Rotary Cutter JD rotary cutter ran over T-post

[rootytoot]

A couple of years ago when I was even greener than I am now, I bought a Fordson Power Major (used, of course!) and a used JD 516 rotary cutter (bush hog). A tenant on my remote rural property offered to mow the 5 acre pasture, so I let him. Not such a great idea... for one thing, he wasn't paying attention to the Fordson's fluids, and blew up the engine with too little oil.

He also managed to run over a 4' steel T post (fencing post) that was marking the location of a PVC hose pipe. Well, of course the hose pipe was toast, and the T-post looked like it took a beating: twisted and gnarled, but he got past it without stalling the cutter or the tractor.

He managed to get the tractor and cutter back to the garage. The local dealer picked up the Fordson, and promptly pronounced it DOA with a blown cylinder 3. The cutter has sat unused in the garage for two years while I decided whether I would get another tractor.

I recently purchased a newer tractor (Ford 1920), and so I got curious about the old rotary cutter; was it usable? I jacked it up, and took a look. The swing blades seem symmetrical and not obviously damaged; though a little rusty from disuse, and not very sharp. In fact, the leading edge was as rounded as the trailing edge! The cutter shaft seems to turn the PTO drive easily, and it's not loose or leaking oil. I'm guessing that the T-post hasn't done damage, but I'm open to opinions on what to look for...

As for sharpening, should I just get under there and file away on the leading edge of each swing blade to give it some semblance of a chisel profile?

I've enclosed photos for your enjoyment.

Thanks for your help in advising a pretty green tractor owner.

[IslandTractor]

Hitting a T post with a rotary cutter shouldn't damage the cutter. The pivoting blades would just pivot away and make a lot of noise. No reason to sharpen the blades either on a rotary cutter as it works primarily by bashing or breaking whatever it is "cutting". A finish mower would be different story. Some people do sharpen their rotary cutter blades to get a better cut on grass but even then you would only grind something like a 45 degree bevel otherwise the cutter blades will be too delicate for the normal bush hogging activities and surviving T posts intact.

[greg_g]

I restore some semblance of a factory edge to my rotary cutter blades at least once a year. But since it appears to be years since yours have seen the correct angle, I'd suggest taking them to your JD dealer for a one-time refacing. Assuming they do it correctly, that should give you an idea of what they should look like after you finish touching them up once a year or so with an angle grinder.

Either that, or go to a farm store and examine the cutting edge of a replacement blade - then do it yourself in a bench vise. Warning though, that's gonna be a helluva job restoring a factory edge with a 4" angle grinder (I use a 7" or 9" as required).

//greg//

[rootytoot]

Thanks for the advice... sounds like I can deal with the sharpening at my leisure (which ain't often). I just noticed one of the photos I posted is upside down! Heh heh.

[LetsRoll]

My Woods bush Hogg came with the blades sharpened. I sharpen them on my 12 inch disc grinder that I got mounted on my work bench in my shop. It doesn't take very long to sharpen them. I have a vehicle lift in my shop and I put the bush hogg on it and take the blades off and sharpen them on the disc grinder. I also put my grasshopper zero turn mower on the lift and take the blades off and sharpen them as well. By the way, sharpening the blades on my bush hogg or I should say, keeping them sharp, it will cut a lawn like a finish mower.

Also, I grind my grasshopper mower and bush hogg blades to 23 degree's. The grasshopper manual says to grind the blades at that angle. So I grind the bush hogg blades the same. I have a block that I use on the 12 inch disc grinder that has a 23 degree angle cut into it. Since I have the block that cuts 23 degree's, both the grasshopper and the bush hogg blades get sharpened to 23 degree's. Just mount the blade to the block and slide it across the disc grinder deck and in a few minutes. The blade cutting edge looks new. Totally straight and a even grind.

[LetsRoll]

The link below is the disc grinder I use from harbor freight. It makes sharpening blades a easy task.

Harbor Freight 12inch Disc Grinder

[flusher]

As for sharpening, should I just get under there and file away on the leading edge of each swing blade to give it some semblance of a chisel profile?

I've enclosed photos for your enjoyment.

Thanks for your help in advising a pretty green tractor owner.

That may be your best bet. Trying to loosen those rusted nuts on the bolts that attach the blades to the stump jumper looks like a chore. Of course you could use your 4-1/2" angle grinder with a thin blade and cut the heads of those bolts if you want to sharpen those blades with a bench grinder. I've been restoring a pair of old Minneapolis Moline P3-6 grain drills and have had to cut about 150 small rusted bolts to get those things disassembled.

[sandman2234]

I put my tractor on a trailer and leave the rear of the bush hog hanging out a little to prevent it falling on me. Then I put on my safety googles and a pair of welding gloves and go to work on grinding them to a sharper image than they were. I never sharpen them completely, as has been well explained many times in this forum.
I have never had any luck removing blades from bush hogs, but some people do.
David from jax

[Kfbeal]

We have found that the best and easiest way for us to put an edge on shredder blades was to use a cutting torch. Dull blades will also tear good grass and stunt that grass and it's better to cut it rather than just rip it apart.

The torch takes a little practice, but it puts an edge on it and seems to temper the edge where it doesn't dull quite as fast IMO.

[Barneyhunts]

I've never sharpened mine, but, I've been told that if they're too sharp I'll end up with sharp brush stumps? or stubs which can puncture tractor tires.