwheel until about an 8th of an inch gap shows between the chain and the bottom of the bar when you lift the end
  21. Tighten the cover and you're good to go

I grabbed the chain and ran it back and forth to confirm that it was moving through the sprocket without binding, and declared it good to go, though I haven't actually tried to cut wood with it yet. By the time I was done reassembling the wretched thing I couldn't bear to have it near me any more.

Two weeks later the burn is healing nicely. The inch-long blister has burst, the old skin has sloughed off and I can finally bend the finger again.

So the time is ripe for a rematch with Mr Bushtree.

  1. So many of my life's more exciting moments start with that harridan's "suggestions"
  2. singular
  3. One of my old chainsaws had had it's automatic oiler fail. That's how I know this
  4. Don't know what that looks like? Look it up! I recommend Squadron Publications' T34 in Action. Squadron is based in Texas somewhere I think. Good luck
  5. Normally

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