F3680 Center Blade Intermittent Problem

[ProjectKing]

I checked belt, pulleys, tension arm and tension spring and all are OK. The fact that the spline in the mower gearbox, and the pto shaft from machine to mower gearbox both continue to turn after I have blade blocked is the concern. I would think that once the middle blade under the gearbox is blocked, nothing should turn except the blade bolt. I'm wondering if these machines have a "slip clutch" :muttering:

No they don't I don't think. You have problem with blade to spindle interface. You should not have to block the pto shaft to tighten blade. Only block the blade. I still think you have a bad bolt or hole the bolt goes into. Or a piece is missing allowing bolt to bottom out before blade is tightened.

 

[jcummins]

I took a look at my blades on my F this morning. I found nothing amiss at all, blades were dull, so I sharpened. This was the first time I lifted the deck vertical, the previous time I got them off from the bottom because I had stupid brain issues with raising the deck properly.

I noticed, that splined nut will go in thru the washers....and contact the blade incorrectly. With the deck vertical, the blade drops down. I tighten the first one, and it was tight, but the washers weren't contacting the blade correctly. I fixed, but without watching, you could run into that with the deck in the vertical position. My bladed did not move at all when I tightened them, without a block even, but I was using an air impact wrench.

 

[JOHNTHOMAS]

With the deck vertical, the blade drops down. I tighten the first one, and it was tight, but the washers weren't contacting the blade correctly. I fixed, but without watching, you could run into that with the deck in the vertical position. My bladed did not move at all when I tightened them, without a block even, but I was using an air impact wrench.
i DID THE SAME THING EXCEPT i DIDN'T NOTICE ONE BLADE HAD SLIPPED OUT OF PROPER POSITION. The one blade didn't engage. I didn't understand what had happened and bought new washers or two new washers since they were not cheap. I actually reattached the blade with the old washer and haven't had a problem since other than blades are now very dull and grass is really tough/stringy. I use drill or air impact wrench.

 

[kthompson]

If this was asked I missed it, are you sure the center blade in not on backwards where the back edge is trying to cut rather than the cutting edge?

 

[1bush2hog]

If this was asked I missed it, are you sure the center blade in not on backwards where the back edge is trying to cut rather than the cutting edge?

Yes. blades are oriented correctly. I have them all tight for now, but will go ahead and order a couple of those cup washers to have on hand in case it happens again.

 

[jonsstihl]

if you blocked the blade from rotating and the spindle still turns when you tighten the bolt. the blade is not on tight. something is wrong with the thickness of the blade or the holding power of the cup washers.