cutting ferrite

Umm.... try it?

John

Hey, Snooky:-

Diamond will work for sure. SiC grinding, maybe.

If your tile saw can cut a groove all the way round it might be able to split the cut with thermal shock, try warming the rod and cooling the "button" with freezer spray.

You can cut a groove around the rod with a Dremel tool and a cutoff disk. Then snap it at the groove and clean it up on a bench grinder.

It's _not_ pretty, or clean, or an efficient use of the rod, or easy on the abrasive materials, but for a few shortened rods it works OK.

Let us know if the tile saw works -- it sounds like it'd be cool if it does.

Any possibility of using a toroid as your button? Mike

I have a little Makita hand-held tile saw with a very thin blade that should do that OK.

My regular table-saw-sized water saw would eat the ferrite _and_ your hand ;-)

...Jim Thompson

Alternatively, the craziest way...

DIY EDM machine style.

Items required:

Spin the ferrite in a drill and let the arc eat through the ferrite. Alternatively, spinning the electrode can be done.

Dangerous and full of problems..but what fun to see! :)

May not work at all..I didn't check ferrite resistivity..

D from BC myrealaddress(at)comic(dot)com British Columbia Canada

No, but I've soldered on a shirt button. Then I married and my wife told me in no uncertain terms that this ain't the proper method and from then on she'd do the sewing.

It's done industrially using a diamond saw in the manufacture of custom magnets, such as the ones I had made for my "interesting" guitar pickups.

Clifford Heath.

Man, you must have *some* solder station! :-)

Ed

On the cable TV show How It's Made they have showed both how magnets are made and how guitar pickups are installed in production environments.

The magnets are sort of pre-programmed as magnets then heated or something and then only at the tail end of the processes exposed to a machine that I assume generates a massively strong electromagnetic field.

Just out of curiosity, do the super strong neodymium magnets actually work good for guitar pickup magnetic bias?

How about weak magnets? Do they work just as well as medium strength magnets?

Do the amps see them as all the same?

Has anybody ever tried using smooth DC powered electromagnetism for the bias magnetism? I would think it would make some kinds of trial and error with bias magnet strength much easier.

It might be interesting to make the voltage into the bias coils a signal which would blend into the output...

Has this all been done before?

How about carrying the bias even further and turning the pickup into an electromagnet to vibrate the guitar string?

When you said you had "interesting" pickups, what exactly did you mean? LOL

I had to do exactly that once or twice. The tile saw works, although the cut is not exactly very clean. Keep in mind that the magnetic properties of the material are affected; there is a significant amount of anisotropy after cutting.

Vladimir Vassilevsky DSP and Mixed Signal Consultant

A magnetizer, yes. This is the procedure with ceramic magnets, not with AlNiCo though. Hard ferrites are used, not the magnetically soft ferrites as used in electronics. After the ferrite has been cut to shape, it's placed in the magnetizer for a minute or so, while the foundation of the building hums. Did I mention that a magnetizer uses a lot of power? :-)

Probably, but you need to get the right size and magnetic orientation. neodymium magnets are plated because the surface is weak, brittle and even reactive I believe, so custom manufacture is expensive.

Pickups don't generally need very strong magnets. If you have too strong a field at the string it affects the vibration by introducing a node in the vertical direction due to the non-linear magnetic drag. Some Stratocaster PUs do this on purpose, but most don't.

The amps see the coil impedance (complex), modified almost not at all by the magnetic environment its in. Coils often have a kilometer of wire, with significant self-capacitance, and a high DC resistance (5-10Kohm) leading to a broad resonant peak that defines the sound of that pickup.

I believe it was tried in the 50's (patents would indicate so anyhow) but now we have better permanent magnets and there's no need.

That sort of modulation is easier to do electronically now.

probably, yes. All kinds of wacky things have been tried, and many have been patented. Do a search.

It's been done I believe.

It's a "Sidewinder" layout such as was patented in 1974 by Bill Lawrence while he was working for Gibson, but with a difference. Mine are much more compact, and work better. I use a central ceramic blade magnet with coils mounted either side, where the axis of each coil passes through the face of the magnet. This gives a compact humbucking action with the single-point response of a single-coil pickup. It also gives higher output, as the string can induce larger changes in magnetic flux than where the magnet runs through the coil axis.

Clifford Heath.