⇒Polyolefin heat shrink sleeves -- Example: Gardner Bender HST-750 – QTY: Three untreated 4” {102mm} sleeves

HP I say you should specify that tubes are 3/4 inch preshrunk id cuz that works for all FBT ferrites I've ever used!

HP I also say readers should have have Corona Dope and High Temp Epoxy on hand for debugging arcing troubles and to repair broken ferrite if needed

HP JC says he'll have time to thoroughly read it later on tomorrow so I say once he does that I'll give it final pass after you link pics for auto-displaying

Indeed! It appears to be a matter of 'what the standard don't know - the vendor understands'

HP what are you paraphrasing there? Cuz it's just eerily familiar

Are you certain you saw that in a CRC publication? My general impression of their 'handbooks', etc... has been quite favorable...

HP No! I don't mean that CRC (which is abbreviation for silly name Chemical Rubber Company which is publisher of totally FIRST RATE science and math reference materials!) I meant from silly ancient Gernsback collection that some ppl are trying to revive in comments on sites like Instructibles and like that

 

LOPT preparation tutorial development
Last action @ 9/30/2016 --- 18:47 UTC


====Introduction====

Scope of series:

Central topics:
This tutorial is one in a (prospective) series with focus upon low ripple, medium current/power PSU solutions for radiography and other modest photon energy (≤ 2 MeV) particle accelerator applications - and, to a lesser extent, exploration of certain 'current intensive' electrostatic phenomena (e.g. electret photography, electret formation, electrokinesis, establishment of electrostatically 'cordoned' (atmospheric) pressure gradients, high volume ion-flow systems, etc...

Peripheral and extraneous topics:
While everyone is welcome to view and post questions (within the confines of this site's TOS/UA) - Please be advised that those having interests confined to the following topics/applications will not likely find this series particularly useful (owing to the availability of significantly less 'labor-intensive' solutions to same):

--'Pedestrian' and 'Quasi'/'Peri'-EHT applications:
(e.g. CRTs, PMTs/Image tubes, Gas discharge devices, lasers, ionization air purifiers, TC primary drivers, GM tubes, etc...)
--Low current demonstration topics (e.g. 'Lifters', 'Jacob's Ladders', 'Plasma Spheres', 'Kirlian photography', 'Ion Motors', etc...)
--Capacitor discharge demonstration: (e.g. 'Quarter Shrinkers'/'Can Crushers', 'Rail/Coil Guns', 'EMP generators', electrical weapons, etc...)

Please be advised that site policy prohibits my assistance with most inquiries coming under the latter category...
=================================================

Scope of this tutorial
Provision of a detailed, 'step by step' procedure for modification of 'heavy duty'
AC LOPTs for 'serious' EHT application/research...

Said procedure having the following principal goals:
-- Improvement of insulation integrity via removal of auxiliary windings coaxial to the EHT winding.
-- Enhancement of versatility via electrical 'floating' of the EHT winding.
-- Appropriate adjustment of reluctance gaps.


The desirability of LOPTs:
Of the commonly available magnetic components applicable to low through medium power EHT production, the LOPT offers the advantages of relatively high power intermittent operation (several hundred to >1kW per transformer) and useful continuous power operation (to Ca. 600 Watts each transformer under forced air cooling). Moreover, LOPTs' amenability to resonant (and, hence, sinusoidal) drive permits development of systems productive of highly desirable mean output EMFs (≈70% peak) as opposed to the rather low (< 1% through 5% 'spike' EMF) characteristic of flyback and similar pulse driven/energy storage topologies. Additionally, the inherent output symmetry attending resonant drive topologies facilitates implementation of effective external EMF 'multiplication' schemes.

Prominent among the LOPT's disadvantages are the common expedient of integral rectification/EMF multiplication circuitry and 'end point' grounding schemes --- While the former objection is readily addressed via judicious transformer selection, the latter requires minor 'reconstruction' - said procedure being the subject of this tutorial.

A few words regarding the unsuitability of DSTs and their ilk:
Principally:
1) Integral components electrically unsuited to general application.
2) Practical impossibility of modification for improved EHT winding to core insulation.

Re: point 1 (above) Although asymmetrical drive may permit peak forward (and hence output) EMFs well in excess of the internal rectifiers' PIVs - such is, of course, inapplicable to 'filtered' or otherwise capacitively loaded schemes sans additional external rectifiers - moreover, internal rectification greatly complicates cascading of multiple LOPTs for increased EMF and/or development of balanced output schemes...

Re: Point 2 (above)
'DC' LOPTs are constructed as indivisible units sans 'margin' for modification -- moreover (in the case of DSTs) the rectifiers are 'distributed' throughout the winding...

LOPT Selection:
The most desirable transformers are those intended for direct production of full (AC) EHT potential for application to external 'non-multiplicative' rectification pursuant to development of accelerating potentials for large CRTs -- Contrary to 'conventional wisdom' such units are yet readily available from long-established electronics supply houses (whom, in my experience, are only too happy to wave 'minimum purchase' and 'wholesale only' policies at the prospect of disposal of what they regard as 'dead stock') --- That said, one should expect to size their purchase so as to offset the supplier's 'invoicing costs'... Prices ranging from $20 (USD) per transformer (in reasonable quantities) are not uncommon...

The following images are offered as an aid to recognition of the desired form factor:

Assorted LOPTs typical of the desired geometry:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopts-jpg.101773/

Detail - Axial view:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt2-jpg.101772/

Detail - Transverse view:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/nos_tyre_lopt-jpg.101774/


The modification procedure:
--Please do not commence disassembly of the transformer prior to reading and comprehension of the entire tutorial...

