Ecore Air Gap Creation
in [Design]
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From: Jim Flanagan on 25 Mar 2010 23:17 I have some ungapped Ecore material that I want to create an air gap in the center leg. How would you properly 'grind' the center leg without breaking it? I've heard about using a plastic shim but how does that work on the outer legs? Do I add a shim to the outer legs as well? As you can tell, I have much to learn. Your help is appreciated.
From: Phil Allison on 25 Mar 2010 23:27 "Jim Flanagan" > > I have some ungapped Ecore material that I want to create an air gap in > the center leg. > How would you properly 'grind' the center leg without breaking it? ** Send it to a workshop that has the special grinding gear required. > I've heard about using a plastic shim but how does that work on the outer > legs? Do I add a shim to the outer legs as well? ** Unless you want the core to break in half - yes. ...... Phil
From: Spehro Pefhany on 26 Mar 2010 00:57 On Thu, 25 Mar 2010 23:17:15 -0400, the renowned Jim Flanagan <jflan(a)tampabay.rr.com> wrote: > >I have some ungapped Ecore material that I want to create an air gap in >the center leg. >How would you properly 'grind' the center leg without breaking it? I've >heard >about using a plastic shim but how does that work on the outer legs? Do I >add a shim to the outer legs as well? As you can tell, I have much to >learn. >Your help is appreciated. You can add shims to all three legs, of half the thickness of the air gap that you wanted in the center leg. The field won't be quite as contained. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Wimpie on 26 Mar 2010 06:33 On 26 mar, 04:17, Jim Flanagan <jf...(a)tampabay.rr.com> wrote: > I have some ungapped Ecore material that I want to create an air gap in > the center leg. > How would you properly 'grind' the center leg without breaking it? I've > heard > about using a plastic shim but how does that work on the outer legs? Do I > add a shim to the outer legs as well? As you can tell, I have much to > learn. > Your help is appreciated. As others said, you can distribute the gap over the inner and out legs. As this halves the gap in the center leg, eddy current loss may reduce. If, for some reason, you only want the gap in the center leg, you can use a small silicon carbide sharpening stone that fits in between the outer legs. Some water with very little soap and patience will give you the gap. I used this method to make some gapped cores for leakage transformer experiments. Best regards, Wim PA3DJS www.tetech.nl remove abc before using PM
From: Bob Eld on 26 Mar 2010 11:04
"Jim Flanagan" <jflan(a)tampabay.rr.com> wrote in message news:4bac273d$0$4888$9a6e19ea(a)unlimited.newshosting.com... > > I have some ungapped Ecore material that I want to create an air gap in > the center leg. > How would you properly 'grind' the center leg without breaking it? I've > heard > about using a plastic shim but how does that work on the outer legs? Do I > add a shim to the outer legs as well? As you can tell, I have much to > learn. > Your help is appreciated. The ground gaps have to be carefully ground flat and true without chips or other faults. It could be done by hand but why bother? For production, cores are machine ground with diamond tools. For one core, add shims. It's the easiest and is changeable to alter your design if required. It gives you the greatest flexibility. A gap on all three legs has to be half the distance of a center leg only gap. Paper or paper tape is the simplest material to use for gapping. Masking tape works well because it sticks to the core making assembly easy. Because paper or tape is thin, several mils, gaps of any dimension can easily be piled up with multiple layers and of course they can be easily changed. Use a caliper or micrometer to measure the gap pile. Do not assume that the actual dimension is necessarily the sum of the layers. Air and glue can alter the dimensions slightly. If the design is going into production, you can have cores gaped by grinding to any spec. by the manufacturer. For small quantity experiment and bread boarding, use shims. |