waxy plastic gear repair

On Mon, 5 Nov 2012 03:51:30 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

Micarta is the trade name for the company that created the process.

The original micarta was developed by George Westinghouse. As a laminate,
Westinghouse sold it well into the 1960s. GE had a similar product,
textolite, which was used for countertops, gears, etc. Both are similar to
Formica.

Micarta is also know generically as "Phenolic". However, phenolic does

not always mean it is made with phenolic resin. The first Micarta was
made with Bakelite, a phenolic resin, but for years now a very common
phenolic is G10, which every one here would recognize as fiberglass
filled epoxy circuit board material. I have machined several different
types of phenolic over the years, linen filled, fiberglass filled,
carbon fiber filled, paper filled. etc. G10 is quite strong and is
easy to glue with epoxy if the surface is roughed up a bit first.
Eric

 

[Jamie]

etpm@whidbey.com wrote:

On Mon, 5 Nov 2012 03:51:30 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:


Micarta is the trade name for the company that created the process.

The original micarta was developed by George Westinghouse. As a laminate,
Westinghouse sold it well into the 1960s. GE had a similar product,
textolite, which was used for countertops, gears, etc. Both are similar to
Formica.


Micarta is also know generically as "Phenolic". However, phenolic does
not always mean it is made with phenolic resin. The first Micarta was
made with Bakelite, a phenolic resin, but for years now a very common
phenolic is G10, which every one here would recognize as fiberglass
filled epoxy circuit board material. I have machined several different
types of phenolic over the years, linen filled, fiberglass filled,
carbon fiber filled, paper filled. etc. G10 is quite strong and is
easy to glue with epoxy if the surface is roughed up a bit first.
Eric
G11 is better, stronger! FR5

Jamie

 

[Splork]

On Sun, 4 Nov 2012 09:00:35 -0000, "N_Cook" <diverse@tcp.co.uk> wrote:

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:4kjls.17182$Be.2080@newsfe13.iad...
Splork wrote:

On Mon, 29 Oct 2012 10:37:59 -0500, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


N_Cook wrote:


isw <isw@witzend.com> wrote in message
news:isw-66F96C.22243727102012@[216.168.3.50]...


In article <ltvo88ln7d3pf3c8uglhvp7rh34o5pdta9@4ax.com>,
Splork <splork@splork.net> wrote:



My low tech pencil sharpener has a drive that uses a 2.2" gear to
drive

the


mechanism from the motor. The gear broke into 3 pieces.

I can probably repair it but am unsure of the composition and what to

use for

cement/ strengthening.


Cut a groove around the perimeter, deep enough to get past the gear
teeth. Wrap a steel wire around the gear in the groove, and twist the
ends to make it tight. If cyanoacrylate will stick to the plastic, use
that to get the pieces assembled before you add the wire.

Isaac


Are you saying cut a slot through the middle of the teeth into the bulk
under the teeth?
I suspect a .4mm saw in a Dremmel would end up as a melted mess and not
a
slot, perhaps a heated scalpel blade in a jig

Or perhaps use some nicrome wire with some silone sleeve at the
overlap,
apply a weight and some adjustable current. Hope the wire melts into
the
bulk of the plastic and perhaps ypu can ignore twisting off of the
wire.
May need to recess 3 pins into the disc part , then swathe in hotmelt
or
something, if the 3 sections have failed with smooth edges, before
doing the
wire job



what is a waxy plastic gear? I can't picture any gears being made of wax
or material soft like wax?

Jamie



Thanks to all the replies!!

The unit is at least 20 years old.

The gear is brown Bakelite in color. I say waxy because it has a soapy
feel and
I can scrape the material with my thumbnail and get some to come off.
Like very
hard wax. Odd for a drive gear material so I suppose it changed in
nature over
time. The exterior seems most changed so perhaps there is some material
strength remaining.

They call it micarta
http://en.wikipedia.org/wiki/Micarta

Jamie


I suspect its this material , upper left cog but I don't know what its
called
http://www.rennbay.com/pics/928installgear/Fig.%2050.jpg
from
http://www.rennbay.com/odotutorial.html
structurally poor but decouples vibration from a gear train

Here are 2 scans. One lighter to show some detail, the other both sides, one
which easily reassembles.

I think JB weld must might do a good job after each piece has a couple of holes
to the other side to form a clamp.

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

 

[Charlie+]

On Tue, 06 Nov 2012 22:57:02 -0500, Splork <splork@splork.net> 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

 

[Splork]

On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ <charlie@xxx.net> wrote:

On Tue, 06 Nov 2012 22:57:02 -0500, Splork <splork@splork.net> 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........

 

[Charlie+]

On Wed, 07 Nov 2012 20:49:51 -0500, Splork <splork@splork.net> wrote as
underneath my scribble :

On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ <charlie@xxx.net> wrote:

On Tue, 06 Nov 2012 22:57:02 -0500, Splork <splork@splork.net> 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.

 

[N_Cook]

Charlie+ <charlie@xxx.net> wrote in message
news:j9lm98laptdjp6m71lon0od96jtjsgumm5@4ax.com...

On Wed, 07 Nov 2012 20:49:51 -0500, Splork <splork@splork.net> wrote as
underneath my scribble :

On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ <charlie@xxx.net> wrote:

On Tue, 06 Nov 2012 22:57:02 -0500, Splork <splork@splork.net> 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.

 

[Splork]

On Thu, 8 Nov 2012 08:19:11 -0000, "N_Cook" <diverse@tcp.co.uk> wrote:

Charlie+ <charlie@xxx.net> wrote in message
news:j9lm98laptdjp6m71lon0od96jtjsgumm5@4ax.com...
On Wed, 07 Nov 2012 20:49:51 -0500, Splork <splork@splork.net> wrote as
underneath my scribble :

On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ <charlie@xxx.net> wrote:

On Tue, 06 Nov 2012 22:57:02 -0500, Splork <splork@splork.net> 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

 

[Leif Neland]

Splork udtrykte prćcist:

My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the
mechanism from the motor. The gear broke into 3 pieces.

I can probably repair it but am unsure of the composition and what to use for
cement/ strengthening.

It is an Amber waxy looking/feeling material and it scrapes like wax.

Perhaps you can find somebody with a 3D-printer who will print a new

gear?

Somebody who has made their own 3D-printer might be looking for
interesting stuff to print.

But then again, get a new one, unless you have lot of free time and no
money.

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.