There you are with your Hilti GX120 in hand. Time to drive those concrete anchors into floor. Solid thud… nope, just a dull click and the tool doesn’t budge.
That’s the bad part of being on a jobsite; there’s a schedule to follow and this isn’t helping. Here’s some good news; the GX120 is a precision instrument that rarely quits for no reason. When it does quit, chances are pretty high that you’ll find clue(s) as to why.
Don’t send it right back in; most problem are solved by performing some simple maintenance and inspection. The most likely culprit is the cartridge itself. It must seat propery in order for the firing pin to hit the primer hard enough to ignite it.
Quick Fixes for Hilti GX120 Firing Issues
Cartridge Seating and Condition
Not fully inserting the cartridge into the barrel or positioning it slightly off-center will result in a no-fire. Look at depth gauge on the side of the tool and make sure your cartridge is far back enough on the gauge. That safety aspect will keep it from firing dangerously.
Lastly, don’t use old cartridges that have dampend powder; they won’t blow up as harder. Now let’s address battery condition. To get that piston moving, you need a steady power source with the GX120.
Battery Condition and Power
A partially drained, cold or old battery will cause the tool to spin up but not produce enough blow to ignite. Give it a try with new, fully charged battery pack. Now you’ll see the tool seems a little slow in the cycle part due to less kinetic energy being delivered from a weaker battery.
That added force trigger the charge. The blinking battery light indicates the tool recognize its power source isn’t enough and may stop the cycle to protect itself. The firing sequence can be blocked by debris in the barrel as well.
Cleaning Debris from the Barrel
Dust from concrete is powdery and fine and likes to get everywhere, including mechanism of the tool. The dust hardens over time creating a compacted mass near the cartridge area. This physical barrier prevent the cartridge from seating flush.
Inspect the barrel with flashlight after removing the cartridge. Use compressed air or brush to clean the barrel if you notice any residue. A clean barrel ensures good strike every time.
Mode Selector Switch Settings
Let’s do a quick check of the mode selector switch while we’re at it. This switch allows for various firing modes based off different materials on the GX120. If this isn’t fully engaged or is stuck between options, the internal electronics will not be able to complete the firing command.
Toggle back and forth until you feel it click into place. You want to hear it make a distinctive mechanical engagement. Should the switch feeling gritty or loose, you may need to have someone look at it or clean it up.
Also remember, you don’t want to use wrong mode for the concrete/material you are setting. Double check your settings against concrete type and anchor size. Last but certainly not least is state of tool.
Internal Mechanical Damage
Internal parts can get thrown out of alignment from drops or hard impacts. You knock that tool off your scaffold lately? The firing pin assembly may have been moved around.
Listen for any unusual rattling sounds when you cycle the trigger. It’s telling you there’s something loose inside mechanically which means something has been physically damaged. Most problems is easily remedied with a battery check and some cleaning, but a good technician will take care of damage.
You should of checked it sooner. Opening up the firing mechanism and trying to clean or tinker with it on your own is not advisable. That thing is under a lot of tension and will get you in trouble if you don’t know what you’re doing.
So if your Hilti GX120 is not firing, most times it’s an easy fix with just a little attention to detail and some patience. Make sure the mode is right, clean it out, check that the batteries are charged, check your cartridges. It’ll be something simple most of the time, not that it’s broken.
And when you take good care of your tools they make good partners in keeping your project going.