Harden them, i believe that carbon content is very low, steel for transformers is infused with silicium to aid magnetic abilitys
Please do not use chemicals...acid...or vinegar or coka cola .. ...look at the picture, I easily cleaned the rust Very easy and in little time /
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I tried everything. Water had caused 60 kilos of my new core to rust in a week. This was the only thing that worked without removing the coating.
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I tried everything. Water had caused 60 kilos of my new core to rust in a week. This was the only thing that worked without removing the coating.
Citric acid is more effective than vinegar, it does smell less, and it is also better for the environement when you pour the residue in the drain.
To remove rust from small hardware, such as screws and nuts from vintage gear, I put a teaspoon of pure citric acid pulver in warm water inside a transparent glass container, then I drop a small amunt of rusted screws, nuts etc inside. They need to be completely submerged. Then I place the container in the microwawe owen at full power (750w) for 10 seconds, and I check if the reduction reaction has started (gas starts to bubble - do not boil). 10 seconds is not enough to overheat and damage the magnetron, and since the metal is submerged there will be no arcing. It may be required to repeat the heating a few times to start the reaction. The reaction does not smell, so the microwave owen can still be used for the intended purpose afterwards. The main reaction products are carbon dioxide, water and a iron citrate complex. When the reaction speed slows down, I stir the container and put it again in the owen. The rust is being dissolved aggressively and in a short time is gone. I then rinse screws and nuts with water and put them in a small ultrasonic cleaner filled with warm water with a drop of dish soap. This removes the residues; after another rinse with water I dry the screws with a cloth then I place them in a ziplock bag. I spray WD40 inside the bag to cover the surface with oil. This is important because after the treatment the Fe surface is completely naked and will oxidise and rust in just a few hours if left untreated. If painting is required instead, it must be done immediately. The end result is very good. Brass parts looks like copper with this treatment, and whats left of the original paint is mostly stripped away. Do this at your risk.
To remove rust from small hardware, such as screws and nuts from vintage gear, I put a teaspoon of pure citric acid pulver in warm water inside a transparent glass container, then I drop a small amunt of rusted screws, nuts etc inside. They need to be completely submerged. Then I place the container in the microwawe owen at full power (750w) for 10 seconds, and I check if the reduction reaction has started (gas starts to bubble - do not boil). 10 seconds is not enough to overheat and damage the magnetron, and since the metal is submerged there will be no arcing. It may be required to repeat the heating a few times to start the reaction. The reaction does not smell, so the microwave owen can still be used for the intended purpose afterwards. The main reaction products are carbon dioxide, water and a iron citrate complex. When the reaction speed slows down, I stir the container and put it again in the owen. The rust is being dissolved aggressively and in a short time is gone. I then rinse screws and nuts with water and put them in a small ultrasonic cleaner filled with warm water with a drop of dish soap. This removes the residues; after another rinse with water I dry the screws with a cloth then I place them in a ziplock bag. I spray WD40 inside the bag to cover the surface with oil. This is important because after the treatment the Fe surface is completely naked and will oxidise and rust in just a few hours if left untreated. If painting is required instead, it must be done immediately. The end result is very good. Brass parts looks like copper with this treatment, and whats left of the original paint is mostly stripped away. Do this at your risk.
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Good to know, ill leave them soft. If I were to harden them, they would be very fragile and prone to fracture as well.
Alot of talk about the coating. I think the rust has already compromised the coating to some degree. So for now the plan is to strip, and re-coat them. But like all things, this to may change.
Use 'Rustolene' on rusty plates.
Or get liquid WD40, sold in 5 liter cans. Spray is too expensive.
Or see equivalent products.
Just dip, leave for some time, drain off, carry on.
Do not try anything agressively chemical, that would spoil the surface, or distort flatness.
Or buy another set of laminations, no more than 0.40 mm thick CRGO grade laminations, used for transformers.
Heating will cause warpage, do not try that.
Or get liquid WD40, sold in 5 liter cans. Spray is too expensive.
Or see equivalent products.
Just dip, leave for some time, drain off, carry on.
Do not try anything agressively chemical, that would spoil the surface, or distort flatness.
Or buy another set of laminations, no more than 0.40 mm thick CRGO grade laminations, used for transformers.
Heating will cause warpage, do not try that.
Sorry to stray from original topic, just an idea here. Not sure how much heat in the transformer effects sound, but I was thinking, it's an I/E core, what if I replace every say 10 or 15 ( I ) plates, with inverted ( E ) plates extending up. Would act like a heat sink. But also may pick up noise?
