Why your Hakko might have poor thermal recovery

[dorin]

I have seen here and there people claiming that the FX-888 (D or simple) iron has a tight coupling between heater and tip unlike the Chinese ripoffs, but it's unclear to me what does "tight" really mean, because I feel mine is on the loose side. So I made this video to show exactly what I mean, because I don't have anything else to compare against.



I sent the video to the shop I purchased it from and they forwarded it to Hakko a few weeks ago, but there's no official reply yet so this makes me wonder if all 888D are actually like that, or only those for European market because it's possible they have different quality grades.

[amyk]

Have you heard of thermal expansion?

It's supposed to be loose when cold. It will be tighter when it gets to operating temperature. If it was tight when cold, it might crack the heater when hot. The genuine heaters and tips are not a tight fit when cold. Of course, the clones may be even looser.

[anishkgt]

Hmmm physics basics "metals expand when heated" so do others. Grade 10 example railway tracks have small gap between two tracks[emoji6] so they can expand during the summer.


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[dorin]

Before trying to teach an engineer and physicist about thermal expansion you should probably consider that ceramics have a lower thermal expansion coefficient than metals. What that means is that the metal tip with its ring like cross section will expand and increase the hollow space inside more than the ceramic is able to expand, therefore increasing the gap further, and NOT tightening it.

Now let's consider the worst case, in which the tip stays cold (doesn't expand at all) but the heater expands:
Ceramics typically have a coefficient less than 10 * 10ˆ-6 but let's again consider the worst case. The relative expansion at 480 C is (480-20)*10ˆ-6 = 0.0046.  The absolute expansion for a heater diameter of 3.85mm is 0.0046 * 3.85mm = 18µm. The actual space between the heater and tip is about 50µm so go figure.
Of course, there is a combination of both volumetric and linear expansion, but since the coefficients are not that different, the rough estimation can't be that far off to change the conclusion.

Anyways, I am not saying the gap is huge (I should probably get a clone and check how loose is that) I am just saying that it COULD be better.

[xrunner]

All of my tips do the same thing ... 

[dorin]

All of my tips do the same thing ... 

Then I assume this is an acceptable tolerance..

[technogeeky]

All of my tips do the same thing ... 

Then I assume this is an acceptable tolerance..

For what it's worth, the Hakko has many patents for various soldering parts, irons, tips, etc. There is probably a specific patent covering the tip in question. It ought to include details of heating, expansion ratios, tolerances, etc.

[Shock]

The irons design hasn't really changed a lot in over 20 years probably been around way longer than that, they have always been a loose fit.

This is not a high end station from Hakko, it's the entry level station, reliable with cheap tips. Tips are regularly around $5. On special in the US the stations have gone for as little as $70. On some more high end stations that is the cost of an element/tip alone.

One of the Hakko designers/engineers in a later patent talks about the element in the heater expanding, material choice of the ceramic coating over the element being a problem due to expansion and issues with the element becoming conductive. They also mention about corrosion building up on the surface of the inside of the tip which I'm sure influences the fit as well.

Hakko says that you should periodically loosen the nut and tip enclosure and move the tip on the heater back and forwards to ensure the tip insertion pipe (that is the pipe inside the tip) does not become stuck to the heater. Apparently caused by flux seeping in and burning onto the heater.

For your info, fake tips say Hakko Japan as well, but if you buy your tips from a genuine Hakko dealer you should avoid getting ripped off.

[FlyingHacker]

More importantly, how did you get that sweet silver Hakko? Did they finally give up on the Teletubbie style color scheme?

[Back2Volts]

More importantly, how did you get that sweet silver Hakko? Did they finally give up on the Teletubbie style color scheme?

It seems both are available now. I found it searching for "hakko fx-888d silver"

http://www.hakko.com/english/products/hakko_fx888d_set.html

[dorin]

One of the Hakko designers/engineers in a later patent talks about the element in the heater expanding, material choice of the ceramic coating over the element being a problem due to expansion and issues with the element becoming conductive. They also mention about corrosion building up on the surface of the inside of the tip which I'm sure influences the fit as well.

