Mower won't mulch like it used to

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A problem I've been fighting for a few years now and have not found a solution.
Simplicity Regency 12hp lawn tractor (about 1996?- last year the hydrostatic drive handle was in the middle). It has a mulching kit (which is just a discharge shoot block) and I use 'leaf cutters' on the leaves. When I first got the tractor, it did a superb job of mulching - both the grass clippings and leaves in the fall. The lasts three years or so, it has started leaving a trail of grass clippings down the middle, and it take repeated passes to chop up the leaves in the fall.
I typically mow once a week.
I have tried all the following with no success: Sharpened the blades Changed the blades Cleaned the deck Leveled the deck Tilted the deck forward and backward Changed the drive belt Cheched the RPM Mow more often
Still it leaves unsightly clippings. The neighbor with a cheap MTD gets a better cut.
Any suggestions? What have I yet to try?
Dave
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You said you changed the blade. There is a special mulching blade, different from normal blades. They have more tilt to them and a curve about halfway between end and center. The theory is that it sets up upward air curents around the blade which blow the cutting up and as they fall, the blade cuts them again, and again. They kinda work okay, but you need to travel slower since (in theory) you are cutting more grass by cutting the same grass more than once. The second thing is that the blade must be kept very sharp for maximum effectiveness. By very sharp, I don't mean new blade sharp, because most new blades are not sharp. I mean knife-like sharp. The edge doesn't hold long, so blades need to be sharpened frequently.
Don't know if any of this will help you or not. Hope so.
Bob-TX
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Bob wrote:

The new blade I tried was called a 'gator' blade. It looked like it had greater lift, and a serrated trailing edge.

I normally have the blades sharpened at the local hardware store. When they are done, they have all the nicks ground out, but they are not knife sharp. I'll have to see what kind of an edge I can get on them.

Me too, thanks.
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DaveL wrote:

Well, I spent quite a bit of time and put the best edge I could on the blades. They were not razor sharp, but there were knife edge sharp- I wouldn't have wanted to run my finger down one.
Cleaned the deck again when I was working on the blades. Bearings are all snug, there is no up and down or side to side play in the shafts. The blades pass each other with about 1/4 inch clearance. The belt appears OK, and I retensioned it.
No improvement. It's almost as if the airflow under the deck is blowing the clipping into the ground down the middle of the deck. It leaves a trail right down the middle. Multiple passes over the same area in different directions only move the clippings around.
There has got to be something simple I am missing, but I sure can't figure out what it is.......
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You may have the blade mounted backwards or upside down. It happens. I know (first-hand). It's easy to check.
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News Man wrote:

I'm sure it happens, but I've checked that at least 3 or 4 times....

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Is your mower a mulching mower? Does it have a discharge chute attachment that forces the discharge back onto the blade? Just adding a mulching blade will not make a mower "mulch," per se. What's your brand etc.?
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Bill Freeman wrote:

Yes. It's a Simplicity Regent Hydro12, with 36" cut. (somewhere around a 1996 model year) It has a 'mulching kit' on it, which really consists of just a plate across the discharge chute. Worked well at first, but for the last few years just will not chop up those clipping.

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DaveL wrote:

Has it lost blade speed? Is there some way the blades could be turning backwards (not likely, but possible with a few mowers)?
Austin
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AustinMN wrote:

Blades are turning the right direction, and are mounted properly. Check RPM on advice of an email from Simplicity service and found it proper at 2500 RPM. Belt has been tightened and then replaced. A real mystery...
Dave
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there are other reasons. At one point you mentioned that in recent years, it has not been mulching good. Are you mowing a different grass?
No doubt this problem can be fixed. But, without seeing it, I am at a loss. Your descriptions are good, but are only what you observe. Sometimes a different person may notice something that someone else has overlooked and therefore could not include in a verbal/written description.
I'd suggest taking it to a local mower shop - not a large company like Sears that sells mowers - just a fixit shop where you can talk to the owner, manager, and mechanic (all in one person). Just talking doesn't cost, and he might look at it as a challange (I know I would) and get real interested in the problem.
Sorry I can't come up with anything better than this to offer.
Bob
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Bob wrote:

Just a thought. How long are you letting the grass get and how much are you cutting off? 1/3 the height of the grass is what's recommended. Mulchers don't work very well in tall grass.
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GFRfan wrote:

I mow normally once a week. It's tough to get it done more often. 1/3 is probably about what I am cutting.
Dave
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Bob wrote:

Funny you mention that. It seemed to stop mulching the second year we had a 'Chem-lawn' clone doing our yard. But we stopped that service, and nothing has changed. The neighbor still is having his lawn fertilized and he does not have the mulching problem.

That's very true.

I talked to the service guys at the (small-medium sized) lawn and garden shop where we bought the mower. They suggested the 'gator' blades which did not help. I may break down and take it in to the shop, but I'm concerened I end up being charged hundreds of dollars and there will be no improvement.

I appreciate hearing your thought....
Dave
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I assume you're mulching "dry" grass at approximately the same time/day as you did before? What do the cuttings look like? How does the mower discharge "without" the mulching blowback bar in place? Almost sounds like your blade is put in upside down (not backwards .. . which would be obvious). Does the mower "cut" at all?
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Bill Freeman wrote:

Thanks for the reply...
I always shoot for the dryest day possible. The clippings appear to be about the length of what was cut off. As if the blades cut ok, but the clippings are not recirculating and instead are just 'blown down' into the middle of the cutting path. I haven't tried it at all without the blowback bar.
Putting the blades in upside down would also mean they are turning the wrong way; i.e. sharp edge trailing instead of leading. You don't know how many times I've checked that possibility. The blades are mounted such that the sharp edge is moving into the uncut grass. The pitch on the blades is such that the air should be drawn up into the deck. The 'flat' part of the leading edge is down, and the tapered part is up.

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Dave,
What's the "angle" of the new mulching blade vs that of the original blade? I've noticed that my Honda cuts better at a 45 degree blade edge (more vertical) than at a 67 degree (more angle) (from the vertical. You DO have an interesting problem.
Bill
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Bill Freeman wrote:

On both sets of blades, the originals and the 'gator' blades, 67 deg sounds about right. Certainly not 45 deg.
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Dave,
What do your normal blade and discharge chute cuttings look like? How long are they on a 3- 4" grass height? What is your normal grass cutting height?
Bill

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Bill Freeman wrote:

Not quite sure what you are asking. I haven't tried it without the discharge blocking plate (blowback bar?) for a long time. I have the mower set at it's highest clipping height, clipping at a lower level seems worse as there is not as much turf left to drop the clippings into. I'm guessing that the grass is about 4" long when I cut it, and I cut off about 1/3 (perhaps a bit more) of that length.
The clippings that remain on the lawn appear like they were cut once and dropped - not recycled into the blade for further 'processing'.
Dave
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