Required materials:
Note: the quantities/dimensions cited below represent those necessary for completion of the modification - Minimum purchase requirements (while reasonable) will, in most cases, be significantly greater...

⇒Acetone -- QTY: 946ml ‘tin’
⇒Acrylic based hot-melt compound – Example: Surebonder Acrylstik - QTY: 100g
⇒CPVC tubing (3/4” Nom. id {CTS}) --- QTY 120mm (lineal)
⇒Elastic bands (latex) --- QTY ≈ 40g assorted sizes (≈20mm -- ≈70mm unloaded diameter)
⇒Electronics grade RTV Silicone -- Example: GC 19-155 – QTY: 90 ml
⇒Polyolefin heat shrink sleeves (3/4" untreated id) -- Example: Gardner Bender HST-750 – QTY: Three untreated 4” {102mm} sleeves
⇒Polypropylene pharmaceutical vial ( ~33mm Dia, ~64mm Len.)
⇒PTFE sheet stock – Example: http://www.eplastics.com/Plastic/ptfe_sheet -- QTY: 100mm x 60mm rectangle of 0.093” {2.35mm} stock and 40mm x 20mm rectangle of 0.015” {0.381mm} stock

Hardware:
#4 solder lug (‘inside-tooth’ fastener surface)
#4 { ≈7/64” ≈3mm} bit
#4 nut and bolt
#6 {0.83mm} burr or bit

Recommended implements:
Note 1: The reader is assumed to be in possession of standard electronics/basic ‘hand’ - tools...
Note 2: The reader is advised that 'workarounds'/'alternates' are possible for the following - please let us know should you have any questions...

⇒Dremel Moto-Tool or Equivalent
⇒Locking forceps
⇒Micrometer (Vernier) Range = 0-25mm / Res=1um {metric} -OR- Range = 0-1" / Res= 1/10,000" {imperial}
⇒Nitrile Exam Gloves
⇒Scalpels or 'X-ACTO' set
⇒Sims Uterine Curette (#3 sharp, fenestrated) -- Example: Sklar 90-5423
⇒Stainless Picks (non-magnetic)
⇒Tweezers (‘splinter’)
⇒Welder's Gloves (Supple varieties preferred for maximum dexterity)


=== Part 1 -- Disassembly of the LOPT unit ===


Step 1-1) Identify construction style of LOPT to be optimized.

Task:
1) Identify construction style via the description most closely matching the reader's device in the following...

Full EMF AC LOPTs feature one of two general construction styles as outlined below:

Style 1) Features a single piece frame ('clamp') -- the rails of which maintain compression on the core via a single linear ligature fashioned of a metallic strap or bolt extending from frame rail to frame rail across the top of the upper form leg 'facet' or 'furrow'.

Example of style 1
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_desc-jpg.101778/

Style 2) Features two independent metallic frame pieces OR a metallic half-frame and a backing plate/PCB -- such assemblies are bound by a single "U- bolt"/"U-strap" or two linear bolts/straps extending along the outer aspects of each horizontal form leg...

Examples of style 2

View of LOPT from 'closed' side of "U bolt" ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt1a-jpg.101781/

View of LOPT from 'open' side of "U bolt" Ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt1c-jpg.101784/

View of LOPT from 'closed' side of "U strap" Ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt2a-jpg.101785/

View of LOPT from 'open' side of "U strap" Ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt2b-jpg.101786/

Step 1-2) Removal of form frame ('clamp')

Tasks:
1) Remove any tape, looped conductors, ground leads, etc. ensnaring/bonding the frame to the form.

2) Free each end of the frame ligature{s}

3A) In the case of cylindrical bolt{s} or a cylindrical shaft 'U Bolt':
Remove backing fasteners (i.e. nut{s}/burs{s},etc...) then carefully withdraw the bolt{s} from the assembly.

3B) In the case of independent strap{s}, or a 'U Strap': Straighten and/or unsolder each fastening 'tab' then splay the frame rails such that the frame 'ears' clear the ligature 'tabs' --Or-- if so constructed, remove the backing plate/PCB from the ligature ends ('tabs').

4) Remove the transformer (i.e. form and winding assembly) from the framing/clamping/mounting components -- please retain the frame and all associated hardware!

Image of transformer following removal from a single strap-ligature frame:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptdesc2-jpg.101780/


Annotated image of assembly features referenced in following steps:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/annotated2-jpg.110920/

Step 1-3) Procedure for removal of strap ligature{s} from LOPT core/winding assembly:

Tasks
1) Meticulously straighten and deburr exposed segments of the frame ligature{s}.

2) Carefully 'work' the frame ligature{s} free of the adhesive, then withdraw it/them from the space intervening the form and winding (and, hence, from the assembly) -- Under no circumstances apply counter-thrust or torque to the EHT winding!

Ligature partially withdrawn from assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptligwdr-jpg.101790/

Ligature (in foreground) fully withdrawn from assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptligout-jpg.101789/

Note: Inasmuch as same will be removed and discarded in later steps, damage to the external auxiliary windings (i.e. those on the form leg opposite the EHT winding) or coaxial auxiliary windings immediately adjacent to the core/form leg is of no consequence -- Care must be exercised, however, to avoid damage to the brittle ferrite form/core via excessive force or mechanical shock... Also - avoid handling the assembly by the EHT winding!

Step 1-4) Removal of external auxiliary windings from 'lower leg':

Tasks:
1) Using an appropriate scalpel, 'X-Acto knife' or similar implement, linearly section the full length of the external Aux winding assembly. --- Again, the referenced winding resides on the form leg opposite that carrying the EHT winding!!!