Hakko says that you should periodically loosen the nut and tip enclosure and move the tip on the heater back and forwards to ensure the tip insertion pipe (that is the pipe inside the tip) does not become stuck to the heater. Apparently caused by flux seeping in and burning onto the heater.

I think oxide/flux buildup is the most likely cause. I didn't know about the Hakko recommendation since it's not in the manual, thanks!

[GreyWoolfe]

More importantly, how did you get that sweet silver Hakko? Did they finally give up on the Teletubbie style color scheme?

It seems both are available now. I found it searching for "hakko fx-888d silver"

http://www.hakko.com/english/products/hakko_fx888d_set.html

They need to do that for the 951 and make the housing available for sale by itself.  I would snap it up in a heartbeat.

[RoGeorge]

The gap between the heating element and the tip is not the biggest problem when it comes to tip temperature control and thermal recovery. The main problem is the temperature sensor location.

The poor thermal recovery is "poor" only when it is compared with monolithic cartridge type, like JBC tips, Hakko T12, etc. This happens because, for ceramic heaters, the temperature sensor is in the heater. So all it can control is the temperature of the ceramic heater, and not the temperature of the soldering tip. On the contrary, for monolithic cartridge type tips (like Hakko T12), the tip itself is also a heater and a thermocouple.

These are my findings after measuring different types of soldering irons: https://rogeorge.wordpress.com/2016/09/23/zero-parts-thermostated-soldering-station/

[eKretz]

That's not necessarily so. Ersa i-Con and Vario stations use an element inserted into a hollow tip and they have extremely tight temperature control and rapid response. The tips fit with some slight friction to the element when they're hot, just barely touching.

[Shock]

That's not necessarily so. Ersa i-Con and Vario stations use an element inserted into a hollow tip and they have extremely tight temperature control and rapid response. The tips fit with some slight friction to the element when they're hot, just barely touching.

Ersa I-Con Nano is between double to well over triple the price of the USA Hakko FX 888D on special. The Ersa I-Con Pico while a bit cheaper is not ESD safe. Anyway they have a metal enclosed heater and a newer design. Not sure about all the other versions, but the two products aren't really comparable unless you can pick them up for 65 euro a few times a year.

If I was in Europe I'd probably buy a Ersa over a Hakko FX-888D, so I'm not arguing it's not superior. But then I'd probably buy a $20-25 Hakko T12 clone instead for the same performance. Then ditch that and buy a nice Pace handle with a homebrew supply. Wait a sec what am I talking about, I'd go out and get a Metcal or Hakko FX-100.

Still happy with my $15.74 Yihua 936 clone with genuine T18 tips for now

[KL27x]

Your tips are fine. I have noticed poor thermal transfer in a Fakko, and the tips were loose. Like way looser than that. My real Hakko tips/iron fit just like yours.

[tooki]

That's not necessarily so. Ersa i-Con and Vario stations use an element inserted into a hollow tip and they have extremely tight temperature control and rapid response. The tips fit with some slight friction to the element when they're hot, just barely touching.

Ersa I-Con Nano is between double to well over triple the price of the USA Hakko FX 888D on special. The Ersa I-Con Pico while a bit cheaper is not ESD safe. Anyway they have a metal enclosed heater and a newer design. Not sure about all the other versions, but the two products aren't really comparable unless you can pick them up for 65 euro a few times a year.

Yeah but he wasn't saying they cost the same, only that you don't need a cartridge type iron to have that level of performance. The claim was that an iron where heater and tip are separate won't perform well; Ersa is showing that it can be done. That's all.

(As for the price, in Europe, the FX888 ends up costing only slightly less than the iCon Nano. Hakko is crazy overpriced here. And in contrast, Ersa is crazy overpriced outside of Europe!)

P.S.  I love my iCon Nano!