Blade Style Pickup - Ceramic Magnet Orientation

[Freekmagnet]

Hi,

Noob here, so any help is appreciated. This is the first time I've posted. I've been lurking around here for a while now.

I'm building blade humbucker using steel blades as poles. I'm sort of (emphasis on "sort of") copying an old pickup (T-40) with specs I've gathered on the internet. I was hoping to use a ceramic bar placed underneath placed across both poles with the edges of the magnet in contact with sides of the poles. I can't seem to find a ceramic bar magnet oriented across the width of the bar. Instead, they are all magnetized front and back. I am looking for a bar that is 2.5" L x 0.875" W x 0.125" D oriented in the 0.875" direction. I've spoken to a few vendors, one of which (Adams) was willing to cut them for about $12.00 apiece. Other than that, I've gotten a few quotes with huge minimums.

My questions are:

A) Does the orientation matter, and should I just go for it?

B) Is a ceramic magnet oriented in the 0.875" direction something I should just forget about unless I'm willing to suck it up and buy 50 of them? Does anyone know of a source that stocks such a thing?

C) Is there an alternative material?

Thanks in advance.

[big_teee]

Not sure your exact intent?
Usually blade buckers use these parts.

2 bobbins.
Blade Humbucker Bobbin Black

2 blades
Steel Blade for Humbucker Bobbin

Either 2 or 4 of these magnets on the bottoms of the blades.
1 or 2 magnets per blade.
Ceramic 8 Bar Magnet 2.35'' Long

Baseplate
Humbucker Short Leg Frame Nickel Silver 50mm

T

[Freekmagnet]

Not sure your exact intent?
Usually blade buckers use these parts.

2 bobbins.
Blade Humbucker Bobbin Black

2 blades
Steel Blade for Humbucker Bobbin

Either 2 or 4 of these magnets on the bottoms of the blades.
1 or 2 magnets per blade.
Ceramic 8 Bar Magnet 2.35'' Long

Baseplate
Humbucker Short Leg Frame Nickel Silver 50mm

T

Maybe this will help...

I made these bobbins. They're Lexan and 1018 mild steel.



And I want to place a ceramic magnet on the back from rail to rail.



From what I understand, these ceramics are oriented in the 0.125" direction (this magnet is more like 0.1875"). Should the magnet be oriented in the 0.75" direction for it to work properly?

The Mojo magnets you posted are only .25" wide. I need one that's 0.875" wide.

[big_teee]

Looks like you have it all but the magnets.
just use the small magnets on the bottom instead of the big magnet.
That is what we all use.
You won't tell any difference.
Put one or two on one blade Negative, and one or two on the other blade positive.
T

[Freekmagnet]

I see. I guess the 0.25" magnets will work OK.

So they don't make too many ceramic magnets oriented width-wise, do they?

Thanks for your help!

[big_teee]

Most bar magnets are no more than 1/2 inch wide or edge to edge.
You can use those small magnets, or use 1/2 inch wide magnets with steel shims between to fill the gaps.
Other options would be rod Neo magnets between the blades.
If you want Alnico tone use 1/2 inch Alnico bars and steel shims.
If You're just making a few.
If you are mass producing them, then you may want to have custom parts made.
Maybe someone else will have some suggestions.
GL,
T

[Freekmagnet]

Ah-ha... steel shim... I'm so glad I posted...that might do it!

What do Neos sound like?

[big_teee]

I don't have any experience with NEOs for pickups.
Here Just Alnico 2 through 8, Ceramic 5 & 8.
T

[rjb]

Nice work!
I once rebuilt a pair of Peavey T-60 pickups (the guitar version of T-40 bass pickups), but I was a total noob at the time (still am, actually).

Question:
Does the spacing between the blades have to be .875"?
Are the pickups going into T-40 covers with T-40 baseplates?
Reputedly, Chip Todd once said that T-60 pickups make better bass pickups than T-40 pickups.
T-60 blade pickups use ~.50" magnets - which are readily available from pickup parts suppliers.
Just a thought.

PS: I see Mojo sells .30" wide ceramics; maybe use 3 side-by side for .900" total?
http://www.mojotone.com/Pickups_x/Pi...gnet-2-30-Long
The blades wouldn't be perfectly centered in the slots of a T-40 cover, but could be hidden behind plastic "toaster" inserts,like this:

[Freekmagnet]

Nice work!
I once rebuilt a pair of Peavey T-60 pickups (the guitar version T-40 bass pickups), but I was a total noob at the time (still am, really).

Question:
Does the spacing between the blades have to be .875"?
Are the pickups going into T-40 covers with T-40 baseplates?
Reputedly, Chip Todd once said that T-60 pickups make better bass pickups than T-40 pickups.
T-60 blade pickups use ~.50" magnets - which are readily available from pickup parts suppliers.
Just a thought.

Thanks! That means a lot! This is my first pickup build, and it's been a lot of trials with a few tribulations so far.

T-60s are cool. There's some kid in some local punk rock band rockin' an old T-60. I look at it and I always think, "Hmmmm..."

I'd like them to be as close as I can get to .875". The bobbins are pretty wide and the blades are .875" apart. I guess using 3 x 0.30 would be pretty close. Right now the bobbins are snugged nicely right against each other. Somebody posted some T-40 dimensions on a thread in another forum, and I'm trying to stick to those dimensions as closely as I can given the materials I have at my disposal.

