ferrite machining?
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From: Bill Sloman on 13 Jun 2010 11:44 On Jun 13, 10:28 am, BlindBaby <BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: > On Sun, 13 Jun 2010 00:51:50 -0700 (PDT), Bill Sloman > > <bill.slo...(a)ieee.org> wrote: > >In so far as small-pox doesn't exist - as an infectious disease - any > >more, the fact that it comes to your mind is illustrative of your > >feeble grasp of reality. > > Actually, due to terrorist strains, it may make a comeback, and I know > far more about it than you do as I never received a vaccination, and I > was born in 1960. > > Had I gotten one, I would have contracted the disease (a deadly version > of cowpox). My brother did not get one either as he would have given it > to me. I had a condition at the time known as spots. > > So I knew more about the disease at age five than you do now. Or so you seem to think. I'm old enough to have been innoculated against small-pox, and I know enough to have heard about Jenner and where the term vaccination came from - it is a reference to the cow- pox which you claim includes a "deadly strain". http://en.wikipedia.org/wiki/Edward_Jenner If you had got all that on board at the age of five, you'd have been a bright kid. The fact that you don't seem to have retained much of it as an adult does suggest that you were dropped on your head sometime in the intervening period. -- Bill Sloman, Nijmegen
From: John Fields on 13 Jun 2010 14:54 On Sun, 13 Jun 2010 07:35:35 -0700 (PDT), MooseFET <kensmith(a)rahul.net> wrote: >On Jun 13, 1:40 am, John Fields <jfie...(a)austininstruments.com> wrote: >> On Sat, 12 Jun 2010 09:20:37 -0700 (PDT), MooseFET >> >All sintered things are brittle. Watch the temperature. >> >> --- >> I don't believe that's right, since at least some (if not most) >> sintered metallic parts retain the mechanical properties of their >> parent metals or alloys. > >The cores I have experience with are metal oxides not metals. >They are brittle. --- Ah, but that's a subset of "all sintered things", yes?
From: Archimedes' Lever on 13 Jun 2010 15:11 On Sun, 13 Jun 2010 10:31:10 -0400, John Ferrell <jferrell13(a)triad.rr.com> wrote: >On Sat, 12 Jun 2010 13:43:58 -0700, Archimedes' Lever ><OneBigLever(a)InfiniteSeries.Org> wrote: > >>On Sat, 12 Jun 2010 15:59:17 -0400, John Ferrell >><jferrell13(a)triad.rr.com> wrote: >> >>> the tiny >>>abrasive disk that shatters every time you use one hand held. >> >> The fibrous "concrete saw" type disc works better. "dado" two together >>for wider cuts. >If it is small enough to do the job it is a better choice. I don't >throw the away until they are dime size! >John Ferrell W8CCW They are great for trimming way material of just about any strata, and they can be used for all types (methods) of said removal. I buy 'em buy the five pack, I think. Great for trace cutting. Great for PCB 'slotting' for HV isolation/creepage, etc. There are so many places where it does the job, and leaves little abrasive debris behind in doing it. I have used those little cut-off discs for soooo many things.
From: BlindBaby on 13 Jun 2010 15:29 On Sun, 13 Jun 2010 07:35:35 -0700 (PDT), MooseFET <kensmith(a)rahul.net> wrote: >On Jun 13, 1:40 am, John Fields <jfie...(a)austininstruments.com> wrote: >> On Sat, 12 Jun 2010 09:20:37 -0700 (PDT), MooseFET >> >> >> >> <kensm...(a)rahul.net> wrote: >> >On Jun 12, 11:48 am, BlindBaby >> ><BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: >> >> On Fri, 11 Jun 2010 20:24:34 -0700 (PDT), MooseFET <kensm...(a)rahul.net> >> >> wrote: >> >> >> >On Jun 12, 1:33 am, Bill Sloman <bill.slo...(a)ieee.org> wrote: >> >> >[...] >> >> >> Wrong. Permeability drops with rising temperature, and leakage flux >> >> >> rises. Ferrite cores don't have to get very hot before they become >> >> >> magnetically insignificant. Read the relevant data sheets for the >> >> >> material used to make your core on the manufactuere's web site. >> >> >> >This has nothing to do with the reason to watch the temperature rise. >> >> >It is just plain a mechanical issue. The material is brittle and a >> >> >bad >> >> >conductor of heat. >> >> >> And grinding it doesn't hurt it at all. It got heated when it got >> >> made. It is a sintered, stamped, baked manufacturing process. >> >> >All sintered things are brittle. Watch the temperature. >> >> --- >> I don't believe that's right, since at least some (if not most) >> sintered metallic parts retain the mechanical properties of their >> parent metals or alloys. > >The cores I have experience with are metal oxides not metals. >They are brittle. There are two types of ferrites. Hard ferrites will retain magnetization effects. Soft ferrites will not. Soft ferrite ARE 'machinable', typically though only by way of grinding. Manufacturing processes for each type are similar, but do differ from maker to maker. There are many 'styles' however, that are manufactured in a common way so that designers can choose form more than one producer for their raw goods, and get like performance expectations. Common sense again... duh. Lots of cutting edge hybrid stuff out there though. That's also how we got advanced magnetics science over the last 60 years too. The colleges toyed with materials, and the factories made the goods to be tested to prove the science.
From: BlindBaby on 13 Jun 2010 15:31
On Sun, 13 Jun 2010 07:37:09 -0700 (PDT), MooseFET <kensmith(a)rahul.net> wrote: >On Jun 13, 1:21 am, BlindBaby ><BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: >> On Sat, 12 Jun 2010 09:29:32 -0700 (PDT), MooseFET <kensm...(a)rahul.net> >> wrote: >> >> >On Jun 12, 8:30 pm, Grant <o...(a)grrr.id.au> wrote: >> >> On Fri, 11 Jun 2010 20:20:54 -0700 (PDT), MooseFET <kensm...(a)rahul.net> wrote: >> >[...] >> >> Anyway, 150 grit diamond tool rips into the stuff, black dust everywhere, >> >> easy to fracture pieces off, very harsh if one applies too much pressure. >> >> >The problem is mostly the local temperature rise. If you are careful, >> >you >> >can cut an O-ring groove into a rod core to seal the place where it >> >goes >> >through a wall. Fine work can be done but when making any sort of a >> >groove a lot of care is needed. >> >> Your brain is on overkill, and you can't even get that right. > >I stand by my warning. What you claim doesn't matter because >I know I will be shown to be correct. The temp rise is not what you have to watch for. It is the RATE of temp rise, and that rate is not going to be exceeded by dremeling, unless you are a total idiot when you get the dremel in your hand, in which case, you should be on a different career path, such as street sweeping. |