2) Peel, crumble and/or break the 'external' Aux winding assembly off of the lower form leg.

Step 1-5) Separation of form pieces

Caution: In performance of the following tasks, it is of paramount importance that neither torques nor linear forces are applied to the EHT tyre! -- Moderate forces may be applied to the auxiliary shell and moderate compressive force may be applied to the ferrite form longitudinal to the EHT winding 'leg' only!

Tasks:

Please note that task #1 is with reference structures coaxial to the EHT winding

1) Endeavor to remove (or loosen) any shims intervening the form and inside surface of the auxiliary sleeve -- While damage to the auxiliary sleeve or winding is of no consequence, care must, nonetheless, be exercised to avoid breakage of the form!

Image of wooden shims (indicated by pick)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptshim-jpg.101791/

2) Using a #3 sharp fenestrated uterine curette, or similar non-ferromagnetic stainless steel instrument, carefully 'clean' the lower form leg of superfluous epoxy -- Note: Use of razor blades or other ferromagnetic or 'soft' metallic instruments will likely 'foul' the ferrite via metallic transfer to same!

3) Submerge the lower leg of the form (prepared as per task #2 above) in acetone for a period of ≈ 90 minutes at 7°C (45°F) through 33°C (90°F) - Note: the EHT winding assembly must not be submerged, splashed or otherwise wetted with acetone! - nor should acetone be allowed to condense on same! Owing to the flammability of ketones, said procedure is best preformed in open air or in an open container 'under' an OSHA (or jurisdiction-equivalent authority) certified fume hood (caution! - this does not include 'range-hoods', 'range fireplaces', 'walk-in fireplaces' or their ilk!) -- Moreover, a closed container is not recommended owing to liability to condensation...

4) Upon removal of the lower form leg from the acetone bath, drive the reluctance spacer out of the lower form joint using an appropriate feeler gauge leaf --- Note that during and following removal of the reluctance spacer/adhesive from the lower form joint, application of even moderate constrictive or distensive forces to the form will result in significant cantilevered forces at the upper form joint with (almost certain) breakage of one or both form pieces.

Of special concern in this regard:
A) Do not attempt to expand the gap while removing the spacer! -- The leaf thickness must be less than the gap width. Maintenance of a parallel relationship between leaf and form piece ends (i.e. gap 'walls') is imperative!

B) Following removal of the spacer, take care to avoid application of constrictive/distensive forces or piece-to-piece torsion to the form! -- The safest handling method is manipulation of the assembly from one 'side' (i.e. by one form piece) only!

Note: Following clearance of the lower form joint of its reluctance spacer and adhesive, continued half-to-half form tenure owes to the upper form joint adhesive (at the center of the EHT winding assembly) - and, to lesser extent, adhesion of each form piece to the form sleeve of said assembly.

5) Using a 'heat gun', play a stream of hot (≈200°C /400°F) air in a swiftly alternating, sweeping pattern upon each 'form rail' taking great care to avoid directing said stream upon the EHT winding tyre! - In this fashion gradually and evenly increase the temperature of each 'rail' to ≈ 100°C / 200°F.

6) Wearing "welder's gloves" grasp form rails (each to a hand) then apply torque (not to exceed 5.5 N⋅cm!) axial to the upper form leg.

A) If/when form-rail to form-rail angular motion is evident, continue rotation until the pieces rotate freely relative to each other -- If necessary, the form sleeve may be used as a 'counter torque' but under no circumstances apply force of any kind to the EHT tyre!

B) In the event that relative angular motion is not discernible following 30 seconds' application of torque, repeat Task #5 (above) but heat the rails to ≈ 150°C /260°F then promptly repeat task #6 (above).

c) In the event that, having begun to move, sustained rotation becomes impossible prior to 'defeat' of the adhesive, repeat steps 5 and 6 (above) exactly as presented.

7) Carefully 'work' each form piece free of the form sleeve -- Again, avoid application of thrust or torque to the EHT winding tyre!

8) Thoroughly clean the form pieces of adhesive residue via 30 minute's immersion in acetone followed by scrubbing with an acetone wetted cotton cloth.


=== Part 2 -- modification and reassembly of LOPT unit ===

Here we will consider four (coaxial) features of the EHT winding assembly:

To Wit:
(Peripheral to central).
1) The EHT 'tyre' (comprised of the EHT winding proper, potting material and bunting).
2) The Auxiliary shell (a paperboard or polymer 'collar' intervening the central aspect of the EHT winding and the peripheral aspect of the Aux winding...
3) The Aux Winding{s}.
4) The form sleeve (intervening the central aspect of the Aux winding and the ferrite form).

Please note said features in the image below:

Image of unmodified EHT winding assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_1-jpg.101749/


Step 2-1) Locate the lug carrying the EHT return:
The EHT return generally emerges with one or more AUX leads from the peripheral circumference of the AUX winding whence they are tied to a shell lug...

In the case of the demonstration transformer, said lug occupies the 2-o'clock postilion -- The image below shows said leads emerging from the Aux winding immediately below the CCW edge of the lug (as indicated by the ball-point pen) -- of special significance is the extreme peripheral position of the break-out point.

Image of the bundle containing the EHT return.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_2-jpg.101750/

Step 2-2) Separate and identify the EHT return:

Tasks:
1) Carefully unsolder all leads from the lug identified in Step 1 (above).
2) 'Untwist' and otherwise separate said leads.
3) Using a resistance indicator, check each lead for continuity to the EHT output contact (i.e. 'output tower') --- the return lead will show a resistance of between 400Ω and 1000Ω -- All other leads should show infinite resistance.

