Just finished a rewind of two Rickenbacker Horseshoe 8 string pickups. These are from a 1950s DC-16. Both of them were open. I have read that many of these were wound with #38 AWG, but these were definitely wound with #42 PE. Maybe that was because they are for 8 strings but made on a 6 string bakelite bobbin. I measured the wire diameter at .0028 and the resistance checked 1.7435 ohms per foot on a 12 foot sample. No good way to unwind them, I tried. But I weighed the bobbin before and after cutting the wire off and also weighed the wire. For the weight of wire I calculated that the original resistance was something just under 8K. I rewound them to 8500 turns which came out to 7.64K on one and 7.79 on the other. Of the four horsheshoe magnets, one was still pretty much full charge, but the others were around half. I recharged them all and also buffed and re-chromed them. It is kind of crude they way they were made, with the extra two poles just drilled into the end of the six pole bobbin. My guess is that's where they failed, with corrosion or damage at one of the outer poles. I taped those good before rewinding so maybe it won't happen again for another 60 years. Another thing that I wasn't expecting was the way the inner lead was connected. They just put a brass screw through the bobbin and soldered the start to that. I gave it a short lead of #28 and taped over that screw too. Here are a few photos. You might have to click on the first three to get them to open, dont know why this is.
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Rickenbacker Horseshoe rewinds
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Rickenbacker still uses a similar method for the start wire amazingly enough. Did you count turns per layer? Anyway, good job, man. Wish I could find some cobalt steel like they used back in those days, but there is no equivalent steel now days, I think it was 18% cobalt content.
BTW your other post links don't work so can only see the one photo. I'd love to see the other shots, so try again....http://www.SDpickups.com
Stephens Design Pickups
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Rickenbacker has been using a stainless steel screw on their pickups the last couple years apparently which makes no sense to me! Can't solder to it very well at all!! There have been some failures of pickups due to this and one well known luthier who used to work at Rickenbacker in the 70's changes them back to a brass screw as before.
Greg
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Originally posted by Possum View PostWish I could find some cobalt steel like they used back in those days, but there is no equivalent steel now days, I think it was 18% cobalt content.
http://www1.mscdirect.com/CGI/NNSRIT...MTERM=02605202
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Originally posted by soundmasterg View PostRickenbacker has been using a stainless steel screw on their pickups the last couple years apparently which makes no sense to me! Can't solder to it very well at all!! There have been some failures of pickups due to this and one well known luthier who used to work at Rickenbacker in the 70's changes them back to a brass screw as before.
While brass is certainly easier to solder than stainless steel, one can certainly solder stainless steel, if one uses the correct flux. The problem is that the flux is corrosive, and the fumes will damage things.
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Originally posted by soundmasterg View PostRickenbacker has been using a stainless steel screw on their pickups the last couple years apparently which makes no sense to me! Can't solder to it very well at all!! There have been some failures of pickups due to this and one well known luthier who used to work at Rickenbacker in the 70's changes them back to a brass screw as before.
I removed the screw and used a piece of hookup wire.
Here's my '72 bridge pickup, striped. The foam rubber was wrapped around the poles.
Here's a newer pickup:
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
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Originally posted by SonnyW View PostYou might have to click on the first three to get them to open, dont know why this is.
Invalid Attachment specified.
Try attaching them again.It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
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Originally posted by Possum View PostRickenbacker still uses a similar method for the start wire amazingly enough. Did you count turns per layer? Anyway, good job, man. Wish I could find some cobalt steel like they used back in those days, but there is no equivalent steel now days, I think it was 18% cobalt content.
BTW your other post links don't work so can only see the one photo. I'd love to see the other shots, so try again....
Here are the first three photos again, maybe they will work this time. Not sure if I got the exact same ones. I took quite a few.
Last edited by SonnyW; 07-08-2012, 03:20 PM. Reason: changed one photo. The one that is attached at the end is how I connected for the rewindwww.sonnywalton.com
How many guitars do you need? Just one more.
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Question about the bobbin.
Does it come a part, or is it riveted together?
Can't really tell, but everything really heavily built.
Also What's the deal about the cobalt steel, what is the purpose of it I wonder?
T"If Hitler invaded Hell, I would make at least a favourable reference of the Devil in the House of Commons." Winston Churchill
Terry
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Originally posted by big_teee View PostQuestion about the bobbin.
Does it come a part, or is it riveted together?
Can't really tell, but everything really heavily built.
Also What's the deal about the cobalt steel, what is the purpose of it I wonder?
T
About the steel, the magnets were made of cobalt steel originally because that was about the only magnet material around. Alnico had been invented by then but was way too costly I suppose and it isn't amenable to bending like they did. Possum is right you probably can't get that exact steel anymore, because the way they made steel then was different. I worked in a steel mill in the 60s. I guess it is probably open hearth steel that they added the cobalt in the ladle, after the heat was poured. Just my guess. The other possibiity is the Bessemer process, but I would guess that is less likely. Neither one is in use these days. The electric furnace is used these days. Where I was we didn't get an electric furnace until about 1966, and it was a new thing. Just thinking out loud, I haven't researched this much.
On the Rickenbacker magnets, they supposedly changed the alloy around the early to mid 60s and the newer magnets lose their charge more easily. By the way, the magnets measured around 300 gauss at the ends of the horseshoes when fully charged. But the field at the poles in the assembled unit was more like 400+. None of the magnets was fully charged, but one measured about 280. The rest were more like mid 100's before I recharged them.
Edit: just found this link it might explain a little about the cobalt steel magnets of the 1950's/ 1960's.
http://www.permanentmagnetco.com/history.aspwww.sonnywalton.com
How many guitars do you need? Just one more.
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This has gotten me googling for answers about the cobalt steel. I found this link where there is a company that still has 17% cobalt steel magnet alloy. Don't know one thing about them, but for those interested it might be worth asking for a quote. The Rickenbacker magnets were made of bent bar stock about 3/16 by 1 1/4 inch. The bent horseshoe shape is 2 1/4 overall length and 1 1/4 inch tall.
Check Mark Worldwide, Inc. Permanent Magnet Cobalt Alloy Magnetic Neodymium
Possum, if you check their spec sheet on the #81 alloy it is nominally 18.5% Co, even though the alloy is known as 17% Cobalt. It looked like they only had round stock though.Last edited by SonnyW; 07-09-2012, 02:43 AM.www.sonnywalton.com
How many guitars do you need? Just one more.
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Originally posted by jason lollar View Postmaybe the pre war horsehoes were high cobalt steel I dont know because I never had a set of those tested destructively but I have burned up early 50's to late 50's shoes and there is very little cobalt in them- less than 1 percentwww.sonnywalton.com
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The later shoes were hardened after machining, if the hardening wasnt done properly they wont hold a charge for long. Hardenoing is one reason why the shoes often dont line up in the center- one will be higher than the other due to warping, people often try to level them out by bending them and they snap off at the elbow- OOPS....
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Originally posted by jason lollar View PostThe later shoes were hardened after machining, if the hardening wasnt done properly they wont hold a charge for long. Hardenoing is one reason why the shoes often dont line up in the center- one will be higher than the other due to warping, people often try to level them out by bending them and they snap off at the elbow- OOPS....www.sonnywalton.com
How many guitars do you need? Just one more.
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