How do you get 600 ft/lbs torque on a rotary cutter blade nut?!?
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sixdogs
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I've been to at least three farm or ag dealer type auctions in the past few years where high capacity torque wrenches were for sale. All looked close to new and I recall very high sticker prices. On two, $650 for one and $1,200 for the other comes to mind but I wasn't paying close attention. Since I'm always on the lookout for a deal, I almost bought when the prices struggled to get much over $175. That's a giveaway price but I figured I would never, or rarely use it.
There's some pretty clever thinking in this thread where guys use the length of the lever and the weight applied to come out with a close estimate of torque.
There's some pretty clever thinking in this thread where guys use the length of the lever and the weight applied to come out with a close estimate of torque.
RalphVa
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You get a 6 ft breaker bar (a piece of pipe that goes over your socket wrench) and exert 100 # of push or pull on the end. For me, that's generally about all I can push or pull. Same for tightening.
RickB
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And likely to be at least as accurate as a Chinese torque wrench.
Have you ever wondered why standard hand wrenches are the length they are.....
arizona98tj
Gold Member
dnw64
Veteran Member
A couple observations.
First, as to using the length of bar/extension, remember that the force applied (which is multiplied by the length) is going to be from the center of said applied force. So a 6' long bar will not apply 6x the force applied, unless you can apply ALL of that force at the VERY END of it. If you are putting your weight onto a bar, you are likely using two hands, spread apart at least 6". So to use your weight times a length, your extension needs to be 9-10" longer than the length you are using as a multiplier. IOW, a "5 foot" bar is only going to give you a 4.2 or so multiplier.
Further, for weight to be fully used, the bar needs to be exactly parallel to the ground. If it is above or below that, the force is reduced, as the effective "length"(horizontal distance from center of bolt to center of applied force) of the bar is also reduced.
Regarding the length of standard hand wrenches, they are based on average* strength and the typical standard grade 2 bolts. For instance (totally pie in the sky numbers), since a typical 1/2" bolt should be torqued to about 40 lb/ft, a 3/4" wrench is 10" long (8" center of force for one hand) because the average mechanic can apply 25-30# of force from any position.
*extremely variable and mostly irrelevant, but you have to start somewhere, right?
First, as to using the length of bar/extension, remember that the force applied (which is multiplied by the length) is going to be from the center of said applied force. So a 6' long bar will not apply 6x the force applied, unless you can apply ALL of that force at the VERY END of it. If you are putting your weight onto a bar, you are likely using two hands, spread apart at least 6". So to use your weight times a length, your extension needs to be 9-10" longer than the length you are using as a multiplier. IOW, a "5 foot" bar is only going to give you a 4.2 or so multiplier.
Further, for weight to be fully used, the bar needs to be exactly parallel to the ground. If it is above or below that, the force is reduced, as the effective "length"(horizontal distance from center of bolt to center of applied force) of the bar is also reduced.
Regarding the length of standard hand wrenches, they are based on average* strength and the typical standard grade 2 bolts. For instance (totally pie in the sky numbers), since a typical 1/2" bolt should be torqued to about 40 lb/ft, a 3/4" wrench is 10" long (8" center of force for one hand) because the average mechanic can apply 25-30# of force from any position.
*extremely variable and mostly irrelevant, but you have to start somewhere, right?
tractchores
Veteran Member
A couple ideas...
I have an electric impact wrench that goes to 450 lbs, not sure if they make them bigger, but if so that might do it. Of course they're $150+.
I had a bolt that I could not get off even with my impact wrench, so I just brought it to a tire place and gave a guy $20 and he took it off for me and put it back on to spec. I think this is your best bet if you want to do it super cheap, just find a garage with the tools and give someone a tip to do it. Tractor dealer likely would do the same..
One suggestion - if you do go the big breaker bar or pipe method make sure you have the exactly right socket and a good grip on it. I did this on the above mentioned bolt, the nut rounded because I was a tad off on size and I broke 2 fingers and went flying when the bar gave way... Not fun
I have an electric impact wrench that goes to 450 lbs, not sure if they make them bigger, but if so that might do it. Of course they're $150+.
I had a bolt that I could not get off even with my impact wrench, so I just brought it to a tire place and gave a guy $20 and he took it off for me and put it back on to spec. I think this is your best bet if you want to do it super cheap, just find a garage with the tools and give someone a tip to do it. Tractor dealer likely would do the same..
One suggestion - if you do go the big breaker bar or pipe method make sure you have the exactly right socket and a good grip on it. I did this on the above mentioned bolt, the nut rounded because I was a tad off on size and I broke 2 fingers and went flying when the bar gave way... Not fun
crazyal
Super Member
I think you'll find that a 1 11/16" wrench size is standard for a 1 1/8" nut. If it was me, I would spend a couple of extra bucks and buy a good quality socket and breaker bar. If you have to put 600 lbs of force on it to get it tightened correctly then you are going to most likely be putting a lot more than that getting it off. I've broken too many sockets over the years and it usually leads to either an injury or near injury. Now I use good quality heavy wall impact sockets (when I can) for nuts like that. For less than $20 you can get a Proto impact socket (made in the USA). As for the breaker bar, ebay. You should be able to find a good quality one made in the US for under $40. Much cheaper than a potential trip to the ER and some stitches.