In this case three leads were tied to the lug -- the resistance examination identified the 38 AWG lead as the EHT return (said lead indicated by the pen in the attached image).

Image of separated EHT return --- Note that the associated lug was broken out of the way.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_3-jpg.101751/

Step 2-3) Removal of the form sleeve:

Please note: Far and away the most significant challenges attending this procedure owe to the 'gossamer' nature of #38 and #40 AWG conductors... From this point onward it will behoove the reader to remain mindful of the EHT return whenever handling the assembly - while a severed or broken return lead is not necessarily 'fatal to the cause' - such will greatly complicate matters via the requirement of 'teaseling out' the end of a #40 or even #42 (AWG) lead from the lacquered winding!

Tasks:
1) Carefully dress the return lead out of 'harm's way'.
2) Twist, pry and/or break the form sleeve out from the center of the Aux winding.

Image of EHT winding following removal of the form sleeve. Note the EHT return at ~ "2 O'clock"
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_4-jpg.101752/

Step 2-4) Remove the AUX winding:

Precautions:
A) While 'unraveling' the Aux winding, apply counter-thrust only to the shell --
as opposed to the tyre!
B) While debriding residue from the 'central gap' following removal of the Aux Shell - great care must be exercised is damage to the central layer{s} of the EHT winding to be avoided!

Tasks:
1) Cut all leads attached to all remaining lugs.
2) Using a surgical pick or similar instrument, pry a few 'layers' of the Aux winding into the center such that they may be grasped with forceps.
Image of Aux winding prepared for removal.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_5-jpg.101753/

3) Grasp the the loosened layers and begin withdrawing ('unraveling') the Aux winding -- Taking great care to avoid application of tension to the return lead as the periphery is approached.

Image of Aux winding in an intermediate stage of removal.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_6-jpg.101754/

Note: The EHT return will typically be 'laminated' between the penultimate and ultimate layers of the auxiliary winding bunting.

4) Cautiously break (not tear!) the bunting material away from the return lead.

In the image below you may observe the end of the EHT return (as per the pen) and its emergence from the bunting in the gap intervening the shell and the deflected bunting medial to the remaining lug at 4 O'clock

Image of EHT return embedded in peripheral Aux winding bunting.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_7-jpg.101755/

Image of EHT winding following complete removal of Aux winding
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv[/B]
http://forum.allaboutcircuits.com/attachments/i1_8-jpg.101756/

Step 2-5) Remove the AUX Shell:

Tasks:
1) Carefully break, crumble and/or fold the auxiliary shell into the 'central gap' via symmetrical application of force to the distal aspects of the former at quadrature to the plane of the return's emergence.

Under no circumstances attempt to pry the shell from the interstices!!! Doing so will almost certainly damage the EHT winding beyond repair!

2) having thus loosened the shell, carefully remove the fragments being ever mindful of the return...

Images of the EHT winding following removal of the auxiliary shell...

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_1-jpg.101757/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_2-jpg.101758/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_3-jpg.101759/

Image of EHT winding and debris following removal of the form sleeve, Aux winding, and Aux shell:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_4-jpg.101760/


Note: Should the reader's EHT winding be potted in silicone (as opposed to merely 'jacketed' as in the case of the demonstration transformer) it will be desirable to arrive at this juncture sans disruption of the potting material -- Should a breach occur, prompt repair via application of electronics grade RTV is advisable...

Step 2-6) Preparation of The Dummy Shell:

Note: Owing to the 'brittleness' of 'Purell' grade polypropylene, use of a sharp instrument is recommended!

Tasks:
1) Excise the base of the polypropylene pharmaceutical vial.
2) Section the (resulting) cylinder longitudinal to its axis.
3) Temporarily mount the dummy shell on the ferrite form -- Verify end clearance ≥ 5mm (form pieces in firm apposition). If end clearance < 5 mm, trim the dummy shell to 'compliance' but try to keep end clearance < 1 cm.

Image of prepared dummy shell
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_5-jpg.101761/


Image of correctly 'trimmed' dummy shell on leg of LOPT ferrite form:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_6-jpg.101762/

Step 2-7) Prepare Return Lug:
Tasks:
1) Form a #4 solder lug such that the 'tab' is at a right angle to the plane of the fastener surface.
2) Drill a #66 (~0.83mm) hole through the lug immediately above the bend.

Image of properly prepared lug -- Note the small (#66) hole near the fastener angle.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_7-jpg.101763/

Step 2-8) Installation of the dummy shell:

Image of EHT winding at this juncture - note return lead:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_8-jpg.101764/

Tasks:
1) Furl the dummy shell, then position it in the central gap from the side of the winding opposite the emergence of the return lead such that the 'cut' faces opposite the output 'tower'.
2) Using a stylus, scribe, etc - mark the dummy shell at the point 5mm (back) from the edge lateral to emergence of the return.
3) Carefully remove the dummy shell.
4) Using a 7/64” {≈3mm} drill bit, bore through the dummy shell at the point marked in task #2.
5) Liberally coat the dummy shell and gap surfaces with electronics grade RTV. -- Avoid application of RTV to the return lead!
6) Reinstall the shell as described in task #1, taking care to position the cut opposite to the output 'tower', and the bolt hole lateral to the emergence of the return lead.
7) Mount the EHT winding/dummy shell assembly on the ferrite form.
8) Adjust the (linear) position of the winding tyre on the shell such that the former is equidistant from the form piece angles while the end of the shell emerging from the 'return lead side' of the winding tyre extends as far as possible from the winding sans contact with the form piece.
9) Remove the form from the assembly taking care not to alter the relative position of the shell/winding.
10) Manually expand the shell as much as possible -- smooth and 'touch-up' the silicone... --- Again keep the return lead free of adhesive!
11) Allow RTV to cure for at least 72 hours at temps of 7.2°C (45°F) through 15.5°C (60°F) -OR- for at least 48 hours at temps >15.5°C (60°F)