I've stripped rust from a number of hand tools with vinegar and have never witnessed any corrosion due to the treatment. Most recently, last winter when I had a run of outdoor control systems come under contract. Each and every installation was in the rain at around 40°F. As you might imagine, at 59 y/o and after 7-8 hours of working in those conditions, the first thing on my mind afterwards was certainly not cleaning, drying and oiling tools. I dealt with the inevitable rust later... sometimes several days later. I also found a nice pair of garden pruners that had been lost and spent 8-10 months outdoors. They looked like a loss but 3 days in a jar of vinegar, a thorough brushing and oiling, they were put them back into service. I'm not sure how much difference there might be in tool steel and tranformormer laminations, but I would try a test piece as follows.
Place a lamination in vinegar and give it a brushing every hour or so until satisfied. Rinse thoroughly with water (you can use a baking soda/water dip followed by a clean rinse), dry thoroughly and immediately wipe on thin coat of mineral oil. Any excess oil can be wiped off with a paper towel or left as is. Just prior to spraying with lacquer (or whatever) clean with the solvent of your choice. I use acetone for most paint prep.
Place a lamination in vinegar and give it a brushing every hour or so until satisfied. Rinse thoroughly with water (you can use a baking soda/water dip followed by a clean rinse), dry thoroughly and immediately wipe on thin coat of mineral oil. Any excess oil can be wiped off with a paper towel or left as is. Just prior to spraying with lacquer (or whatever) clean with the solvent of your choice. I use acetone for most paint prep.
Clean the laminations, assemble transformer, paint only what is exposed to atmosphere.
Damaged cores will pick up noise.
Use only clean flat cores.
You can gently rub cores on silicon carbide paper, 600 or finer grit, kept grit side up, supported on newspaper kept on a flat stone, tile or metal surface.
Clean up with a dry rag to remove abrasive residue.
The newspaper layer, if at least 20 mm thick, is nearly surface plate quality in flatness, important here.
Also, before painting, you can varnish the assembled transformer with motor or transformer grade varnish, it fills the gaps in the laminations.
Furniture varnish works in an emergency.
Damaged cores will pick up noise.
Use only clean flat cores.
You can gently rub cores on silicon carbide paper, 600 or finer grit, kept grit side up, supported on newspaper kept on a flat stone, tile or metal surface.
Clean up with a dry rag to remove abrasive residue.
The newspaper layer, if at least 20 mm thick, is nearly surface plate quality in flatness, important here.
Also, before painting, you can varnish the assembled transformer with motor or transformer grade varnish, it fills the gaps in the laminations.
Furniture varnish works in an emergency.
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Yeah I was thinking about lapping them with 600, or 800 grit on one of My telescope mirror blanks. The most flat thing I have.
Don't use a glass flat, not worth it for a damaged lamination.
Too much chance of damage.
Use a newspaper layer, like I suggested.
Too much chance of damage.
Use a newspaper layer, like I suggested.
I would, but I don't have 2mm of newspaper let alone 20mm, and they aren't optical flats. Just disks of different types of glass blanks. That Will be ground eventually into newtonian mirrors. One is a nice 8" BK7 blank, that should work.
Evapo-Rust works well. If you have rust, the coating is already damaged. This thread on insulation might be useful- https://www.diyaudio.com/community/threads/need-to-insulate-e-i-laminations.342344/
For a flat even finish with limited access to tools, I'd dry lap them flat on a scrap piece of float/window glass with fine grit paper. Then a use spray can paint/varnish for a thin even coating. But for the time and cost involved I'd prefer to scrap it and buy new.
Yeah, thinking about getting new. I cant find anyone selling small quantities. They had minimal 200 pound requirements. Any suggestions?
We get ready sections for transformer cores in standard sizes here in India.
But considering that you need a small quantity, either you salvage this lot, or buy a new, better, transformer.
Finding a small quantity of good flat electrical steel is difficult, ask around for sources.
My city is a big center in India for distribution transformers, and I know that there are many grades and thicknesses of that material. It is much more expensive than standard low carbon steel or roofing steel.
But considering that you need a small quantity, either you salvage this lot, or buy a new, better, transformer.
Finding a small quantity of good flat electrical steel is difficult, ask around for sources.
My city is a big center in India for distribution transformers, and I know that there are many grades and thicknesses of that material. It is much more expensive than standard low carbon steel or roofing steel.