Rail Pickups

[Joe Gwinn]

I have verified that even very strong neos on the bottom of steel slugs do not cause the steel to saturate.

How was this verification accomplished?

One would think that the ratio of volumes of neo and of steel would matter.

[Mike Sulzer]

How was this verification accomplished?

One would think that the ratio of volumes of neo and of steel would matter.

I made a small coil with a single humbucker slug as a core, put a couple thousand or so turns on it, and put a capacitor in parallel to resonate it in the audio range. Then I put various magnets on the end, and did not observe any change in the resonant frequency. I forget what the biggest neo was, but it was probably a disk 3/8" in diameter, 1/4 long. It is much easier to saturate a material when the core geometry is closed, I believe.

[Mark Hammer]

I've pondered experimenting with a pair, or even trio of blades, but the thing that tends to stymie me is the wrapping. First off, my winding apparatus demands that there be a place to stick a bolt through the middle of the bobbin into the chuck of the hand drill I use. I gather any sort of apparatus for winding around a blade/rail would require that it be held in place from two sides

The other thing is that the snugness of the wind is partly a function of the steepness of the "turnaround" at the ends of the coil. Seems to me that the further one moves away from the format the wire comes in (a round spool), the less snug the windings will be. That is, they will be tight as a drum at the ends but spongy in the middle.

So how do people get their coils to be snug when winding around a blade? Or is it simply a matter of tension and being slow and methodical?

[Dave Kerr]

I do wind more slowly with blade cores than with more traditional bobbins. As far as mounting to your drill, why not chuck up a rudimentary faceplate and use double stick tape?

[David King]

You could hold the rails to your face plate with a neodymium magnet - and check the output as you wind.

[Joe Gwinn]

I made a small coil with a single humbucker slug as a core, put a couple thousand or so turns on it, and put a capacitor in parallel to resonate it in the audio range. Then I put various magnets on the end, and did not observe any change in the resonant frequency. I forget what the biggest neo was, but it was probably a disk 3/8" in diameter, 1/4 long.

That sounds like a reasonable approach, but I would try it with a far larger neo, something on the scale of the neos used to charge alnico magnets, just to know how much margin we have.

It is much easier to saturate a material when the core geometry is closed, I believe.

True, by a goodly ratio.

[David Schwab]

Mark, I use double stick tape to secure the bobbin/rail assembly to the winder.

I do notice that if I wind fast the middle of the coil can be a little on the spongy side, but I just tape it snug with the teflon tape and when I pot it, it's nice and solid.

[Possum]

...

Yep you use double stick but what works best is the sorta foam type double stick stuff, I forget what its called but every 3M tape area in any grocery/hardware store sells it. Its about 1/16" thick and holds anything for winding really well. You can to be careful not to leave it there when you're done or its a bitch to get off.
I've noticed that vintage blade type pickups are wound pretty loose and I do and pot them always. A rubber band on your pulley drive helps even wraps all around the coil, Leo Fender spent years to figure that out..

[David Schwab]

Yeah, I use the 3M foam tape. I have a piece of blue masking tape on the winder's platen, which helps to remove the foam tape. I've had the foam tape pull apart bobbins, so I run my finger over it to kill to stickiness a little before I stick the bobbin on.

[Peter Naglitsch]

Jsut let me second the "do not leave the tape on for too long" statement. I have seen oven bakes finishes been ripped of steel parts when someone was trying to get the double stick tape off...

I just use simple double stick tape intemded to hold ordinary carpets in your home. But I have a bunch of different faceplates, each with a recession for made for every type of bobbin I wind, meaning I never need to move the end stop (for the wire) closest to the faceplate. Regardless if I'm winding a Tele bridge with a really thick bottom flange or a mini HB (thinnest bobbin flanges I have used this far) the coil always starts in the same plane as the faceplate top surface. The recession also means that I need less "stickyness" from the tape as the twisting motion is stopped by the walls of the recession. For rail pickups (just started to experiment with those) I have a recession and a blade set into the faceplate to hold the bobbin as the bobbins for SC sized HBs are really thin and I wouldn't trus only double stick tape to hold the bobbin in place.

[Joe Gwinn]

But I have a bunch of different faceplates, each with a recession for made for every type of bobbin I wind, meaning I never need to move the end stop (for the wire) closest to the faceplate.

You mean "recess" (a pocket cut into the faceplate), not "recession" (a drop in economic activity, leading to reduced sales of guitars and guitar pickups).

[David Schwab]

He probably combined "recess" with "depression", making a spoonerism.

I like to take a recess every now and then, to ward off depression, especially in this recession.

[Mike Sulzer]

That sounds like a reasonable approach, but I would try it with a far larger neo, something on the scale of the neos used to charge alnico magnets, just to know how much margin we have.

The margin is already large since you cannot use magnets so large in a pickup. A humbucker with slugs in both coils and one of those magnets on each slug has very high output, but is useless as a result of the string pull.

[David Schwab]

I use magnets that measure 1" X 1/2" X 1/4" in pickups with no string pull. But that's with blades. Would probably be more of an issue with round poles.

[Peter Naglitsch]

You mean "recess" (a pocket cut into the faceplate), not "recession" (a drop in economic activity, leading to reduced sales of guitars and guitar pickups).

Jupp, recess, not recession. Probably a Freudian slip on account of the way the economy is right now...