Step 2-9) Installation of the Lug and connection of the return:
Tasks:
1) Carefully insert the #4 bolt from inside the shell.
2) Secure the lug to the top of the shell as shown in the images below.
3) Solder-tin the end of the return lead.
4) Insert ~ 2 mm of the return lead into the #66 hole near the base of the lug then secure it with solder.

Note: It is imperative that the return lead is neither trimmed nor glued at this point! - Please loop any slack as shown in the images.

Images of the assembly; Dummy shell & Lug installed, return connected:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_9-jpg.101765/

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_10-jpg.101766/

5) Verify that the DC resistance (lug to output tower connector) -- is that measured in step #2-2, task#3

Step 2-10) Prepare the CPVC Form sleeve:
Tasks:
1) Cut a length of 3/4" id (CTS) CPVC tubing equal to the total length of the form-leg on which it will be placed (In the case of this demonstration 8.5 cm) See the two images immediately below...

Image illustrating desired sleeve dimension
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_1-jpg.101767/

Image of form and adjacent CPVC section cut as per task #1
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_2-jpg.101768/

2) Cut 'shoulder stirrups' into the CPVC Sleeve:
Note: the stirrups must be sufficiently deep as to allow a slight amount of end-clearance when mounted upon the form (such that form piece apposition is assured).

Image of form pieces and 'prepared' CPVC sleeve
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_3-jpg.101769/

Image of form and CPVC sleeve in an intermediate state of assembly
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_4-jpg.101770/

Image of (temporary) fully assembled form and CPVC assembly
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_5-jpg.101771/

Step 2-11) Permanently install CPVC form sleeve in EHT winding assembly:

Image of components referenced in this step:
(L to R) CPVC sleeve, EHT winding assembly, Form [core] pieces
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/1-jpg.101711/

Tasks:
1) Assemble EHT winding, CPVC sleeve and form as shown (below).
2) Using PTFE shims, center EHT winding assembly about CPVC sleeve (both sides).
Note: While the adhesive does not bond PTFE it is, nonetheless, essential that the shims be so formed as to preclude (interlocked) captivity in the former!

Images of mounted and centered EHT winding as seen from 'EHT return side':
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/2-jpg.101712/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/3-jpg.101714/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/5-jpg.101717/

4) Using acrylic-based 'hot-melt' adhesive, tack the CPVC sleeve to the polypropylene shell at several points each side.
5) Remove form pieces.
6) Fill the space intervening the CPVC sleeve and the PP shell with acrylic-based 'hot-melt' adhesive taking care not to disturb the relative positions of said structures!
7) Allow the adhesive at least 60 Minutes to cool/cure.
8) Withdraw the shims.

Image of assembly immediately following withdrawal of shims as seen from EHT return side.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/7-jpg.101719/

9) Fill the 'shim gaps' with acrylic-based 'hot-melt' adhesive.

Image of EHT winding assembly following completed installation of CPVC sleeve.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/8-jpg.101721/

Identification of components/materials referenced in steps #12 through #15 (inclusive):
1) PTFE insulator.
2) EHT Winding assembly.
3) Form pieces.
4) LOPT Frame.
5) Polyolefin (heat shrink) sleeves.
6) Elastic cushions.
7) Frame ligature.
8) Form standoffs.
9) Reluctance gap spacers (see text).

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_partsnum-jpg.101730/

Step 2-12) Prepare form guides

Prior to proceeding, it is imperative that the form pieces are absolutely free of adhesive residue, etc!

Tasks:
1) Trim two pieces of polyolefin tubing such that they extend the full inside length of each 'winding leg' of the assembled frame (as shown below).
2) With the sleeves in place on the form, clamp or otherwise place form pieces in firm apposition with close attention to alignment of same.
3) Heat-process the polyolefin tubing -- Note: expeditious completion of this step will significantly reduce liability to ferrite breakage (secondary to uneven application of heat) and/or permanent shift of magnetic properties (secondary to excessive temperature)...
4) Allow at least 20 Minute 'cool down' period then carefully disassemble the form such that the heat-processed polyolefin tubes remain installed on each 'half-leg' of a single piece.
5) Trim another sleeve then repeat the above procedure such that one leg is bound by a double layer of polyolefin.

Image of assembled form 'sporting' the unprocessed polyolefin sleeves (Post task #1)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/preshrink-jpg.101742/

Image of form piece following processing of sleeves (Post task #4)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/separated1-jpg.101743/

Image of form piece following processing of second sleeve on (arbitrarily chosen) EHT winding 'leg' (Post task #5)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/separated2-jpg.101744/

Step 2-13) Fashion and place reluctance gap spacers
Note: Reluctance gaps will be incorporated to reduce liability to saturation (in all cases) and to leave the transformer compatible with 'flyback' topology should same be desired --- That said, this series prefers forward transfer paradigms (as explained in the introduction to this tutorial).

