Magnets & Copper Wire: A Pickup Building Thread

[slowburnaz]

What thickness do you use?

I use the 1.5mm thickness (0.06").

Another cool thing about PCBs is that, if you're creative, you can even use them as structural components. I suppose you can also do that with fiberboard or whatever, but PCBs are always perfectly flat, and as you mentioned, the cuts and placement of pads and all that are very accurate.

EDIT: Corrected 0.6" to 0.06"

 

[Jeff Siddall]

Has anyone here used PCB as flatwork for winding bobbins? I note that it is reasonably cheap, can be quite thin (down to 0.4mm) and can have plated through holes that serve as ferrules. With accurately cut outlines and magnet holes, it seems like a reasonable plan. Are there any pitfalls?

Yes!

See: Magnets & Copper Wire: A Pickup Building Thread

Those are for blades, so no magnet pass-through, though I do use a copper layer on one side as a ground plane.

Mine are 1.6 mm, which is a pretty common PCB size. You can also get 0.6 mm(half thickness) or even 0.2 mm, but the 0.2 are intended to be flexible so probably not suitable for a pickup.

 

[slowburnaz]

Yes!

See: Magnets & Copper Wire: A Pickup Building Thread

Those are for blades, so no magnet pass-through, though I do use a copper layer on one side as a ground plane.

Mine are 1.6 mm, which is a pretty common PCB size. You can also get 0.6 (half thickness) or even 0.2 mm, but those are intended to be flexible so probably not suitable for a pickup.

Ah yes... 1.6mm, not 1.5mm.

 

[Jeff Siddall]

Ah yes... 1.6mm, not 1.5mm.

I don't think anyone will notice 0.1 mm here or there!

 

[SamanthaCay]

Fwiw here's how I've been making bobbins very cheaply and thus far having good success.

The outsides are just thick paper/ cardstock. I'll super glue two layers together to thicken it up and rub the entirety with super glue to plasticize it. This makes a material that is nice and thin and imo just the right amount of flex vs rigidity.
I cut my holes with a hole punch a little smaller than the poles to form a nice friction fit. I had a few where the were a little loose but that was fixed with a tiny dab of super glue.

On these I used binding to form the core but I also did a tall coil just using my poles as the core and that worked just fine. Although I like leaving the poles out during winding as it's a lighter bobbin so there's that.

Post wind. Notice the edges are flared a little? I'm doing that to lesson the risk of going outside the bobbin or snagging on an edge, donno if it's necessary but it seems logical.
This is my method for splicing in the leads. Kinda taking a page from some of the old Japanese pickups I've repaired over the years. It's not my favorite and I'll probably end up using eyelets via the fender method. I'll need a thicker bottom bobbin for that but I'll cross the bridge when I get there.

Heat shrink to insulat the splice (only heated on the lead side as to not break the magnet wire. Than I tape it all down with 1/4" masking tape vinyl tape would probably be better but I have this tape so I'm using it.

I just punch a couple tiny holes for those leads to come through. Than join it with the final lead from there. Also something worth mentioning I'm using cold color as the inside and bright as the outside and testing resistance at every step to insure if I do break it I have a better chance of correcting it before I get the whole assembled.

Brass plate on the bottom (I need a template/jig for making these) these came out pretty ugly because I rushed it. Covers are just mini humbucker ones I got off eBay. Soldered together.

With that I also made my first adapters to throw these in the test bed, these need a little polishing but they're working great and allow me to swap any mini humbucker on the fly. As I intend on making more of these they should come in very handy.

This set sounds great btw. I spaced the poles separately for neck and bridge and wound the coils thusly, neck 5.52 straight wound and bridge 4.72 straight with a 2k scatter in the middle. Nice contrast between the two and probably what surprised me the most is they're actually really quiet even in high gain through my 50w sovtek cranked. The magnets and poles were harvested from cheapo start pickups so ceramic bar/ steel slugs.

 

[smart51]

Well I've worked out why my stacked humbucker hums, and why it sounds so much like a single coil. Because it is a single coil, with a piece of cardboard between the two halves of the coil.

With a side by side humbucker, the north side of the magnet points through one coil making it north up. The south side of the magnet points through the other coil making it south up. I naively thought that turning one of the coils though 180° would make it a stacked coil. You also rotate the magnet direction too, so the south up coil becomes a south down coil (AKA north up).

Rule 1 of a humbucker, you have to reverse the magnetic field in one coil, so that the signal is inverted with respect to the noise. Can you stack 2 coils and reverse the magnetic field? I'm not sure you can.

 

[smart51]

I've just made a sidewinder pickup using the same recipie as my humbucker. The only difference is the sidewinder has 2 magnets and one rail where the humbucker has 2 rails and 1 magnet. The sidewinder is noticeably quieter. Maybe 6dB. Is this normal for a sidewinder design?

 

[Max Bogosity]

Well I've worked out why my stacked humbucker hums, and why it sounds so much like a single coil. Because it is a single coil, with a piece of cardboard between the two halves of the coil.

With a side by side humbucker, the north side of the magnet points through one coil making it north up. The south side of the magnet points through the other coil making it south up. I naively thought that turning one of the coils though 180° would make it a stacked coil. You also rotate the magnet direction too, so the south up coil becomes a south down coil (AKA north up).

Rule 1 of a humbucker, you have to reverse the magnetic field in one coil, so that the signal is inverted with respect to the noise. Can you stack 2 coils and reverse the magnetic field? I'm not sure you can.