I haven't figured out what to do about the covers and the baseplates yet. Initially, I was going to make a baseplate out of sheet brass and screw it into the bottoms of the blades. Didn't work - I couldn't tap a small enough hole without breaking the tap off in the blade. I was going to make a cover out of sheet nickel silver, but right now I'm leaning towards using a casting resin to make a cover. I don't really want to get into silver brazing a lid for it right now. If I go down the casting route, I'll have to decide if I'm going to encapsulate the bobbins and if so, with what. The permanence of cast epoxy freaks me out, but wax seems like it would dry out eventually.

Is it possible to drill and tap the Lexan?

[big_teee]

I've found life for me, to be simpler if I stick with factory available parts.
Especially if it is a guys first pickup.
I recommend getting all the winding techniques perfected before using custom parts.
Regular blade bobbins will fit on regular baseplates.
Also narrower aperture pickups usually sound better than big wide pickups.
IME wide aperture pickups usually sound dark, & possibly muddy.
The more metal you use, the more possible eddy currents you have.
Another advantage to a standard humbucker route?
If you don't like the blades, you can go back to a regular conventional PAF style humbucker.
YMMV,
Good Luck in your endeavours!
T

[Freekmagnet]

I've found life for me, to be simpler if I stick with factory available parts.
Especially if it is a guys first pickup.
I recommend getting all the winding techniques perfected before using custom parts.
Regular blade bobbins will fit on regular baseplates.
Also narrower aperture pickups usually sound better than big wide pickups.
IME wide aperture pickups usually sound dark, & possibly muddy.
The more metal you use, the more possible eddy currents you have.
Another advantage to a standard humbucker route?
If you don't like the blades, you can go back to a regular conventional PAF style humbucker.
YMMV,
Good Luck in your endeavours!
T

Ha-ha-

Can't argue with you there!

Thanks for the help.

[rjb]

If you don't like the blades, you can go back to a regular conventional PAF style humbucker.

Hold the phone. Are we talking guitar or bass?
T-40 is a Peavey bass from the '70s and '80s.

That's why I asked if the pickup is going into a T-40- "normal" parts won't fit.
I'm not sure about the T-40 bass- but with the T-60 guitar, earlier "toaster" pickups (with hidden magnetic blades) and later exposed-blade pickups used different sized covers. So Peavey is even incompatible with Peavey.

I agree- a pickup with smaller aperture should be less muddy than one with wider aperture.
That might be why Chip Todd reportedly said T-60 pickups sound better on bass than T-40 pickups.
And building a dual-blade pickup from off-the-shelf parts would be infinitely easier than a scratch build.
That would be the sane way to go.

But if you absolutely must make a T-40 pickup reproduction, and you have the skills to build all the parts, go for it.
Good luck finding a .875" wide magnet. People pay stupid money for PV replacement parts- like $25 for a knob.

And (maybe because I have no metal-working skills) I would find the cover and baseplate a bigger challenge than the bobbin- and would work on those first, not as an afterthought.

On winding skills:
If my sample of two T-60 pickups is any indication, lack of winding skill may be a plus in capturing Peavey "mojo".
Mine had coil wire flying out beyond the bobbin flanges, all encapsulated in black epoxy.

On mounting the pickup to the baseplate:
The trick is not to mount the pickup to the baseplate.

With magnetic blade "toaster" models, the bobbins were dropped into a plastic tub, which was then filled with epoxy. The tub was inserted in the cover, a strip of rubber tape placed over the back, and the baseplate soldered to the cover.

I'm not sure how the exposed blade models were assembled. My pickups were some undocumented version- unplated steel blades in old bobbins (with RTV filling the wide slots), old backplate with the sides sawed off, in an epoxy-filled tub like the magnetic-blade toasters. (The blades don't align with the slots in the covers, but are hidden from view).

On my rebuild, I used double-sided foam tape over the magnet and blades.
I think the gap between the pickup and backplate may reduce eddy currents in the brass.
At any rate, the pickups are plenty bright.

On potting:
I would avoid yucky epoxy at all costs. It makes repair nearly impossible, and some folks suspect it shrinks over time- tugging the coil wire and killing the pickup. Use wax.

ymmv,
-rb

PS - If you search T60 on this forum, you'll find several threads that may be helpful.

[big_teee]

I thought he meant guitar.
I never saw where he specified one way or the other.
If those are for bass, I bet they will sound dark.
Most of the info I gave, will apply either way!
T

[David King]

The T-40 was a bass, the T60 was a guitar. These were some of the least expensive instruments around back then and they sounded OK but apparently fondness for Peavey gear has come full circle. The only T-40 I ever worked on had P style pickups.
Looking at the mass of steel and the size of the magnet required I'm going to estimate that these monsters had very low turns or they would have sounded abysmal. That said there is enough room on the coils pictured above to put a lot of wire. Perhaps they were wound with 40AWG? I'd start with 3000-4000 turns and see what that sounds like in series/parallel before going any further.
Perhaps the OP can list the dimensions they have and someone here can verify those and save us all some time.
I found these photos: https://reverb.com/item/918879-peave...s-and-controls
5.22K Ohms in series is on the low turns count side for 42AWG.
Notice that the blades are quite a bit thinner than the blades the OP is planning to use. A thinner blade would definitely help here I think.