Introduction: DIY Hot Air Soldering Iron

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Charper's Hot Air Soldering Iron
An easy DIY project on a college student budget

This project stemmed from the desire to remove (and perhaps one day re-solder) surface mount components. In it's entireity (pictures and all), it took less that two hours and $20. Even if you have to buy everything, I believe the cost could easily be kept under $30. Comparatively, I could not find a hot air soldering iron retain for under $200. Every entrepreneuring young electrical engineer needs to work on some project to satisfy curiosities and take things apart... right? Well, at least I do!

Step 1: Purchased Items

I can't remember where this soldering iron came from, and I've been asked questions about it - if somebody could send me a link or tell me a location where a similar iron could be purchased, I would greatly appreciate it.
Update 2:  A reader, Daltore, suggests the "Hakko 503" soldering iron.  His full suggestion and reasoning is in the comments below.

Also, there has been a lot of comment on the heat exchanger. Instead of the stainless steel, you could try stripped copper wire, solder wick, or purchase actual copper mesh somewhere.

Items Purchased

Aquarium air tubing: $1.13
Aquarium air pump: $6.97
"Chore Boy" Stainless Steel scrubber: $1.37
"Zebra F-301" pens: $4.73

Total: $14.20

Other items needed:
Super Glue
Soldering Iron, 40 watts or higher
Silicone Fuel Tubing

Dremel (or similar drilling/grinding tool)

The silicone tubing is used as a fuel line in model airplanes, it's reasonably cheap and I'm sure you could find it easily at a local hobby shop or from Froogle, Amazon, or Ebay. Fortunately for me, Aerospace Engineering is big here at MSU, so it wasn't hard to find a friend that didn't mind giving me some. Feel free to come up with a substitute for this if you can - but this stuff seems to hold up extremely well to the heat of the soldering iron.

Step 2: Take Soldering Iron Apart

This is what you get when you take a soldering iron apart: a handle, a simple resistive heater, and a sheating to protect the heater (or protect other things from it). The tip has been removed in this picture. The nut shown at the far right side of this picture holds the soldering iron tip in by a small lip.

Luckily, the entire thing is hollow! Every single part of it - including the heating element. It's almost as if this thing were made to be modified.

Step 3: Add Heat Exchanger

In order to effectively heat the air, we have to do something to increase the surface area it passes over. I was hoping to use copper rather than stainless steel for this; but I couldn't find any copper scouring pads. The closest thing available was the "Chore Boy" stainless steel scouring pads. I feel however, that if it were available, copper would be superior. As you can see in the picture, simply stuff a few strands into the end of the heating element. Be careful not to get too much. You should test blow into the end of the heating element and make sure air still flows relatively unobstructed.

Note: Stainless Steel can catch fire... Use copper if at all possible

Step 4: Pipe Air Into the Heating Element With Silicone Tubing

Simply push the silicone tubing into the end of the heating element. You can't see it in this picture, but I sealed the end firmly using scraps of silicone tubing and super glue. This part is relatively vital - I had to go back and make the improvements mentioned here - without them the soldering iron loses a lot of air from the back end and smokes a lot (although I could never find the source of what was burning).

Step 5: Put the Aquarium Tubing in the Handle of the Soldering Iron

I used a dremel tool to put a hole in the handle of the soldering iron, near the top. The hole the power cord went through was not quite large enough to accomodate both the power cord and the aquarium tubing. Your results may vary.
This shows the tubing through the hole I created in the soldering iron. The placement of this hole actually seems superior to running the line straight out the back of the iron. The air flow can be crudely regulated with a little bit of pressure, pinching the air hose against the handle.

Step 6: Splice the Two Hoses Together and Re-assemble

This is how I attached the silicone tubing to the aquarium air line. I simply removed the tip from one of the pens, stretching the silicone tubing across the smaller end, and pushing the aquarium hose firmly into the wide end, securing it with a generous amount of super glue. These particular pens have a relatively wide opening at the tip - if yours aren't quite so generous, you may have to widen the opening a bit to avoid restricting the air flow.

