@Hypatia's Protege , Alpha testers and other ppl with opinion:

So here's big quandary! Do we give proper lesson on magnetics or just basics of inductor (including mutual inductor) design? Cuz most ppl on team (who I say represent good cross-section [NPI] of _target readership_) have major issues with magnetic concepts! So for example since they don't understand totally basic concepts and relationships they are totally lost knowing how to wind coil and gap core for desired inductance and saturation current! HP I've tried and tried to teach them concepts even on just intuitive level but they're way too intimidated by the math and new concepts So now I'm resorting to just handing out formulae so they can just plug in the manufactures' material and core data w/o even understanding it! HP now I'm saying even though that approach _works_ it also STINKS! Cuz it's just empiricism and pragmatism which I say is basically Tech-Ed NOT science! So I totally agree with you that whole point is for ppl to UNDERSTAND not just be _make do followers_!

So other side of argument is that we need to limit scope if we plan on ever getting on with it cuz like I said we can't teach whole history of universe! So I say target readership should be expected to know basic electric/electronic principals but magnetic principles are a totally different skill-set cuz like you say even a lot of scientists and engineers are weak in that! So I say giving like _primer_ on magnetics is appropriate cuz of that and also fact that subject of electromagnetic transformation is vital means to end of central theme and practical objectives of tutorial series!

Now to all Alpha team members having problems designing collector/drain chokes:
To clear air on one point which I'm VERY tired of receiving email abt: E-Core forms which are equally gapped on central leg and each outer leg are only gapped to TWICE the thickness of the spacers NOT three times! Please just think on it! The magnetic circuit is only broken TWICE cuz both outer legs are part of concurrent magnetic path! So in case it helps, some ppl say concept is obvious when they think on _pot cores_ (where shell is equivalent to legs on E core).

Just so you can know you have your minds right on this here's _thought experiment_
How would it effect the effective permeability (μe) of an E-core form if it was machined so core had gap on just a SINGLE outer leg? Only hint I'm giving is to say that Ae comes into part of solution but in TOTALLY different way than you're prolly thinking!

 

@Hypatia's Protege so just in case you don't see my e before you're on here tomorrow plz post pics of pot core and bobbin showing detail and names of features so I have reference for lessons! Cuz magnetic components are like extraterrestrial fauna to more ppl than you'd believe!

Alpha team now plz don't take that the wrong way! I'm not ridiculing any of you! I'm just embarrassed that we (by which I mean alpha test coordination staff including myself) didn't make allowances beforehand for subject we recognized as potential problem months back!

 

plz post pics of pot core and bobbin showing detail and names of features so I have reference for lessons! Cuz magnetic components are like extraterrestrial fauna to more ppl than you'd believe!

--Emphasis Added--

Oh! I believe! -- No fear of that!

Please be advised that I'll attempt to re-visit this thread later today/tomorrow with the aim of elaboration upon the subject of this post and response to your many excellent points/observations (above).


Annotated view of 'pot core' components; Please note that the 'form pieces' are identical...

Example of bobbin wound to seven 'turns'...

Partial assembly; Wound bobbin positioned in single form piece sans reluctance gap spacer...

Partial assembly; Note position of the reluctance gap spacer upon the spindle land...

Fully assembled (side view); Note the separation of the shell skirts/lands (owed to the intervention of the core spindle by the gap spacer)...

Fully assembled (end view)...

Fully assembled (alternate end view)...

Very best regards
HP

 

Alpha team now plz don't take that the wrong way! I'm not ridiculing any of you! I'm just embarrassed that we (by which I mean alpha test coordination staff including myself) didn't make allowances beforehand for subject we recognized as potential problem months back!

And I'm 'just embarrassed' that what passes for 'higher education' now deems engineering a technical (as opposed to scientific) subject!

All of which is to say I concur with @Aleph(0) -- You've no cause for abashment whatever!

Most sincerely
HP

 

--Emphasis Added--

Oh! I believe! -- No fear of that!