Note: The (.95mm) reluctance gap spacers salvaged from the disassembly process are shown in the "component identification image" for completeness of presentation only --- Based upon core material properties and desired output current, optimal operation requires development of reluctance gaps consistent with the inequality: 0.25mm < Gap < .5mm -- To this end 0.4mm (0.015" nominal) PTFE sheet stock will be used.

Tasks:
1) Cut two small disks of PTFE having maximum major axes slightly less than that of the form piece 'ends'...
2) Check actual spacer thickness with a mechanical vernier micrometer (Resolution = 1 um -OR- 1/10,000 inch) note that a 'metric' instrument offers slightly finer resolution (inasmuch as 0.0001"=2.54 um)
3) Very lightly smear one side of each spacer with electronics grade RTV.
4) Place each spacer (RTV side down) flat upon each form piece end (inside each polyolefin sleeve).
5) Via firm tamping with a pencil eraser or similar implement assure that the RTV film 'tacks' the spacers to the form piece ends...

Image showing representative spacer and measurement of thickness:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/airgapmic-jpg.101728/

Image showing correct pre-assembly placement of spacers:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/airgapinplace-jpg.101727/


Step 2-14) Assemble LOPT

Tasks:
1) Tack elastic cushions and form standoffs to frame then position as shown:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptframechoks-jpg.101732/

2) Verify that the reluctance gap spacers are fast to the form piece.
3) Hold the frame ligature in lengthwise apposition with the utmost facet of the form's EHT winding leg. (i.e. the leg carrying a double thickness of polyolefin).
4) Carefully place the EHT winding assembly over the form piece leg and ligature such that the shoulder stirrup engages the form piece as shown below:

Form ligature in pre-assembly position:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/asm1-jpg.101729/

Views of EHT winding, form piece and form ligature in intermediate state of assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_preasmby-jpg.101731/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpartialasmby-jpg.101735/

5) Slowly press the opposite form piece into place allowing time for displacement of air from the polyolefin tubes.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpreframe-jpg.101737/

6) Install transformer assembly into frame such that the ligature strap ends extend through the 'ears' of the frame.

7) Very carefully but firmly clamp the assembly preparatory to fastening...
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpresoldered-jpg.101739/

8) Solder ligature ends to frame
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpostsoldered-jpg.101736/

Step 2-15) Install lateral insulator

Tasks:
1) Form a cardioid of 0.093" (AKA "93/1000'ths") PTFE sheet stock as per item #1 in the image (immediately below):
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_partsnum-jpg.101730/

2) Size, shape and fit the insulator to the EHT winding assembly in a manner consistent with the following images but do not apply adhesive at this time.
Note that the insulator must be trimmed to closely fit the shell and extend beyond the peripheral aspect of the EHT winding by at least 1 cm.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/final-jpg.101745/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/strikeshldside-jpg.101748/

3) Having properly formed the insulator, 'de-gloss' one side of same using '00' grit emery cloth/paper.
4) Apply liberal quantities of electronics grade RTV silicone to the appropriate surfaces of the EHT winding assembly and the entirety of the 'sanded' side of the insulator.

5) Attach the insulator to the EHT winding assembly as shown in the above images.
6) Apply an excess of electronics grade RTV to the exposed side of the insulator and adjacent areas of the EHT winding assembly...
7) Distribute the RTV over the insulator and EHT winding assembly surfaces such that an interlocking bond is established.
8) Position the LOPT 'insulator up' then allow at least 48 hours curing time.

 

Attn: @Aleph(0) & @Jazz2C

Please note that the most recent revision of the tutorial has been moved to post #723

HP I say you should specify that tubes are 3/4 inch preshrunk id cuz that works for all FBT ferrites I've ever used!

I thought I had! --- Well spotted! - thank you!

HP I also say readers should have have Corona Dope and High Temp Epoxy on hand for debugging arcing troubles and to repair broken ferrite if needed

Excellent points! -- Inasmuch as maintenance of comprehensive treatment requires additional text to 'cover' such contingencies, I suggest that my best course of action at this juncture is completion of the tutorial - following which (but prior to 'publication' of same to 'Projects') I compose and post a 'remediation guide' to my Blog -- Said entry to include (with neither explicit nor implicit limitation to) the following topics:

-Repair of broken ferrite core pieces.
-Mitigation of return lug arcing/corona.
-Recovery of broken EHT return lead 'end' from winding.

Thoughts?

HP JC says he'll have time to thoroughly read it later on tomorrow so I say once he does that I'll give it final pass after you link pics for auto-displaying

The return of the prodigal student? Will wonders never cease!?

HP what are you paraphrasing there? Cuz it's just eerily familiar

Would you believe? Lyrics by that rather dreary band you've (well-neigh aptly) dubbed 'Zep Light'

HP No! I don't mean that CRC

Thank you! -- I very much doubt I can endure many more 'shattered illusions'

All the best
HP

 

Hola Hp! I read through the course and it's awesome! But you want nit picking so here's the best I could manage

⇒Digital caliper -- Example: Grainger 29AD39

That's an $800 instrument!

Step 2-4 Task 4, The images are duplicates FWIW it looks like the first instance is correctly placed.

Step 2-10 task 1, Shouldn't you remind them the CPVC size is according to the copper tubing schedule?

Step 2-13 preamble, I suggest you reminded them that 0.4mm is actually the standard 0.015" stock I totally relate to your preference for SI units but the manufacturer sells it according to imperial units so whatcha gonna do?

Hey Hp I know you're probably joking but I hope you don't really think games are getting in the way of helping you out School's been a total bitch and I'm all used up by the weekend Hp I'd never lie to you! When I play online games it's only to unwind from school! When I'm in that state of mind you wouldn't want my help anyway b/c I'd be useless! Believe it!

