Gapping Pot Core

I had some ferrite magnets made by these people: , and they used a wet diamond saw to cut blank ferrite blocks. The diamond blade went through them like butter. This was non-magnetised hard ferrite (hard meaning it can be permanently magnetised IIRC).

I reckon you have nothing to lose by trying a Dremel and a diamond burr. Set the Dremel up on an angle in a stand if you can, so you can start it with the burr in a gap and just slide the core around until all the center section is ground to the same height.

Clifford Heath.

die grinder, foredom, dremel - small grinding burr, patience. If lacking patience, be prepared for things to fly about and break. No need for that to happen with a bit of care.

- Cats, coffee, chocolate...vices to live by ^^^^^^

And none of this stuff before firing up that Dremel ;-)

Speaking for yourself. Takes me a couple of full pots to get all jittery, and I haven't been at that level for years (spent a while there, backed off from it to 2-3 mugs of half-caf). Not being able to think does not help my work, so the coffee goes in regardless. Otherwise my day starts all wrong and continues not too well.

I can solder TSSOP and 0603 in that condition, and I can grind in that condition. Regardless of coffee intake or lack thereof, some work is aided by having a place where you can rest your hand or wrist set up, so that you are mostly holding steady with your fingers, rather than needing to hold your hand and arm steady all the way back to the elbow or shoulder.

Doing a lot of heavy lifting or the like is about the worst thing I can do for fine motor skills - takes several hours before things return to normal. I get the BIG twitches from that - either letting go of small things I mean to hold onto, or jerking a good 6 inches to a foot when intending to make a small adjustment (or both, so the item is flung rather than merely being dropped).

I can get that done as well but at about 0402 sizes my eye don't want to comply, at least not for a long stretch of soldering.

That's kind of unavoidable around here. There is a wood stove ...

Silly rabbit! You buy some UN-gapped cores, and use fish paper to achieve the right gap. Remember that when gapping the entire core as this paper gap process does, you have to double that gap value when you go to order the properly tuned (gapped), gapped core.

Instead of paying for a set of cores with incremental gaps, you should get un-gapped core sets, find out what your gap needs to be by gapping the entire core (inner post is one path, and the outer ring is the other)(note how the surface area of the outer ring is the same as that of the center post). Then the gap you order is a mil or two less than double the paper gap tuned figure. That way, you can have it closer, or do some fine, flat plate abrasive sanding on the center post (the dremel is a BAD idea) to make changes. You can easily pull off a mil or two or ten, if you wish with the flat plate method.

Your proto tuning point which you arrive at should transfer over well to a center post only gapped cores set, where you take a single, non gapped core half, and mate it to a core half that you have had gapped on the center post. You would double the gap you used in the proto session to get the gap thickness you would order from the core presser. They usually remove the media abrasively.

You can buy 1 mil (fish paper) or find "Nomex" high dielectric transformer paper (that's the brand you google for), which comes in precision thicknesses. Try Farnell for a source.

You can get a mil, 1.5 mils (important for making half steps),

You can also use transformer tape to gap with for lab proto, as it also comes in precision thicknesses. A razor knife edge trims transformer tape excess well.

It isn't really a ceramic. It is a sintered plug essentially, and acts like a very brittle, hard packed clay. Not end mils, but bladed cutters can be used on it, though abrasive grinding is far easier, safer, and cheaper.

It's called transformer paper, and the most common brand I know of is "Nomex". Specifically for use in transformer applications, including precision gapping.

And not the slightest wobble. I tried cutting toroids with a diamond blade and in a pinch I only had a wet tile saw and the blade had been used on porcelain before, despite repeated dressing attempts. Not good, >50% scrap, but at least I got enough good ones to complete the test.