Please be advised that I'll attempt to re-visit this thread later today/tomorrow with the aim of elaboration upon the subject of this post and response to your many excellent points/observations (above).


Annotated view of 'pot core' components; Please note that the 'form pieces' are identical...

Example of bobbin wound to seven 'turns'...

Partial assembly; Wound bobbin positioned in single form piece sans reluctance gap spacer...

Partial assembly; Note position of the reluctance gap spacer upon the spindle land...

Fully assembled (side view); Note the separation of the shell skirts/lands (owed to the intervention of the core spindle by the gap spacer)...

Fully assembled (end view)...

Fully assembled (alternate end view)...

Very best regards
HP

Huge thanks HP!

Just so ppl know, slots on bobbin allow for easy turn counts in 180° increments and slots in form halves (which don't have to be lined up) allow leads to exit winding at any angle to each other (so any fraction of a turn). But since turn count with fractional component can have non-intuitive implication it's best for now to just wind to integral number of turns.

Also it's totally important to remember effective gap = 2X spacer thickness!

 

Hey @Aleph(0) -- No! I'm not neglecting you or The Project -- Seems my 'half-tick' was 'absorbed' adding my $.02 to the 'Feedback' thread you so 'kindly' 'tagged' me into --- No worries! - I shall return again! -- Albeit, one can but hope, prior to that juncture whereon the dust is seen to 'luft high in June'

Best regards and TTFN
HP

 

Seems my 'half-tick' was 'absorbed' adding my $.02 to the 'Feedback' thread you so 'kindly' 'tagged' me into

HP sry for distraction but I just assumed you'd want heads up on matters of forum culture too! So anyhow I say your taking time to make comprehensive response proves my assumption right!

No! I'm not neglecting you or The Project

HP Like I've said 1,000,000 times I totally understand! So I'm not criticizing or pressuring but I say sooner you're back the better cuz I'm feeling lost in limbo here and JC, TV, BB, LH, LK, AP, TW and rest of them are basically in like _holding pattern_ until your return! So if you can't be back on it for awhile yet plz give them direction cuz despite appearances my _role description_ is NOT project cheerleader! So I might be bimbo but I'm not entirely brainless!

BTW to coordinators who's initials I _missed_ don't be all ragey! Cuz it's just that I only gave out initials of ppl I know are ok with that so scuse me for respecting your privacy!

Also here's important request! Plz consider registering on AAC forums! Cuz it would make communication much easier and way more transparent to 3'rd parties! Also I say you'd like it here! Now I know some of you have privacy issues cuz of some questions on registration form. So if that's all that's holding you back plz contact member of Admin team to discuss your concern! Now o/c I can't promise anything but I say it's the right thing to do since just being hosted on AAC is putting EHT thread on first Google search page! So I say it's little enough to ask that we all reciprocate with active memberships!

Now just so everybody in Alpha team knows, HP has totally solved problem of her cryptojacked server (v112) so your accounts are all reactivated! But since she's blocked connections from _adware injecting browser_ (FF Quantum), FF users need to use ESR version (which is a little slower but a lot safer and more malleable!) So anyhow it's not bw intensive traffic anyway! So you'll have formal announcement from HP by e-list soon if not already!

@Hypatia's Protege when you have the chance plz post 100% algebraic formulae for winding AND gaping ferrite forms on here! So I know they can just Google them but pure algebraic discussions are harder to find and I say some of team have like biliary colic cuz calculus is giving them pain!

 

@Hypatia's Protege I'm saying it right here so ppl can know ongoing delays aren't my fault!

So to Alpha team and all other ppl following or just interested in HV courses: I asked HP for algebraic equations for ferrite inductor construction here:

@Hypatia's Protege when you have the chance plz post 100% algebraic formulae for winding AND gaping ferrite forms on here! So I know they can just Google them but pure algebraic discussions are harder to find and I say some of team have like biliary colic cuz calculus is giving them pain!

