Horseshoe magnet pickups

[David Schwab]

(I hate that term...it's a vibrato...)

Yes! One of my pet peeves.

[jason lollar]

"Those old horseshoes were nothing special. If I recall, they were hardened cobalt steel or tungsten steel. If you can get the metal stock, you can easily make your own horseshoes.

Or, make the horseshoes of hardened W-1 or O-1 alloy, perhaps energized with a small ceramic magnet. There are many modern alloys that make OK permanent magnets. We don't typically use them as such because we now have far better permanent magnet materials, but almost any physically hard steel alloy can be made into a permanent magnet. "

Oh there is no modern equivalent of the material they used- i have had them analysed but you can use a substitute.
Making a horseshoe come out the perfect shape and size everytime with the correct hardening and with a chrome plated mirror finish is not something many people can easily make on thier own- i certainly dont have time to do it myself and i am not as good polishing and plating as the pros- i can do it but it takes me forever and i cant charge customers the time it would take for me to do it.

[David Schwab]

The mother of all horseshoes...

[Joe Gwinn]

I just put Alnico 5 magnets in the bobbin as per Strat or Tele pickup and wrap the horseshoes around them. The net effect seems pretty similar to the originals which I swear had cut off 16 penny nails as polepieces. They were pretty funky pickups!

So, you use 1018 steel for the horseshoes? I thought of that, but recalled that the original horseshoes were made from magnetized steel, which will have lower eddy current loading effects than mild steel, which is physically and magnetically soft.

The quick and dirty test would be to get some W-1 water hardening carbon steel, form it into horseshoe shape, heat to a red heat, quench in water, temper in an 450 F oven for one hour. W-1 is available from MSC and the like, and is cheap.

I'm going to try slipping some fairly hot flat ceramic or rare earth magnets between the horseshoes and the base plate in addition to the Alnico magnets to see what happens. And yes, I know which way to polarize it all! I think it is possible to make the magnetic circuit too hot and thus damp string vibration with these...or any other magnetic pickups, for that matter. Strat-itis...

The horseshoe magnetic circuit using mild steel is far more efficient than the usual for pickups, so it may not take a very large magnet.

As for Stratitis, this is mainly caused by a nonuniform magnetic field, which pulls the string sideways in a nonlinear way. However, a string in a horseshoe experiences a fairly linear field (the side pulls being balanced), and so you may be able to use far stronger magnets than usually possible.

[Possum]

How well does hardened tool steel magnetize? Wouldn't you have to magnetize in a magnetic field while it was red hot? You want to lock the domains in a directional manner? Wasn't the horshoe magnets cobalt steel? And if so was it magnetized while heat treated?

[Mike Sulzer]

How well does hardened tool steel magnetize? Wouldn't you have to magnetize in a magnetic field while it was red hot? You want to lock the domains in a directional manner? Wasn't the horshoe magnets cobalt steel? And if so was it magnetized while heat treated?

It is not necessary that the steel be permanently magnetized unless you making something that is vintage accurate to one degree or another. Small neos can be used to magnetize the steel temporarily, and thus the strings as well. The main thing about the horseshoe shape is that it provides a magnetic circuit with smaller gaps. They are still quite large however, and without some practical demonstration of the reason for doing this, I wonder how big the effect is.

[soundmasterg]

How are these ones different and superior to the older ones you used to make Jason? I haven't got the bass finished that the old shoe from you was supposed to go in, so I haven't heard it yet....too many things going on, but I hope to get it done to where I can at least try the pickup soon. I think from the picture that these new ones certainly look prettier than the old ones......

Greg

[Joe Gwinn]

How well does hardened tool steel magnetize? Wouldn't you have to magnetize in a magnetic field while it was red hot? You want to lock the domains in a directional manner? Wasn't the horshoe magnets cobalt steel? And if so was it magnetized while heat treated?

Hardened steels all can be magnetized. Many will remain magnetized. The old-time horseshoe magnets were very likely cobalt steel, but tungsten steel was also used. Typically, the harder the steel physically, the better the magnet they make.

While steel that cools from red heat in a magnetic field becomes magnetized to the level of that field, it's a pretty clumsy way to do it. Just magnetize as if it were a weak kind of alnico.

[soundmasterg]

The old Rickenbacker horseshoe pickups tend to demagnetize over time and become non-functional. This happened to Paul McCartney's 1960's RIC 4001. Nowadays people have figured out that the shoes can be remagnetized but back then most artists didn't know that and a lot of the old pickups that have become demagnetized have probably been thrown away.....

Greg

[Possum]

So, is there an ideal type of easily bought hard steel that would hold the highest charge? Is there cobalt steel in rod form easily found and purchased?

[David Schwab]

The old Rickenbacker horseshoe pickups tend to demagnetize over time and become non-functional. This happened to Paul McCartney's 1960's RIC 4001. Nowadays people have figured out that the shoes can be remagnetized but back then most artists didn't know that and a lot of the old pickups that have become demagnetized have probably been thrown away.....

I guess like with regular horseshoe magnets, you need to put a keeper on them. Of course that wouldn't be easy with a pickup.

I always wanted a hourseshoe pickup for my '74 4001. I've never even heard one in person, but they do look cool.

Now here's a guitar I'd like to see reissued by someone:

[jason lollar]

No its not 1018- its harder than that. I would tell anyone of you guys if you wanted to know but i dont want to post the exacts on a forum for everyone in the world to see.
Those old shoes were never tempered- guys try to bend the shoes down flat and the snap at the elbow!!!
I talked to a few guys in thier 80's that know the old ways of making magnets for magnetos on farm equipment and airplane parts and old cars- its been forgotton or overlooked and thats where I found out alot of this stuff about making these types of magnets.

The shoes we use to make were bent by hand with a bending tool and then polished by the guy doing it for me- he was not experienced polishing- he did a great job for never having done it before but then i would have to repolish them and they were often over worked already so i never got a perfect finish.
Now these are made on a great big press and its done with a die and I send them off to a place that polishes and plates them so the fit and finish is perfect and its a better type of steel for this than what we used before. (even though the old stuff was suppose to work better as a magnet it didnt) The new material gets a higher magnetic charge than before which is important as you go toward the bends in the magnet- the magnetism rapidly dies off as you go toward the outer poles on the bobbin so if the shoe is too weak to begin with they get fussy about string gauge and tension.
its been a fun project for sure