DIY Hot Air Soldering Iron

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Posted in TechnologySoldering

Introduction: DIY Hot Air Soldering Iron

Also Available on my website

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

UPDATE
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

Tools:
Screwdriver
Scissors
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.

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    97 Comments

    This project actually worked surprisingly well. Impatient I instead blew air into the air tube and successfully desoldered a surface mounted nvram chip from a spare board. I didn't bother with the air pump. Worked like a charm! I guess the question now is whether I can re-solder on the surface mount nvram chip on the replacement board. I need to experiment on that a bit and attach the air pump this time. Stuffing the head of this with copper wire balled up scouring pad and applying additional heat from my 135 watt Weller soldering iron probably didn't hurt. I suspect that adapting the existing desoldering head to a really hot $20 old fashioned soldering iron using that 2+ inch copper shaft attached to it's head would produce some great results. Or even a butane torch or kitchen stove to get it really hot fast would work great!

    I think I found the perfect source for copper wool. "Pyramid Power RSW12100 12AWG" speaker wire. The conductor wire in this is super thin copper strands that can balled up to a fine copper wool to be put into the nozzle end. A couple of inches of this wire would be plenty.

    I haven't tested this yet as I am waiting for ebay parts to arrive for this planned project which will use an "ECG J-045-DS Electric Corded De-Soldering Iron" (same as the discontinued Radio Shack model - 45 watt, 420+ deg F) & (about $20 on ebay) and a small aquarium air pump (I chose a "Mountable 6V DC 370 High-power" 1 gallon air pump - less than $10 on ebay). Both parts are "FAST 'N' FREE" shipping.

    Success will hinge on how hot the air coming out will be (I need about 400+ deg to get to solder melting point and perhaps more being for surface mount work). Getting that will be a function of combining air pressure and heating element running through the copper wool at the nozzle. I may have to fine tune with a higher air pressure, more copper wool and hotter watt heating element but the design of the desoldering iron takes all the construction work out of the project - I hope. I found a picture of the desoldering iron disassembled which shows a long thick copper shaft that sits inside the heating element that transfers the heat to the nozzle. Worst case is that if the 45 watt element is not enough the heating iron could probably be replaced and adapted to a much hotter one - like an inexpensive 200 watt heavy duty type or maybe even butane. I suppose if you went with butane and a battery for the air pump the whole thing could be hand held and independent of AC. Trial and error will prevail. Some others have been successful, some not. We shall see.

    As a footnote, that red rubber hand pump bulb that you remove to attach the air hose can always be put back on, or better you could reverse the direction of the air flow to suck instead of blow if your air pump has both an inlet and outlet, swap back the nozzle to restore this to a desoldering iron and you still end up with a useful tool either way. I will follow with a post of my results when I am done.

    the tube is burning and melting

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

    4 replies

    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. http://www.maplin.co.uk/module.aspx?ModuleNo=3887&doy=18m12

    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.

    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.

    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.

    How many watts was this solder iron ? :)

    1 reply

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

    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.

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

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

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

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

    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!

    4 replies

    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.

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

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

    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.