What is the science behind baking coils?

[davidwyby]

Recent experience :

266xp fresh build stalls in cut | Outdoor Power Equipment Forum (opeforum.com)

I have a handful of bad coils now, I'm gonna try baking (again). 266, 2139, 2166. I once baked one for a 266 and it came back and quit again. Side note: 250* right?

So what's going on while baking? Expansion and contraction making better contact? Cooking moisture out? We don't have much of that here...

 

[cuinrearview]

Have you tried half baking them?

 

[Stump Shot]

Recent experience :

266xp fresh build stalls in cut | Outdoor Power Equipment Forum (opeforum.com)

I have a handful of bad coils now, I'm gonna try baking (again). 266, 2139, 2166. I once baked one for a 266 and it came back and quit again. Side note: 250* right?

So what's going on while baking? Expansion and contraction making better contact? Cooking moisture out? We don't have much of that here...

It melts the googha that's around the windings that is cracked and leaking, once resealed will function properly again.. This of course is only for really old points type for the most part we're talking about.
Modern coils have electronics inside them and this is usually what has failed, there's no amount baking going to bring them back.

 

[davidwyby]

@Stump Shot thanks, interesting. So the 266 I baked was actually what I think is the trigger by the flywheel. I had gotten it wet, maybe I just dried it out…and then it quit again.

Probably no point in baking the 2139, 2166, etc.

 

[Stump Shot]

@Stump Shot thanks, interesting. So the 266 I baked was actually what I think is the trigger by the flywheel. I had gotten it wet, maybe I just dried it out…and then it quit again.

Probably no point in baking the 2139, 2166, etc.

Not much, today's coatings are much different and aren't going to melt.

I've found that on 266's(if it hasn't been messed with that is) once one goes out(original) the other won't last very long(here again original) weeks to a month depending on use. I just replace both now and a good spark is the end result and no repeat drama with no spark.

 

[davidwyby]

@Stump Shot you mean both trigger and coil right?

 

[Maintenance Chief]

Weird thing but my cousin who used to work for Samsung was baking a lap top in his oven one time and he told me that he was soldiering the board for the screen. Apparently whatever brand this was had pretty crap soldering connections and baking it at a certain temperature melts the solder and fixes the connections.
Ive baked a Blue homelite super Ez coil that fixed it. 250 for 45min.

 

[huskihl]

Weird thing but my cousin who used to work for Samsung was baking a lap top in his oven one time and he told me that he was soldiering the board for the screen. Apparently whatever brand this was had pretty crap soldering connections and baking it at a certain temperature melts the solder and fixes the connections.
Ive baked a Blue homelite super Ez coil that fixed it. 250 for 45min.

Not nearly long enough for prime rib, but probably about perfect for thick steak

 

[davidwyby]

Meathead

 

[Stump Shot]

@Stump Shot you mean both trigger and coil right?

Mmmhmm

 

[Sawrain]

Weird thing but my cousin who used to work for Samsung was baking a lap top in his oven one time and he told me that he was soldiering the board for the screen. Apparently whatever brand this was had pretty crap soldering connections and baking it at a certain temperature melts the solder and fixes the connections.

Reflow soldering.

 

[blacksmith]

The reason for baking as stated above is to get the moisture out.

When it's cooled to around 125⁰ then after that what you need to do is to put it into varnish under vacuum (-30psi) for about 40 mins then under pressure (72 psi) for 40 mins. After the dip process put it back in the oven to cure the varnish.

Above is the process for what I do at work when dipping motors, stators, coils and armatures. The heat is 300⁰ for 10 hours bake for impregnation and 12 hours @300⁰ to cure the varnish.

This is the process that I do for our components and the varnish that we use.

The temperature I am sure will be much lower for such a small coil that has a plastic case. You can also buy varnish that is air cured as well.

 

[Basher]

I have a friend and next door neighbor, type of guy that won`t easily give in and buy a new part until he exhausts all avenues he can think of , plus he`s a Scott. He has been having running issues with his saw for more than a month now, I told him it was spark related around the time it first began acting up, would loose spark soon as it warmed up, wouldn`t re start til it cooled off. He has thoroughly cleaned the saw, needed that, sanded the flywheel, sanded the coil lamination's, reset the coil air gap, checked the switch and wiring over and over. First he watched a bunch of YouTube videos , one showed where spinning the saw over in reverse using a drill, must turn at least 2 thousand RPM was supposed to fix it, didn`t. He seen where baking the module would fix it and did bake it this past week, showed up at my place all excited with the news that it was fixed but it failed after one cut. We put the new module on and it ran both Sat and Sunday, first time in over a month of messing around. Morale of this story, don`t believe all the fixes you see on, YouTube.

 

[Al Smith]

I can only remember one coil failure on a points ignition McCulloch 10 series .I gave a little time in the oven, tested it then sprayed it with Glyptol . As been mentioned on a solid state once the internals fail they are pretty much toast .
I've dried out tractor mag coils a time or two also .One was an Issiacson mag on a 1943 Cat D4 I had to unwind about 3 layers of winding to find the open .Blind luck but I got it finally .Prior to I used two battery coils through the points with a dry cell lantern battery to power them on the pony motor which worked just a pain the buttocks to do . Nothing is impossible but on something they have not made replacement parts for 70 odd years you might have to get creative .

 

[Basher]

Many of the old points/coil blue Prestolites were brought back to life by baking them at 250F overnight or around 12 hours to drive off moisture. If the saw and coil was kept in dry condition it would do its job of producing high tension current but if left sitting in damp places it would fail again. On a couple I did for myself I dropped them in a bucket of 30 wt while still warm out of the oven, let them absorb oil for a day or so and after reinstall they still work on my Pioneers.