(800) 853-2651
SHOP NOW

JD 3960 Chopper Knife Wear

L

LonM

Member
I ran out of stationary knife travel on our 3960 silage chopper, so I need to either set the old cutterhead knives out, or put on new knives. How much wear is too much to reuse the knives? Attached is a picture showing a new knife next to one that came from the cutterhead. Attached is also a picture of the knives as they currently sit on the cutter drum.

I do not know what to do, as there is still a good bit of hard facing left on the knives, but if I move them out much, the knife hold-down plate will lap over beyond the bottom edge of the knife, and will not have as much contact area with the knife to hold it in place.

We do not chop a lot of corn silage, as the wear you see is from at least 15 years of use.

Thank you for any advice!
a171025.jpg

a171026.jpg
 
It does not hurt anything for the holder plate to not have full contact in the back side away from the cutting edge. You can safely slide them one more time. Especially no more than your using the chopper.

Do you know how to set them back to full height???? Rotate the setting bar out to do it. I usually remove the shear bar when I set them back out. You can then clean behind the shear bar and it will them slide back to where it needs to be. Usually the bar will NOT move back enough with out removing it to clean behind it.

Any more questions feel free to email me.
 
You can move them out some.... but I never liked going much past flush on the clamp plates. For the amount you chop and given it is corn I probably wouldn't worry about it. If you were chopping haylage I'd think twice about it...
If the bolt heads are getting round you best think about changing them now too or you'll not get them out easily next time.

Rod
 
It's your call, but I would not re-use the knives. Over half of the tungsten carbide is gone and the one knife shows it has serious chips out of it. When you sharpen it, there is not enough left. You have gotten the goodie out of them!

Yes, replace the bolts. Use the built in bar to set the new knives. IF using the old knives, use the sharpening stone to set the knives. IF one old knife breaks, as you mentioned the contact area, is it worth the down time to re-build the cutterhead from resultant damage to other knives or stationary knife.
 
Roger the sad thing is his JD 3960 chopper is not hardly be worth the price of rebuilding the cutter head. You correct on there not being much left on his knives. The thing is it took him 15 years to wear them to there. The amount left on the old knives will last him 3-4 more years. His call but his old knives will work for a time longer.
 
What kind of shape is the stationary knife (shear bar) in??? Most all choppers have a reversible shear bar. I'd remove it, and turn it around so you have a nice new edge, providing you has a hardened edge that hasn't been used. Then do as JD seller said. Seeing you are doing corn, you can probably get by a few years at your current use rate by turning the shear bar and advancing the knives. Knife wear in corn silage is minimal, especially if you have a sharp shear bar.

If you were using this thing more, I'd say spring for new knives and a shear bar. They are wear items, and are replaced frequently. You can by after market knives from places like Kooima and Lancaster too.
 
Thank you all for your advice! I took a wire wheel on a drill and cleaned all the cutterhead knife mounting surfaces so that they are down to shiny steel. I still have to clean up the knives, nut bars, and hold down straps. Then I plan to advance the knives about a quarter of an inch or so. I put in a whole row of new knives in 2008, and I have some spare used knives from then. So any questionable knives will get replaced with those. I am also familiar with the process of setting in the two pins and lowering the knife gauge bar in place to put the knives at full cutterhead diameter. I doubt I can get away with going that far out, but I will see how things look as I put the knives back in.

The stationary knife is in good shape, having been turned to a new edge in 2008. This machine sees around 270-340 tons of corn silage per year, so I hope to get several more years of use with what I have. Again, thank you for your guidance- I have a tech manual for this, but I really appreciate the real-world experience that those on this site are willing to share.

Lon
 
You must log in or register to reply here.

Similar threads

S
JD 1214 haybine cutter bar issues
Replies
2
Views
260
300guy
3
N
CaseIH 8330 Adjustments
Replies
1
Views
168
caterpillar guy
C
Absent Minded Farmer
Chopper Garden Update Video....
Replies
1
Views
120
casecollectorsc
casecollectorsc
R
NH 488 Haybine breaking knife drive bolt
Replies
7
Views
1K
Round3Ranch
R
S
question about removing a pulley from a shaft
Replies
6
Views
315
steve-in-ga
S
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top