Hi Willib.
The round coils are 2 and 3/8" on the outside diameter and have a 1.5" center hole that matches the magnets. They are .25" thick.
I hade found an odd dual rotor disc type motor. It came with 8 round NEOs per disc. So i'm acomidating it size with these coils sizes.
Funny thing. I'm using 18 gage for the large coils and 24 gage for the small coils.
The round coils weigh 3 oz. each both wire gages. Same for the small 1"X1/2"X.25" coils they weigh 1 oz. each.
I wanted the coils to be the same phisical size, weight the same and have a 4 to 1 turns ratio.
Turns out 18 gage is 1624 circular mills and 24 gage is 1/4th that at 404 circular mills.
I'm in the prosess of building the 4ft Hugh machine. It calls for 85 turns of 16 gage. I will also be winding coils for it from 22 gage at 340 turn per coil.
I'll most likely test the first machine when done then move onto the next, rather then building all 4 then testing.
JK TAS Jerry