WHY would you want to make your hot glue gun cooler?
Well, hot glue guns are great. They will stick just about any two materials together with a strong and flexible bond which hardens in less than a minute. But . . .
I occasionally make radio control model planes out of Depron foam and EPP sheets (foamies) and these materials have quite a low melting point. At its normal temperature, hot glue will spread across the surface of the foam and eat into it causing bubbles of gas to blow into the glue and making a very messy joint. The same is true of fanfold foam and Styrofoam (expanded polystyrene) which is much the same thing and melts into nothing at full heat.
Look at the photo. At its normal temperature my gluegun makes a mess of the foam. Turning down the heat reduces the bubbling until the glue is below the foam's melting point, which still gives a solid join much stronger than the foam, but so much neater. With my modified glue-gun I can now make repeatable neat joints in the foam with no distortion due to overheating.
Temperature controlled glue guns are available, but these are still too hot for Depron or EPP. You can also get adjustable guns, but these come in way more expensive than my idea here. There are also cool-melt guns, but I've never found them to have the adhesive power of hot glue.
*** Warning : This project uses potentially lethal mains voltages ***
*** Safety should be the main consideration during construction ***
( Contrary to what appears on the blog sites which have picked this up, I did not ruin
several sheets of depron using too hot a glue gun. I'm not quite that slow a learner #;¬)
Step 1: What you will need
Unless you have a particularly long mains lead on your glue-gun, you will need a length of mains wire with a mains plug on the end. You'll find one around the house somewhere, probably attached to a defunct gadget. It should be no thinner than the lead to the glue-gun.
You will also need a cheap switched light dimmer (£5, $8) which you can get from any DIY shop electrical department. Get as low a power one as possible; 250W is much more than enough. My glue-gun is 35W and the dimmer cuts off about 1/5 travel which is probably due to it being below the minimum (60W rating). Not a problem as this is below the glue melting point.
As I'm in the UK I'm using 3 pin mains plugs and a 240V dimmer but obviously you would use items suited to your local mains. You will also need a standard single surface mount plastic back-box to mount the dimmer in. Additionally, you'll need the trusty soldering iron, a couple of lengths of heat-shrink and something to provide strain-relief on the cable; I used a cable tie here.