I was repairing some garden hose today, softening the rubber with the Milwaukee cordless heat gun to make it easier to slip over the new hose end, and I thought: “why haven’t I reviewed this tool yet?” I don’t use it every day, but it’s one of my favorite new tools.
We first talked about the cordless heat gun after NPS17. Milwaukee introduced it at that show and said it would be out in September of 2017. I think it was late September when I got my review sample, and I’ve loved using it ever since.
To review, the cordless heat gun specs are:
- 875°F max temp
- 6 CFM Airflow
- One charge, 40+ connections (w/ 5.0Ah battery)
- Reaches temp 30% faster than corded
- Guarded nozzle and stands on battery pack
- Ladder hook
- LED light
- Length: 6.35″
- Weight: 3.2 lbs
Some specs have changed since we first wrote the preview post. We were told at NPS17 that the max temperature would be 1000°F, but when the press release came out in late August 2017, they had changed it to 875°F. Milwaukee also rewrote the the 20+ minute run time with one 5.0 Ah battery to be 40+ connections on one 5.0Ah battery.
The nozzle is about 1.3″ (or 34mm) wide and works with my WEN heat gun accessories, or you can purchase the Milwaukee heat gun accessory assortment (49-80-0300).
The M18 cordless heat gun kit is now sold both as a kit and a bare tool. The kit includes a 5.0 Ah battery, M18/M12 charger, 3/8″ concentrator nozzle, hook nozzle, and carrying case for $239. The bare tool runs $119. You probably won’t be able to find either locally and will have to resort to ordering online.
Interestingly enough, there’s a hard to find 2688-21K kit that Acme Tools and a few other retails sell, combining an M18 cordless heat gun kit (2688-21) with a bare tool soldering iron (2488-20) and an M12 battery (48-11-2420) for $349. That’s $239 for the heat gun kit, $69 for the bare soldering iron, and $49 for the battery all totaling $357. The bundle ends up saving you $8.
Buy Now (via Acme Tool)
When you pull the trigger of the M18 cordless heat gun, not only does it energize the heating element and start the fan blowing air, it activates the LED workplace illumination. Once you remove your finger from the trigger, the LED stays on for 10 seconds then fades away.
One thing that Milwaukee touts is the guarded nozzle. Even though the cordless heat gun can stand on the battery, the nozzle is shrouded so that the hot element can’t touch anything if the heat gun accidentally falls over.
Above, you can see thermal images of the heat gun after I ran it continuously for 90 seconds. If you look directly at the heating element, you can see that its temperature is still 381°F, but looking at the heat gun from the side you can see the hottest part of the heat gun that’s exposed is 98°F.
After taking the thermal images and seeing only 381°F, I wondered what the actual output of the heat gun was. I setup the gun with the hook nozzle and put a K-type thermocouple in the center of the nozzle. I thought this would give the best chance of getting the highest temperature reading, since the hot air will be reflected back at the probe.
I ran the heat gun for about 90 seconds, and logged the results. This would show me two things: how fast the air stream climbs to a usable temperature, and how hot the air stream gets.
I show the results below, but before I get to that, I ran some more tests because I was puzzled by the low temperature results. With this setup I only reached a little under 500°F in 80 seconds. According to the specs, I should be seeing 875°F.
For the next test, I stuck the thermocouple junction inside the mesh screen and logged for 90 seconds. This time I reached a max temperature of a little over 700°F, still below the stated 875°F.
Wondering if this was just Milwaukee’s specmanship, or if this was an issue with other heat guns, I decided to test my WEN Model 2010 2-speed heat gun. It is supposed to reach 700°F and 920°F on the low and high settings respectively. I ran the same test with the hook nozzle on both low and high speeds and recorded the results from all the tests below.
From this limited data set, I suspect that the temperature stated in the specs really has little to do with the actual temperature achieved at a workable distance from the nozzle of the heat gun. I don’t know if the stated temperature is the temperature the heating element reaches or some other mysterious measurement. All I can make out from this test is that the stated max temperature seems to be meaningless for actual operation of either heat gun.
From the graph, you can also see the amount of time it takes for each heat gun to get to a usable temperature.
I previously tested the M18 heat gun, and it takes about 10 seconds from a cold start before it will begin shrinking 1/4″ heat shrink, which means the start up time for heat shrink tubing is about 10 seconds. Looking at the chart, this would put the temp around 350°F. This is consistent with most heat shrink tubing specs that call for heating at 250 to 350°F.
I tried the same test with my WEN heat gun on low, and the heat shrink started shrinking in about 5 seconds. Looking at the graph above, it doesn’t get hotter any faster on low than the M18 Heat gun, but I think it has more airflow.
