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Potting compound

  • Thread starter Orrin Iseminger
  • Start date
O

Orrin Iseminger

Jan 1, 1970
0
I'm re-winding an antique coil that was used in the low tension
ignition system for a very early internal combustion engine. The
original was embedded in a potting compound consisting of tar. It has
aged and at room temperature more closely resembles brittle hard coal.
There's nothing soft and "tar-ry" about it.

I will be using a plastic bobbin for the new coil. Because the old
tar has a fairly high temperature melting point, I'm afraid to re-use
it for fear of melting the bobbin.

That brings me to my questions:

1) Where can I obtain for a reasonable price a small quantity of
potting compound, say, a pound or two? It can be thermosetting or an
epoxy type. I would much prefer something that can be melted and
poured our of the cannister, should re-winding ever become necessary,
again.

2) Where can I obtain Glyptal, either in quart quantities or in spray
cans? I'd like to give each layer of the coil a coat of Glyptal as
I'm winding.

Thank you.

Orrin Iseminger
Colton, Washington, USA
http://users.moscow.com/oiseming/lc_ant_p/index.htm
So many projects. So little time.
 
L

Lou

Jan 1, 1970
0
Hi

You could use wax or paraffin; they are cheap, good insulators and are
easy to melt. 60 years ago, before polymers were available, electronic
components were often impregnated that way.
Lou
 
H

HankG

Jan 1, 1970
0
Lou said:
Hi

You could use wax or paraffin; they are cheap, good insulators and are
easy to melt. 60 years ago, before polymers were available, electronic
components were often impregnated that way.

How about hot-melt glue?

HankG
 
O

Orrin Iseminger

Jan 1, 1970
0
On 4 Mar 2005 07:35:46 -0600,
Hi

You could use wax or paraffin; they are cheap, good insulators and are
easy to melt. 60 years ago, before polymers were available, electronic
components were often impregnated that way.
Lou

Excellent idea. Thank you.

Orrin
 
H

Harold Ryan

Jan 1, 1970
0
The melting point of wax is 36 deg C. Boiling pt is 342 degC. The flame temp
is 1250C. So you might have a problem with the wax melting in the engine
compartment.

We usually use silicone as a potting material but it can't be removed.

Harold
 
O

Orrin Iseminger

Jan 1, 1970
0
The melting point of wax is 36 deg C. Boiling pt is 342 degC. The flame temp
is 1250C. So you might have a problem with the wax melting in the engine
compartment.

We usually use silicone as a potting material but it can't be removed.

Harold
Harold --

Thank you for the good advice. I'll re-think my plans. I certainly
won't want melted wax running out of the cannister!

I didn't mention this in the original post, but this is a stationary
engine that isn't housed in a compartment. I'm not so worried about
ambient temperature melting the potting compound, but coil heat,
itself, might.

On this type of ignition system there is very little resistance. Coil
resistance is very low, so for the brief moment it is energized,
current is quite high. I expect that coil heating will be
considerable.

I suspect there was good reason to pot the original coil in something
with a high melting temperature.

Regards,

Orrin
 
R

Robert Baer

Jan 1, 1970
0
Harold said:
The melting point of wax is 36 deg C. Boiling pt is 342 degC. The flame temp
is 1250C. So you might have a problem with the wax melting in the engine
compartment.

We usually use silicone as a potting material but it can't be removed.

Harold
General Cement has a spray Red Dielectric Sealer.; insulating dope
with a high dielectric strength.
Can be used instead of Glyptal if you cannot find that.
 
O

Orrin Iseminger

Jan 1, 1970
0
General Cement has a spray Red Dielectric Sealer.; insulating dope
with a high dielectric strength.
Can be used instead of Glyptal if you cannot find that.

Thank you for the information. I appreciate it.

Best regards,

Orrin
 

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