After putting the soldering iron back together - this is what we are left with. What woud be a fully-functioning hot air soldering iron, missing only one small piece: the nozzle. Another pen tip is unscrewed and cut using the dremel cutting accessory shown in this picture.

Step 7: Make a Tip

This shows the pen tip after being cut in two. The idea is to get a tip with a wide end barely larger than the hole in the soldering iron's nut. This way the tip can rest on the outside of the soldering iron's male end, and fit securely when the nut is tightened on the modified pen tip.

Step 8: Final Assembly

This is the result after securing everything together. The tip from this pen seems to fit perfectly. I would recommend actually using a pen tip - as the mechanical pencils I found all seemed to have too small of an opening. Of course, it could easily be filed down to something wider.

Step 9: Final Results

Here are some initial results - these tiny devices are surface mount diodes from a damaged network card. The soldering iron seems to work absolutely flawlessly. After waiting a few minutes to heat up, just turn the air pump on and bring it close to the device you want to remove. Using tweezers to apply gentle pressure against the device, it quickly loosens up and falls off.

So, how well does a hot air soldering iron really work?

Light on both time and money, I found this project a worthwhile investment, especially for a college student on a budget. Not only can it remove surface mount components, but I found it works really well as a general use soldering iron because of its less-intense heat. For example, a transistor can be soldered in only a few seconds, without the need for the usual soldering heatsinks. For anything but heavy wires, this is a vast improvement over the soldering iron I started out with. In fact, if it weren't for the heating time typical of soldering irons, I would greatly prefer this for general use even to my Cold-Heat device.


CrisA13 made it!(author)2016-07-26

the tube is burning and melting

Jack+Daniels made it!(author)2006-12-16

i was thinking of buying one of those butaine irons are they really that great?

_soapy_ made it!(author)2006-12-18

Argh! java.sql.SQLException: Deadlock found when trying to get lock; try restarting transaction ate my post! Again!

If you are in the UK, Maplin do a great one. I just searched for it, they still do it.

I've had mine for at least ten years now, brilliant bit of kit. The case means everything stays together. I never wet the sponge because it's a pain inside the kit, but hey. And I own a second one, just in case they pull these off the market for some spurious health & safety reason.

If you want the heat right now, keep the lighter under the tip for 20 seconds to get it started fast. If you are in a hurry to be off, turn it off and take the tip off with pliers, it will be stone cold in about 2 minutes. If you want to change the tip, simply take it off with pliers and swap it, then wait a minute or two for it to be hot again (or boost it again with your lighter)

Great for working outdoors, comes with a flame spreader thing, various tips, a hot knife thing, a sponge and even some solder in a holder. Best thing? They left a space so you could add your own lighter to the kit. There is even a hot air tip, but I've not had much success with it, except for on heatshrink.

floydt100 made it!(author)2014-11-06

Yeah i have a simular kit from burnsomatic. The main thing i use the hot air tip for is heat shrink too since it shrinks quick but doesnt burn unless you hold it on there for a wile. The solder included is the perfect gauge for small electronics too which is a plus.

WesDoesStuff made it!(author)2006-12-16

yes. i suggest the radio shack one.
it is realy easy to hold and i love it. i don't suggest the gun type butane soldering irons because i find them harder to hold.

Polymorph made it!(author)2011-11-27

Yow! Reviews filed since you posted that on RS's site indicating that they've experienced valve failures, or even had the back of the butane chamber blow off.

I'll get the Weller.

nickxab made it!(author)2014-07-28

How many watts was this solder iron ? :)

floydt100 made it!(author)2014-11-06

Im guessing by the size of the coils inside that its most likely around 30 watts

floydt100 made it!(author)2014-11-06

For anyone below interested in a butane-powered iron, home depot sells the burnsomatic straight irons for around $14.99 and includes variable heat, 2 soldering tips, a hot knife, and a hot air tip (yes works just the same as this one). Ive had mine for about a year and so far ive had nothing but good experiences with it. It takes a little hotter to heat up than my electric one but its perfect for automotive electrical and speaker wire because you dont have to bring an extention cord around with you. I highly recommend.

