MMM - poor cutting

fredbear241 · Nov 27, 2001

Have a kubota mmm. when cutting (long grass) a strip down the middle is 'missed'. But I have noticed that even on shorter grass, there is a longer strip left. Seems to be related to speed of cutting. Going very slowly improves the result.
just wondering if the 2 blades need to be syncronised somehow (I have hit a rock or 2, and they are not syncro right now).
Ant other ideas / suggestions / checks
Sorry if this is wrong forum to ask. Thanks in advance for any info.

TWINKLE_TOES · Nov 27, 2001

fredbear,
No synchronization is really viable, the blades are belt driven. I would inspect your blades. Take this opportunity to sharpen them/w3tcompact/icons/smile.gif When they are off, stack them one on top the other and see how tightly they stack. If one is bent it will show up pretty quickly this way.
Al

fredbear241 · Nov 27, 2001

Hi Al,
Thanks for reply. I was thinking that the blade had to come together to cut properly, on second thoughts they spin so fast this prob doesn't make sense. I've hit a few rocks over time & the blades do look 'rough' so I'll try & get them off to sharpen / inspect. How important is it to have a "square end" on the blade? ie should I remove more material to square it up, or just focus on the cutting edge? or maybe just replace the whole thing? Can the center bolts (if they come out cleanly) be reused with any margin of safety?
Is it usually easier to remove whole deck than the blades...or just the blades while deck is still mounted. Not sure how easily that centre bolt will come undone, been there a while by the looks of it.

Yukon · Nov 27, 2001

Balance is important when sharpening so that all the blades are even weight and especially both ends of the blades. The bolts can be reused but you might want to apply some lock tite.

fredbear241 · Nov 27, 2001

No prob re the balancing. Any comments on the quality of steel used in the center bolts? Do they usually come out easily? or should I be planning for a heat source & penetration oil, big hammers (oops) & profanity repremands etc.

rbargeron · Nov 27, 2001

Sounds like your blades are no longer "overlapping" enough. The offset in spindle centers is pretty small so if the ends of the blades get worn (or trimmed in sharpening) the blades can develop a "gap" perpendicular to the travel direction. The answer, I think, is probably new full-length blades.

From your comment on the expected resistance to removal of the center bolts, I'm guessing this is a MMM with some hours on it. Do you know if the blades are the right length for the mower model? I don't know what the radial gap between your blades is suppposed to be, but on my 90" finish mower they only miss each other by about 3/8".

Yukon · Nov 27, 2001

Well, I don't have the same deck but as for reusing them I could not see replacing one unless I broke it or stripped the nut. As for getting it out, I used the longest wrench I had which was my tourque wrench and I had no problem. As for clearance, I have a rear mount so I can lift it higher and it's easier to get under. Good luck.

fredbear241 · Nov 27, 2001

I wish Kubota put the spec on the net somewhere. eg the 'gap' between the blades. 3/8" (of non cutting) sounds a fair bit, but I assume you don't get a row of grass left behind

. I'll check mine and see. My deck is only 40", but I guess the gap should prob be in the same ballpark. When combined with rounded ends possibly I have an explanation. I'll take 'em off, sharpen 'em & see if it makes a difference.

rbargeron · Nov 28, 2001

On my finish mower the spindle offset is 6" - the center one is 6" behind the outer ones. This gives a good overlap of the cutting circles, when viewed along the direction of travel. But some mowers have a smaller offset so they have less overlap to play with - blade length and end condition are more important. Hope this is useful.

TresCrows · Nov 28, 2001

I have your solution!!! Trade your tractor with it's 40 inch two bladed deck in on a new BX with a 60 inch three blade heavy duty deck and watch the grass cower in fear! Glad I was able to help you out here. /w3tcompact/icons/smile.gif . Kubota has attractive rates right now. J