Recent posts

#81

General Tormek Questions / Re: Capacitor Impedance for To...

Last post by Dutchman - July 29, 2025, 10:11:23 AM

Now we know enough about possible misunderstandings regarding capacitors.
Thank you.

#82

General Tormek Questions / Re: Capacitor Impedance for To...

Last post by tgbto - July 29, 2025, 07:59:17 AM

The impedance is a complex number, containing both a real part and an imaginary part. For an ideal capacitor, the impedance is purely imaginary, with no real part.

But for a real capacitor, there is a real part. Quoting from Wikipedia:

"The magnitude of the impedance |Z| acts just like resistance, giving the drop in voltage amplitude across an impedance Z for a given current I."

My calculation gives the magnitude of the impedance as about 210 ohms.

That's why I said "loosely" speaking. I'm ignoring the imaginary part, which is, as you say, responsible for the phase shift.

Agreed, *but* you based your calculation on the capacitance only, meaning you assume an ideal capacitor.

So you are not ignoring the imaginary part, you are dealing only with the imaginary part. The 210 ohms value you computed is a pure reactance, or said otherwise, no resistance at all.

To quote from the same wikipedia : "A pure reactance does not dissipate any power."

#83

General Tormek Questions / Re: Capacitor Impedance for To...

Last post by Herman Trivilino - July 28, 2025, 07:08:18 PM

So, loosely speaking, the capacitor offers a resistance to the flow of electricity of about 210 ohms.

The capacitor offers no resistance to the flow of electricity at all, it essentially alters its phase by 90 degrees (and multiplies it by a factor that depends on frequency).
 The resistance is the real part of the impedance and the impedance of a capacitor is purely imaginary : all the energy is conserved in an electrical form, none is lost to Joule effect.

The impedance is a complex number, containing both a real part and an imaginary part. For an ideal capacitor, the impedance is purely imaginary, with no real part.

But for a real capacitor, there is a real part. Quoting from Wikipedia:

"The magnitude of the impedance |Z| acts just like resistance, giving the drop in voltage amplitude across an impedance Z for a given current I."

My calculation gives the magnitude of the impedance as about 210 ohms.

That's why I said "loosely" speaking. I'm ignoring the imaginary part, which is, as you say, responsible for the phase shift.

#84

Knife Sharpening / Re: Beyond Basic BESS

Last post by tgbto - July 28, 2025, 09:01:21 AM

One note though, if you come over for dinner don't stick your hand in the knife drawer.

Do you mean you keep you ultra-sharp knives loose in a drawer   

#85

General Tormek Questions / Re: Capacitor Impedance for To...

Last post by tgbto - July 28, 2025, 08:55:44 AM

So, loosely speaking, the capacitor offers a resistance to the flow of electricity of about 210 ohms.

The capacitor offers no resistance to the flow of electricity at all, it essentially alters its phase by 90 degrees (and multiplies it by a factor that depends on frequency). The resistance is the real part of the impedance and the impedance of a capacitor is purely imaginary : all the energy is conserved in an electrical form, none is lost to Joule effect.

#86

Knife Sharpening / Re: Beyond Basic BESS

Last post by Ken S - July 27, 2025, 03:39:03 AM

Al,
I apologize if I offended you with this ropic. That was certainly not my intention. I sometimes start topics like this to inspire dialogue. I certainly do not consider myself "the expert" and I always enjoy learning from others.

So much has evolved, especially with honing since I began using my Tormek in 2009. I welcome constructive change.

Keep posting.

Ken

#87

Knife Sharpening / Re: Beyond Basic BESS

Last post by BPalv - July 26, 2025, 09:54:20 PM

Ken,
I also wanted to give my thoughts on "Basic Bess" and me.
My journey started Many years ago trying to get my filet knives sharp for the mountains of Lake Erie Walleye we would catch.  Later my kids bought me a set of Shun's that added fuel to the fire.
After spending a bunch, reading mountain's of studies, techniques, years of practice and of course endless videos, it doesn't feel very "basic" to me, nor was it a short journey.
Sharpening becomes a personal thing, why you sharpen, how you sharpen and the results you expect.  I love a super sharp knife but understand that most folks couldn't care less.

One note though, if you come over for dinner don't stick your hand in the knife drawer.
Al

#88

Knife Sharpening / Re: Beyond Basic BESS

Last post by Ken S - July 26, 2025, 07:50:46 PM

I really can't comment on super steels. I have never used or owned any.

I believe some of these ideas have merit, but only within reasonable limits.

Ken

#89

General Tormek Questions / Re: Capacitor Impedance for To...

Last post by Herman Trivilino - July 26, 2025, 05:20:01 PM

I once watched a marvelous VHS tape explaining Einstein's E=MC2. It gave the example of when a baseball is thrown at the speed of light squared, the baseball (matter) becomes Energy. for me, that was very informative. I would like to better understand the Tormek motors.

Yeah, you gotta be careful of those popular science publications and videos. What the formula really tells us is that the baseball has a rest energy of mc². So when at rest, it has an energy of about (0.145 kg)(300 000 000 m/s)², or about 13 000 000 000 000 000 joules. For comparison, if you heated 0.145 kg of water from room temperature to the boiling point (at sea level) it would take about 50 joules of energy. You could convert the energy of the baseball into, say, radiation by annihilating it, but unfortunately that would be very dangerous. Such things have to be done very carefully, using the correct materials (not baseballs) under carefully controlled conditions. We call such devices nuclear reactors.

The speed of the baseball has nothing to do with mc². In fact, c is a speed, whereas c² is not. It's just a conversion factor between units of mass and units of energy. Analogous to the conversion factor between inches and feet.

We all know that inches and feet are both measures of the same thing, distance. What Einstein taught us with mc² is that kilograms and joules are both measures of the same thing. Historically, we thought that mass was conserved, and energy was conserved. Two separate conservation laws. But Einstein taught us that that is just an approximation. There really is nothing special about nuclear reactions. When you light a match you are creating radiation, and that means the mass of the match and the smoke is decreased. It's just that the decrease is too small to measure. Nuclear reactions, though, are much more energetic, so the reduction in mass is quite measurable.

#90

Knife Sharpening / Re: Beyond Basic BESS

Last post by BPalv - July 26, 2025, 05:10:50 PM

Most BESS users strive for very low scores immediately after sharpening. I call that "basic BESS". While that may seem to bring bragging rights, those rights are short lived. In my opinion, using BESS to help determine the staying power of sharp edges is more useful. This extended testing can be to include comparing longevity of edges with different bevel angles, grinds, or steel.

Ken

I will ponder how to go about this and would like to give it a go.  With the sparse equipment I have it will at least be very challenging to get some sort of apples to apples test.  To date my testing, as Ken stated, I have been using the BESS to test sharpness, not longevity. 

I hate to say this but so far I can't really see the difference in supersteels as it equates to a lasting edge.  Many of the manufacturers tout super tough but all that I have used seem very similar in real world use.  That is to say, does my s30V edge last as long as my Magnacut.  Does toughness equate to a lasting edge?
I grew up messing with PC's.  The manufacturers would say how much faster they were.  It was true but that speedier PC could only be measured in nano seconds.  Perhaps it's like that with different supersteels unless they are on opposite sides of the supersteels spectrum.

The only advantage to a super sharp edge may be that because it starts sharper, it will generally be sharp longer.  I could certainly see where a ultra sharp edge could be more fragile...