Inlove made it!(author)2014-07-31

copper scrubber pads can be bought through many stained glass suppliers.

muddog15 made it!(author)2014-01-02

I would replace the silicon tubing inside of the element with copper tubing.

feka made it!(author)2012-11-05

Can somebody post data about the air pump? Or exact models that work so I can further investigate alternatives based on these...?

seraine made it!(author)2012-07-25

Most Walgreen's should have copper scouring pads. I use them for cleaning my soldering iron.

carlitoscr made it!(author)2008-08-06

Well, I think you can use a piece of copper solder wick as your heat exchange element. you can either place the piece of solder wick as it is (being careful it doesn't offer too much resistence to the air flow) or you can take your time to separate all the copper threads and then make a small ball with them (be carefull not to compress that ball, it has to be porous). Use the porous copper thread ball as your heat exchange element. Good luck!

Ian01 made it!(author)2008-08-21

These wicks usually contain rosin flux, which could be detrimental. On the other hand, you might get vaporized flux that could help with the desoldering.

conny17017 made it!(author)2009-09-15

How about using some of the woven copper or aluminum jacketing on coax cables

Polymorph made it!(author)2011-11-27

The aluminum will corrode quickly in the heat, don't know how much that will affect it. Good idea, though.

Ian01 made it!(author)2009-09-26

The copper would probably work, but I wouldn't use aluminium because its melting point may be too low. That's why it isn't used for model rocket launch stands. Those have steel blast plates.

beehard44 made it!(author)2010-10-22

i melted aluminum with the whoosh rocket once

techno+guy made it!(author)2011-03-04

Can you use steel wool for the heat exchanger?

Mirage_662 made it!(author)2011-11-21

Thermal lance anyone?

charper made it!(author)2011-03-04

I wouldn't. Steel wool can be flammable.

charlieb000 made it!(author)2011-11-02

just an idea, perhaps it is possible to replace the tip with a tube and use that as an air duct. then you can use the iron as a iron again when you want. i have a 40W thats not really suitable for soldering but if i need it to burn stuff again then i can just put the old tip in.

ledartist made it!(author)2011-06-20

Amazing. Only if I knew this before I purchased my hot air tool...
Live and learn. Thanks!

omnistructable made it!(author)2011-06-12

Velleman TSS5 50W soldering iron works great. It is almost air tight. Use information in this instructable to make the nossle and heat exchanger. I didn't put a silicone tube inside the heater, I have just drilled a hole in the handle and connect the aquarium hose to it with an aquarium T-piece with the one end blocked.

PetervG made it!(author)2006-12-15

I got a ColdHeat yesterday! XD

WesDoesStuff made it!(author)2006-12-15

i pray for your soul. the cold heat soldering iron is probably the worst soldering tool ever created. tips break too easy and are far to expencive. the entire concept of how the cold heat soldering iron works is completly retarded. go to radio shack and get yourself a butane soldering iron.

charper made it!(author)2006-12-16

Oh come on... if you use it for what it's really good for, it's great. Quick, short jobs where a low-power resistance soldering iron really shines. You're right about the tips, but I found that a nail file (black emory board?) works realllly well for re-sharpening and cleaning the melted plastic out of it. I've had moderate use out of my cold heat for about 2 years now and have never replaced the tip.

Crash2108 made it!(author)2006-12-16

If you use it you know what it's good for. Nothing. The stripper it comes with is worth more.

WesDoesStuff made it!(author)2006-12-16

my stripper broke after 3 uses :/

Crash2108 made it!(author)2006-12-17

You should put more money in her panties.

_soapy_ made it!(author)2006-12-18

lol. I didn't even get a stripper with my ColdHeat, which was the worst £20 I ever spent. It takes longer to get the darned thing to solder than it does to get my great butane one, and fire that up, unless it is a *single* joint. It doesn't even heat the solder hot enough half the time, even with Duracells. I'd say it was just Cold.

toogers made it!(author)2009-06-04

lol, coldwarm tool. it solders 2 % of the time!

lilshawn made it!(author)2009-10-13

i had the cold heat, problem is... it's a resistive type of heat generator... if you slip (which i have done with it before) and bridge 2 connections, your dumping your electricity into the device.