HP I know it doesn't make any difference but I want you to know my feelings are not simply misdirected gratitude! My infinite gratitude is reflected in my academic pursuits and in all things you want me to accomplish! Nobody knows better than I that my feelings are futile and totally inappropriate but there's nothing "dirty" or disrespectful about them! When you say I'll get over it I believe you at an intellectual level but I can't relate intuitively so all I can do is beg your patience and know that my feeling for you is the real deal and that entails respect above all!

@Aleph(0) I know you're not loosing any sleep over it but I owe you a public apology! I know you're not vain! There's nothing aberrant about a beautiful young woman taking pride in her appearance! Anyway if you were any part of vain no way could you bring yourself to keep up your Aleph persona! b/c I know you put mind light years ahead of corporeality!

So I'm asking both of you! If you want to ridicule me for worrying too much abt what other ppl think, fair enough! But plz don't question my sincerity!

 

Re: the recommended digital caliper

That's an $800 instrument!

That sounds correct (IOW I'll take your word for it) -- but what's your point? I can't see where I said otherwise?

Step 2-4 Task 4, The images are duplicates FWIW it looks like the first instance is correctly placed.

Well spotted! - thanks! - Flagged for correction

Step 2-10 task 1, Shouldn't you remind them the CPVC size is according to the copper tubing schedule?

Step 2-13 preamble, I suggest you reminded them that 0.4mm is actually the standard 0.015" stock I totally relate to your preference for SI units but the manufacturer sells it according to imperial units so whatcha gonna do?

Correct on both scores! -- I see where I made such specification in the 'bill of materials' yet failed to do so in the text -- Many thanks! -- Flagged for correction!

HP I know it doesn't make any difference but I want you to know my feelings are not simply misdirected gratitude! My infinite gratitude is reflected in my academic pursuits and in all things you want me to accomplish! Nobody knows better than I that my feelings are futile and totally inappropriate but there's nothing "dirty" or disrespectful about them! When you say I'll get over it I believe you at an intellectual level but I can't relate intuitively so all I can do is beg your patience and know that my feeling for you is the real deal and that entails respect above all!

My infinite gratitude is reflected in my academic pursuits and in all things you want me to accomplish!

Please know that I am very pleased with your effort and achievement! - but please do it for yourself not me! -- While I sincerely appreciate your gratitude please understand you are under no obligation whatever...Ok?

When you say I'll get over it I believe you at an intellectual level but I can't relate intuitively

That's called being young - Given time, you'll get over that as well - I know I did!

so all I can do is beg your patience...

My patience in this matter is in direct proportion to your manners - IOW all's good!

Best regards and again, many thanks
HP

 

@Aleph(0) & @Jazz2C

Re: The tutorial (Post #723)

Please note that I've applied the corrections (to date) in addition to some 'polishing' for 'disambiguation' and enhanced readability...

JC -- I'm yet awaiting elaboration upon your remark/(suggestion?) regarding the caliper (Re: Post #725) --- Tapping fingers

Very best regards and many thanks!
HP

 

http://www.harborfreight.com/4-inch-digital-caliper-47256.html
Westward accuracy: 0.002"
Price: $722.00
Harbor freight accuracy: 0.001"
Price: $14.99

 

http://www.harborfreight.com/4-inch-digital-caliper-47256.html
Westward accuracy: 0.002"
Price: $722.00
Harbor freight accuracy: 0.001"
Price: $14.99

#12 I say problem with harbor freight is total lack of integrity and qc Anyhow IDK how critical gap spacers are so maybe hf caliper is ok cuz HP says to double check spacer with plain micrometer too Anyhow @Jazz2C needs to explain his comment abt caliper cuz I just read whole tutorial twice and HP didn't say anything abt price at all so it doesn't make any sense unless JC thinks tutorial readers are just pikers or like that

Now I'm still convalescing from wasting 90 minutes of my life watching two knuckle dragging clowns stalemate each other in $#it flinging contest! I never thought I'd see politicians who can make the lowly likes of JPJT look good So there's my silver lining

 

Anyhow @Jazz2C needs to explain his comment abt caliper cuz I just read whole tutorial twice and HP didn't say anything abt price at all so it doesn't make any sense

Hey @Aleph(0) -- Inasmuch as you're into SMS/IM or whatever passes for communication this week - Please 'get on his case' as regards clarification of his vacuously ambiguous remark -- To wit:

That's an $800 instrument!

The import of which entirely escapes me as well? I've heard tell of 'walking encyclopedias' but 'walking Granger catalogs'?!

Anyhow IDK how critical gap spacers are

Not terribly but we're talking less than $1k?

unless JC thinks tutorial readers are just pikers or like that

Yebut -- even 'pikers' can find multiple uses for a quality 10uM resolution @ 0.009% Tol caliper...

Now I'm still convalescing from wasting 90 minutes of my life watching two knuckle dragging clowns stalemate each other in $#it flinging contest!

You mean to say you actually watched the debate?!?! --- Am I to infer you've now added masochism to your litany of vices?

Re: your opinion of the debate and the candidates in general:
+∞

Best regards
HP

 

Hey @Aleph(0) -- Inasmuch as you're into SMS/IM or whatever passes for communication this week - Please 'get on his case' as regards clarification of his vacuously ambiguous remark

HP So I talked (yes! talked!) to JC and he's having trouble with connecting cuz of his VPN so I suggested Zenmate for now cuz it's still Leaseweb service but access through Zenmate is sometimes more reliable! I know cuz I use it a lot of the time so everything is still encrypted and he can keep his default servers so sites that check IP against username for security (like financial institution and school sites) will still work. HP I asked him about enigmatic caliper comment but he said he wants to explain it himself on here because he's totally devastated about causing you a hassle (and that's exact quote) so abt all I can say is to keep looking for his response! As if we don't have enough 11'th hour BS finishing tutorial

 

Not terribly but we're talking less than $1k?

