On Thu, 8 Nov 2012 08:19:11 -0000, "N_Cook" wrote:

Charlie+ wrote in message
.. .
On Wed, 07 Nov 2012 20:49:51 -0500, Splork wrote as
underneath my scribble :

On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ wrote:

On Tue, 06 Nov 2012 22:57:02 -0500, Splork wrote as
underneath my scribble :

Crack on the left is the original, the gear has been running eccentric
some time, wear on the right teeth is considerable, if you do a repair
pay considerable attention to concentric-icity(!!) to the centre. Is
the equipment worth it? A dirty repair might be to use hot glue for
thin metal or fibre washers in the rebates... try first to see if hot
glue will stick to the soft gear material, might have to abrade.

http://users.rcn.com/healer//Gear1.jpg
http://users.rcn.com/healer//Gear1a.jpg


That's the word I was looking for yesterday. Concentric.

This is a pencil sharpener.
When I reach to use it and it is gone . . . Yeah, worth it.

The only repair that I think worthwhile, which is potentially long
lasting, is
on each piece, to place 2 holes halfway between hub and teeth, 3 holes on
the
largest, to allow jb weld (Strong metal bearing epoxy) to join obverse
and
reverse of the gear (2 operations). Once sandwiched between the "weld",
being
restrained and driven by the pins that form through the holes, I can
place the
gear on the drive shaft and greasing the gear end to prevent adhesion,
make a
third gluing operation for a strong tight fit around the shaft end.

So the cracks will not be repaired, but the pins/vias that form in the
holes
will keep it together, sandwiched between plates which prevent it from
divergence in any axis. The 3 segments held and driven separately.

Now if laziness prevails........ :-)

Good luck with it, hot glue has some 'give' in it which would provide
the required flexibility.


What I call hotmelt string is more convenient in this sort of operation.
With the gun hot, squeeze out a long run of hotmelt over clean metal sheet.
When cold , use like soldering operation with an old soldering iron, melding
original material and the string.


Thanks for the suggestions. Sounds interesting to me. Never used hot glue so I
find the use of it like solder intriguing, and I like cleverness.

Perhaps I am over estimating my need for strength. Rarely successful at
repairing plastic gears and one of this size seems an unlikely candidate for
glue. I do have a glue gun here somewhere.

There is a lot of force applied to the shaft via the hub. Lots of torque needed
to turn the sharpener blades. Manually un-movable.

Will probably use the idea I had using JBWeld to create the least amount of
give, but will experiment with hot glue to experience it's usefulness, and use
it when I attempt small plastic gear replacement.

Good stuff!

Thanks again