Introduction: Soldering Gun

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A soldering gun is a pistol-shaped soldering tool, named for their rough appearance to a firearm.
Why settle for an approximation when you can have a realsoldering gun?! Bring this little baby to bear on your next PCB. Point, pull, and let the heater rip.

It's not so far fetched: A steady hand, a careful aim, an unsafe quantities of lead...soldering and firing a gun have an awful lot in common. Making your own is easy, all you need is an air pistol and a hand-held, battery powered soldering iron and you can make your own soldering gun.

Here's what I used to make mine:

  • hobby knife
  • wire strippers
  • screwdrivers
  • soldering iron
  • JB Weld (or very strong epoxy)
  • rotary cutting tool

Modified toy/prop pistols can be mistaken for real firearms, use common sense and leave this gadget at home.

Step 1: Disassemble Soldering Gun

The soldering iron I used was the equivalent of a 15W soldering iron, battery powered by 4 AAA batteries, had one 3mm white LED near the tip. The package boasts: "the tip heats to 365°F (185°C) in about 7 seconds, and can reach a maximum temperature of 1050°F (565°C)".

I used a small Phillips screwdriver to open the plastic housing of the soldering iron and pry it apart. The circuit inside has a 51Ω resister, one small white LED and a socket for the heating element.

After sketching the circuit onto paper I desoldered the components and set them aside.

Step 2: Disassemble Air Pistol

The model of airsoft pistol I used has a removable magazine which can hold about 30 small pellets. Start by removing this magazine and setting aside, this will be our battery compartment. This model of pistol also has a sliding action, sharply jolt the slide forward on the pistol frame which will cause the slide to separate off the frame guide rails. You should have 3 large component assemblies of your airsoft pistol.

Inside the slide are several smaller components which make up the firing pathway, each of these can be carefully removed which will allow you to feed electrical leads to the tip. You may need to use small screwdriver to pry apart the air pistol insides.

With our airsoft pistol and soldering iron disassembled we're ready to plan our the wiring schematic.

Step 3: Planning and Wiring

Referring to the sketch of the disassembled soldering iron I made earlier, I planned out how the wires would work inside the confined insides of the airsoft pistol.

The wiring will stay mostly the same as it was originally in the soldering iron, but with the addition of a second LED (to have one on each side of the slide) and a momentary switch to operate the soldering gun instead of the manufacturers' toggle switch.

Step 4: Wiring Solder Tip

With the slide disassembled you can plan out the route which your electric leads will take from the tip of the pistol to the handle. I had to make a few minor modifications to the firing array to get my leads installed, but it wasn't difficult. 

Using two long electrical leads feed the wires through the firing array, I enclosed the leads nearest to the soldering tip in heat-resistant tubing which was connected to the wires using heat-shrink tubing. The soldering socket from the soldering iron was attached and heat-shrink tubing was added to prevent any short circuits.

The wired were weaved through the firing array and the barrel was reassembled, leaving the two electrical leads trailing. Two small holes were drilled where red painted divots were located on the airsoft pistol. I installed two 3mm red LED's inside these openings and hot-glued them in place. The positive lead from the soldering tip was cut and soldered to the anode (positive) side of the two LED's. The negative lead was cut next and the 51Ω resistor was soldered to it, the other end of the resistor was soldered to the cathode (negative) of the LED's.
The negative wire will next be attached to a momentary switch behind the trigger.

Step 5: Trigger

Two electrical leads were soldered to a small momentary switch and protected with heat shrink tubing. I chose to use all black, thereby hiding the switch to the casual observer. After soldering the switch was installed using a strong epoxy, the switch leds were fed up behind the trigger into the gun, they emerge between the handle slides. One end is soldered to the negative lead from the soldering tip and resistor (see previous step).

Step 6: Milling Magazine

I wanted my magazine to house my "ammo", which in this case was the batteries. Just like a real pistol I wanted the magazine to be removable and reloaded with fresh ammo when I was out. I opened the magazine casing an removed the feeder spring and small weigh located inside. 

Using a rotary tool with a large milling bit I carefully removed the pellet guideway, making sure to leave the plastic posts which protected the screws that hold the magazine together in tact. Make sure to wear goggle or a face mask as this part can get very messy, with removed plastic flying all over the place.

Once your magazine is gutted take the 4 AA batteries and fit them inside, you want the fit to be snug, but not to inhibit the magazine from closing properly. I added a small 3mm scrap piece of foam inside the magazine housing to hold my batteries in place and prevent them from knocking around.

Step 7: Magazine Contacts

I made contacts for the battery magazine. Using junk electronics that I salvaged from the Dollar Store I found a stiff metal plate which I hot glued at the bottom of the magazine, this connected the positive end from one column of batteries to the negative terminal of the other column of batteries, replicating the array of batteries found inside the store-bought soldering iron I purchased.

The leads that were exposed at the top of the magazine needed a way to make contact to the rest of the circuit inside the pistol, but could not be hard wired because I wanted the magazine to be removable. To solve this I used springs from junk electronic battery holders. After stretching the springs to create an elongated contact they were hot-glued in place, making the positive and negative ends of the battery array poking out th etop of the magazine, ready for contact with the circuit when inserted into the body of the gun.

Step 8: Completing the Circuit

The last step to this circuit is the contact plate for the battery leads to connect to, this will be located in the handle of the pistol. I epoxied two stiff pieces of metal to a piece of plastic with the bottom portion of the plastic acting as a contact plate and the leads for the contact plate protruding above the plastic.

The positive connection from the barrel and the negative connection from the trigger can now be soldered to this connection plate. 

The profile place can now be placed inside and above the handle of the pistol between the slide, the profile of the plastic piece will need to be carved down to fit. Do not glue in place yet! Next, install the modified battery magazine and align the contact plate to meet with the battery magazine springs. There will probably be some modification required to both the battery magazine and the contact plate to ensure a secure connection. Test your circuit before gluing in place!!

When you are satisfied that you have a solid connection with the plastic connection plate and battery magazing springs the plastic contact plate can be epoxied in place.

Step 9: Epoxy Pistol Action + Close Assembly

I wanted this soldering gun to have a working slide, but the wiring inside made this impossible. Instead, I used a strong epoxy to seize the slide action in place. After the epoxy had dried I carefully snapped the slide back on to the pistol body, careful to tuck any bunched wires back inside the gun assembly.

Make sure your soldering gun works correctly before epoxy sets, this is your last chance to make any final corrections to your circuit. After this, you may need to remake some of the circuitry of you have to pull it apart after the epoxy dries.

Step 10: Shoot Some Lead

This soldering gun operates just like the one original one it's modified from I bought at the store. It heats up fast and can melt solder in under 10 seconds from a cold start. I've even used it for solder a few simple electronics projects so far!

While not very practical it's a fun twist to my regular soldering iron and sure gets people talking!

This idea modifies an already realistic pistol and makes it look even more menacing. This project, while fun, can easily be mistaken for a real firearm and get you in trouble. Have fun with this project, but be smart.

Happy making :)

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