Removing Blades from Rotary Cutter

[trook]

I need to change the blades on my JD MX6 rotary cutter, and the nut in question is 1.5". For those of you who have already done this, can the 1.5" nut be removed with a normal 3/4 drive socket and ratchet, or will a 1/2 drive air impact wrench do the job? Please don't tell me I will need a 3/4 drive air impact wrench.............

 

[BlacknTan]

Most nuts on rotary cutters are in the 450 ft/lb range.

Check the torque capabilities of your impact gun, make sure you have enough air pressure and go to it.

About a 5' cheater bar should also do the trick.

 

[Avondale]

I have a Bush Hog (5 ft) with twin blades. It has 1 & 11/16th" nuts. Pretty hard to find a socket but found a 3/4" drive one and a reducer to 1/2" drive for my impact. Worked ok after soaking everything with pen oil. Big problem was bashing bolt out. You need to support the blade while whacking the bolt (leave the nut on at the end of thread) to release the keyed shank from the boss. Good luck.

 

[jdtractor]

hi i would just use the cheater bar method,works for me everytime! impact would be nice but i dont have one at my convience, right now its at another job site.just my .02cts

 

[dex3361]

I have used my HF earthquake impact to remove the bolts on my King Kutter several times with no issues.:thumbsup:

 

[deere5105]

Just took the blades off my MX6 to sharpen this past weekend. Used 3/4" drive set with pull bar and about 3' cheater pipe. Had to put some pressure on it, but came right off.

 

[twoone]

Well now you know how to remove the bolt. Putting it back on is another story you will need a way to hold the other end(help) while you torque the bolt. to 450lbs as the blade swings free. Paul

 

[deere5105]

I was suprised that while using a breaker/pull bar and extension through the access hole in the deck that I didn't experience a lot of movement. Once I got the pull bar and cheater bar together and the extension against the access hole nothing else moved. The square head of the bolt kept it from turning when the nut is being turned and the bind through the access hole kept the stump jumper from turning. I put it back the same way I took mine off. I can't guarantee it is a specific amount of ft lbs. but it is equal to the pressure it took to get it off.

 

[gwdixon]

Well now you know how to remove the bolt. Putting it back on is another story you will need a way to hold the other end(help) while you torque the bolt. to 450lbs as the blade swings free. Paul

Hey twoone! Esparto - I'm just south of you in Allendale.

Anyway, a good 1/2" drive impact wrench will work just fine with a 3/4" adapter. Check the specs on it to make sure it will handle the torque requirements. The high torque models don't come cheaply. Mine was just under $300 some years ago.

Been taking off those nuts for 30 years with no problem. I do coat them once with anti-seize, which will get the safety police screaming, but never have had one come loose.

The weight of the blade will usually pinch the bolt enough to hold it in place while the nut is screwed in from the top through the access hole. Not sure exactly how a MX6 looks underneath but that method works on Bush Hog and Landpride.

 

[psj12]

I use a 3/4" impact. The problem with using a large impact on a small compressor setup is not the lack of pressure but the lack of flow or volume caused by the small hose and tank fittings. I temporarily screw a 1/2" ID hose directly into the drain hole on the bottom of my tank and then I have several second of full 3/4" power before I have to stop and let my compressor cath up. This is ususlly plenty to break the nuts loose.

 

[trook]

I have a 1/2" impact wrench and the 1 1/2 socket, but the wrench is only rated for about 250lbs. I'm afraid this will not be enough

 

[twoone]

HI" GW,
Should say neighbor: My problem was my arms were not long enough to reach around also I did not have a 450# torque wrench and tried to apply the same torque putting it on as taking it off. I must say that every time I use the machine I wonder about it. yes included in my tool shop is my favorite cheater bar and best tool investment. take care, Paul

 

[clemsonfor]

When i went to change my lower seal a few months ago, i used my fingers to remove mine!!! I dont remember what i put them on with, did not get close to 450 im sure, but thats not how tight they were adn i will just recheck them frequetly.

 

[twoone]

Gee I wonder what they were when you removed them bet you did not take them off with your finger's or did you? I hate to think about that thing coming loose or? werling around like it does. Come's a thought how fast are the blades spinning? all we know is that the pto is turning at 540rpm. Paul

 

[clemsonfor]

Gee I wonder what they were when you removed them bet you did not take them off with your finger's or did you? I hate to think about that thing coming loose or? werling around like it does. Come's a thought how fast are the blades spinning? all we know is that the pto is turning at 540rpm. Paul

They were finger loose!!!!! Thanks to my dealer "prep" assembly. I still needed a wrench as the grit on the threads was to much to overcome with fingers and all the lube on there from the bad seal.

I think most under 40 hp gear boxes are 1:1.7 ratio, so you can figure it out. If your turning 540 at the shaft that means the blades are 915ish RPM. Which base upon blade diameter and some calculations you can figure blade speed, but im to lazy to do all that.

 

[twoone]

You know am not to sure but being so loose there must have been a lot of vibration to the gear case and that probably caused the seal to go. I would have been down the dealers throat and really give him a piece of my mind and have him rebuild the gear case. Things being as they are there must be a lot of accesseve wear on the shoulder bolts as well. seems the whole thing will take a beating the way it is, If the dealer wont back you up I'ed clean up the bolts or replace them if necessary and make sure there tight . Like I said that's a lot of steel werling around. Paul

 

[gwdixon]

I have a 1/2" impact wrench and the 1 1/2 socket, but the wrench is only rated for about 250lbs. I'm afraid this will not be enough

If the impact wrench will take off the nut you should be OK putting it back on. Just let the wrench rattle on the nut for 15 seconds or so.

That should cycle your compressor also. Then hit the nut with the compressor fully charged. Also, be sure to oil your impact wrench right before using it on the nut. That will get the most out of your wrench.

 

[gwdixon]

Gee I wonder what they were when you removed them bet you did not take them off with your finger's or did you? I hate to think about that thing coming loose or? werling around like it does. Come's a thought how fast are the blades spinning? all we know is that the pto is turning at 540rpm. Paul

The blade tips are going from 15,000 to 18,000 fpm. That is 170 to 200 mph. It also depends on the length of the cutter blades and the gearbox gear ratio.

These numbers are from the Landpride RCR2596 owner's manual and a Howse 8' mower that was researched just a short time ago. The Landpride has dual 4' blades w/3 gearboxes while the Howse had a single (well, actually two) blades.

 

[twoone]

Hi" Gw,
I was referring#13&15 to clemsonfor he took the nuts off with his fingers. Thanks for math I was afraid before but now I know why. Paul

 

[hidden hollow]

Some of these responses worry me. I understand trying to sharpen the blades while they are on the brush hog but if the blades are in anyway seized up and they don't swing easily on their bolts you will not get a good cut and you will be taking a chance on not having your mower continue working. If you hit something with seized blades all the impact of the hit is transferred to the gear box and then to the clutch on the mower. If the clutch is not set correctly and checked at the least every season all that impact also goes to your PTO. So please make sure that you blades swing freely and that they are sharp. Sharpe blades cut with less strain on the tractor to say nothing of leaving a clean cut. I take my blades off every time they need to be sharpened. Before they go back on the mower, I balance them so that I get a smooth running mower. Another thing that I always check is the fluid in the gear case. If it has any white color to it there is water in there. I have seen a lot of tractor implements that the dealer leaves out in the weather prior to selling them. They get sold and then they are returned because the gear case gave up the ghost. It was full of water. I guess from snow and ice freezing and thawing around the breather hole in the gear case.