I hadn't thought of the possibility of left-hand threads either. But
before possibly making the situation worse by tightening the nut rather
than loosening it you can tell if the threads are left-hand or not by
examining the threaded shaft if the threads extend a little bit beyond
the nut (which they probably do). Just take a peek at the threads and
you'll figure out whether they are left or right.
I assumed at first that one could tell by looking only at the direction
of rotation of the impeller. I thought that a good mechanical design
would have the nut loosen by turning in the same direction as the
impeller moves when operating. That way start-up toque and forces
applied by the air would apply pressure on the impeller in the opposite
direction and tend to tighten the nut in operation rather than loosen
it. But, no, that doesn't work. I've forgotten the brand name but one
of the YouTube videos clearly shows a unit whose impeller turns
clockwise but has a right hand thread which loosens when turned
counter-clockwise. That's probably the engineer's decision that
right-handed threads are about the only thing that will be understood in
the US even if it doesn't (IMHO) make the best mechanical sense.
Chuck Norcutt
On 11/17/2013 2:43 PM, Chris Barker wrote:
> Chuck
>
> Thank you very much! Why did I not think of the World Tutorial Channel, aka
> YouTube?
>
> I'll get out the WD40 and loosen the nut, trying the thread the other way.
>
> And thanks for the pointer to the stopper knot . . .
>
> Cheers
>
> Chris
>
> On 17 Nov 13, at 16:11, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>
>> I've never owned a leaf blower but assumed their designs are all pretty
>> much the same. I checked YouTube using [ leaf blower pull cord ] as
>> search terms and came up with pull cord replacement on several other
>> brands. On most of those the impeller nut loosening was so easy that it
>> wasn't even shown except for final removal with fingers. One showed
>> using an air impact wrench but there was no real indication that that
>> was necessary. In any case the construction of all of these units was
>> pretty much the same as regards access to and removal of the impeller.
>>
>> I guess I'm surprised that you can't easily remove the impeller nut.
>> The impellers shown are quite large diameter (6-8") and the impeller
>> shafts appeared to be small in comparision (perhaps 5/16" or 3/8"). If
>> it doesn't loosen easily with you just hand holding the impeller I would
>> look for either rust on the threads or thread lock. If the threads are
>> rusty it may be necessary to soak them with a solvent like "Liquid
>> Wrench" and perhaps for several days. If there is thread lock like
>> LockTite on them I don't know how to handle that except via heat. It
>> requires heating to 475-500F with a heat gun or soldering iron. But I
>> don't know how your plastic impeller would handle that.
>>
>> If the threads are just rusty and you still can't get the nut off after
>> soaking in a solvent I think I'd take it to a local garage where they
>> have an impact wrench and ask them to hit it with the impact wrench. I
>> should think holding the impeller by hand should be sufficient.
>>
>> ps: I also discovered this little tutorial on tying "stopper knots" in
>> pull cords <http://www.youtube.com/watch?v=ZxYjqUm5G7I>
>
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