i am just going off of what mother deere has told me the several times i have asked.
a big reason for the change in blade style is because the old ones wore out so fast. i have seen blades that were wore out on a combine with 125 separator hours, they were about 3/4" shorter than a new blade
most of the machines that i look at (1 year old custom cutter machines w/ anywhere from 300 to 800 sep hours) need new knives. it has come to the point where its almost automatic on any trade in coming in
The swinging hammer/blades on our newly acquired 9650STS with the fine cut chopper have 1000 sep. hrs. on them are shot so we're replacing them. It's an all new beast to us and the mechanic gave us this advice:
1.Run the stationary knives into the chopper ONLY as far as needed to do the job. It'll take less power and the hammers /knives will last a lot longer.
2. If you feel a vibration in back, the chopper has probably thrown a hammer and you should stop to fix it immediately or the vibration will destroy the chopper in 4 hrs. or less.
A friend of ours with a 9860 advises to leave the stationary knives pulled out entirely when doing soybeans. He says you don't need to have the straw completely pulverized into dust coming outta the machine and it takes less power and less wear and tear on the chopper too.
Our mechanic told us about the OWNER of the JD dealership taking the 1st new 9650STS delivered to them out to his farm and destroying the straw chopper after 4 hrs. of use. He said he felt the hammer let go AND the immediate vibration but he kept goin' anyway 'til it was totally wrecked.
Just put in a Redekop extra fine cut MAV chopper kit and be done. Long life blades, wide spread, less or equivalent power usage for a better job.
Starting with the first fine cut choppers back in 1997 on 9600s Deere was using rotors made by some company in Pennsylvania. They were a one piece design with the end shafts being fused onto the center tube. I guess they are cheaper to build but I've seen so many problems with them over the years. Often the end stubs would just snap off. Naturally that would make a mess of the chopper housing too. I had several new choppers that were out of balance and no machine shop could balance them. We just threw them away and ordered another one. That same design was used right up into the last 60 series non-premium choppers. The Redekop choppers have a solid shaft through the whole rotor, the tube is larger and heavier, and the knife towers are thicker and stronger.
We installed our blades according to the instructions but when we started it up it had some vibration. My brother was not happy with this so we took them off and weighed each one individually on a scientific gram scale and writing the weights of them on the knife with a paint pen. There was a big variation of knife weights even within the same box. After weighing they were reinstalled on the rotor according to how they would best balance. We also determined that the rotor itself with no blades on was in good balance. It took him about 4 hr's to do all that but it was time well spent. After that the chopper had no vibration and has a nice "hum" to it.
back a few yrs ago.....on the 50 series.....we put in all straight sharpened blades from redekop in saskatoon....call them....they worked great.....if fact better than original.....jd needs to go bak to the drawing board on their chopper blades....we've never a machine go more than 1 season without wore out blades......even our new 9770 is in need of blades at 300 hrs......maybe jd is using steel from china????
I have a 9750 that i changed the hammers at 900hrs and within 20hrs half the hard surfacing was gone. I tried to get new ones from deere but they sent me back to the dealer and it was just a run around. i got so pissed off at them i just ran them. i now have 1800hrs on it and there almost straight blades now. Ive priced out the mav rotor conversion at $3000 and am going to get it.