A hot glue gun is one of those standard tools of the hardware hacker’s bench, called upon to provide adhesion between an astonishing range of materials, and to provide a handy filler and strain relief in the form of blobs of polymer glue. We’ve all got one, but how many of us have taken a look inside it?
[Andrew Lorimer] bought a super-cheap eBay glue gun, and subjected it to a teardown. As you might expect, he found it to be a pretty simple device with only a trigger mechanism and a dumb heating element, but his write-up is of passing interest because he’s characterised its heating element. It has a positive temperature coefficient, which means that its resistance increases from around 2.5 kΩ at room temperature to about 7 kΩ at its 150 ºC operating temperature. This limits the current, and provides a very simple thermostat action.
The build quality is surprisingly good for such a cheap appliance, and he notes a surfeit of screws holding its shell together. But the quality of the insulation and strain relief leaves a lot to be desired, and he wonders whether it truly qualifies for its double-insulated logo. The LED pilot light is simply fed from the 240 V mains supply through a 250 kΩ resistor which he replaces with a 12 kΩ component for a brighter result.
We cover plenty of teardowns here at Hackaday. Often they are of extremely expensive and complex devices, but sometimes they are of much simpler subjects.
No it isn’t!
+1. I’ve had a glue gun for decades, and am still on the first stick. IME, hot glue is only good at sticking to two things – itself and skin.
perhaps it’s something you have to learn how to use? I know I did. Plus there’s hot glue and hot glue – not all are created equal.
I use it often and normally with good success. If hotglue does not stick use more hotglue :-) Ok, don’t try to glue polethylene/polypropylene.
Maybe you got crappy glue stick? Mine sticks to everything pretty well. I get glue stick from local Walmart so it’s probably better quality than the cheapest stuff one finds on eBay.
Buy better glue! The difference between bargain stuff and high-end stuff is huge.
https://youtu.be/vw5jrFX82so
Normally I don’t buy craft items from the local drug store like Rite Aid and prefer to support craft and hobby stores, but did buy an inexpensive glue gun there once. Used it for a kids project (bridge to support weight) and it worked well for plastic, wood, and foam board. Just need to make sure it’s on the high heat setting (pretty much useless at low setting) and warmed up enough.
If I bue something, I buy it where I get it cheapest in an acceptable amount of time. If I can wait, I order online from Aliexpress (slow, cheapest) or Amazon (little more expensive but faster) and if I need it immediately I go into a store.
There are different sorts of glues out there. Some do required the low heat setting.
My 2 goto guns are
-The Bosch PKP18E but you need 12mm sticks, it runs at 200c and has backflow issues if you use cheaper 11mm 11.2mm sticks
-The allmighty Dremel 940 http://www.dremeleurope.com/general/en/dremel%C2%AEgluegun940-425-ocs-p/;jsessionid=BDA80E141385B91335787E5C6757930E.sl171-vm_1
My two glue guns are from the $1 store. I also have a lot of different sticks from the $1 store. For a quick tack I use one of he guns I am happy with them, though I would not turn my back on one for an extended amount of time. For bigger jobs I put a few sticks in a steel can that something from the store came in and use my induction heater to melt it. I can accurately control the temperature to get it exactly where I want it and I can change the temperature almost instantly.
Did he consider that his modified LED series resistor is going to draw more than 2 W? That sounds a lot for a small resistor in a closed casing.
Interesting! Could we see a soldering iron teardown too?
My glue gun is dual-voltage 110V and 220V.
Unfortunately, my soldering iron is only single-voltage. I haven’t found a dual-voltage soldering iron in the stores nearby.
Both are just heating elements, right? Why would the soldering iron not allow the full range of AC voltage?
because in a simple heating element, the resistance, and hence power, is chosen based on the supplied voltage. So plugging it into the other supply, 110 or 220VAC it will either halve, or double the power output.
And for temperature controlled soldering stations, the transformer (judging by the
weightmass of mine) is chosen in function of the supplied voltage, also doubling/halving the voltage at the secondary winding. Some brands might have a multiple tap transformer with a selection switch on the back.visiting your website now (GP post) (who knew some of these username links actually go to anything other than a dead wordpress site) it seems you obviously knew that already, so i must have misunderstood your question ?
Actually it is quadrupling the power if you double the voltage. P = U²/R. Half the voltage would give you a fourth of the power.
Then there is the cheapest way out, you have a 220v iron. On the US setting a diode haves the power. In the US you have full power only, don’t flip that switch!
double of halve? nope, if you have a pure resistive element it’s P=U^2/R
right you are, i need more cofffee
Take it on holiday with you.
I see these a lot when perusing random taobao sellers. They’re usually like, 7 yuan which is about $1.
Hey, I guess once you have the injection molds, you basically just pay for the materials and lab- uh, yeah, just the materials.
I’m thinking about how much cycles will a single mold withstand. Looking at quantity of those cheap guns, they must have machines which mass produce those molds.
Not sure what they expected to find when tearing down the gun – seems pretty obvious it has a self-regulating heating element and feeder mechanism?
Something is not right, that 12K resistor for the LED should dissipate 4W.