Mower Blades

[djg618]

If you bothered to check that chart then you would have seen 15/16" is a std blade hole size
Blade thickness is not important for fit
Thicker blades have a lot more momentum so will not die as quick in long tough grasses and of course will take more punishment before it bends .
Thicker blades also require more sharpening to do a good cut and reduce load on the engine . I explain this in terms of line trimmer thickness as almost every one has run line that was too thick through their trimmer at lease once .
Blade width is important as a blades that are too wide will hit each other .
Because blade length is measured diagonally a 20 x 3" blade is actually shorter than a 20 x 2.5" blade so the narrower blades may strike the sides of the deck just the same as blades that are too long will
The notch where the flute starts is there to prevent cracking & allow the flutes to be bent easily it has no functional difference in use
Unless the blade is centred in a 4 jaw chuck and you use a pedestal grinder you will not be able to open out the holes by hand.
The tinest bit off centre left right or front back will have the blade out of balance
The height between the cutting edge & the underside of the deck is CRITICAL ( yes I am shouting in the hope you will listen ) .
Too close and the deck will get overwhelmed with clippings so will clog which can quite easily cause the belt to break
Too far away and the clippings will not discharge properly and the deck will also clog all the time when cutting long grass
In both cases you will end up with blobs of cuttings all over the lawn ( we call them grass turds ) .
Pressed decks are less fussy about this but with fabricated decks with a flat steel plate on the top it is critical


If you find that you can not get original blades then buy a set of all that look like they fit.
Blades are not all that expensive particulaly when compared to buying a replacement mower .
A lot of my customers use different blades at different times in the season and in any case having a spare set ( or 2 ) of sharp blades encourages people to change them when they start to go dull
You get a much better cut & can cut a lot faster with sharp blades

Alot of good information here. Thanks. I'm currently looking for a 20.75" drop blade 2.5" wide (not 3") and a thickness of no more than 0.25" and a center hole of 1-1/8". Someone pointed out 1" to 1-1/8" reducing bushings are available that I could cut the flange off and grind to the thickness of the new blades. These are friction fit blades.

 

[djg618]

Alot of good information here. Thanks. I'm currently looking for a 20.75" drop blade 2.5" wide (not 3") and a thickness of no more than 0.25" and a center hole of 1-1/8". Someone pointed out 1" to 1-1/8" reducing bushings are available that I could cut the flange off and grind to the thickness of the new blades. These are friction fit blades.

I see that was you.

Oh, and the deck is a fabricated deck. Very heavy. Took two people to git int my truck.

 

[bertsmobile1]

Search "Steel reducing bushes" you should come up with a dozen supplier in the USA .
I assume this mower has a 60" deck
If you flip the deck over and measure the distance spindle centre to spindle centre this is basically the right length for your blades
I usually measure inside to inside then outside to outside , add them up & divide by 2 because that tends to be more accurate than trying to guess the middle of the spindle
Probably worth doing both sides , left to middle then right to middle .
Not all that long ago there used to be a good 1/2" of blade cutting circle overlap but as decks get shorter front to back the amount of overlap is reducing
Husqvarna now uses 2 x 21" blades to do a supposedly 42" cut and you are lucky to get a season out of them before they start to leave rooster tails between the blades .

 

[djg618]

Search "Steel reducing bushes" you should come up with a dozen supplier in the USA .
I assume this mower has a 60" deck
If you flip the deck over and measure the distance spindle centre to spindle centre this is basically the right length for your blades
I usually measure inside to inside then outside to outside , add them up & divide by 2 because that tends to be more accurate than trying to guess the middle of the spindle
Probably worth doing both sides , left to middle then right to middle .
Not all that long ago there used to be a good 1/2" of blade cutting circle overlap but as decks get shorter front to back the amount of overlap is reducing
Husqvarna now uses 2 x 21" blades to do a supposedly 42" cut and you are lucky to get a season out of them before they start to leave rooster tails between the blades .

I'm looking at these:

Amazon.com

Only 20-1/2" long. Not sure how the manufacturer measures theirs. Would these leave the rooster tails? Thought the middle blade overlapped the outer two. Yes 60" deck. Don't know what the drop is. They don't say.

 

[MParr]

I'm looking at these:

Amazon.com

Only 20-1/2" long. Not sure how the manufacturer measures theirs. Would these leave the rooster tails? Thought the middle blade overlapped the outer two. Yes 60" deck. Don't know what the drop is. They don't say.

They could leave uncut strips. @bertsmobile1 had some good advice earlier about measuring the distance between the outside spindles and center spindle.
It would be nice if you could replace your spindles with Exmark spindles.

 

[VegetiveSteam]

You may already have this info but in case you don't.....

 

[djg618]

You may already have this info but in case you don't.....

View attachment 65725

Yes I do, but thanks. As I said before, I believe they are closed. Production stopped 20 years ago but parts remained available from them a couple years ago. I've called both numbers several times last week and no answer. I'll keep trying.

I have emails out to three US manufacurers and If I don't hear back from them, I've got a slightly longer, 20-15/16" blade, picked out.

 

[StarTech]

This is why I suggested the Land Pride blades in an aftermarket version (B1LP1002). They are 20-7/8" long which only an 1/8" longer instead of 3/16" and have a 1" hole. That will bring the blade tips a 1/4" closer at they meeting point instead of 3/8" so might need to trim them.

 

[djg618]

This is why I suggested the Land Pride blades in an aftermarket version (B1LP1002). They are 20-7/8" long which only an 1/8" longer instead of 3/16" and have a 1" hole. That will bring the blade tips a 1/4" closer at they meeting point instead of 3/8" so might need to trim them.
View attachment 65733

I must have thought they were flat the first time or I didn't notice that. My apologies. I do need the "offset" and "air lift" as pictured. I'm learning a lot about blades as I go (lol). I'll have to measure mine. I butch my grass so I would hate loosing height by using a blade without an offset.

I did put the old blades back on and measured the minimum distance between blades and all the way around and it was 3/8". So now I'd be down to 1/4" which would be doable. If I have trouble locating those, I'll get back to you....Thanks.

 

[djg618]

Update:

This is what I ended up with. 20-15/16" blades just missed each other on a trial fit. So for comfort, I ground off 1/16" each end and made sure the blades were balanced. Mowed the grass twice until the belt broke. Got another one and will install tomorrow. Don't think it's added pressure on the belt since the blades are the same thickness design. Belts just break. and I had the same problem a couple of years ago. Went through two belts back to back. Found out the belt retainer post was dragging. Moved it out of way and re-tighten. Worked fine. I think I may have bumped it when removing the deck.


Thanks everyone!