To which she responded (via my e) with proper mathematical discussion and put it on me to _break it down_ to pure algebraic expressions for step-by-step inductor construction for benefit of math-phobic readers (on original basis of her being _pressed for time_!) So I say heaven save us from simplification that's more time-consuming than just proper discussion!

Also, just so you know, despite my _jab_ at end of quoted text{} math dumb-down is HER idea which I totally disagree with!

So HP you are always saying like _concept rules_ (which I totally agree!) I'm also in total agreement that we should never insult readers with assumption of illiteracy or ignorance! But I say that's exactly what YOU are doing assuming they can't handle basic HS/undergrad calculus! So I say anybody who can't handle basic math isn't really interested in physical science anyhow and so prolly bad risk for potentially (npi) hazardous projects!

HP I totally understand abt not scaring ppl off at critical early stage of interest in subject! But I say assumption of BASIC math skill isn't intimidating it's just showing basic respect!

So HP here's sugestion! Now that we've totally proven beyond shadow of doubt that formal presentation and discourse is vry well received and totally appreciated by _target readership_ I say let's give non-numptified math a try?

Now just so nobody gets wrong impression! All of us (HP, me and all of coordinator team) totally recognize fact that magnetics is like outre topic to a lot of ppl even with scientific background! So we're very patient and open to suggestions from ppl with concerns! That also goes for ppl with genuine _math phobia/mental block_ (which does NOT include ppl afflicted with just _math laziness_!)

So anyhow I and rest of team are all set as soon as @Hypatia's Protege quits LARKING AROUND and gets back on here!

 

Hi y'all!

@Aleph(0) Just look and believe it! Zenmate's FF addon is three months in the grave and counting but here I am coming to you through Globalcity right down the line! Now is that process by procrastination or what?

Before I get to topic how about some advice? Yeah I should just ignore it but Kayla has a point as re: my avatar being wrong for a project aimed at serious HV applications! Sure she could use a sense of humor but give her a break! Going through life with a garden vegetable for a first name is enough to wear anyone down So I wanted to follow HP's and your leads of using an avatar pic that's a drop dead ringer without using my real image! So I tried your trick of just plugging my pic into Google SBI. Unfortunately, in my case, the "visually similar images" were anything but! (unless my eyes were blinded by vanity) So that's where it stands as of now. I'd rather make the change ASAP b/c I want it settled when my presence here and on your site increases following HP's return to active tutorial duty! For some reason many ppl are disturbed when others change their avatars and you know none of us want disturbed ppl on our project So... oh yeah! My point! Plz help me scan the web for a pic that passes for yours truly! It needn't match as closely as HP's and yours! The only criterion is that it would pass as me to personal acquaintances. I think that's not too tall an order for a still?

===On Topic===
What are HP's recommendations for fabrication of the air gap spacers in post #1320? Her memo calls for a gap of 500 μm = a gap spacer dimension of 250 μm therefore it's from a piece 10/1000" PTFE sheet stock. Got that! But how to cut a 13cm disk with a 10mm center hole w/o causing wrinkles and burs that throw out the gap is beyond me? FWIW All I can come up with is that a 13 mm Dia segment from a large telescoping antenna might be sharp enough to use as a circle punch on PTFE but that's not something most ppl have laying around.

My second question pertains to wire economy. HP suggests winding four gaped inductors with values of 33 μH each (10 turns in a PC-3019 pot core gaped for an AL of 327 nH/N^2) series connected for ~ 130 μH with Bsat characteristic ~ 20 Amps. Got it!
My thought is we could use less wire by paralleling X identical coils wound to X times the target inductance by dint of the non-linear quadratic relationship of N to AL. O/C I'm not questioning HP's decision! (I wouldn't dare!) She's stressed the nonliterary many times! I'm just curious

Aleph(0) please don't ask me to contact HP about all this! You know I'm trying every way I can to get back to her good graces! Hassling her now would be bad enough but risking annoying her with a further demonstration of my obtusity is not an option!

 

@Jazz2C So is this what passes for _holding down fort_? One post that's like 50% OT?

