Laminated Blades

[FunkyKikuchiyo]

Fender single coils were hand wound up til '65, then CBS auto wound them from then on. Is one superior to the other? No. I just did a '1965 strat repro set and copied the machine wound I found on a '65 and they sound awesome. You can do a hand wind on an auto winder but it has to be pretty much infinitely programmable which almost none of them are. The tone is not in the machine winder, its in the knowledge person operating the machine.

Funny you should bring that up. The 65ish era pickups were always my favorites, and I was up late last night trying to figure out which iteration my favorites were. It seems they could be pretty much anything. Hmm....

[David Schwab]

Fender single coils were hand wound up til '65, then CBS auto wound them from then on. Is one superior to the other? No. I just did a '1965 strat repro set and copied the machine wound I found on a '65 and they sound awesome. You can do a hand wind on an auto winder but it has to be pretty much infinitely programmable which almost none of them are. The tone is not in the machine winder, its in the knowledge person operating the machine.

In the Fender Stratocaster book by A. R. Duchossoir, he mentions that they started phasing out hand winding all the way back in 1960. They would then figure out the winds on the machines to best match the hand wound pickups. So he says they came up with a conversion radio that they kept changing until settling on some number. So from '60 to '64 they probably had a mix of hand and machine wound. I'd guess the higher production pickups like for the Strat were probably some go the first to end up on the machines. I seem to remember reading that's why they went to the machines. Their orders had gotten to the point where it wasn't practical to hand wind everything.

[Possum]

There's also alot of wrong information in that book ;-) I rewound a set of strat pickups from '65 a couple were grey bottoms and one black bottom. The black was hand wound and the greys were all machine wound. Most of the data on pickups in there doesn't match up with what I found in real vintage examples, good book otherwise.

[Joe Gwinn]

If only there were a way to cut the pre-laminated steel into the blade shapes without messing up the insulating layers. Perhaps you could work with continuous rolls of steel strapping tape of the correct width and then chop them off at the right length without delaminating them or causing a short internally.

There is a way - photo-etching. There are companies that will provide the material and etch it to your master; google finds many vendors.

As mentioned above, some of them, usually ones that serve the prototyping market, will provide the metal sheet as well, and I do recall some that offered silicon steel, permalloy, mild steel, et al.

One can also do it yourself, but I bet it's cheaper to hire this out.

[Joe Gwinn]

Doing a few for fun/practice/experiments aren't that much harder than solid blades. It may even be easier depending on what tools you have available. The trouble comes when you do them en masse. You just need to go slow enough in shaping that you don't burn the insulation. I do the same thing I'd do when grinding stainless steel fret ends: just rotate through pieces and do them a bit at a time. As you're working on other pieces, they'll have a chance to cool off and you do the rotation again and again.

If everything is well epoxied, the assembly is waterproof, so I would flood the workpiece with a water-based cutting fluid while machining.

Tap water works well for this kind of grinding - lots of white-wheel grinders for high-speed steel tool bits keep the wheel wet to prevent overheating the workpiece. One should also use the correct kind of grinding wheel - it makes a big difference.

[David Schwab]

There's also alot of wrong information in that book ;-) I rewound a set of strat pickups from '65 a couple were grey bottoms and one black bottom. The black was hand wound and the greys were all machine wound.

Well he said they were phasing hand winding out, so in '65 you would have both methods of winding happening at the same time.

[Possum]

Yes they were machine winding the grey bottoms in '65 and also using up the older remaining hand wound black bottoms.

You don't need to cut laminated blades any special way, I cut mine on the band saw, then hit it with the disk sander, then hand sand the edges on a flat surface. Of course if you have extremely thin non-conductive material between the blades, then you could have major problems cutting the stuff. I don't recommend making them with just a varnish or extremely thin insulation as you'd probably end up with extremely bright sounding blade that way. Maybe. I use a certain kind of paper, but then thats where the problem of making the sandwich perfectly uniform thickness with epoxy. I made two blocks of thick plexiglass, make the blade way oversize and have two C-clamps and bind them down tight. Sometimes they come out uniform and sometimes they don't ;-) It might help to use acetate or maybe mylar insulation material, but not sure epoxy might melt that stuff too.... The other thing is the metal leaves have to be absolutely spotlessly grease free and it helps to rough them up with sandpaper or you get blades where part of the epoxy didn't stick well to the metal. OVerall they are a hassle to make but worth the effort if you're just making it for yourself....

