DIY Hakko Sensor for Solder Tip Thermometer 191-212 or Weller WCU T0058771712

[Kiriakos GR]

Did you ever thought of how easy it is for you to make your own Sensor for Solder Tip Thermometer?

Basic theory of manufacturing of regular K-type thermocouple this is two dissimilar wires and these be connected with spot welder at the end of them.
The bubble at the end of welded thermocouple, this is in theory a bubble of pure silver metal.

The construction of all 191-212 (Hakko code) and or of T0058771712 sensor (Weller code) both are identical.

All that we need so to make our own sensors,  this is a full size of K-type thermocouple wire this be cut in length and be twisted.
Central connection path can be made due Ferrule Terminals / Ferrule single Terminal this be cut in half. 
Ferrule Terminals they are designed for crimping. 

By approximation, a length of seven centimeter of a pair of dissimilar wires this is enough so to make a single sensor.
One ready to use, manufactured K-type thermocouple with plug, this has a length of two meter long wires over it.

According a brief calculation,  a single 2M long thermocouple it can converted in the quantity of 27 Sensor.   
The appropriate thermocouple this should be constructed due Chromel Alumel.

Chromel Alumel wire this is standardized (accuracy) at the factory that the wire this is produced (T max = 1100 Celsius).
The only challenge for us this is to give it the appropriate shape.

As anchor at the two end (color marking heat-shrink tube) you may used regular black heat-shrink tube, or colored one if you do have some.

There is no other magic in this simple design, and this explains of how easy it is to be replicated from any tiny factory in China. 
     
Note:
Chromel Alumel can be found with insulation over the wires too,  color code is Yellow and Red.
You do not need the color coded version, a regular K-type thermocouple terminated to a plug this all that is needed. 
         

[Kiriakos GR]

For the sake of comparison,  I did purchase one pack for personal testing.

First ever 191-212 Datasheet with was created at 2004 and internal content this is very poor.
All that HAKKO brag about this is of some sort chemical insulation, which this works as protection so the wire this to deteriorate with a slower rate.

Also you have to check three different HAKKO documents so to discover actual wire diameter of 0.20 mm.

While 191-212 this were designed as Lead-Free Sensor,  the confusing documentation of Hakko, this delivers the warning that Lead-Free solder this will deteriorate the sensor faster.
And finally Hakko does not take any responsibility of their own,  if the sensor goes down prematurely this might be fault of your solder composition and not of them (Hakko factory). 
In simple English, Hakko does intentional forwards and backwards steps in their marketing documentation, so to avoid answering complains regarding premature sensor failure.   

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Chapter No 2:   Product packaging 

It is obvious that HAKKO Japan this distributes BULK pack of 10 PCS of sensors.
Product package this is a plastic bag within another larger plastic bag, this be the host of the printed label.
Both bag with air-tight sealant for the avoidance of corrosion when in storage.

The so called retail version, with blister card,  this is made in Indonesia.
They are very few proofs (samples of packaging) about it on-line.
This type of blister card, this is more practical to use, and to keep unused sensor in storage.

Branding over this blister card, might be HAKKO or hakCo or No-Brand at all.
At the back side of blister card, only the Indonesian / Hakko version this will include company details.
In most other cases this will be a blank white card. 
   
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My current plan this is to make my own triangle base for this sensor, and it output will feed directly a high performance handheld multimeter.   
If I have good success?  This will prove that the purchase of a separate tip thermometer this is a waste of money. 

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Build quality of the sensor: 
This is a matter of which machinery did the job?
One well adjusted machine, this will produce a cleaner result = Sensor in correct dimensions + fewer wasted wire in turns in use as anchor.

All long distance buyers will have to wait for their pack to arrive so them to discover the truth =  Build quality of its one sensor.
I will strongly recommend, test all ten sensors at your thermometer = correct fitting / dimensions, and then deliver your on-line feedback.   

The worst scenario can be the sensors, them to be totally hand made. 
Last photograph.
In this scenario, just imagine that if you dare to go DIY,  your sensors will be much better 
(Regular thermocouple specification this is Max 250C,  which is good enough for medium power soldering station)

[Kiriakos GR]

I believe that with this last photograph below, we have now a complete 191-212 packaging collection. 

And now I am obligated to inform of one last fact, the warning of not measuring above 500C with these sensor, this has scientific roots.

Even HAKKO this buy thermocouple wire from a major provider,  for example this could be OMEGA from USA.
OMEGA makes high temperature K-type wire this named as GG K 20 and Max operating temperature this is 482C   (900F).

And therefore any one wishing to be at the safe side, he should stick up to 450C, especially when thermocouple wire origin this cannot be verified.   
If you go DIY,  with regular thermocouple wire, your upper limit will be 250C.

Naturally the adventurous brain, he might purchase one by Omega assembled thermocouple for 482C , and with this wire at your hands, your DIY triangle sensor will be as good as is the ones sold by Hakko or Weller.

The new catch is that for industrial grade thermocouple wire, you are out of luck if you live in EU, due Ali-Express they are much more chances to find it.
China this is heavily industrialized, and they do buy large quantities of products even from OMEGA USA at much friendlier prices.
The lowest that I manage to find for OMEGA 2m (long) wire for 482C,  this is approximately at 18 Euro (assembled thermocouple).   
 
Naturally eBay will deliver results from American sellers mostly,  but the shipping fee this is THE deal breaker.
   

[Kiriakos GR]

This is no major punch in the stomach to me as News ... ( I am industrial electrician after all = Familiar of industry and factory).

I did read several hilarious comments at other Electronics Forum, YouTube , Ali Express / Reviews / complains.

Now allow me to clarify a few real life facts to you: 
K Type Thermocouple Wire Type this is item with universal production, everyone can manufacture it.
The conversation about genuine and not genuine sensors it must stop here...
For example when we buy assembled sensor from Ali Express, then believe it or expect it, you are shopping for Made in China Thermocouple Wire.

The ones talking of measuring precision about the FG-100 and similar (devices) this is  +/_  3% =   the meter plus the thermocouple tolerances. 
300C - 3% = 291C
300C + 3% = 309C
And therefore the product it can deliver a measurement as accepted even if it includes 18C as room for error.

Now lets talk the language of industry,  China makes their own wire as general purpose K-type with 1.5% tolerance / measuring accuracy.
This is sold by the kilo (weight), while us we buy it according to length.

Quality and medium to high priced portable multimeter, they come with much strict measuring accuracy of +/_ 1C.
Their escorted K-type probe this is build also according much strict tolerances, but their are limited to Max of 250C.

I did quick review of product specifications from two major factory in China, their wire while this is not that strict in tolerance, it is advertised as capable for 600C at the diameter of 0.20mm.
The diameter of 0.3mm it can handle 800C etc etc ...

What I am trying to say, our expectations regarding measuring accuracy they should comply with REAL facts and not with imaginary ones.   

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At the year 2024, industry all over the world has perform significant progress,  all products are now made with strict tolerances.
The worst electronic component over a PCB this has +/- 1% of tolerance.

The Japanese HAKKO it has a range of products to sale, but they are not innovators.
And or they are not Test and Measurement innovators.