impact torque question

[M_thomas231]

ok guys, so i recently bought the new mac AWP050 1/2 impact. the next day a commercial zero turn mower came in. to have blades changed. (they hit something and bent one) now bolts are initially torqued to 125 ft-lbs. when you hit something it will really tighten the blade bolt down. so i threw my brand new impact on there and began trying to take it off. much to my disappointment, it would NOT remove the blade bolt. now mac rates the AWP050 at 1260 ft-lbs. so i went to the shop cabinet and retrieved bertha (IR2141 3/4 impact) which according to IR only makes 1140 ft-lbs. put the socket on, put it on the bolt and squeezed the trigger. the impact actually impacted about 2, or MAYBE 3 times and the blade bolt FLEW out. i talked to my mac rep the next time he was here and he told me thats because the torque rating is different between 3/4 and 1/2 guns. and that 1140 ft-lbs on a 3/4 gun is MUCH more then 1260 ft-lbs on a half gun. now im no professional, but that does not seem correct to me. is this true? or am i being had? thanks for any and all input. have a nice day guys!

 

[bcradio]

maybe the thicker socket on the 3/4 gun helped get the bolt out.

 

[M_thomas231]

i guess I'm not sure what you mean. ?

 

[Astro_Pneumatic_Tools]

I have a sneaking suspicion "Nut Busting" or "Breakaway" or "Peak" or "Ultimate" or some other mumbo jumbo created by the marketing department much to the chagrin of the engineers is at play here.

Max and working torque are both real things. Everything else might as well be "Torque w/ Techron©." There may be a real test that the number is based off of, but that process was decided on by the company and is not replicated across the industry.

This is why the product/engineering department here writes the specs, and no one can touch them. If you allow the goal to be solely a number, or a number that's specific to your line, then that's what you end up making: a number generator, and not a good tool that's supposed to do a job day in and day out.

A couple years ago I must have had a desk that was layered and stacked 3-4 high of boxes of mini impact prototypes. All rated for 430-500 ft/lbs. But only one became the Nano, and it wasn't because I could write as high a number as possible on the side of the box.

 

[M_thomas231]

so in other words i was fooled max torque on ir 2141 is 1200. "recommended torque range" is 200-900. bummed i bought the damn thing now. probably wont ever buy another MAC impact again

 

[Astro_Pneumatic_Tools]

so in other words i was fooled max torque on ir 2141 is 1200. "recommended torque range" is 200-900. bummed i bought the damn thing now. probably wont ever buy another MAC impact again

I wouldn't say you were fooled. It's commonplace in the market for these type of "new" ratings, and also pretty much required for tool truck brands because they are compared so side by side. And I have one of those guns, I've used it on some pretty beefy stuff.

 

[M_thomas231]

I don't know, that just seems shady. to advertise some thing that makes "1260" ft-lbs of torque, but probably doesn't even make 600... i mean the blade bolt is is a 3/4" bolt. seems like if it made anywhere near that torque if the bolt wouldn't come out, it would just snap. i mean the IR gun is rated for less torque and didn't even have to try to take the bolt out. i felt a few impacts, and then the 2" bolt was out. just really disappointing that i traded up my old 1/2 mac impact that was paid for. to get a "better one" when i dont think it was really any better. i guess just chuck it up as a lose

 

[rlitman]

I have a sneaking suspicion "Nut Busting" or "Breakaway" or "Peak" or "Ultimate" or some other mumbo jumbo created by the marketing department much to the chagrin of the engineers is at play here.

Max and working torque are both real things. Everything else might as well be "Torque w/ Techron©"

This is why the product/engineering department here writes the specs, and no one can touch them.

LOL. Very insightful.
Yeah, number inflation, whether it be in torque, horsepower (lawnmower and compressors are notorious), battery voltage (20V MAX?!? I mean really?), and lumens (Chinese flashlights are the worst blatant liars when it comes to this one) is something that really ticks me off. Damn marketing people always want their product to appear better than the competitions, even when it really isn't.

But my sneaking suspicion is that the OP's "brand new impact" is either using a too restrictive quick connect, or is just not performing right. I just don't see how a 1/2" impact would fail at this task.

 

[General Geoff]

Were you using just a 3/4" socket on the 1/2 impact? If you had any extensions or u-joints, every extra joint is a loss of effective torque.

Also, as was mentioned by bcradio, the more massive socket on the 3/4" gun may have provided just enough extra impact torque to break the bolt loose. Generally, the heavier the socket, the more torque is transmitted to the fastener. Maybe try a deep wall next time?

 

[larry_g]

Did you run the 3/4" gun on the same hose and quick disconnect as the 1/2" gun?

lg
no neat sig line

 

[Rag Roc]

Were you using just a 3/4" socket on the 1/2 impact? If you had any extensions or u-joints, every extra joint is a loss of effective torque.

