Power transformer mounting bolt stuck in varnish???

[Structo]

Years ago when I was into hot rod Chevys I had my share of broken bolts.

Not once (well maybe once) did I ever have luck with those easy out type bolt extractors.

In fact as mentioned I broke most of those off in the bolt trying to unscrew it.

If it was just rusted in there I would use a penetrating oil like Liquid Wrench but since it is the "lacquer" holding the screw in there the only thing to try is what you did with the solvent.

But, did the acetone actually dissolve the lacquer?
If it is some kind of polyurethane then acetone may not touch it.
Not sure a drill press would even drill it out without wandering and make a mess of the laminations.

Tough call but I know what you are going through, that stuff bugs me too!

[billyz]

If you have one of those Gun Type Solder irons you could separate the tip and touch each end of the broken bolt to heat it up. I bet it would let go with a little tap on one end. Or heat up each end with a solder iron one at a time going back and forth. Let the heat work for a minute or two.

[Structo]

Is the screw or bolt threaded into the transformers?
Or is it just stuck with the coating?

Can you use a drift punch and drive it out?

[dehughes]

The deal is that the bolts are installed in the PT before it is vacuum impregnated with varnish, then heated in an oven. As such, the bolts are thoroughly saturated with the varnish, the entire length of the PT. What's more, the PT is very deep, so there's a lot of area for the bolt to be securely stuck.

Heat was suggested, but I was told by the vendor not to use heat or chemicals, as that might do more harm than good. A drift punch slightly smaller than 1/4" was suggested, but that seems like it would also do more harm than good, being as one would have to use such force to remove the bolt in lieu of an acetone or heat application.

So, it seems that I'll just stick with the epoxied bolt repair for now, and then for the future never purchase a tranny with the bolts set in as these are. I'd risk tinkering with the PT if I didn't have an amp show coming up a week from today.....figures...

Thanks for the suggestions! Next time I'll substitute knowledge for tinkering....

[C Moore]

Is this a PT that is out of the chassis? Can you grab onto the bolt at all, wrench, vise grips etc.? If so, you may try wrapping the PT in a rag, then in a plastic bag, then into the freezer for a few hours. The cold might change the physics enough to allow removal of that bolt.
Good Luck

[dehughes]

Is this a PT that is out of the chassis? Can you grab onto the bolt at all, wrench, vise grips etc.? If so, you may try wrapping the PT in a rag, then in a plastic bag, then into the freezer for a few hours. The cold might change the physics enough to allow removal of that bolt.
Good Luck

That'd work, but remember...I sheared off the head of the bolt (and about 3/4" of neck as well) AND I sheared off the tail of the bolt as well (right at the start of the laminations). SO, there is NO part of the remaining bolt sticking out to which one might grab.

However, I checked the epoxy today and it looked to be super hard, so I cut all the bolts to about 1/2" (protruding out of the bottom of the PT). I used a hacksaw on the three "good" bolts, and a dremmel with a cutting wheel on the "sketchy" bolt. The epoxy held up just fine, and I installed it without issue. So far, so good! Looks to be holding....I'll wire it up tomorrow (Lord willing) and without further tinkering (please Lord willing...).

Check out the pictures...the "sketchy" bolt is the one underneath the power cord. Talk about a tight fit! I almost had to take out the DC supply to get it in!

[dano-rator]

And now up to the fourth floor window for the stress test.

Dan

[M Fowler]

Well the SLOclone guys remove all varnish and polish their trannies to such high quality, so how do they do it? Buy unvarnished trannies?

Just like cleaning rifles packed in that crap to seal them from rust I use disc brake cleaner it eats through no problem. Brace the bottom of the transformer iron all around, take the drift punch and knock it out. When they heated up the metal besides the varnish it also caused the bolt to become so tight against the plates. You can buy replacement bolts in either plastic or metal. Got an Arbor press.

[dehughes]

HA. Stress test...I think I was the one undergoing the stress test....

As for arbor presses, etc... I'm going to leave this one alone, as it seems to be all good so far. Lesson learned...

I do get the gun cleaning analogy, though. First thing I did with the last gun I purchased was disassemble it completely and really go through it. It's as smooth as can be, now...

[Funkalicousgroove]

Have you tried a heat gun? Or baking it at around 200 degrees to soften the varnish? may work-

[dehughes]

Have you tried a heat gun? Or baking it at around 200 degrees to soften the varnish? may work-

Nah...I opted out of further "treatment" after speaking with the vendor.