It does take a good impact to remove these blades. Even a good impact will have problem if there is resistance in the air supply line causing line pressure drop.
A good example of this was here. My AirCat 1150 couldn't even loosen my lug nuts on my pickup that were tighten to only 70 ft/lbs. Now of course I using a 100 ft 3/8 air line. My problem was the under size M style couplers and plugs. Even the properly size M couplers and plugs it still struggled. This is when check the supply pressure with the impact free running. The line pressure was dropping to 20 psi from the 125 psi standing pressure. I switch out all the couplers and plugs to V style (high flow) and I haven't had any problems since except for one Scag mower which has always cause problems removing the blade bolts.
The 1/2" Campbell Hausfeld impact that I had and gave was useless for removing many fasteners.
Several times a year I have to cut the heads off blade bolts
Most of the round hole blades use a cupped washer to tension the blade
These will end up dead flat and there sis no way you will undo them
Once the head is cut off you can undo them with your fingers
I usually cut through the head, flat to flat then hit the cuts with a cold chisel
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Youtube's South Main Auto (Erik O) uses the snot out of these in rusty NY. I have a few now and are impressed with the power and small packages.
Well I have been very please with the Air Cat 1150 with 1295 ft-lbs of break away torque. Actually uses less air than many of its competitors and runs around 86 dba noise level. I can use a 7 gallon air tank to remove blade bolts on most mowers. And yes I start at 125 psi standing pressure which drops to around 95 psi on the 100 ft run of air hose.
You people are causing yourselves a wagon full of un-necessary problems with those impacts . Oil the threads , tighten the nuts with a box wrench about 12" long until they feel tight and go mow . Those manufacturers are specifying those ridiculous torque values because of liability .
When a customer brings in a mower i have never seen before and Hercules replaced the blades 7 or 8 years ago i sometimes need the impact. Or when they hit something and it really overtightens a blade OR when they are star center blades and they hit something and twist the blade on the star and wedges it tight i sometimes need the impact.