Painting Crack Transformer

[Herrfish]

I'm waiting for delivery of my kit and am wondering about painting the transformer plates themselves. Can they be painted without problem? Will they require high temp paint or priming? Thanks for your help.

[jrihs]

I think you should if, like mine, it comes with some nasty, dried snot looking stuff stuck to it, and a very dull look as well. I spray painted mine black and it looks great. I didn't paint the top plate but only polished it. Sand w/ a orbital sander the sides of the transformer to the desired smoothness and spray paint whatever color. I Alternated light sanding and painting, especially if a coat got on to thick. I took care to keep the edges nice and sharp looking. Do 2-3 coats of paint, drying completely between. Does not take much paint. think I used flat or semi-gloss...I forget but love the results.

PS...I used regular krylon

[porcupunctis]

The transformers get warm but not "paint-blistering" hot.  I've seen some pictures of builds where the transformer plates were painted and as far as I can recall they used Krylon or Rust-O-leum.  

On one build, I used a bondo-like substance to cover the plates and smooth them out.  I then painted that with slate-gray rust-O-leum.  There are a lot of hours on it and no problems.

Since then, I just use a gun bluing treatment on the bell and leave the plates as they are.  I start by removing all the paint from the bell and smoothing the metal with steel wool until it is pretty shiny.  It's a nice simple look that is fairly easy to do.  

If you paint, give it plenty of time before you try bolting it all back together.  A good long "cure" will save you a lot of chips and frustration.  

[Paul Joppa]

The transformers are vacuum impregnated with some kind of "varnish" - probably NOT the stuff your grandfather called varnish, though! That's the dried snot-like substance.

I would advise against sanding or otherwise mechanically attacking the core material. Some materials are sensitive to mechanical shock, losing some of their magnetic properties, and the laminations are slightly insulated from each other in order to reduce eddy currents.

[Grainger49]

IIRC, Wardsweb filled the outer laminations and smoothed them on his SEX amp.  It is a different way to get to a smooth finish.

[Herrfish]

Thanks for the advice. Sounds like I can paint them without causing any harm.

[jrihs]

I would advise against sanding or otherwise mechanically attacking the core material. Some materials are sensitive to mechanical shock, losing some of their magnetic properties, and the laminations are slightly insulated from each other in order to reduce eddy currents.

Thanks Paul, you don't think I did any damage sanding off that varnish do you?

[Paul Joppa]

I would advise against sanding or otherwise mechanically attacking the core material. Some materials are sensitive to mechanical shock, losing some of their magnetic properties, and the laminations are slightly insulated from each other in order to reduce eddy currents.

Thanks Paul, you don't think I did any damage sanding off that varnish do you?

I can't say. Probably not, but there is a non-zero possibility. Heat would be the most likely symptom. The Crack transformer gets pretty darn hot in normal use, but if it seems excessive we can do a temperature measurement to be sure. It's quite simple, you just measure the resistance of a winding cold and hot, and calculate from the resistance temperature coefficient. It takes 2 or 3 hours for a transformer to get up to full temperature. Here's a link: http://www.allaboutcircuits.com/vol_1/chpt_12/6.html

[jrihs]

Ok, thanks again, I would say it gets hot, but not that hot. I will check with the info you provided.
Heck, I figured I was just makin it a bit more like my minimax, and couldn't have taken more than a nano-milli-micrometer off under the grime..er...paint, if that even. wow...who da thought! (guess not me anyhow)

BTW, that's a great link ! thanks mucho

[i luvmusic 2]

Is it safe to Powder Coat the Transformer?

[Paul Birkeland]

Is it safe to Powder Coat the Transformer?

No.  The powder won't stick well to the transformer's varnish, and the 400 degree oven will melt that varnish (and plastic bits).

[i luvmusic 2]

No.  The powder won't stick well to the transformer's varnish, and the 400 degree oven will melt that varnish (and plastic bits).

Ok THANK YOU!