[AT] Coating for small engine mag

[Mike M]

Care to explain further? Can rust re-channel the shape of the magnetic 
field as to make it less available? Too many real world experiences to 
simply dismiss it.

Mike M


On 12/8/2017 12:25 PM, Rena Glover Goss 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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