[AT] Coating for small engine mag

Fri Dec 8 14:07:14 PST 2017

I have experienced this many times no spark and shine the magnets and coils
and presto it now works. 

Bruce Fallon
Langley, WA 98260

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Mike M
Sent: Friday, December 08, 2017 11:30 AM
To: Antique tractor email discussion group
Subject: Re: [AT] Coating for small engine mag

All I can tell you is this. I had a very weak, almost not existent 
spark, and a rusty magnet. I shined up the magnet and the coil leads, 
and I instantly had a very strong, very visible spark. What else could 
it be, the only variable that changed, was that the rust was gone, I 
made no other changes.
Mike M

On 12/8/2017 2:02 PM, Ken Knierim wrote:
> Larry,
>       With all due respect, maybe I misunderstand your statement but
> electric materials are, by definition, insulators. Please see
> https://en.wikipedia.org/wiki/Dielectric
>
> Magnetic fields and electric fields are certainly different. There are no
> magnetic insulators, but there are lossy materials. Red rust is generally
> an iron oxide and it's not the same as the silicon steel generally used in
> transformer laminations in a few key respects. It has hysteresis that
> translates to magnetic losses in a varying magnetic field (the same field
> that induces electricity in the winding that creates the spark). It also
> can affect the fringing fields which define how far the fields extend.
>
> Straight iron (such as rust from the steel laminations) can be charged
with
> magnetism. Hit a nail (or a magneto magnet) with a magnetic field and it
> will retain a certain amount of the magnetism. The silicon steel in the
> laminations is designed to resist this or it would charge up and resist
the
> change of the magnetic field on the next rotation. So there is loss and it
> dissipates energy lost charging and discharging the iron into a magnet as
> heat.
>
> If rust sticks to a magnet, it is interacting with a magnetic field. It
> will also channel the field as you note, and if it's not channeling the
> correct direction you'll also get degradation of the field. This isn't
> usually significant when running but during startup it's most needed and
> most detrimental.
>
> Cleaning off the rust and putting a light coating of a rust-preventing,
> dielectric coating (many great suggestions have been presented, glyptal
> used to be real common for this) is prudent in my opinion. It's not my
> stuff though.
>
> Ken in AZ
>
>
>
>
> On Fri, Dec 8, 2017 at 10:25 AM, Rena Glover Goss <rlgoss at twc.com> wrote:
>
>> Umm.  Hey guys!  This has been an interesting thread, but I think there
>> are a lot of "old wives tales" floating around on it.  Please learn the
>> difference between a dielectric and an insulator, and that magnetism
works
>> differently than electricity.  You can channel the shape of a magnetic
>> field, but there is no such thing as a magnetic insulator.  Just because
>> red rust is non-magnetic does not keep a magneto from working, and
>> polishing or painting the laminations of an electro-magnet will have no
>> effect on its operation.
>>
>>
>> Larry
>> ---- Ken Knierim <ken.knierim at gmail.com> wrote:
>>> A lot of modern electronics are potted with a very thin layer of plasma
>>> deposited PDMS. I would guess that in the case of the small engine
>> ignition
>>> parts they aren't coated as that material is a bear to make electrical
>>> contact through once it's been applied. It's tough to see too; it's very
>>> thin. It's largely replaced lacquer because of the environmental and
>>> handling issues except in potting of magnetics (they're still lacquer
>>> dipped in many cases).
>>>
>>> For me, I'd consider using some sort of lacquer, either dipped or
sprayed
>>> on heavily to prevent moisture from getting into the coil. If it has a
>>> magnetic pickup side (next to a flywheel with a magnet for instance),
>>> you'll want a light coating of something non-conductive to keep the rust
>>> off the cores as rust degrades the magnetic operation. You also want to
>>> keep this layer thin as you need to have a rather specific gap between
>> the
>>> magnet and the core laminations. The magnetic field drops off at the
>> square
>>> of the distance and a large gap can make it a bear to start.
>>>
>>> As far as the points are concerned, the newer (cheaper, "environmentally
>>> friendly") metals don't hold up well to corrosion and arcing. Arcing can
>> be
>>> mitigated by using the proper condenser (or an electronic ignition) as I
>>> remember this being a subject of my old 4-H Petroleum Power manuals (how
>>> the arc erodes the points could tell you if the condenser size was wrong
>>> and how to adjust for this).
>>> Since chromium and other materials formerly used in points manufacture
>> that
>>> resisted corrosion can be expensive and have toxic application phases
>> (like
>>> hexavalent chrome), manufacturers in this country can't use them. Silver
>> is
>>> good but very soft (and not cheap) and silver is one of the few metals
>>> that's also conductive in oxide form. (the other I can think of is ITO,
>>> indium tin oxide, which is also transparent and you're probably actually
>>> looking through it right now in your LCD computer screen.) Lots of
>> contacts
>>> (heavy AC contactors for example) use silver and other metals to provide
>>> good contact when exposed to air... these are usually costly and most
>>> ignition points are considered wear items (meaning "keep 'em cheap") so
>>> quality isn't what it used to be. So keeping them clean requires regular
>>> maintenance or a dry environment because anything that drives the water
o
>>>
>>> Sorry for all the off-topic stuff this morning. Mind is wandering from
>> lack
>>> of coffee.. Hope some of this helps someone.
>>>
>>> Ken in AZ
>>>
>>>
>>> On Fri, Dec 8, 2017 at 4:41 AM, Henry Miller <hank at millerfarm.com>
>> wrote:
>>>> I'm sure there is a reason, but I would guess cheap. These engines are
>>>> designed for machines that are expected to be replaced every 7 years or
>>>> so. If it runs that long they have their money and the customer thinks
>>>> it was reliable since it lasted that long. That it could last much
>>>> longer with just a little more cost is a bad thing.
>>>>
>>>> --
>>>>    Henry Miller
>>>>    hank at millerfarm.com
>>>>
>>>> On Thu, Dec 7, 2017, at 08:24 PM, John Hall wrote:
>>>>> I've can't ever recall encountering a flywheel magnet or a magnet
>> inside
>>>>> a magneto that was coated---must be a reason.
>>>>>
>>>>> John Hall
>>>>>
>>>>>
>>>>> On 12/7/2017 1:25 PM, Mike M wrote:
>>>>>> My wood splitter wouldn't start the other day, had plenty of gas,
>> wet
>>>>>> plug, but weak spark. I suspected rust on the flywheel, so I tore
>> it
>>>>>> apart and I was right. Cleaned it up, and now have a nice strong
>> spark.
>>>>>> Question is, can I coat the mag and coil pickups with anything to
>>>>>> prevent the rust from re-occurring?
>>>>>>
>>>>>> Thanks,
>>>>>> Mike M
>>>>>>
>>>>>>
>>>>>> -
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