Iv'e blown a couple of transistors and leds with the cold heat. I'm a regular iron user now.

MaXoR made it!(author)2011-03-03

lol, I always thought that could happen! I've never really used it, since mine couldn't even get solder to solidify on it's own, let alone attached to a metal post. I've always wanted to make it into a "wired" iron by giving it a battery pack, so it can have top amperage for the longest time. However since you mention this LARGE draw back (Because lets face it, what other application does the cold heat soldering iron have than to be used on small electronic parts), it's a failed product that sadly can still be purchased today.

If you are just soldering two wires together, then maybe this will be a practical tool for you, however those that need to do computer repair work, just go get a 90W and be done with it. A 90W heats up quickly, allows for almost instantaneous melting of the solder joint, so less time to transfer that heat to the parts.

As well, I want to make a side remark about de-soldering wick, it's made by "Goot" and a few other companies. It takes forEVER to heat up, you have to KEEP it hot enough to melt solder, and if you don't have a monster iron, you will likely just fuss with that sort of thing. I've long since learned a good cheap solder sucker is all you really need.

hore made it!(author)2009-10-13

are you build this device,hot air, is it work, what type of soldering iron.

aaaaoooo made it!(author)2010-02-24

it works !

Sync made it!(author)2007-08-15

omg yes. cold heat ISNT that bad. ive been using mine for a while and nothings broken...

YummyPancakes made it!(author)2008-03-02

Yeah. I remember my first soldering iron was a ColdHeat... *shivers* Won't use THAT one ever again.

disturbedreaper made it!(author)2008-03-02

i have the cold heat my god its a complete mockery. it makes a complete disaster you cant solder anything smaller than an inch in diameter.

beehard44 made it!(author)2010-10-22

cold and heat. Mix 'em together you've got a crappy product

PetervG made it!(author)2006-12-16

Yea, its hard to get it to work, i'm a beginner so I like having a wireless one and you dont have to wait. Anyways, good for fast jobs, sorta. I have to get the hang of it.

static made it!(author)2007-09-11

Personally I wouldn't recommend the Cold Heat tool to a beginner, because the way you you have to futz with it to get it just so to heat the connection. I have to consider the Cold Heat a tool for those who have already mastered soldering and, instinctively know when the job should be good. 30 years ago I had a Wahl rechargeable and just loved it. Anyway if you already have it, no need to toss it in favor of another style of cordless iron.

PetervG made it!(author)2007-09-12

Yeah, that comment is old. The tip broke.

Bigfish_102390 made it!(author)2011-02-23

I have a soldering iron I'm curious as to how u get the sheathing loose without hurting the iron because it is riveted to the handle.

Astinsan made it!(author)2011-02-15

The epoxy your talking about is QuikTitanium Epoxy PuttyQuikTitanium Epoxy Putty. It can do a Service temperature -40 to 500º F (-40 to 260º C)(hd has it in the paint department) . There are also exhaust pipe patch kits for cars that will work, Then there is the stuff for fireplaces that is in a calk gun container made by 3m (hd has it in the paint department)

soldering+iron made it!(author)2010-12-23

Recently, I had to replace the heater assembly for the TJ-70 Mini ThermoJet hot-air handpiece - this is part of  my Pace MBT250 soldering station. The cost of the part was $125.00 (without shipping charges). It is also possible to buy the complete ThermoJet hot-air handpiece assembly (TJ-70 for the Pace MBT250-SDPT) for $335.00.  You made  similar hot-air  soldering iron for much less money!

DiscoElf made it!(author)2010-12-18

What diameter / gauge is the silicone tubing please

CalcProgrammer1 made it!(author)2009-07-16

I just built one of these using the RadioShack 45W desoldering iron. It's a lot easier to make, just pull off the bulb and slip on the air tube and stuff some steel wool into the chamber where the tip goes. I had to put a lot of steel wool in but I finally got it hot enough to remove and solder SMD components. Total cost was $11 considering I already had an old air pump and air hose, just had to buy the desoldering iron.

charper made it!(author)2009-07-16

That, sir, is an excellent use of pre-existing products. As a bonus, I'd imagine it's easy to remove the air hose and continue using it as a suction device.

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