Experimental rail pickup construction: wiring question

[David King]

I don't think velveeta qualifies as cheese under anyone's definition but it's as "cheesy" as it gets.

[Jamie Unden]

I was going to do the same thing, only make an acrylic lid that will seal and draw down a vacuum.

[Jason Rodgers]

In cheese? Gosh, I didn't realize the potential of dairy-based lutherie!

Seriously, though, I was thinking about using vacuum in the potting process, too. I built a vacuum clamping system and I rigged up a peanut butter jar to try dying some maple veneer for purfling strips. Do you think a soak in the wax, then a couple minutes under vacuum, then back in the wax would give better penetration into the coils? Of course, I've also read that some folks have different potting schedules for getting different degrees of desired microphonics.

But no more cheese jokes? Where's Tweedy?

[John Sonksen]

I thought any microphonics are bad? Haven't had any time to research this lately though... Pup's are looking sharp Jason!

[David King]

You don't need a vacuum to get a fully saturated coil, you just need the coil to get up to temp internally and that takes about 20 minutes. If you were producing dozens of pickups an hour then I can see where a vacuum might be useful but it's totally unnecessary in my view.

[Jason Rodgers]

Yeah, I'm not sure where I read it (maybe more pickup lore?), but potting duration is apparently one of the variables in a pickup winder's bag of tricks. Wrap count and coil tightness can also be controlable variables, though that would be in the hands of a very experienced craftsman.

I wonder if vacuum would work with epoxy potting (if one was so inclined).

Still looking for cheese pickup jokes. "That neck pickup really has some creamy lows, but the bridge is a little too sharp for my tastes." That's all I got, and it's awful.

[David King]

Your reliable variables are wire diameter and insulation thickness, just try to be consistent and see what you get.

[Jason Rodgers]

Well, last night I wound my first coil!

It was an okay experience. Right away, I found out that my plexiglass traverse limiter gap thingy was total crap, so I tossed it and used the long arm guide.

The biggest issue I ran into was some funny wraps that caught on the ground wire that is attached to the core and creates a lump in the winding path. I ended up unwrapping a hundred or so turns to track that down. Having a pile of what looks like copper hair pooling at your feet is a little unnerving. Fortunately, it all went back on without kinking or breaking. The next iteration will put the ground and starter leads somewhere out of the way of a clean wind.

I put about 5000 wraps on this one. I say "about" because I didn't use my counter on/off switch correctly when unwrapping the errant loops. "About" in this case is probably 5000 + or - 200. Either way, it came out to 4800K ohms on the multimeter.

I have to thank John Sonksen again for having me over to his place a while back, where he wound one of his first few coils and let me have a go. Still, this was a pretty loose wind. Thank goodness for potting!

I'll try another one tonight! Hopefully it will go a bit easier.

[Mark Swanson]

It seems like it would be a bit weak. 4.8K isn't a very high reading, it should be above 6K if you ask me. I'd put more winds on there I think.

[Jason Rodgers]

This is the north coil of a neck humbucker, Mark. If I get the south coil in around that resistance, I'll have something in the neighborhood of 9,600+k, right? Wouldn't that be considered an ok range?

There was gobs of room left on this bobbin, though, so I'm going to take the bridge coils to 7000 turns each to try to push the total DCR up around 11,000-12,000k.

Does it seem like I'm understanding all of this correctly?

[Jason Rodgers]

Second coil just wound.

Aw, now this one is a beauty! It wound to 5000 turns with no issues. Look at that even coil build!

And here's the crazy part: it tests at about 4,800k! It's within 100k ohms of the first coil! When connected together, the humbucking pair reads at 9,600k and change. I can't believe that they came out so close on my first attempts!

On to the bridge coils! Woo!

[Hans Bezemer]

That's starting to look very cool.
Looking forward for the next pickup!

[Mark Swanson]

Yeah, that sounds about right- looks good.

[Jason Rodgers]

I was surfing around on the interwebs and came across this guy's blog, where he posts interesting/funky/odd guitars he finds online. This one was on ebay Germany in 2011. It has some thick rail pickups, but the coils are under the pearloid top and the rails fit through slots to reach up toward the strings. Interesting.
http://guitarz.blogspot.com/2011/07/sym ... -cant.html

[Jason Rodgers]

Wound another coil tonight. The northbound coil of the bridge was given 7,000 turns and clocked in at about 6,800k. Hmm, the two neck coils were wound with 5,000 turns and came out to about 4,800k. Would it be safe to make some predictions - at least with the dimensions on these bobbins - that my turn count equals my resistance minus about 200k?

Whether or not that algorithm is true, I've wound one pair to within a couple hundred k, so I'm feeling pretty confident that the south bridge coil will also clock in around 6,800k, giving me a humbucker in the neighborhood of 13,600k. As my friend says, "Awesome-sauce!"

[David King]

I think 200 Ohms difference would be good but 200K ohms off would be monumentally bad (along with a 6800k Ohm coil. You want 6.8K or 6800 Ohms.

[Jason Rodgers]

Yeeesh, I've been getting my decimals wrong, haven't I. Yes, the neck coils are 4.8k ohms and the bridge 6.8k ohms (or 4,800 and 6,800 ohms). Thanks for pointing that out, David! We learn, here.

[Jason Rodgers]

I was home with a sick kid today, and while she napped I finished the last coil. 7,000 winds, also clocking in at 6,800 ohms and change. Here are the two pairs.

Next step is potting.

I ordered some 1/2" x 1/8" x 1/8" neodymium magnets from K&J Magnets: six magnets will sit end-to-end along the 3 inches of the steel core on the bottom of each coil (these magnets are polarized through their thickness, not their ends).

This has really been a lot of fun!

[Can a moderator change the title to "Jason's experimental rail pickups"?]

[Jason Rodgers]

These crazy p'ups are potted! We stopped by Value Village today (a second-hand store, like Goodwill) and I found this classic, avocado green Crock-Pot for $7.99. Thanks, David, but I won't be needing your fondue pot! I threw in a box and a half of paraffin, plus a few chunks of beeswax for good mojo, and set the crock on high. It took a while, but it all melted nicely, and I turned the unit down to low (though turning it off would have been fine, too).

My wife has this plastic-coated wire that's used for wrapping around and training small plants and trees. I used some lengths to make holders to keep the pickups horizontal in the wax (and off the bottom). Look, there are the little bubbles coming out of the coils!

I set a timer for 20 minutes, pulled them out, wiped them down with some paper towel, and set them to cool. I haven't checked the continuity again to make sure there weren't any shorts, but they look great!

The magnets should be in the mail tomorrow or Tuesday, and I'll get some bases made to mate them up.

All along the way in this process - from building the winder, to building the bobbins, to winding, and now potting - I've been just amazed that it's all worked so well! Of course the proof is in the sound, but it's just so much fun! I feel like a little kid!

[Jason Rodgers]

My neodymium magnets arrived in the mail today. It's a little silly: shipping was about a buck more than the magnets, and a little cluster of twenty five 1/8"x1/8"x1/2" (about the size of a thumb drive) came in a six inch cube box. Purchased from K & J Magnets. Crazy selection of neos, though, from tiny blocks and discs, to stuff big enough to pick up your motorcycle.

Anyways, I'm identifying the poles with a compass. Strong little blighters! They can swing the compass needle from at least six inches away.