I was not by any means suggesting a crude, cobbled up substitute transformer. Not one bit! I am questioning the process of winding a coil of transformer grade steel around a completed set of transformer windings, and the possibility of it being done well at a reasonable production rate.

I’m thinking it must be some very thin silicon-iron foil, and I wonder if the foil is would onto a bobbin, the way the clip-together two-part bobbins are used in R-cores.
If the iron is very thin, then the core losses should be good.

 

The claim I read is that the core is wound on AFTER the copper wire is wound on the plastic bobbin. THAT is the basis for my questioning.

 

RE:""
What would I discover if I constructed a 20 pound transformer
"" - You`ll get the pancake cooker instead of transformer. But pancakes sure will be cooked in 50 Hz magnetic field. Taste it, and then tell us, do their taste was another or just as always.

 

I am very skeptical as to the truth relative to the claim that the cores are wound after assembly. consider the challenge of repeatedly feeding that steel strip thru a constantly narrowing gap, and then pulling it snug. It simply makes no sense that it would be done that way in a profitable manner.
The cores I have, which were produced about 40 years ago, do not appear to have gaps when they are placed together.
I have not yet done the aluminum foil crush test yet to confirm that, but the appearance and feel is that of two llapped surfaces touching.
A video of the machine claimed to do it would be very interesting, also hard to believe.

Here is a link to a DIY Coil Winding Machine.
https://hackaday.com/2020/06/05/homebrew-coil-winder-makes-toroids-a-snap-to-wind/
(I think it is modelled on this industrial device, but I am not sure where it came from.)

 

Presently I am trying to figure a method for unwinding the high voltage secondary of a MWO transformer without cutting thru every tun and making all of that wire into scrap copper. That is certainly a waste with the current price of copper wire.

 

If it does not have a weld bead across the laminations, I have simple removed the screws and taken apart the E/I laminations, re-move/rewind the required secondary and replaced the laminations, bit of a pain, but easier to wind.

 

They all appear to have welds. BUT I may be able to remove the weld on one using a cutoff wheel. That would work much better if the cutoff wheel were held by an end mill and the transformer clamped to the table. But I don't have a milling machine.
Does anybody near 48067 know where I could borrow one for a few minutes??