After all this temperature testing, I wondered how much current the gun was drawing from the battery, since the WEN heat gun supposedly draws 1000W on low and 1500W on high (actually 947W and 1323W). To match the output on low, the Milwaukee cordless heat gun would have to draw something like 50A, or be much more efficient.
I removed the top shell from the heat gun and found I could not get my clamp meter around either of the battery wires, as they were too short and extremely stiff. The best I could do was measure the current to the fan motor and the heating element — which should account for most of the current draw anyway.
First, I measured the current draw from the heater to be about 16.4A. Then, I put both the motor and heater wires into the clamp meter and measured 16.6A. It’s not a surprise that most of the power goes into the heating element.
After adding in the LED and the other circuitry, let’s call the total current draw from the battery 17A. That’s only about 300W! This is almost 3X as efficient as the WEN heat gun on low, with only a little lower performance.
To get runtime, you divide 5Ah/17A which is about 0.3 of an hour, or about 18 minutes.
Later it occurred to me that what I was measuring was the current during the heat up time of the element. Looking at the chart above, the heat gun never reaches a steady state, it just keeps slowly rising. So I don’t think the current draw would decrease significantly after time. Plus it still is going to take a lot current to maintain the heater temperature with air blowing across it.
Also, this cordless heat gun is designed for quick heating jobs like bending tubing or heat shrink, not long term applications like stripping paint. So the heat gun is probably only going to be used in bursts of 90 second of less.
In the beginning of the article I mentioned I was using the heat gun to put a new end on a garden hose. I’ve found that instead of struggling to force the end completely into the cold hose, that it is much easier to heat up the end of the hose so that it stretches easier.
The easiest attachment for this task is the hook nozzle, which lets you heat the entire circumference of the hose without having to rotate it.
Once the hose is warm enough, you can simply press the end into the hose with very little effort. Just don’t overheat the hose so that it gets too soft.
One of the most common uses for a heat gun in electronics is for shrinking heat shrink tubing. Again, I find the hook nozzle to be the best way to concentrate the heat around the entire tube. Above, I’m finishing a connection between two servos as part of a 3D printer upgrade.
When I upgraded my air hoses to V-Style air line couplers, I couldn’t get at the nut to remove the old coupler because there was a strain relief in the way, and it wouldn’t budge. After less than a minute using the cordless heat gun with the spreader nozzle (sold separately), I was able to slide the strain relief out of the way to access the nut.
Another use I found for the heat gun was to soften 3D prints made from ABS. The custom K’Nex piece I made is designed to be fit with a ball bearing. It’s a really tight fit, but if you heat up the part, it’s much easier to install the bearing.
The finished K’Nex bearing holder is for the drive of a K’Nex RC car – I still haven’t finished this project.
Heat guns can be extremely useful for removing stubborn labels without tearing and leaving gummy residue.
Finally, the last thing I’ll highlight is using a heat gun to make using a wax filler pencil easier to use. I sometimes use wax filler because in some circumstances it matches the wood better than putty, plus once it’s in it doesn’t shrink, so you don’t have to go back for a second coat.
But it can be extremely frustrating to use because it is hard to get into a nail hole and wants to pull out when you try to wipe away the excess. Warming it up a bit helps to make it flow better.
You can also resoften the wax while it’s in the hole to it makes it easier to get a clean and invisible fill.
I didn’t strictly need a cordless heat gun for any of these uses, but for some tasks the cordless tool made things go a lot faster. For example, it was easier to use a cordless heat gun to help with attaching a new fitting to my garden hose, rather than dragging the hose to an outlet, or bringing the running an extension cord to the hose so that I could use a corded heat gun.
Since I only ran one trial of one sample for most of my tests, you should take the results as a general indicator, not a real performance measure, but I think it gives a good picture of the M18 heat gun.
It may not get as hot, blow as hard, or warm up as fast as an cheap corded heat gun, but it will get the job done in a reasonable amount of time.
Despite not being as powerful as a corded heat gun, the M18 heat gun offers several significant advantages. It’s portable, so you can take it to where it’s needed and quickly get the job done, rather than taking the work to an outlet or running an extension cord. It’s designed to stand on it’s battery and be ready to grab quickly, plus if it does fall over, the hot end is shrouded in most situations. With most corded heat guns, you have to be particularly careful where and how you set the heat gun down.
Is this the heat gun to make 40 heat shrink connections sitting at your workbench or to strip all the the paint off the side of a building? Probably not, but if you have some quick jobs in the field, especially when you are away from AC power, this M18 cordless heat gun is going to save you some time.
I find that I frequently reach for the M18 cordless heat gun over my corded heat gun, even when I’m at my bench. It’s one of those tools that puts a smile on my face every time I use it because it is so convenient.
Thank you to Milwaukee for providing the review sample.