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Pick up help

I've never made a pick up but I like the look of the correct number of poles to strings (Ya OCD is strong within me) which is why I'm thinking I want to make a humbucker pick up with 3 or 4 poles.

First I need some clarification on Pup anatomy, a single coil the pole pieces are the the magnets vs the steel slugs and a bar mag in the bottom of a HB, Right?

In my thinking I'm wondering about the effect of a shortened bobbin on the length of wire used. While the # of wraps would stay the same it it will use less wire thus give less resistance right? Is this going to effect the field enough to worry about perhaps needing to overwind?

How much of an effect do you think shortening the magnet will cause? I know magnets are tough to cut, that's a hurdle I'll have to overcome and worry about either weakening or killing it all together in the process. I've also though of just finding the right size magnets but that maybe cost prohibitive. Which leads me to the thoughts of using neodymium because I've actually found some in what I think would be the correct size. Any thoughts on this part would greatly appreciated.

I'm sure I'll have more questions but these are the ones I've come up with so far.

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Permalink Reply by Rand Moore on October 13, 2012 at 4:52am

I found these 2 drawings on CBN maybe 2 or 3 years ago illustrating how to adapt a 6-pole mag pickup for use with a 3- or 4-stringer without making it obvious you are using a 6 pole pup. Essentially, you hide the 6 pole mag pickup under the sound board, but extend the pickup thru the sound board using a suitably sized metal (iron or stainless steel) bar as shown below:

This method might be difficult with neck-thru designs because of potential "clearance problems between the neck and the sound board. But, this method should work pretty well with bolt-on necks.

-Rand.

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Permalink Reply by The Phrygian Kid on October 13, 2012 at 5:50am

Heh see above :p
Yup, exactly right. Nb. You can turn the strat pup on its side to save a bit of depth too ;)
I've never seen those pix but I'm not even remotely surprised others have done it, it's pretty obvious really. Thanks mate

Ps you can do better than this pic, don't cut a stinkin big hole like that, completely unnecessary, just drill wee holes for your pole piece extenders (nails)
As for 'steel bar' well I'll be amazed if that helps in anyway other than diffusing the magnetic flux, I wouldn't bother with that personally

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Permalink Reply by Rand Moore on October 13, 2012 at 12:49pm

Oh, I got you now! In my mind I was thinking laying the nail across the poles as the metal bar is done in these pictures, but your idea is to use 3 or 4 cut nails as pole piece extenders. Very clever!

I guess the head of the nail can be used on the underside of the sound board holes to keep the pole piece extenders from falling out,

-Rand.

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Permalink Reply by The Phrygian Kid on October 13, 2012 at 11:54pm

Just drill too small an tap em in they wont fall out. Polish up with sander etc. I'm so mean I cut the nail into a few pieces with dremel ;)

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Permalink Reply by Rand Moore on October 13, 2012 at 11:58pm

Right.

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Permalink Reply by TruckDrivingFool on October 15, 2012 at 3:37am

Update,

I got a second working coil and have it all put together. The good news is it works, the bad news is that it's just as noisy as a single coil.

Just to make sure I wired it right - Since my lathe only goes one way both the coils are wound the same direction. I used the starts for my leads to the jack and tied the finishes together. This should give me reversed coils correct? The pole pieces are put in flipped so I know that those are out of phase.

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Permalink Reply by TruckDrivingFool on January 28, 2013 at 7:09am

Even though the one I came up with works, went into a build, and sounds good I'm still not happy with the results as far as being a humbucker. I'm still plugging away on this, short of the tap for the the pole piece screws I've gathered up the parts I think I need and finally made some progress today.

With the cold weather I've been putting off the cutting the magnets but with mid 30's today I decided to brave it and out to the garage I headed. I used my pneumatic die grinder (rotozip on steriods) to cut a five gallon bucket down to make a water bath.

With my bath made I made a small wood brace to clamp the magnet onto so I would have something to hang onto.

Put the brace in the water and cut away. A bit messy but it worked like a charm. Then I took some 1/8" x 1" steel stock and cut /ground out some bases.

I don't know how good of an idea this is as it has a definite effect on the magnetic field strength. A quick test using a compass and the scrap wood at the bottom of the picture I can measure the distance of how far the field is effective. The two lines show the difference in how far an uncut magnet and a cut magnet effect the compass. I'm chalking that difference up to the magnet being smaller. But one they are placed on the base plate the distance really drops. Since I don't know the effect a factory base plate has on the magnetics I'm going to keep plugging away and see what happens.

I'd appreciate any thoughts on the field strength.

I've also picked up a pair of the magnets from StewMac for charging PU magnets and would take some direction of how recharging the magnets should be done should I need to.

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Permalink Reply by hocuspocus on February 17, 2013 at 8:20am

You have a lot of questions here, but I sure can give you one answer, if that helps. I've just built my first 4 poles pickup (strings space around 0.420 thousands of an inch), and I ran 9000 turns of 42 gauge wire. The final resistance of the pickup is 5K Ohms. Have fun. !

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Permalink Reply by TruckDrivingFool on February 17, 2013 at 5:35pm

Thanks for looking in on me Hocus, I've been winding to 10-11k w/ 42gauge wire and getting ~ 5.5k. The one that I posted the test video of on the OCT 15 2012 went into a guitar and sounds great(sound test demo below) but still hums like a single coil.

I finally have a second attempt done but having problems with it too. I asked in Skeesix PUP group but I'll ask here too. Before installing the coils they measured 4.6&4.3k Ohm now installed they measure 4.0 & .6k. Trying to figure out what could of happened, if it's normal, and if it could have something to do with the weak sound I'm getting. It has a nice clean sound but takes gobs of gain to get any volume. It's also noisy like a single coil PUP.

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Permalink Reply by TruckDrivingFool on April 1, 2013 at 11:18am

I've finally accomplished it. No great redesign from a standard bucker, just imitated it in a three pole version. My origional base design this go round

was a fail since with the magnet on the bottom it didn't transfer the magnet's field to the pole screws effectively. It worked but was extremely weak, so I started over on my base.

The finished product

To try and put words to the pictures - Mounted to the AL base plate are steel spacers that are tapped for the pole screws. The spacers are fitted so that the magnet fits tight between them. As i assembled it I tightened the pole screws to hold the cover and coils in place then installed the two screws that hold the cover to base plate. These clamp/hold the coils in place and allow the pole screws to be adjustable.

Finally a sound demo of the guitar it went into. Hopefully in the next reply I did it wrong here.