Psst...your elitism is showing again.
On a personal level...I don't think you understand that some 30% of America is unemployed, and "less than $1k" is a month worth of food and housing. Not only am I jealous of your affluence, I feel angry that you don't even realize how well off you are.

 

Psst...your elitism is showing again.
On a personal level...I don't think you understand that some 30% of America is unemployed, and "less than $1k" is a month worth of food and housing. Not only am I jealous of your affluence, I feel angry that you don't even realize how well off you are.

#12 Sry cuz I know this is between you and HP but I'm just curious abt those 30%? I'm just saying cuz if only $1,000 is make or break money to them how can they find room in their lives for hobbies?

So you're saying you think JC was saying $800 is more than some readers want to spend for a good caliper? That's important to think on cuz HP is worried about chasing ppl away on how she says _practical grounds_

So I say if money is a problem they can buy nice mechanical micrometer which is super inexpensive (like $40 or less) and a lot more accurate than cheap digital caliper

 

if only $1,000 is make or break money to them how can they find room in their lives for hobbies?

That's a very good point. Unemployed people with no reserve cash will not even consider building this project. After all, who needs a personal x-ray machine when they can't feed their children?

I just think that recommending several hundred dollars for a caliper is absurd when you can get a sufficient caliper for less than one hundred. I own 2 of the HF cheapo calipers because I wore the first one out. (The zero position is not repeatable by 0.0025 inches.) Still, I could own 5 or 6 of these cheapos for less than $100.

I feel that being oblivious to that fact is a personal problem caused by having so much money that one would pay 48X merely for the convenience of not spending 20 minutes shopping. I'm sure there is a population that does this. Us poor people call them, "suckers". There's one born every minute (P.T. Barnum)

 

I feel that being oblivious to that fact is a personal problem caused by having so much money that one would pay 48X merely for the convenience of not spending 20 minutes shopping. I'm sure there is a population that does this. Us poor people call them, "suckers". There's one born every minute (P.T. Barnum)

#12 I better leave all that for you and HP But being serious I'm happy for feedback (and I know HP will be too) Cuz it's too easy for us to forget large audience means ppl from different walks of life! So we don't want to send wrong message

 

Exhibiting frugality might not increase your readership by 10%, but even the affluent might resent being advised to pay that much when the job can be done for about 2% of that price.

 

@Hp I'm sry I didn't get back to you sooner! So Aleph showed me Zenmate and it's working well so far!

So plz accept my apology for the confusion surrounding my comment on the price of the Granger caliper! It was just me expressing surprise at the range in price and quality! I figured lab grade instruments of that sort "weighed in" at around $200?

On a personal level...I don't think you understand that some 30% of America is unemployed,

I'm just saying cuz if only $1,000 is make or break money to them how can they find room in their lives for hobbies?

Hey peeps! I'm telling you there IS a demographic who totally live for their hobbies but don't like spending even $1000 more than absolutely necessary and I'm one of them! Namely STUDENTS

HP you want feedback and suggestions so here's my thoughts
It seems to me the major intimidating factors for readers will be (mainly) availability and for some folks (like me) cost of supplies. There's no arguing that giving examples of only high quality tools is the right move! But IMHO it would be helpful for ppl with limited market access or on a budget if you also specified the minimum requirements so we know how to look for alternatives if need be

So I say if money is a problem they can buy nice mechanical micrometer which is super inexpensive (like $40 or less) and a lot more accurate than cheap digital caliper

Aleph that's an excellent suggestion b/c cheap digital calipers are unpredictable! So It's either a high quality digital caliper or high quality analog micrometer which BTW is priced closer to $20 than $40 Hp in the course you suggest measuring the spacer with both a caliper and a micrometer? Can we get by with just one of either admitting only high quality instruments? TNX!

 

So Aleph showed me Zenmate and it's working well so far!

Terrific, JC! Now if HP could be bothered to put in an appearance we might have first tutorial done b4 we're in long term care

PS Be happy, HP cuz I opted against macabre metaphor to show you I could! But I say thought of _long term care_ is more depressing anyhow

 

@#12 @Jazz2C @Aleph(0)

Many thanks for your input! -- Please be advised that your advice is well taken and much appreciated! - pursuant to which I will add, as suggested, a 'minimum requirement statement' Re: all tools/materials available over significant price/specification ranges...

I promise more detailed responses tomorrow

Very best regards
HP

 

I would like to comment on that thing called a Rongeur. It looks like it has massive mechanical advantage. I have never seen anything like that as a Tradesman/Craftsman.

 

So I say if money is a problem they can buy nice mechanical micrometer which is super inexpensive (like $40 or less) and a lot more accurate than cheap digital caliper

I'm late to this because of a computer malfunction. As some one who spent his entire adult life as a die maker/machinist, no person would use a digital caliper for "precise" measuring. No matter what your measuring, a caliper whether digital, dial, or the older vernier style, would not be used for something"precise". A caliper is used for "rough" measurement not "precise". They can be too easily over tightened on the material being measured to make them "precise". A micrometer is the instrument to be used for "semi-precise" things like this, there are other methods for "precise" measurement that I won't go into.