Hot Air Soldering Gun From a Desoldering Iron With a Vaccume Pump





Introduction: Hot Air Soldering Gun From a Desoldering Iron With a Vaccume Pump

Here I'll show you how I converted my desoldering iron into a hot air soldering gun.
Some may ask why is this tut when there is the easier one wit the iron from digikey. Well the answer is, digikey doesn't ship to europe and all I managed to find here is this type of desoldering irons. One more thing is that this conversion is totaly reversible, you can use your desoldering iron to desolder in just one minute - no modifications to the stock irons are made.

What you will need for this tutorial

1. Desoldering iron 40W with a built-in vaccume pump - $ 6
2. One bottle cap
3. One screw 5x20mm
4. One fishtank air pump - $ 6
5. 1m (3ft) flexible hose-pipe - $ 0,3
6. 1cm of hard hose-pipe
7. 1m (3ft) thin copper wire

You will need a drill machine and 2,7 or 3mm drill bit

so let's start...

Step 1: The Iron

First we need a desoldering iron. I bought mine for 4 EUROs or about US$6 from the local electronics shop.
It is 40W and you can find the same at ebay.
First we must disassemble our desoldering iron. It has a body, a yellow cylinder, a spring and a piston.
The spring and the piston we don't need, so we pack them together, in case we deceide to use the iron as it is meant to be used.

Step 2: The Cap

Now we need a bottle cap. These caps are used with many bottles, mainly bottles for chemicals or from the drugstore.
I was wondering how to put the hose from the air pump into the yellow cylinder, when I found that this cap fits perfectly to it.

Step 3: The Screw

This is easier to find I think. We need 5mm screw, that is about 20mm long.
The idea is to drill a hole through it. I try drilling with a 2mm bit, but I broke it, so I dill a hole with a 2,7mm - no troubles this time.

Step 4: Fishtank Air Pump

I think any fishtank air compressor will do the job. However I was looking for a cheap one, but with variable speed control.
It turns out that the speed control cost much than I was ready to spend, but found this 200L/h with 2 speeds for 4 EUROs or US$6. I thought - that's what I was looking for.
The same can be found on ebay too.

1m or 3ft from the propper sized hose-pipe will be sufficent, it costs me about 30 cents.

You will notice that, when the piston is removed, the yellow cylinder becomes loose and we need something to press it against the body. I use about 1cm of somekind of a hard hose-pipe I've got at home. You can use whatever you find fit.

Step 5: Tunning

Now that we have everything ready, we just need to connect the parts.

With this assembly I managed to get as high as 240'C, enough to melt a sn63/pb37 alloy but just not enough to reflow a smd board.
So I made just one more tunning of the device.
You'll need about 1m or 3ft of thin wire, copper will be best, then wind this wire into a coil with a 1,5mm diameter.
I wound it around a watchmaker screwdriver, but everything that is 1,5mm, hard and stright will do.
Now put this coil into the desoldering iron shaft. This way, the coil will be heated from the iron, and when the air flows through it, it will release more heat than the bare shaft itself.
With this tuning the temperature rised to above 310'C, that is high enough to reflow the smd parts.

Step 6: Some More Tunning

So you have a Hot air soldering gun for just under 10 EUROs or US$15.

One more tunning. I sewed myself a strap to hold the yellow cylinder to the iron body, but you can use a rubber band or scotch tape.



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    Great idea! I've ordered one of these desoldering irons, but I could only find one with 30 Watts. Maybe nobody is making the 40w version anymore. I'm wondering if it will even be hot enough for this project. After you insert the copper wire into the tip, is it still possible to use the iron as intended with the desoldering pump installed or do you have to remove the coil every time? I'm thinking the solder would stick to the coil and clog the end. Have you used yours as a desoldering pump after the mod? Also, those bottle caps don't seem to be available anywhere online. Do you know where I could find one? I've seen some made from silicone, but they seem a bit too flexible for drilling holes and mounting screws. There are some wine bottle stoppers with stainless steel pouring tubes with a 5mm outer diameter. Do you think the 4mm inside diameter aquarium tubing would fit over a 5mm tube? The stoppers are also 2.5 cm in diameter so I'm wondering if there is enough room in the soldering iron casing. It looks like you cut off some of the bottle cap's diameter to fit in the casing. Is that correct?

    My comment is for readers with some electrical background since AC voltage are dangerous never attempt this if you don't have that type of knowledge! You might consider a used nebulizer air pump used by millions with breathing problems. Virtually any model will do but you may have to disassemble the unit to get access to the pump's vacuum port. A foot operated power switch may be wired to the AC source and pump's power leads. Make sure to consider grounding the pump and metal metal heater housing of the desoldering iron for ESD protection. I find silicone vacuum hose used in drag/racing cars to be the best suction tubing since it doesn't harden like PVC tubing but, it's expensive. Speaking of tubing use 1/4"/6mm or larger for faster pick-up. You must install a solder trap between the iron the the pump and silicone hi-temp tubing or equal , better closer to the iron or risk pump failure. My experience has found the best solution for this is those reusable gasoline filters with a glass tube and metal ends. You'll need to remove the nylon filter screen and replace it with steel wool or similar material which blocks extracted solder from reaching the pump. In my unit I simply installed a polyethylene body disposable gasoline filter near the pump inlet for any particle of solder that slips by your steel wool screen. By the time any particle of solder reaches this filter it will cool enough not set the paper element on fire. If your not able to build the extraction tool (iron) you may consider the following option like I did but, you'll need a 20 amp solid state relay ($3.50 ebay) or package with temperature controller and 24VDC laptop power supply remember to fuse pump and 24VDC power supply. The advantage of this option is the desoldering gun has an electrical trigger eliminating the need for a foot switch and personally I prefer this approach. I'm not affiliated with this suppliers and similiar desoldering guns can be had on eBay and USA source so shop around to meet your needs and budget. I found my diaphragm nebulizer pump has more than adequate suction with a 160W motor better than my Pace PPS-100 when you opt for a temperature controller and you aren't tweaking the iron temperature once set. If I can find space in PPS-100 I want a temperature controller in it. Since the extractor gun comes with a DIN plug you may want to mount the pump and relay or controller w/SSR in a ATX power supply case which is already ventilated for the pump motor. One last thing eBay also has digital temperature controllers for $15 and the extractor gun does contain a type K thermocouple so a constant temperature under load can be had. Listed below are the part sources. With careful shopping and equipped with temperature controller the finish cost should be in the neighborhood of $100-120 and you'll have a finished desoldering station better in functionality to $150+ OEM stations since you can easily repair it at low cost with bragging rights besides.

