Simple DIY soldering station for Hakko 907 iron

[Julez]

Hello together,

I recently finished a project some of you might find interesting.
I needed a soldering station, so I bought a Weller WS81, which works really well.
But I also wanted to have a "cheap" station for work not relevant to safety, and because I like to build stuff.

So basically I put a slightly altered digital controller in a neat case, and added some controls for a more "analog" feel, as this is often easier compared to tapping at buttons of digital stuff.
My design is basically based on "nukies" findings:

https://www.eevblog.com/forum/reviews/genuine-vs-fake-hakko-936-ceramic-heater-a1321/msg239393/#msg239393

With his measurements concerning the temp. coefficient of the typical ceramic heater elements, I calculated how a system, in which I use a poti in series to fool the controller into thinking that the iron has a different temperature as it actually has, would behave. It works excellent.
I used Sn62Pb36Ag2 solder (180°C) and pure lead (330°C) with their respective melting points to calibrate the station, and it works very well. The cloned ceramic heaters may be off concerning the resistance, but as long as their temperature coefficient is the same, my principle works.
I made a youtube video to explain everything. I hope you like it.

https://youtu.be/qk1ttUM5XTQ

On another note, I think that I successfully circumnavigated the problem of the clearance between the ceramic heater and the bore of the soldering tips which is a problem at cloned products. I took a piece of 0.1mm copper sheetmetal, 25mm wide and 12mm long. Rolled up and slid over the ceramic, it provides a very snug and slightly difficult to push fit, which I consider thermally superior to an airgap. I also used a bit of ceramic paste which I normaly use on the exhaust system bolts of my car as an anti-seize agent.

[Fat]

Looks very nicely done.

[krivx]

Do you notice any difference with your sheet metal shim? 0.1mm sounds like a thin foil, it doesn't seem like it would make much difference.

[Julez]

Thanks, Fat. 

Krivx: Well, I figured that practically anything would conduct heat better than an airgap. But I have a second Iron in the mail. I will test this one with a before- and after-test, and also against the current already modded one.
I have a little piece of copper sheetmetal with a heavy wire soldered at one end and a blob of solder at the other. I compare irons by sticking them into the blob of solder and counting the time until the solder melts and causes the big wire to fall down. So far, my modded Hakko clone is not quite as good as the Weller, but the difference is not huge. I will report back as soon as I have new results.

[Isad]

Love it.

Great project.
I am trying to do the same thing but a little bit more
portable and battery powered but with a high quality
Ersa icon handle.

[Julez]

Good idea!
Concerning portability, or "range", I found the cable of the clone Hakko a bit short. The lenght is reasonable for a dedicated soldering workplace, but not if you need to work at the opposed ends of a 3m RC plane wing at a separate table. So I thought what kind of cable would work well as an extension. After a short while, I remembered a writeup about USB charge cables:
http://lifehacker.com/cables-can-significantly-impact-the-charging-speed-of-y-1532784722

The key is that standard USB cables have AWG28 conductors in them, whereas dedicated charge cables have 2 conductors with AWG24 or 22 for the charge current.
This is just what I need for soldering. Two small conductors for the temperature sensor, and two big ones for the heater element.
So I bought the corresponding DIN connectors on ebay, clipped off the USB connectors, and soldered the DIN connectos to the USB cable. The shielding braid was folded back and clamped between the outer sheath of the cable and the "wings" of the connector base which hold the cable into place. I also soldered a short piece of wire to the grounding pin and clamped it into place with the shielding braid.

It works beautifully! I can now move the iron around in my workshop as I like, and I could even combine two cables as I made one for each "channel" of my station.

http://www.ebay.de/itm/121696289160

http://www.ebay.de/itm/5-Stueck-6-Pol-DIN-Stecker-gerade-Metallgehaeuse-neu-/281869457107?nma=true&si=DU1MI7E2Qq0T%252BrfU0tO7CjcRR0Y%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

http://www.ebay.de/itm/270769194160

[Julez]

Hi!

Finally, my second 907 clone iron arrived.
I wanted this to be the iron for the "bigger" jobs, so I took a big bevelled tip. I did not do the copper sheet mod yet.
I calibrated the heat using the lead wire melting method, and I had to set my control to 315°, not a big difference to my first iron.
The performance was, however, not very great compared to my Weller.
So I took a close look at the tip, which sat farely loose on the ceramic heater, and noticed that there was a kind of thin-walles stainless steel tube inside the hole. It was farely loose, and was easy to pull out with round pliers. The id was now around 4.35mm.
So I put the tip in the chuck of my drill press, a 5mm drill in my vise, and opened up the hole to 5mm. A 5mm/4mm brass tube was easy to hammer in, so it was a nice tight fit. I deburred the end, folded the copper foil around the ceramic heater, and reassembled everything.
Wow, quite a difference. First thing I noticed was that I had to adjust the heat at the controller to 260° now to melt lead wire with the usual 330° poti setting. Also, it was able to melt the aforementioned test joint much quicker.

I have a little piece of copper sheetmetal with a heavy wire soldered at one end and a blob of solder at the other. I compare irons by sticking them into the blob of solder and counting the time until the solder melts and causes the big wire to fall down.

Weller WS81 - 17s
Hakko 907 clone stock - 37s
Hakko 907 clone mod - 21s

That's not quite as good as the Weller, but almost twice as fast as stock. That's what I call an improvement.

[Julez]

Hi, I just made an overdue video about the Copper Mod, hope you like it!

[abhishekkumar1902]

This is indeed a greater project man, absolutely love your work!!


I just wanted to know that I ordered a Hakko 936 Soldering Iron Handle from: https://www.aliexpress.com/item/DIU-936-Electric-Soldering-Solder-Iron-Station-5pin-Welding-Hot-Gun-50W-24V-Replacement-Repair-Tool/32780915827.html?spm=2114.13010608.0.0.pTeJ0s

Looks like all these elements runs on 24 AC, Will they work the same on 24 V DC??

[Julez]

Thanks for your comment!
AC or DC is irrelevant for heating systems, both will work.
But the price in your link is unbelievable. 

[abhishekkumar1902]

Yup, that is a cheap Chinese iron handle, not anyway the original one from hakko!!