Honestly! With HP's _busy schedule_ your and Theo's LAZINESS and Alpha team's _bashfulness_ I totally wonder why I bother anymore!

So anyhow I have to get to station in abt 3 hours which means I need to leave NOW! I should have chance to respond early AM so plz check back on here then if you think you can stand exertion!

 

Attn: @Jazz2C

Inasmuch as she anticipates delay returning home, Aleph requested that I take a moment to address your questions...

What are HP's recommendations for fabrication of the air gap spacers in post #1320?

---Emphasis Added---

JC! We've had this out before! I don't want to see that again! 'Air' is nothing to do with it! - As well you know! - Which is by no means an endorsement of 'PTFE gap'! -- 'Reluctance gap' is with the not-inconsiderable advantages of accuracy, self-explanation and facilitation of comprehension!

But to move on...

But how to cut a 13cm disk with a 10mm center hole w/o causing wrinkles and burs...

Please be advised that the spacers shown in the above cited post were salvaged from LOPTs in the course of 'rebuilding' -- For present purposes spacers exhibiting ODs = 1/2" (≈12.7 mm) and IDs = 3/16" (≈4.7mm) are quite satisfactory!

therefore it's from a piece 10/1000" PTFE sheet stock. Got that!

Congratulations!

Updated gap spacer fabrication presentation HERE - Thanks!

My second question pertains to wire economy. HP suggests winding four gaped inductors with values of 33 μH each (10 turns in a PC-3019 pot core gaped for an AL of 327 nH/N^2) series connected for ~ 130 μH with Bsat characteristic ~ 20 Amps. Got it!

Correct.

My thought is we could use less wire by paralleling X identical coils wound to X times the target inductance by dint of the non-linear quadratic relationship of N to AL.

Very good! Well conceived independent thought is all of 'fair' and very much appreciated! --

Short answer: While, in theory, your reasoning is spot on, practical complications owed ferrites' thermally-dependent magnetic properties tend to contraindicate casual application of current sharing (i.e. 'parallel') arrangements is maintenance of 'balanced' current distribution, core heating, Bsat and μe to readily be realized...

That said, please rest assured that techniques for paralleling ferrite inductors are both practical and in common use (a 'workaday' example of which might be garnered via a 'gander' inside a power inverter or, better still, a schematic thereof).

Aleph(0) please don't ask me to contact HP about all this! You know I'm trying every way I can to get back to her good graces! Hassling her now would be bad enough but risking annoying her with a further demonstration of my obtusity is not an option!

No worries! - I 'avent sharpened my fangs as of late

So... oh yeah! My point! Plz help me scan the web for a pic that passes for yours truly! It needn't match as closely as HP's and yours! The only criterion is that it would pass as me to personal acquaintances. I think that's not too tall an order for a still?

Well... For my 'money' you're a 'reasonable facsimile' of the lead vocalist of the 'heavy metal' band 'Metallica' (Sp?) in his youth -- I apologize that his name escapes me at the moment - and I'm in no mood for 'five rounds' with what's left of Google's SE --- Thus I defer to @Aleph(0)...

To which she responded (via my e) with proper mathematical discussion and put it on me to _break it down_ to pure algebraic expressions for step-by-step inductor construction for benefit of math-phobic readers (on original basis of her being _pressed for time_!)

Aleph? What's the problem? You're welcome to post the formulas you've been 'handing out'...

math dumb-down is HER idea which I totally disagree with!

No argument there! -- On either score!

I'm also in total agreement that we should never insult readers with assumption of illiteracy or ignorance! But I say that's exactly what YOU are doing assuming they can't handle basic HS/undergrad calculus!

And I would argue that expecting English speakers to be conversant with (would you believe?) English is in no way analogous to expecting (all) prospective researchers, engineers and avid hobbyists to be acquainted with (largely) post-secondary mathematics...

So HP here's sugestion! Now that we've totally proven beyond shadow of doubt that formal presentation and discourse is vry well received and totally appreciated by _target readership_ I say let's give non-numptified math a try?

