On Thursday, May 12, 2016 at 5:36:29 PM UTC-4, MJC wrote:

In article <f6e561cf-16a8-4d0b...@googlegroups.com>,
pf...@aol.com says...

Those fingers are spring bronze, very thin and relatively hard to

duplicate as the bronze alloy is a delicate balance between being too
hard and not having enough spring. Too hard would eat into the
commutator, not hard enough would anneal and fail quickly.
Back in the 1950s (I guess) when my Dad and I were playing with toys, we
also thought that a small motor had phosphor-bronze spring brushes.
Having no idea where to get stock metal we tried cutting up slices from
a roll sold by a local hardware as draught-prevention seals for doors
etc. I don't remember how durable it was!

Not sure if it is the same stuff, but I have some more recent "Atomic
Weather Strip" made of "specially prepared copper alloys" and carrying a
ten year life time...

Mike.

https://www.collectableivy.com/

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Vintage College Football program


https://www.collectableivy.com/

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

In article <fb00fe6c-406e-4a27-ab37-01e2c7757a81n@googlegroups.com>, valuablebook@gmail.com says...

On Thursday, May 12, 2016 at 5:36:29 PM UTC-4, MJC wrote:

In article <f6e561cf-16a8-4d0b...@googlegroups.com>,
pf...@aol.com says...

Those fingers are spring bronze, very thin and relatively hard to

duplicate as the bronze alloy is a delicate balance between being too
hard and not having enough spring. Too hard would eat into the
commutator, not hard enough would anneal and fail quickly.
Back in the 1950s (I guess) when my Dad and I were playing with toys, we also thought that a small motor had phosphor-bronze spring brushes.
Having no idea where to get stock metal we tried cutting up slices from
a roll sold by a local hardware as draught-prevention seals for doors
etc. I don't remember how durable it was!

Not sure if it is the same stuff, but I have some more recent "Atomic Weather Strip" made of "specially prepared copper alloys" and carrying a ten year life time...

Mike.

https://www.collectableivy.com/

I think that is called a "non sequitur". But thanks for reminding me of
what I wrote ~5 years ago, remembering my long-dead father. Mike.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

John Sabino <valuablebook@gmail.com> wrote:

On Thursday, May 12, 2016 at 5:36:29 PM UTC-4, MJC wrote:

In article <f6e561cf-16a8-4d0b...@googlegroups.com>,
pf...@aol.com says...

Those fingers are spring bronze, very thin and relatively hard to

duplicate as the bronze alloy is a delicate balance between being too
hard and not having enough spring. Too hard would eat into the
commutator, not hard enough would anneal and fail quickly.
Back in the 1950s (I guess) when my Dad and I were playing with toys, we also thought that a small motor had phosphor-bronze spring brushes.
Having no idea where to get stock metal we tried cutting up slices from
a roll sold by a local hardware as draught-prevention seals for doors
etc. I don't remember how durable it was!

Not sure if it is the same stuff, but I have some more recent "Atomic Weather Strip" made of "specially prepared copper alloys" and carrying a ten year life time...

I've missed out on the beginning of this thread, but I had a problem
with worn phosphor bronze leaf brushes on a small motor many years ago.
They had worn right through and the ends had fallen off. I took an
ordinary carbon brush from a much larger sized motor and cut a pair of
cubes from it. Then I copper plated one side of each cube and soldered
it onto the remains of the original brush, which just acted as a
mounting spring.

The commutator segments had also been cut through, so I flattened some
copper wire and made some grossly oversized segments which I fixed in
place with epoxy resin. When everything had set hard, I mounted it in
the chuck of a small modeller's drill under a microscope and used a
jewellers file to shape it back to size. The final trimming was done by driving the shaft from the far end and mounting the commutator end in a temporary bearing to keep it exactly concentric.

The motor caried on working for a long time after that and its
performance didn't seem to suffer from the extra resistance of the
carbon brushes.

(We are talking about a very long time ago, when small motors were
almost unobtainable and I had no money to spare.)


--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

In article <1pmtldd.105m2vn1p4x1naN%liz@poppyrecords.invalid.invalid>, liz@poppyrecords.invalid.invalid says...

John Sabino <valuablebook@gmail.com> wrote:

I've missed out on the beginning of this thread, but I had a problem
with worn phosphor bronze leaf brushes on a small motor many years ago.
They had worn right through and the ends had fallen off. I took an
ordinary carbon brush from a much larger sized motor and cut a pair of
cubes from it. Then I copper plated one side of each cube and soldered
it onto the remains of the original brush, which just acted as a
mounting spring.

The commutator segments had also been cut through, so I flattened some
copper wire and made some grossly oversized segments which I fixed in
place with epoxy resin. When everything had set hard, I mounted it in
the chuck of a small modeller's drill under a microscope and used a
jewellers file to shape it back to size. The final trimming was done by driving the shaft from the far end and mounting the commutator end in a temporary bearing to keep it exactly concentric.

The motor caried on working for a long time after that and its
performance didn't seem to suffer from the extra resistance of the
carbon brushes.

(We are talking about a very long time ago, when small motors were
almost unobtainable and I had no money to spare.)

That's a great story; I especially like the successful copper plating!

Conversely, in the early 1960s, I was trying to recondition a 9.5mm
projector (https://en.wikipedia.org/wiki/9.5_mm_film) and after fixing
the mechanics the motor commutator developed a fault.

I had access to company (I was an apprentice) supplies and machinery,
and was allowed to purchase a short lenth of copper rod 1" diameter. (I
don't remember the price but I only needed a few mm length and have
0.565kg left!) I turned a brass central bush, a mandrel to mount it on,
and a short copper tube for the commutator.

See
https://drive.google.com/file/d/15GOegJInJUCxQbS8BduOh73JMqEuaF3t/view? usp=sharing

I don't remember how I kept it all concentric while I filled the gap
between bush and tube with epoxy. But when I started using a
dividing/indexing head to start slicing the copper into the (IIRC) 14
segments, the adhesion failed and th segments fell off; see photo!

At which point I'm afraid I gave up on the projector!

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)