OT-Carbon brush problem
 

My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Ted

Ted Edwards wrote:

My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Here's my idea, may make sense, hope it's clearly stated (I seem to be writing
unclearly lately). What if you made up a little sleeve of copper that just slid
around your wire, and counterbored the back side of the brush so the sleeve
could slide into it (but would be restrained from sliding through by the base of
the counterbore). Then put the sleeve in one side, put your lead in through the
other side, and solder the lead to the sleeve on the backside. Once installed,
hopefully something would keep the sleeve/lead assembly from pulling out the
back -- maybe the side of a slot or something.

Grant Erwin

In article ML%se.62966$HI.20551@edtnps84,
Ted Edwards wrote:

My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

Do the leads come out on only one side? If so, one could find a side
lead brush and file it down. Or a large top lead brush, and cut a
smaller side lead brush out using a small handsaw.


My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

I recall that the leads are inserted into the brush material before it's
pressed and cured, as a part of the original manufacture. I suspect
that one cannot later attach the leads. I've never seen a brush that
didn't have molded-in leads, although I wasn't looking.

Joe Gwinn

"Grant Erwin" Once installed, hopefully something would keep the
sleeve/lead assembly from pulling out the back -- maybe the side of a slot
or something.
^^^^^^^^^^^^^^
Good idea. To secure the copper sleeve, how about flaring the hole on both
sides, and filling the flare spaces with the same solder used to hold the
wire in the copper tube. Another idea would be to flare the copper tube
with a punch (gently.) A third possibility would be to cement it in with
the liquid that is used for repairing the rear window defroster grid on
cars. It's kind of a "correction fluid" consisting of copper dust suspended
in a varnish.

Ted Edwards wrote:
My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

Ted

I'd try silver bearing conductive epoxy. It's saved my arse more than
once when I had to make a low resistance electrical connection to
something I couldn't solder because the heat would damage what it was
attached to, or the metal was difficult to solder to. (Think aluminum.)

I have no idea how well it would bond to carbon though.

IIRC in the olde days stranded leads were attached to brushes by setting
them into an oversized hole and then tamping fine copper powder down
into the hole around the wire. They must use something like hollow
punches for that operation.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

I recall that the leads are inserted into the brush material before it's
pressed and cured, as a part of the original manufacture. I suspect
that one cannot later attach the leads. I've never seen a brush that
didn't have molded-in leads, although I wasn't looking.

Joe Gwinn

I seem to recall from A&P school brush pigtails being pressed in and
cured in as Joe describes... a really specialized process I'm sure.

Starter brushes move a lot of amperage... this one might take some
thought. Can't think of a much better place to ask than here though.

I bet there are company's out there specializing in making up brush
assemblies... there must be.

Good Luck!

Erik

In article ML%se.62966$HI.20551@edtnps84,
says...

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.


How big? I've got a bagfull of replacement brushes that
came in a box of stuff from a surplus auction at the nearby
Naval Air Station. The leads appear to be swaged in and
they look to have a much higher ratio of carbon to copper
than typical high current brushes. On a hunch I whacked one
with a BFH and put a pretty big divot in it rather than
smashing it. They're .343 x .375 x .690, not including the
bump where the leads attach. If you want to experiment,
email me your address and I'll pop a few in the mail.

Ned Simmons

In article -
maine.net, says...
In article ML%se.62966$HI.20551@edtnps84,
says...

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and
mechanically satisfactory way? Suggestions please.

they look to have a much higher ratio of carbon to copper
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Should read, "higher ratio of copper to carbon."

Ned Simmons

On Sat, 18 Jun 2005 18:46:59 -0400, Joseph Gwinn
wrote:

In article ML%se.62966$HI.20551@edtnps84,
Ted Edwards wrote:

My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced.
Brushes have been backordered with delivery expected sometime maybe.
Now, it's easy enough to get some brushes that are a little too large
and file/sand them down to size but the copper flex lead needs to be
attached such as to come out the side. A very unusual arrangement
indeed but there it is.

Do the leads come out on only one side? If so, one could find a side
lead brush and file it down.

Jerry Martes could certainly find you some side lead brushes, though
you might have to file them down to fit. He was in the alternator
repair biz for years, "has sources". I'm sure he'd be glad to
help.

Erik wrote:

snipped

I bet there are company's out there specializing in making up brush
assemblies... there must be.

Good Luck!

Erik

Here's one I used a long time ago. They say they'll make as few as ONE
custom brush. (But at what price?)

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Motorcycle starter brushes are side lead and come in a number of different
sizes. Go to a non dealer repair shop. He probably has a bunch of assorted
sizes in his tool box. Maybe something you can cut to size.
Karl


"Ted Edwards" wrote in message
news:ML%se.62966$HI.20551@edtnps84...
My neighbour has an elderly but still excellent Johnson outboard. The
starter brushes are worn to the point that they must be replaced. Brushes
have been backordered with delivery expected sometime maybe. Now, it's
easy enough to get some brushes that are a little too large and file/sand
them down to size but the copper flex lead needs to be attached such as to
come out the side. A very unusual arrangement indeed but there it is.

My question is, having drilled a hole and inserted a suitable flexable
lead, how do I fasten it into the hole in an electrically and mechanically
satisfactory way? Suggestions please.

Ted