[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: (ET) Another mower motor blows.
On 12 Jun 2018 at 19:56, Charlie wrote:
> Steve Naugler figured out how to reglue the magnets, I think.
Here you go.
=====
>From a message of 8 July 2001:
I've epoxied magnets on two motors successfully. One was a 3-1/2 inch
diameter GE mower deck motor, the other was a SAAB convertible top
hydraulic
power pack motor, and on it the magnet was cracked into 4 pieces. In
neither
case were the cases rusted. Both have been in service for more than four
years, so I believe the repairs are permanent. I don't think you have
much
to
lose by trying.
I used whatever epoxy I had that was not a fast cure. First, I made sure
that
all surfaces were meticulously clean. After the epoxy was hard for 24
hours
I
post cured for another 24 hours on top of one of those portable liquid
filled
electric heaters that look like a radiator, which was set on low. I think
that a post cure can be beneficial because some epoxies soften when they
get
hot the first time after their initial cure.
I learned this from reading about composite homebuilt aircraft, and
virtually all I have read states that a post cure of epoxy structures is
mandatory in critical epoxy/fiberglass structures. Is this an old aircraft
homebuilder wive's tale? I can't say, but I have had good luck with this
technique when several local motor shops will not reglue under any
circumstances. I suspect that they cannot tolerate a failure rate of 5 to
10
%, where we GE tractor folks would be tickled with a success rate of 90 to
95%.
=====
>From 11 June 2004:
I was able to repair both of those motors with epoxy. I used the normal
cure
high strength like you can find in Home Depot, but do not use the 5 minute
stuff. It cures faster at the expense of lower strength.
I VERY, VERY thoroughly cleaned the motor shell and the magnet with
solvent,
smeared the epoxy on, and placed the magnet back in its original postion.
This
may take some doing because sometimes the magnets will fight you. You need
enough epoxy to leave no gaps between the magnet and the shell, but as
little
as possible so that the magnet is as close to the shell as possible.
You will want to clamp the magnets in position for a two reasons.
1. The first is that once glued you can't get the magnet off. You need to
get the right position the first time.
2. The second is that you actually want extra epoxy to be squeezed out.
It
is important that the magnets are as close to the shell as possible. Use a
spring clamp so that clamping force is maintained as the magnets move
closer
to the shell.
Now wait for the epoxy to cure hard, at least overnight. The clamps can
come
off and they stay off.
Think you're done? Nope. This epoxy will be highly stressed, so I
recommend a post cure. What I did was place the shell on one of those
electric oil filled radiators set on low, covered the shell with a box
making a mini oven, and let it stay there for 24 hours. The shell reached
about 150 to 160 degrees and stayed there for the entire time.
You can also use a kitchen oven if your spouse or significant other will
let
you. (Mine didn't, hence the radiator style heater.) Use two cookie
trays,
one on the lower rack, and one on the upper rack, Place the motor shell on
the upper tray. The lower tray protects the motor shell from radiant heat
which could get the shell too hot. Set the oven to warm, and "bake" for
12-
24 hours.
Bill Gunn had bad luck with fixing magnets, so he wouldn't do it at all
after a few failed attempts. But in Bill's case a 25% failure rate would
have
been intolerable. In our cases, if the option is trashing the motor shell,
I'd go for it.
Steve Naugler
=====
David Roden - Akron, Ohio, USA
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Note: mail sent to the "etpost" address will not reach me. To send
me a private message, please use the address shown at the bottom
of this page : http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =