Soldering Iron 'Buddy' - the Lego Way

Introduction: Soldering Iron 'Buddy' - the Lego Way

About: I am a full time I.T guy and part time musician. More recently I have discovered that I like to build things out of stuff. Strange things from normal stuff, or normal things with strange stuff. I hope I can ...

When designing my second project (to be posted soon) I found I was soldering a lot more than I had intended. I was using a 'Third Hand' to assist me in this but thought "wouldnt it be better if my 'third hand' could be used one-handed"...... This prompted me to have a go at building a system that would do the job of the third hand, but in one hand, using your thumb as a sort of trigger to bring the wire down onto the soldering iron, leaving your free hand agile to apply the solder material itself. Or eat bacon, which is also an excellent use of the spare hand.


If I had access to a 3D printer, I could have built this system in a far more compact package, but using lego gave me the freedom to make lots of quick changes as I needed to. It was never intended to be a fully functional tool add-on , but it works perfectly well (it just looks a bit kooky).

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Step 1: A Word of Caution :

Soldering Irons obviously get quite hot, Lego is made from plastic that melts very easily under heat. Keep the hot element away from the plastic element and you will be fine. Fail to do that and you are going to hurt the lego and possible yourself. Be careful :)

Step 2: Tools and Materials :

Materials :


Soldering Iron (to retro fit the device to)

x3 Small cuttings of bike Inner tube.

A 1" compression spring (for the trigger)

x2 (you can use x1 but x2 is steadier) Crocodile Clips

A handful of Lego "technics" pieces. In particular :

- x3 "+" Straight Poles (black)

- x8 Pole 'stops' (grey)

- x2 Elbow joints (grey)

- x1 (2x4) flat piece (for the trigger) (white)

- x2 (2x3) flat piece (to mount trigger to frame) (black)

- x1 (1x6) flat piece (to mount frame to soldering iron/inner tube rings) (white)

- x1 (2x8) flat piece (to stabalise the frame) (black)

- x4 (2x2) standard lego blocks

- x2 (2x2) standard lego blocks (with tunnels)

- x3 (1x2) standard lego block (with tunnels)

OPTIONAL - Super Glue (if you want to make parts of the build permanent)


Step 3: Assembling the Mount and Trigger :

With the soldering iron unplugged !

First off, I wanted a secure mount for the device. I snipped x3 sections from a standard bicycle innertube and pulled them over the top of the soldering iron, securing them in three places. (black bands shown in photos)


x2 bands are used to hold the 1x6 straight piece (white) in place, this will be the base plate used to hold the frame onto the soldering iron.


Next we need to make the trigger, dead easy as the spring fit perfectly into the bottom of the lego piece. I actually used a couple blobs of solder to hold it in place but you could get away without doing that, as once built it would be held in place by the frame


the third innertube is fitted near the top and is used to mount the spring. Tuck the spring under the band (from the top/heat end) so that pressure on the "trigger" presses it into the band. Mounting it in the bottom (cable end) will cause the spring to slide out of the band with each press, so go from the top as pictured.


Once complete, you should have adapted your soldering iron with a base plate and a trigger on a spring. The spring on the trigger is used later to apply the wire to the heat using just a thumb press.

Step 4: Testing the Action :

At this stage I quickly through together a basic model to see if the trigger and action was as expected. You may not need to do this, but I thought it was worth sharing as it shows how the trigger action works without the main frame built up around it. You can see from the side view that the spring is in place below the trigger.

Step 5: The Lego Frame :

who doesnt love lego ! This built was built 'in situ' on the soldering iron, but I have removed the frame so you can see how it was put together. You can use any blocks you like as long as the mechanical parts work in the same way.


Starting from the single black (1x2) base brick, I took the two arms out at 90 degrees using the elbow joint pieces, then extended the arms up parallel to each other to build the frame around.


At the solder end of the frame , i then built down, so that the dropped arms would align either side of the hot solder tip. It is hard to describe it but the images should show you how the blocks have been put together to acheive this.

Step 6: Attaching the Lego Frame :

Once frame has been put together its time to mount it onto the soldering iron.


It attaches in x2 places, the (1x2) block between the elbow joints attaches to our white base plate we attached to the soldering iron earlier.

The second and third places it attaches are either side of the trigger. the black (2x3) flat pieces fit under the white trigger using just two dots, on the far right and far left of trigger.

The frame should now sit comfortably on the soldering iron and will hinge on the base plate, up and down about 2/3 Inch when the trigger is pressed.

Step 7: Prepping/Loading the Item to Be Soldered :

Adding the wires is where the one handed buddy becomes less practical. You need to load the wire/s you are about to join into the crocodile clips. Often I fan the wire out and then twist the ends together to create a temporary hold. once the wire (shown above in green) is loaded intot he clips, the clips simply fit into the tunnel bricks on the end of the frame.


Pressing the trigger should now raise and lower the crocodile clips on and off the same horizontal level as the solder tip.


You can adjust the lego until you comfortably acheive this , once you crack it there is the option to glue some of the parts together. I didnt need to do this, but its an option.

*A tip, Dont glue the white trigger to the frame, or the frame to the base plate. that way you can always take the entire frame off in one easy move and have your untouched soldering iron back.


Pictures show the frame in place with the trigger being pressed and released to get the wire to make contact on the solder tip.

Step 8: The Finished Tool in Action :

And that is it! The video shows the whole thing in action, with the trigger being pressed to show the function of the frame.


Does it allow you to solder the wire with one hand and a press of a trigger, yes. Is it the best way to solder two wires together, probably not, but the theory is there to make the job one handed, which was the goal for me !

I hope it inspires you to try things out, even if its not going to result in an improvement to your technique, you have tried something different and gained an understanding of how some minor automation could potentially help make you more efficient. and also, Lego rocks, just dont tread on it.

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    4 Discussions


    5 years ago on Introduction

    This is another great idea! What benefits have you found over a set of helping hands not attached to your iron?


    Reply 5 years ago

    thank you! Well, the idea was to do it all in one hand and have your free hand available to load and unload the material being soldered. I am in the middle of building something else, nearly finished actually. but miscalculated (or rather didn't consider) that by spacing some elements too far apart it would mean altering cable lengths manually. I had to lengthen something like 26 cables. it meant a repetivive process of loading the third hand, pick up iron, solder, replace iron in stand, reload third hand Etc.Etc. ideally you would hold the iron in one hand, use free hand to load and unload. I may revisit this and try and design a more sophisticated trigger system. one trigger opens the crocodile clips for loading , the other trigger pinches the material onto the hot soldering tip. so Open>close>pinch>solder>open all using just the fingers on one hand. Sorry for long reply !


    Reply 5 years ago on Introduction

    I know how it looks in my head, just need to sketch it out and decide how best to acheive it. will share when done !