Also, as was mentioned by bcradio, the more massive socket on the 3/4" gun may have provided just enough extra impact torque to break the bolt loose. Generally, the heavier the socket, the more torque is transmitted to the fastener. Maybe try a deep wall next time?

Exactly. While I'm no engineer, I ran into the same problem with my lawnmower blades. Installed them myself with my 1/2" impact. 9 months later grabbed same impact with a chrome deepwell and couldn't get any of the three nuts off! Fumed for awhile, then used a short chrome socket, still no luck. Then grabbed an impact socket and they came right off.

 

[WhiffySpark]

I don't know, that just seems shady. to advertise some thing that makes "1260" ft-lbs of torque, but probably doesn't even make 600... i mean the blade bolt is is a 3/4" bolt. seems like if it made anywhere near that torque if the bolt wouldn't come out, it would just snap. i mean the IR gun is rated for less torque and didn't even have to try to take the bolt out. i felt a few impacts, and then the 2" bolt was out. just really disappointing that i traded up my old 1/2 mac impact that was paid for. to get a "better one" when i dont think it was really any better. i guess just chuck it up as a lose

The 3/4 - 1 guns hit different. You weren't really fooled they all do it.

 

[gdocktor3]

The 3/4" has larger veins and internal's. It also probably has 3/8" inlet vs the 1/4" on the Mac. It will hit way harder either way. I highly doubt Mac/Stanley/Proto spent time and money creating a new tool that puts out numbers that were achieved 5 years ago. They are top players in the tool game and aren't going to lie about the torque numbers just to compete with the rest of them. They must match the specs of the other brands or they will never sell any impacts.

 

[rice rocket]

Exactly. While I'm no engineer,

glad you cleared that up.

Installed them myself with my 1/2" impact.

 

[johninct]

Exactly. While I'm no engineer, I ran into the same problem with my lawnmower blades. Installed them myself with my 1/2" impact. 9 months later grabbed same impact with a chrome deepwell and couldn't get any of the three nuts off! Fumed for awhile, then used a short chrome socket, still no luck. Then grabbed an impact socket and they came right off.

I take my blades off in the spring to sharpen them. I believe I used a 3/4" 3/8" drive impact socket on my Snap-On CT761 3/8" gun with no problem. I do put never seize on the threads.

 

[stikman56]

Just playing devil's advocate here. On the mowers I have worked on the blade is able to spin somewhat freely, with only the resistance created from turning the engine over by hand, turning a pulley, etc. Even if there is only a small amount of free play at the mower blade, the "general springiness" of the whole setup will eat up almost all of the impact wrench hit energy quite easily. Your 3/4 wrench might have worked, not because it was more powerful overall, but because it has a lower number of impacts per minute, and each one is more forceful. The increased hit force would better overcome the freeplay in the blade. Before you write off your new impact you might want to try it on something rigidly mounted, like some lugnuts.

Yep, this is correct. Something moving around while the impact hammers is WAY different than something stationary and a 3/4" hammers harder on each hit, thus most likely made a huge difference in this situation.

 

[Marlin]

The break away torque value on the Mac and the max torque on the 3/4" tool are different ratings. The break away number for the Mac is saying that the tool will loosen a fastener tightened to 1260 ft-lbs, however this rating is very hard to compare between manufacturers because some set a time limit of 5 seconds and others may let it impact for 30 seconds. The 3/4" tool rating is the max torque that the tool will achieve while tightening. In reverse this is done using left hand threaded fasteners with a run time of 10 sec. If the 3/4" tool had a break away rating it wold be much higher than the 1140 number. Other things that play into the equation, when the break away value is determined on the 1/2" tool, a large bolt is used (1" or 1-1/4") requiring a very large socket, when loosening, the large socket actually increases the break away capability of the tool as is seen with the Power Socket type products that are out there. So an impact that may loosen a very large fastener tightened to 1200 ft-lbs may not be able to do the same on a smaller fastener using a smaller socket.

Hope this helps.

 

[M_thomas231]

ok well thanks for the input guys. and no they were not run on the same hose. 3/4 gun was 1/2 line. 1/2 was 3/8 line with hi flow fittings. (actually a touch bigger then the fittings for the 1/2 line. but never the less. I was using a deep well socket. no extension, u-joints. etc. also the blade was blocked with a 2X4 (obviously the wood will have some give to it) and also i think i miss spoke in the original post. the BOLT was a 3/4" bolt. socket was 15/16" sorry for that. i guess i just hoped that a gun the would "loosen a bolt that had been torqued to 1260 ft-lbs" would take it off. I dont see how that bolt could have been torqued even that high let alone higher. it zips lugs off no problem. but those are only 100 ft-lbs. so i would hope it would, since my 20v cordless dewalt 3/8 will. but i guess it is what it is. again. thanks for the input and responses guys.