Sincerely! - That's an excellent suggestion! -- And one that I'll gladly entertain at such time as we embark upon subject matter requisite of said skills! (e.g. quantitative analysis of driver topology, radiometry, radiography, radiology, diffractometry, interferometry and... Oh! Yes! IECD topics!)

HP I totally understand abt not scaring ppl off at critical early stage of interest in subject! But I say assumption of BASIC math skill isn't intimidating it's just showing basic respect!

Trust me! As it does you, the abysmal state of contemporary public education (at least) appalls me no end! -- Still, the sad fact remains! We can either welcome and, where necessary, 'nurture' those willing to learn -or- inadvertently 'chase' them back to the likes of YouTube, etc via requirement of skills they --through no fault of their own-- simply do not possess! --- Are we to eschew the base hypocrisy of many contemporary admissions committees (Spec: effective requirement that prospective students have already 'mastered' the curriculum [such that the institution might tout a high 'graduation rate' and, hence, an undeserved illusion of quality instruction]) we must set the bar realistically --even if uncomfortably-- low!

Now just so nobody gets wrong impression! All of us (HP, me and all of coordinator team) totally recognize fact that magnetics is like outre topic to a lot of ppl even with scientific background! So we're very patient and open to suggestions from ppl with concerns! That also goes for ppl with genuine _math phobia/mental block_ (which does NOT include ppl afflicted with just _math laziness_!)

Exactly!

Also here's important request! Plz consider registering on AAC forums! Cuz it would make communication much easier and way more transparent to 3'rd parties! Also I say you'd like it here! Now I know some of you have privacy issues cuz of some questions on registration form. So if that's all that's holding you back plz contact member of Admin team to discuss your concern! Now o/c I can't promise anything but I say it's the right thing to do since just being hosted on AAC is putting EHT thread on first Google search page! So I say it's little enough to ask that we all reciprocate with active memberships!

I wish to add my voice to Aleph's and for the self-same reasons! Moreover, I may --sans fear of contradiction-- aver that, over the course of my three years' tenure on AAC, I've neither experienced, witnessed nor heard tell of anyone having suffered privacy issues! AAC is as safe a site as I've ever participated on! -- You may rest assured that's saying a great deal!

Very best regards
HP

 

ATTN: Kind friends (and long-suffering detractors)

In response to the veritable deluge of complaints and questions in regards to my admittedly over-cursory treatment of 'gap-spacer' fabrication (in post #1328), I here present a non-ambiguous, 'illustration heavy' 'step-by-step'.

Introduction:
The reluctance gap spacer will be fabricated from a small section of 0.01" (250um) PTFE sheet-stock (commonly available in bulk rolls as shown below). The standoffs and fastener are employed as a jig to assist formation of the spacer. Please be advised that my (seeming) 'embrace' of SAE/Imperial units in the following owes to the common commercial descriptions of the materials (Yeah! It's ugly! But whatcha gonna do?)

Materials identification:

Prepare a small piece of PTFE stock as shown below:

With the standoff held in firm apposition to the PTFE stock, run a 3/16" bit at high AV (ideally ≥ 4000 RPM [i.e. 419 Rad/s]) through the standoff's center-bore (and, hence, the PTFE) - Please note: The higher the AV (within reason) the 'cleaner' the cut.

Image of unassembled jig components and PTFE stock (prepared and drilled in the foregoing).

Assemble jig components and PTFE stock as shown.

Firmly secure fastener: NOTE: Standoff alignment is greatly eased via selection of a fastener exhibiting the greatest diameter admitted by the standoff bores (Which being 13/64" Re: the materials used in this demonstration).

With the aid of curved Metzenbaum scissors (or similar instrument), rough-trim the excess PTFE stock.

Using a Sims UC (or similar) 'flush' the PTFE with the periphery of the standoffs.

Remove the spacer (thus formed) from the jig and verify conformity.