[CRU JONES]

Has anyone considered cutting the blade the other way? That is, across the short dimension, so that you have several short blades, kind of like individual pole pieces, but touching except for a thin insulating layer between.

I think this, right here is a good idea (for cutting down on eddy loss).
If you think about how a laminated transformer is constructed, the laminations are parallel to the magnetic field which makes them, perpendicular to the eddy currents. Funky brings up the Kinman patent and how they look like "staples". Right on!

I trust Joe Gwinn when he says that the eddy currents in a blade pickup flow around the perimeter of the blade. By notching the blade, the eddy currents will form smaller loops.

As far as the objective of laminating blades goes, is one not enough? What do you hope to achieve, more inductance? This might need to be tested. Mike Sulzer has an excellent analogy of how the air gap limits the amount of Inductance gains one can practicably achieve by increasing core permeability. If you look at the equation for inductance, the permeability is a huge multiplier... However, because we are creating Transducers, we need a working gap to sense the string... another name for an air gap in our magnetic circuit. The permeability of air versus the permeability of our core are analogous to resistors in a voltage divider. The same analogy(described infinitely better by Mike himself ) Would apply to increasing the permeable mass... What ever you gain by increased permeable mass, must still be weighed against the permeability of air. You just might not gain much at all. Never know until you try

Cheers,
Ethan

Sorry for not providing the actual Mike Sulzer quote, I don't remember which thread I read it in. Pure gold, Mike!

[David Schwab]

As far as the objective of laminating blades goes, is one not enough? What do you hope to achieve, more inductance?

Less eddy current losses. This is why they laminate transformer cores. For pickups you will have a brighter tone, or a larger resonant peak, depending on what you are trying to accomplish. As I had said, I used laminated stainless steel blades on one prototype, and it was far too edgy sounding, which wasn't what I was after. But, it works fine for other designs.

[peskywinnets]

Re using stainless steel for blade cores...bearing in mind how woefully unmagnetic stainless is vs mild steel, I'm curious whether anyone has opinions on the pros/cons of using mild steel vs stainless as a blade core?

Also, why is silicon steel/iron so difficult to source (5 tons minimum order anyone?)

[Mike Sulzer]

Some stainless steels such as the 400 series are magnetic. If you use such a material, you might have to do some experimentation to get the resuts you want.

Re using stainless steel for blade cores...bearing in mind how woefully unmagnetic stainless is vs mild steel, I'm curious whether anyone has opinions on the pros/cons of using mild steel vs stainless as a blade core?

Also, why is silicon steel/iron so difficult to source (5 tons minimum order anyone?)

[Joe Gwinn]

Also, why is silicon steel/iron so difficult to source (5 tons minimum order anyone?)

Because you are asking the wrong question, I suspect. Instead, look for transformer laminations made of silicon steel. There are standard sizes, so many people stock them.

[copperheadroads]

Because you are asking the wrong question, I suspect. Instead, look for transformer laminations made of silicon steel. There are standard sizes, so many people stock them.

I wonder If the silicon steel bandsaw blades that i throw away would be any good for laminating a blade ?

[David Schwab]

Re using stainless steel for blade cores...bearing in mind how woefully unmagnetic stainless is vs mild steel, I'm curious whether anyone has opinions on the pros/cons of using mild steel vs stainless as a blade core?

I used type 430 stainless which is very magnetic. As an example, check some of your stainless steel flatware. You will likely find that the knives are magnetic.

The weird part is they add nickel to stainless steel, and then it's not magnetic anymore, even though nickel is ferromagnetic.

[David Schwab]

I wonder If the silicon steel bandsaw blades that i throw away would be any good for laminating a blade ?

If you can stick a magnet to it, then it will work for pickup blades.