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Thread: Chainsaw woodruff key repair
11-11-2003, 09:34 PM #1
I'm looking for ideas for the repair of an old (1960's?) MacCulloch 380 chainsaw, the clutch seats on a taper on the end of the crankshaft, there is a woodruff key to take the drive. Unfortunately, a chunk of metal has broken out behind the key. The shaft is hard, and seems to be through-hardened as well.
The saw is not worth spending money on, but I would still like to repair it, I can spend time on it, but not $.
Any ideas for a repair? I don't want to remove the crankshaft either, if at all possible!
Strangely enough, I have just come across an article on woodruff key seat repairs, where the author recommends making a disc of carbon to fit where the key used to go, (the carbon will conduct electricity if arc welding, but won't burn away), heat to white/yellow and gas weld. Also says you can MIG weld after preheat, but says arc weld will give slag and distortion problems. Any comments on this?
What sort of filler should I use if I gas weld?
Thanks for any advise,
Believe it or not, but my Pioneer chain saw flywheel is partially held in place with Locktite. Had it tuned up andshop didnot tighten flywheel down. Key is ok but flywheel is wallered out. Locktite has held for around 15 years, reapply when flywheel is removed. Not even the "permanent" grade just plain old 242.
11-12-2003, 10:55 AM #3
Older chainsaw cranks were case hardened and ground. If you put much heat to it, it's going to warp. (The new cheap stuff is just forged steel with no heat treat.)
I'd just clean it real good with laquer thinner or acetone and use Loctite, Super Glue, or one of the metal filled epoxies.
I hate to tell you this, but they aren't supposed to last forever! Ask for a new Husky or Takasawa for Christmas.
11-12-2003, 06:39 PM #4
I had a Lawn Boy lawn mower where the fly wheel hub split and you couldn't tighten it on the tapered chrank shaft (it just spread the hub).
I applied Lock Tite, set the fly wheel in place without tightening it, then snugged up the fly wheel nut after it set. Ran for another 10 years.
Easy to do, and doesn't ruin things worse if it is not successful.
11-12-2003, 09:00 PM #5
Loctite is good, but this is the drive to the chain, not just spinning a flywheel. I think its going to need something more positive?
Yeah, it is old, but just try and imagine it is a new Stihl, just out of its warranty, how would you fix the same problem? (Actually, though old, this saw hasn't done much work, this breakage occurred many years ago, its been lying around since then).
11-13-2003, 10:44 AM #6
Not familiar with the 380 series, but will a superwiz 55 crank fit it? Have an extra one of those, out in the shed...
David from jax
What do you mean they aren't supposed to last forever?
Old chainsaws actually crank up and run when you pull the rope. Can you say that about those new fangled things they are pawning off on everybody down at the local home depot?
11-13-2003, 11:44 AM #7
Why not get or shape a stone the right width and diameter for the keyseat (same dimensions as a milling cutter), and grind a new keyseat on the opposite side of the shaft. Since its a clutch it won't make any difference where the keyway is and grinding will work on hardened materials. Go slow and use coolant so it won't overheat the shaft in that area.