Sounds like you have covered all the bases and know what you are doing. Here's a couple points that may or may not help. Spring grass tends to clump more. You will have less clumping later in the summer. Even so you may still have some clumping because riders tend to do that as opposed to your Lawn-Boy push with it's narrower width. You can try side discharging and experiment with different patterns. I have even side discharged and then mulched second to eliminate clippings. Your idea of 2 blades has been done before. My Ransomes AR250 fairway mower has 2 blades per deck for a total of ten and it mulches quite well. It has a special blade holder. Hang in there and keep experimenting. I think you may have less clumping as the temps go up.

I've got a similar mower. (42" Craftsman LT 1000) And have the same issues. I bought new mulching blades (IIRC they were called Gator blades) and that helped out a lot, but it will still clump with the heavy spring grass.

I think the main problem is the mower deck isn't designed for mulching, it is set up for side discharge and the "mulching plate" is simply a block off for the discharge.

The bottom of a deck with a "proper" mulching kit will have baffles to keep the clippings recycling rather than being passed to the other blades for discharge.

I find that the time savings of the lawn tractor outweighs the mediocre cut quality. I also have a Lawn Boy (last of the two strokes) walk behind that does an excellent job but it takes well over an hour and a half for me to cut the lawn.

I'd give the Gator blades a try, they were about 40 bucks a pair.

Thanks guys! What may be the problem or danger with getting two new gator or similar blades and adding them to the existing blades on the shanks? In effect, a total of 4 blades in an X-pattern on each of the two spindles.

The main problem I can see is that the second blade will not positively engage the shaft, the nut may work loose as a result and the blades may go flying.

My lawn boy has an additional fan on shaft that is meant to blow clipping up I believe, and not to cut them.

I would just try the gator blades as-is and see how they work for you. They do work much better than the stock blades.

2 yrs ago I bought a Husqvarna 23hp 48" rider...for mulching my lawn. Clumped up constantly, even enough to stop the engine occasionally. Heard then about "Gator Mulching Blades" (made just for mulching pupose). Bought a pair, installed them in lieu of the factory mulch blades, what a difference !!! No plugging up or clumping. The dealer that sold me the mower said "THEY" stock em & recommend em'....wish they had done that when I first bought the mower, cause I told em' all we do is mulch. Trust me...just get em. Now with a tad of advice...don't expect miracles if you mow real tall or wet grass...sharpen blades annually. I mow 1-acre of rough lawn every week at 3" height setting.

Adding blades will put an additional load on the engine. A big part of the load created by blades is the bent up rear edge that creates the wind for discharging and lifting the grass. As an example....Once I put Snapper high lift blade "wings" on my Snapper walk behind and the engine could not even spin them up to normal speed because of the increased drag created by these additional wings. For your experiment, if adding additional blades, it might be wise to choose flat blades with little lift.

The Gator blades make a world of difference. I have increased the speed of the mowing and increased the width of the swath, all with no clumping. Thanks guys!