Best regards
HP

 

@Hypatia's Protege so I just looked at gap spacer s-b-s for first time (so no chance of it already being in browser cache or like that) and all nine piccys load and render perfectly for me! So I say since they work through my glitch-o-matc vpn there's no problem anymore if there ever was (which I srsly doubt considering source of complaint!).

So anyhow HP and @Jazz2C I'll be back on here later to give response to your posts

BTW Theodora! Since tagging your known UNs on here doesn't work I say either you aren't registered or you need to publicly post your AAC UN on this thread and start participating here ASAP! Theodora since you are on core development team I say your membership on here is NOT optional! So sry for public shaming but I'm totally tired of ppl making things more difficult with silly foot dragging!

ALSO ALPHA TEAM

Also here's important request! Plz consider registering on AAC forums! Cuz it would make communication much easier and way more transparent to 3'rd parties! Also I say you'd like it here! Now I know some of you have privacy issues cuz of some questions on registration form. So if that's all that's holding you back plz contact member of Admin team to discuss your concern! Now o/c I can't promise anything but I say it's the right thing to do since just being hosted on AAC is putting EHT thread on first Google search page! So I say it's little enough to ask that we all reciprocate with active memberships!

So since ur volunteers I can't insist you join but I say basic common courtesy to us and AAC (which, after all, is our publisher!) gives you moral obligation! Now I'm going to tell you something! Your crying _privacy_ is totally lame since prolly all of ur on FB and Twitter! So I say REAL problem is ur just too lazy or afraid of being branded _science geek_ by peer group! So all I can say is if that's pack u run with it's totally past time to crawl out of playpen and grow up! Confirmed morons are only worth leaving behind and totally forgetting! Also if you're scared abt what some of you are calling _advanced math_ there's no need! Cuz HP and I basically changed sides on that over last year! So now I'm the one calling for inclusion of basic analysis and it's HP who wants to hold it to just Vector Algebra until we get to actual engineering topics! So since it's HP's _ballgame_ it's her call! Also only math ur going to see rebuilding FB and pre-designed test circuit is just arithmetic and like 6'th grade Algebra!
Also I'm not calling mathphobes dumb just victims of education system with totally misplaced priorities!

 

only math ur going to see rebuilding FB and pre-designed test circuit is just arithmetic and like 6'th grade Algebra

Bummer... I was looking forward to some good'ol fashioned differential equations ... but no matter, algebra is fun too ...

 

Bummer... I was looking forward to some good'ol fashioned differential equations ... but no matter, algebra is fun too ...

Cmartinez I say no need to pine away cuz how things usually go around here (by which I mean EHT thread) EQs would prolly all end up separable (so vry boring)

 

Cmartinez I say no need to pine away cuz how things usually go around here (by which I mean EHT thread) EQs would prolly all end up separable (so vry boring)

And by EQ you mean Emotional Coefficient? ... In that case I'd have to say I totally agree!

 

And by EQ you mean Emotional Coefficient? ... In that case I'd have to say I totally agree!

Cmartinez actually I just meant _Equations_ but if the shoe fits...

 

Cmartinez actually I just meant _Equations_ but if the shoe fits...

... like a glove ...

 

@Aleph(0) Just look and believe it! Zenmate's FF addon is three months in the grave and counting but here I am coming to you through Globalcity right down the line! Now is that process by procrastination or what?

JC I think you meant progress by procrastination? Anyhow If you'll take my advice I say enjoy it while it lasts cuz FF ESR is basically stopgap until Mozilla is done debugging Quantum! But since web extensions are totally evil that's bridge we need to cross when we come to it So it's major disappointment to me cuz FF is supposed to be ALTERNATIVE to Chrome so now they decided to betray all their loyal users by chasing Google market! I'd say a lot more but since bashing _big business_ is basically political talk I better shut up!

Plz help me scan the web for a pic that passes for yours truly! It needn't match as closely as HP's and yours! The only criterion is that it would pass as me to personal acquaintances. I think that's not too tall an order for a still?