    eBay searches for:

    Nebulizer (asthma/COPD) compressor ($20)

    Replacement desoldering gun Hakko Clone ($50 expensive option)

    DIN receptacle to match above ($4)

    AC110-240V PID temperature controller + 25A SSR ($15)

    Hoses & clamps (silicone racing tubing) ($20 or buy nebulizer w/tubing)

    24VDC 3A Laptop power supply ($15 controller & desoldering gun/iron p/s)

    Computer power cord ($3 for pump use receptacle on old power supply)

    Motorcycle gasoline filters ($6.50 & $5 glass body and poly ones)

    Misc ty-wraps, screws & nuts, hook-up wire ??? US source searches w/online catalog:

    Replacement gun handle and hoses for 19034-TL Solder Repair station complete with DIN cordset and suction hose. $20 (my choice bought 2)

    Tips for above ($3 each)

    Tip cleaning rods ($1.30 x 3 one each size tip used)

    You may find these items for less at MPJA.COM, eBay for international buyers might be preferred. Price for old DOA ATX power supply case w/receptacle not included!!

    Good Luck Building; Geek1945 Radar & Computers since 1965

    or use vacuum pump instead of blower, to make super handy desoldering gun (why I found this page) :)

    I have the same soldering iron from ebay. and I have the vacuum pump. I´m looking for a way to stop solder without it clogging up the tube.


    simple yet brilliant. kudos to you my friend.

    what voltage did you use to power the copper wire coil?

    2 replies

    the copper wire coil is not connected to any power source, it is only for better heat transfer, it is a kind of a heat sink, increasing the surface of the heated walls of the shaft, and slowing the air going through,

    got it!! thanks!

    Is there anybody who can tell me how to remove pump - mine holds like welded.

    can unsolder atmega 20 PDIP and atmega 664 PDIP (no smd) ?

    Nice idea but shame you didn't do it the other way around - a vacuum powered desoldering iron. I used one once many years ago (£800 worth) and it was absolutely excellent. Those electric suction desoldering irons are still better than normal suction plastic ones but suction desoldering irons are superb because there isn't a limit to the suction.

    I have one in my tool box.. maybe I'll look for a small vacuum and have a go..

    1 reply

    Look for a vacuum pump for air conditioner servicing. Pretty decent power in a small affordable pump. I actually tried to reverse an aquarium pump to suck in air, but it was only good enough to use as an SMD pickup tool. Wouldn't pull solder.

    Thank you very much, I understand everything, copper wire from the transformer (power supply) will be good?
    Will you make a movie from work Hot air soldering gun ?

    1 reply

    I'm glad the explanations helped.
    The copper wire from a transformer ... well these wires have a protective lacquer for insulation, may be you should remove it first, it will bake when you put it in the shaft, also I was using a quite thin wire ~ 0,3mm , but you should try with what you have, it could be even better than mine.
    As for the video ... sorry, I don't have a camcoder.

    I have question to you :

    1 how long it takes the solder melt at a temperature of 240 C ?

    2 I do not understand step 5 Tunning: I wrap the copper wire to the screwdriver and put the desoldering iron?

    1 reply

    Hi luzik1980,
    as I have pointed out in step 5, the 240'C is not hot enough to solder/reflow smd parts, because it is the AIR temperature, and as it gets out of the soldering gun it cools down quickly, also a PCB is a heatsink by itself so the solder won't melt. So step 5 is all about boosing up the hot air temperature.

    Without this copper wire wound into a spring, the air flows through the desoldering iron freely, and what heats the air up is the inner area of the shaft, that the air is going through. Even more the velocity of the air in the tube is quite low, so I guess the flow may be laminar, so only the outter layer of the air is heated, and so not all of the air is heated equally. To solve this situation we create a obstacle in the way of the air flow, that do two things for us. First it make the flow turbulent and second it increase the hot area that the air is in contact with. So now we have more equally heated air and more heat conducted to the air. That's it.
    I hope this clears out the theory behind step 5, but what you have to do is just put the coil into the hallow shaft of your desoldering iron, and that's it.

    Sorry, the pump is 200L per HOUR. My mistake.

    This is excellent guide about how to make cheap soldering hot-air gun. Recently I had to replace heater assembly on my hot-air hand piece ( part of the Pace MBT250  soldering station). The cost of that part (heater assembly only) was USD125.00 (without shipping charges). It is also possible to buy the complete ThermoJet handpiece assembly (TJ-70 for the  MBT250-SDPT  Pace soldering station) for $335.00. When you compare those cost to your costs - it is huge difference.

    Sigh I had too much coffee. I did manage to get an iron to melt solder. Now I just need a 200L/hr pump and some copper wire for the element bore.