I think a conventional stacked humbucker has the lower coil seeing the same magnetic polarity as the top coil. The coils are wound in opposite directions, so the noise cancels out like a regular side-by-side humbucker. The lower coil, being reverse-wound but the same polarity, produces a signal that is out of phase with that of the top coil and tends to cancel the signal from the upper coil. But the lower coil is so far from the strings that it just doesn't produce a lot of signal, so when you sum them it doesn't completely cancel out. The result is noiseless but quieter than the upper coil alone.

 

[Freekmagnet]

The sidewinder is noticeably quieter. Maybe 6dB. Is this normal for a sidewinder design?

Yep. That's normal. You can beef them up quite a bit just by putting poles on the sides. Thicker blades - that's another little trick you can experiment with.

 

[smart51]

Yep. That's normal. You can beef them up quite a bit just by putting poles on the sides. Thicker blades - that's another little trick you can experiment with.

Thanks @Freekmagnet. Blades on the end has made the output match the humbucker, or close enough. It now doesn't fit in a soap bar case but shorter, thicker coils will fix that.

How much difference does the steel blade thickness make? I'm using 3mm mild steel because I have some offcuts of about the right size. Does it matter more in the middle than the ends or both?

 

[RichterScale]

I think a conventional stacked humbucker has the lower coil seeing the same magnetic polarity as the top coil. The coils are wound in opposite directions, so the noise cancels out like a regular side-by-side humbucker. The lower coil, being reverse-wound but the same polarity, produces a signal that is out of phase with that of the top coil and tends to cancel the signal from the upper coil. But the lower coil is so far from the strings that it just doesn't produce a lot of signal, so when you sum them it doesn't completely cancel out. The result is noiseless but quieter than the upper coil alone.

I just watched an hour's worth of his vids. The vids where he films himself talking in front of the camera were very hard to follow. Not because of the accent, but because he bounces all over the place. I got some good stuff from it though, but I have to find another source for info. I need straight, to the point explanations and pics drawn in crayon.

 

[Max Bogosity]

I just watched an hour's worth of his vids. The vids where he films himself talking in front of the camera were very hard to follow. Not because of the accent, but because he bounces all over the place. I got some good stuff from it though, but I have to find another source for info. I need straight, to the point explanations and pics drawn in crayon.

That’s the only one of his videos I’ve seen, but he seems to have the ‘drawn in crayon’ part nailed.

 

[RichterScale]

That’s the only one of his videos I’ve seen, but he seems to have the ‘drawn in crayon’ part nailed.

He seems to know his stuff, but not everyone is good at conveying knowledge with an easy to digest flow. He kinda rambles and interrupts himself by jumping around from thought to thought.
Could just be my lack of focus and tendency to drift off.
I did get some useful stuff from a few of his other vids though. Worth a look.

 

[Freekmagnet]

Thanks @Freekmagnet. Blades on the end has made the output match the humbucker, or close enough. It now doesn't fit in a soap bar case but shorter, thicker coils will fix that.

How much difference does the steel blade thickness make? I'm using 3mm mild steel because I have some offcuts of about the right size. Does it matter more in the middle than the ends or both?

Blade thickness is definitely worth experimenting with. One of the sidewinder "rules" is that more steel gives you more output and more lows. The difference won't be drastic, but it will be noticeable. You'll also hear a difference with the narrower coils as well. The changing wind count on the narrower coils will provide you with some interesting results to play with as well.

 

[Fred Miller]

Yeah I've been using these for internal connections, they're also known as Dupont connectors. Getting the crimpers makes life a lot easier.

I use a lot of Dupont connectors, find it easier to solder them. Never had much success with the crimp tool.
Another option is JST-XH 2.5, they're keyed so can only fit one way, but you can remove the pins and swap them around.

 

[smart51]

So, AlNiCo 5 bar magnets. Can they be belt sanded to size. I made some cardboard bobbins that are smaller than the plastic ones I have so I can fit a sidewinder pickup into a soapbar box. They shrunk in the wash and now the magnets don't fit. More precisely, the glue failed in the hot wax.

 

[Bruce Johnson]

So, AlNiCo 5 bar magnets. Can they be belt sanded to size.

Magnets can be ground on a belt sander....If it's just a little bit, and you go gently. Heat will mess with the magnetic charge. Grind lightly, letting it cool every few seconds. Don't let the magnet get hot enough that it discolors, or that you can't hold it. Use a very coarse belt or grinding wheel.

When magnets are being made, they are ground to size. But that's usually in liquid coolant....and the are charged after grinding.

Also: Don't breathe the grinding dust! It's poisonous.

 

[smart51]

Magnets can be ground on a belt sander....If it's just a little bit, and you go gently. Heat will mess with the magnetic charge. Grind lightly, letting it cool every few seconds. Don't let the magnet get hot enough that it discolors, or that you can't hold. Use a very coarse belt or grinding wheel.

When magnets are being made, they are ground to size. But that's usually in liquid coolant....and the are charged after grinding.

I need to take nearly a millimetre of one of them and half a millimetre of the other. I can alternate them between grinding and a bath of water to keep them cool.

 

[MPU]

I'd make new bobbins, wind them and place the magnet inside the coil before waxing. A lot easier than grinding Alnico to size.

 

[Fred Miller]

View attachment 4840658
So, AlNiCo 5 bar magnets. Can they be belt sanded to size. I made some cardboard bobbins that are smaller than the plastic ones I have so I can fit a sidewinder pickup into a soapbar box. They shrunk in the wash and now the magnets don't fit. More precisely, the glue failed in the hot wax.

I've never tried grinding AlNiCo magnets, I know they are quite brittle so I'd grind very carefully, grinding the edges at a 45° angle to avoid breaking them. I might use a commercial cutting fluid to cool them rather than plain water, as it will carry away more heat.