Well... For my 'money' you're a 'reasonable facsimile' of the lead vocalist of the 'heavy metal' band 'Metallica' (Sp?) in his youth -- I apologize that his name escapes me at the moment - and I'm in no mood for 'five rounds' with what's left of Google's SE --- Thus I defer to @Aleph(0)...

HP so I had to google it too! Anyhow I thought you were one into old time entertainment! So anyhow name of singer is James Hetfield so I searched for pics taken when he looked abt JC's age and OMG! He is JC's ringer! Check this out:


So JC I say anyone who knows you would totally say that's pic of you w/o hesitation! So it totally meets your criteria with with flying colors! So I'm saying _ you're welcome_ in advance for me doing YOUR work finding it!

I'd rather make the change ASAP b/c I want it settled when my presence here and on your site increases following HP's return to active tutorial duty!

JC tnx for maintaining historical perspective of tutorial series!

For some reason many ppl are disturbed when others change their avatars

JC I agree that's true when Avatar is human subject! So I say it's just psychology of association.

and you know none of us want disturbed ppl on our project

Ha ha! Like HP says _saints preserve us!_

Aleph(0) please don't ask me to contact HP about all this! You know I'm trying every way I can to get back to her good graces! Hassling her now would be bad enough but risking annoying her with a further demonstration of my obtusity is not an option!

JC So that's why I asked HP to contact YOU on list and she answered all your questions! So I say BE HAPPY!

ATTN: Kind friends (and long-suffering detractors)

The reluctance gap spacer will be fabricated from a small section of 0.01" (250um) PTFE sheet-stock

HP I say linking PTFE to glossary was nice touch for article and nice olive branch for _ detractors_!

JC! We've had this out before! I don't want to see that again! 'Air' is nothing to do with it! - As well you know! - Which is by no means an endorsement of 'PTFE gap'! -- 'Reluctance gap' is with the not-inconsiderable advantages of accuracy, self-explanation and facilitation of comprehension!

HP I totally agree but I say you need to be more patient with millennials cuz we have double challenge of unlearning over two decades of dreck being beaten into our heads before we can just learn properly

run a 3/16" bit at high AV (ideally ≥ 4000 RPM [i.e. 419 Rad/s])

HP serious thanks for that! Cuz _Revs per minute_ makes me just ragey! So revolutions and radians are both natural concepts but how could anyone think minute (instead of second) was good temporal unit for expression of angular velocity?! Also radians make way more sense than revolutions (cycles) so I say Hertz is totally weird too So HP I know I'm preaching to choir telling you that but you know I have to say it!

So anyhow alpha team is just getting started on your gap spacer s-t-s so I'll keep you all up to date with posts here on EHT thread!

PS
HP plz put copy of spacer s-t-s in blog so it can stay easy to find in future!

 

HP So since you want me posting on-topic technical issues on thread instead of e here's something that's totally Ef'ing weird!?

So before you dismiss it as bad observation just know three Alpha testers discovered it independently and I reproduced it!

So anyhow issue is when series connected pot-core inductors are stacked in end-to-end contact they saturate way below calculated current corresponding to saturation flux density! But if they're separated even just a few mm current for Bsat is exactly what's expected! So o/c when I say _separated_ I'm talking abt space between complete inductors NOT Rel-gaps in inductors!

So I totally get it's cuz of _static_ field around cores (from DC component of current through inductors) somehow biasing neighboring inductor's core material towards saturation but I say that's weird cuz upper limit of flux density in any single inductor in chain of series connected identical inductors is asymptotic to flux density in single inductor's (full) crossection! So that means field from other inductors in setup can't have that effect even if perfectly coupled (cuz they all have same B and o/c B doesn't add, just superimposes maximum) and ayhow they're hardly coupled at all cuz of cancelling (so shielding) effect of pot-core geometry!

HP So anyhow it's not obstacle to test session cuz thin nylon washers between inductors reduce effect below measurability but I'm going to totally lose my mind if I can't figure what's going on!