How do you get 600 ft/lbs torque on a rotary cutter blade nut?!?

[CADplans]

Skinny people need not apply for this job,,,

:laughing:

 

[joefromga]

You're not supposed to use an extension handle on a torque wrench. It will damage the wrench and be inaccurate.

You're supposed to extend the part between the head and the nut using a pre-made extension or make your own by welding a socket to a bar on one end that has a square hole for your torque head on the other end. Then you use a math equation to figure out the multiplier.

 

[sixdogs]

Few, if ANY discount 3/4" drive socket sets will have the reqiured 1-11/16" socket that fits a Bush Hog blade nut properly. Some of the more mainstream brands also skip that size.
That's why I advocated a Bush Hog blade nut wrench, a 24" pipe wrench, and a cheater. A good way to go if you have little need for a 3/4" drive set, especially if one buys a set only to find it won't do the job it was purchased to do.

There is a 1 11/16", 3/4" or 1" drive socket in my seldom used Harbor Freight set. I adapted my 1/2" HF Earthquake impact gun up to a similar sized socket by using adaptors and took a nasty and stuck nut off last year. Impacted the new one on and it's been fine ever since. Took less time to do that than answer this post. I'd bet the factory puts them on with an impact gun.

 

[truckdiagnostics]

http://www.northerntool.com/shop/tools/product_200619498_200619498 Milwaukee M18 FUEL 1/2in
something like the above? not cheap by any means. I have a 1/2 dewalt that is battery operated only puts out 300 ft lbs so won't work for you, but my point is I like it, saves dragging out air hose. We are using more battery operated impacts in the shop, mostly the small 3/8, i am impressed with what they will do. Worth a look and you won't need a compressor.

 

[JimRB]

I don't know what the factory uses to torque those blade bolts down but I bought a less than year old brush cutter than had loose bolts on both blades. Deck was dinged up in a big circle from this, I guess. I used my Titan 40" 3/4" drive breaker bar to tighten the nuts up. I do not recall if I added a persuader to the breaker bar. Anyhow good and tight was how tight they got. Much tighter than quite loose and floppy. I kind of like using hand tools to torque things, I do not trust impact tools. Maybe if I used impact tools every day I might have more faith. I do have three smaller quality torque wrenches but nothing in 3/4' drive.

 

[DaveK OR]

Few, if ANY discount 3/4" drive socket sets will have the reqiured 1-11/16" socket that fits a Bush Hog blade nut properly.

Well, there is that little detail. I hate it when manufacturers use oddball sizes just so they can then sell a special tool to fit.

You can buy this socket at Sears for about $20. Or then, you might try e-bay for the socket. You still want a 3/4" drive breaker bar to go with it.

 

[DaveK OR]

I'd bet the factory puts them on with an impact gun.

LOL! I ran into that very issue when dismounting my backhoe from the Woods shipping skid. It was held to the skid by metal tabs, on one end, a common 3/8" nut and bolt, while on the other 3/4" bolts that attached where 4-point brackets would go. That 3/4" bolt took somewhere around 400 ft-lb to break loose (standing on the end of a 30" breaker bar, and than having to bounce on it!), even though the proper torque on a bolt of that size would be around 200 ft-lb. And for a shipping skid, I'd say hand-tight with blue loctite would be enough.

 

[dnw64]

...for a shipping skid, I'd say hand-tight with blue loctite would be enough.

Seriously? Taking the time to put Loctite on a shipping skid? They just use their 1/2" impact gun set at Max and assume that anyone buying such equipment will have whatever is necessary to remove it, by hook or crook.

 

[mapper]

My neighbor, a retired industrial mechanic and millwright, helped me replace my brush hog blades. We torqued them to the maximum torque with a 1/2" torque wrench (250#?), then he marked one flat on the nut and its location on the seat. He then turned the nut 1/6th of a turn more, using a 3/4 breaker bar and short cheater. He explained to me that any more would just be stretching the threads on the bolt. It never has come loose unintentionally.

 

[RNeumann]

Nowhere did he say he didn't want to invest in hand tools. He doesn't want to buy a big air powered impact and the compressor to run it. And I don't blame him.

My bad- read that part too fast

 

[Ford850]

You can get a Crescent brand 3/4" drive, 1-11/16" 12 point socket at Menards for 12 bucks. I think that's where I got mine years ago when I replaced my blades. I used a 4 or 6' cheater.

 

[sixdogs]

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.

 

[RalphVa]

I'm doing some research for the inevitable blade replacement on my Bush Hog. The owners manual calls for 600 ft/lbs of torque on the blade bolts and 450 ft/lbs on the blade holder pan. I'm not sure how to get that amount of torque with any tools I've researched. I don't really want to spring for a 3/4" high impact air wrench (along with the compressor to run it). Any other suggestions?

Thanks,

HP

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]

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.

And likely to be at least as accurate as a Chinese torque wrench.

 

[tcartwri]

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.

Have you ever wondered why standard hand wrenches are the length they are.....

 

[oosik]

Call your local dealership - have them send out the gorilla that installs/tightens the OEM filters. Problem solved.......

 

[arizona98tj]

Have you ever wondered why standard hand wrenches are the length they are.....

So they can fit in tight places.

 

[dnw64]

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?

 

[tractchores]

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

 

[crazyal]

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.