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Mulching and blade sharpening....

Discussion in 'Homeowner Assistance Forum' started by Sonnie Parker, Jul 8, 2002.

  1. Sonnie Parker

    Sonnie Parker LawnSite Member
    Messages: 167

    I recently purchased a mulching kit for my new Husqvarna ZTH 5223.

    First, this was a headache to install. If there is a drawback to owning this mower, it's installing the kit. Several of the holes did not line up causing drilling.

    Second, the cutting is not nearly as good as with the regular blades and side discharge. I was highly disappointed in how slow I had to cut the grass to prevent stringers. I was also hoping to cut down on the amount of dust generated but was covered up, especially my legs. The dust wasn't as bad as the side discharge but more in a specific area coming in over the front of the deck.

    I'm cutting at 2.5" because that's the height my grass looks best, especially with bahia. Any higher cut and I'll be cutting twice a week instead of once.

    Are there any suggestions short of going back to medium lift blades with the side discharge?

    I do enjoy the discharge shoot being off the mower enabling me to go a few places that I couldn't before and also allowing close cutting next to bushes/trees/post/etc., from the right side of the deck.

    I have read a few posts about sharpening blades but don't quite understand the correct angle to sharpen. I haven't sharpened them yet so I'm thinking this may have an effect on the cut.

    The blades come from the factory sharpened similar to "A". This is about as close as I could simulate the angle.

    Should I sharpen to "B" or maybe "C" or am I way off here?

    Thanks for any help!

  2. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    "C" will result in a dull blade and grass tearing. I've tried this with my mower's blades to get better wear. "A" is a really sharp blade, but the sever angle leaves a thin metal edge that will wear fast. "B" is your best compromise for wear and sharpness. Good luck.

  3. Tvov

    Tvov LawnSite Bronze Member
    from CT
    Messages: 1,157

    The "B" angle is fine. Sharp blades will always give you a better cut, and the mower doesn't have to work as hard. If you are mowing just your home yard (unless it is a monster yard!), you probably only will have to sharpen maybe twice a year, spring and mid-summer.

    "Mulching kits" rarely work as advertised. A lot of commercial guys using mulching blades, but keep the side discharge chute open, as the grass will get chopped up and then disperse. If the grass is high/thick, you just may have to do a "double cut", basically mow the lawn twice, the second time in a different pattern. This will cut down any "stringers", and also chop up the grass clippings even more, pretty much to the point where you can't see them.
  4. Sonnie Parker

    Sonnie Parker LawnSite Member
    Messages: 167

    Thanks guys! I'll go with "B".

    I guess I don't understand the mulching concept too well.

    It would seem to me that if I used the mulching blades which have a higher lift and wider cutting edge that it would cut better than the original set up.....yet I have to cut slower.:rolleyes: With the original set up I could cut at wide open speed (10-11mph) on level ground. I'm down to approx 4-5mph with the mulching kit.

    I haven't read where anyone has tried this but is it safe to leave the side discharge cover off to narrow up the deck or am I risking getting hit by something? I don't see how anything could get to me but I'd rather have some pro advise before trying something that might be stupid and ignorant.

    I was reading a few post about deck angle earlier (front to back). I need to check this on my ZTH. Maybe my angle is not proper (front 1/4 inch or so lower than rear), but then again, it worked fine with original blades and side discharge.

    EDIT: Btw...I do have a massive yard to cut. Between 5-7 acres depending on how I feel when I'm actually cutting. Sometimes 2 acres of this will be a little higher and thicker because I don't always mow it regularly. However when I reference my problems I am mainly referring to the 5 acres that gets cut every week. I realize on the other 2 acres it may take a little longer to cut.
  5. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    The deck on Z's have been designed for max airflow and high lift to facilitate the cutting of grass at high ground speeds with a side discharge chute. Close down this chute with a mulch kit and you disrupt the airflow of these decks. Mulching mowers bog down with high grass and leave a trail of clippings. A side discharge chute will help to dispurse the clipping over a larger area. High velocity blades insure smaller clippings. There is no way that mulch mowing could ever run at the same speed as a side discharge and not leave clumps.

  6. Sonnie Parker

    Sonnie Parker LawnSite Member
    Messages: 167

    Actually I don't have a problem with clumping or bogging down using the mulching kit even at high speeds, but it just doesn't cut as well, leaving some straggling stringers here and there. Whereas using the original set up I very seldom had a stringer.

    When you say high velocity blades, which ones are you referring to?

    Does this mean a mulching blade will have less velocity due to the higher lift resistance? That may well be the problem I'm experiencing.

    Again, thanks for your help!
  7. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    Sonnie Parker,

    with the side shute open, the Z's blades create a vacuum under the deck, expelling air and grass out the side chute. This vacuum helps to lift your grass blades into the path of the moving blades for cutting.

    With the side chute closed by your mulching kit, there is a reduced vacuum under the Z's deck. Air pulled upward by the high lift mulching blades can not escape out the chute. Where does this air go then? Some will escape from under the perimeter of the Z's deck. So you have a much smaller vacuum created under the deck and air is spilling out from under the perimeter of the Z's deck. This spilled air will push the grass baldes down and out from under your deck. You get stringers because the mulch kit reduces the air flow which decreases the vacuum under the deck and the escaping air now pushes the grass down and away from your mower blades. The high lift mulching blades are only trying to keep the grass clippings aloft longer so that they can be cut more than once (into smaller pieces).

  8. Sonnie Parker

    Sonnie Parker LawnSite Member
    Messages: 167

    Thanks jim,

    What you say makes sense. I believe what I may do is leave the mulching blades on but take the kit back off and open up the chute again. Cutting as much as I cut, speed is more important to me. So much for wasting the $130 or so on the kit.

    HOWARD JONES LawnSite Member
    Messages: 233

    I agree with the other comments - and you are probably mistaken when you say the mulching blades have higher lift. They probably are somewhat like gator blades, which push grass back into the mower for a second cut but this lessens the air flow or lift a little.
  10. Sonnie Parker

    Sonnie Parker LawnSite Member
    Messages: 167

    This does appear to be the case.

    I did some cutting yesterday with the mulching kit off and the mulching blades on. It still did not cut as well as the original blades did. I was trying to figure out why.

    I believe mulching would be nice if I only had a little bit to cut but with the large area I have, the original set up I believe is going to end up being my fastest route.

    Anyone need a mulching kit for a Husqvarna ZTH5223???? lol

    Maybe the dealer will take it back or can help me sell it for a reduced price of say $100 or so.

    I appreciate the help you guys have provided. I'm learning a good bit in this forum.


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