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Discussion Starter #1 (Edited)
With the cost of parts for my mower, its age, rarity and many parts NLA, I needed something better than the usual cheap step-cone type blade balancer, which I have, but wasn't giving me the precision I needed. So I set out looking for what others used as mower blade balancers.

Wasn't disappointed as I found many blade balancers, from what one can find on a shelf or tool box in the garage of using a nail driven into the wall, to high precision and costly balancers made by Magna-Matic.

I didn't want to go either of these routes, as one was using gravity/friction to just get close and other was out of the question of what I wanted to spend. Over the years I have used a nail, screwdriver, step-cone, and bolt and while they came close to balance, I just couldn't get that precise balance I wanted for cheap and easy. Until now.

I'd like to give Eric ELM over on LawnSite.com from March 9, 2001 credit as his idea was just what I was looking for.

This simple balancer will benefit many others who want that better blade balance that won't tear up spindle bearings and egg out mandrels from multiple blade imbalances or even that single bladed mower.

Parts List: 1)- 1/4-20x1-1/2" full threaded bolt.
2)- 1/4-20 nut.
1)- Flat style shed/barn door pull.
1)- 1/4" fender washer. I put this washer between the ground down 1/4" bearing washer and door pull to not let blade rub up against door pull and throw off balance.
2)- 1/4" flat washers. These will need to have the outer edges ground down(let washers spin freely on a screwdriver shaft, like latheing the outside edges to be smaller diameter) to fit the inner bearing and let bearing's outer flange spin freely when blade is installed to determine balance.
1)- Bearing. 1/4" ID x 5/8" OD. The outer or inner diameter can change on the bearing depending on if your blade uses a 1/2", 5/8" or 1" blade hole to mount onto the shaft.

I have some blades that use the "STAR" cutout and they fit my 5/8" round deck shaft assemblies and these bearings without any imbalance/excess looseness problems.

If one does get/use a curved type door handle, you'll need a 1/4" spacer sleeve to clear the curved portion to keep everything flat and true.

You'll also notice on the wood where I have my balancer installed, the dark line. That line is a balance line to let me know I have blade balanced.

All the parts I had to purchase cost me less about $20. The bearing is where most expense went to. I had the mount and mount screws.
 

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I also balance my blades but I don't worry about perfection. The problem is that there is usually a good bit of slop between the center hole in the blade and the boss on the spindle. This means the blade will never be centered and therefore will have some imbalance.

On one of my decks there was a spindle with a chewed up boss. I welded it up and chucked it in the lathe and turned it down until it was a precision fit on the blade center hole. I also added some height to the boss as this deck uses 2 blades per spindle. It worked so well that I was inspired to do the other 2 spindles.
 

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Discussion Starter #3 (Edited)
Sounds like you have the type of repair shop I want Rayjay.

My blades don't just slip onto the spindles. They go onto a separate, 1" thick machined steel donut, that's lathed for the spindle on one side, then the other end has a raised boss where the blade's hole fits onto, then a 2-1/2" bolt goes on and holds everything together tightly. This boss sounds about like what you have for yours on keeping the blade(s) centered.

So far after sharpening and re-balancing some already step-coned blades, then installing, I've gotten out most all of my deck/blade vibrations that stress cracked and broke some of the deck safety covers over the years where hold down bolts attached held them on. Most all this damage started from previous owners having this mower as I've only owned it since 2015. I had to get some fender washers to help give the metal a better/larger hold down point to keep from further damage to the safety tins. And these pulley/belt/deck drive shaft tins are 1/8" thick. About same thickness as what today's deck metal is made from. It's a much smoother mowing experience now.

I've already done some research on what my deck mandrel assemblies cost, and manufacturer surprisingly does have them, but only sells as a whole assembly(no parts repair kit). They're $480 each x 3 plus tax and shipping, so keeping them well greased and happy with a 100% better blade balance is money in my pocket.

Here's a couple pics of my mower and it also next to my Craftsman GT5000 for comparison.

I also should say, giving Eric the credit, that I changed a few things of his idea to easier work for me, but the pictures you see in the first thread are mine after final assembly, and having worked out some idea that Eric had and what I thought weren't needed.

Del
 

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I question why the cone type balancer would not be precise enough? Being overly frugal, I've never purchased one but in theory they should work well.

The way I balance my blades is to lay a screwdriver with a round shaft flat on the bench and then lay the blade on top of it. As I turn the screwdriver, the blade "walks" to one side or the other and I watch through the hole to see if it is centered on it. I have never detected any vibration on my deck, have never had any stress cracks, and the only reason I had to change a mandrel was due to water getting in the bearing. My current mower I owned for 16 years.

I may have to try out your method the next time I sharpen my blades to compare.

I did see push mowers that stress cracked but I think that was due to a bent blade as I suspect the blade had never been sharpened.
 

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Discussion Starter #5
I would of thought the cone balancers being as simple as they are and having used them since the late 60's-70's when I was a teenager and helping granddad/dad mow and sharpen blades, that they're idiot proof, but this big old mower was telling me a different story every time I'd sharpen and do a balance.

Now, it's possible that the metal cone balancer that I have, and it's an older model that my dad used for years on their smaller deck blades, could of been molded badly from the manufacture. Doesn't seem possible, but not impossible either since millions of these things are manufactured.

Couldn't believe the difference with just one re-balance on my system made to smoothing things out. For me anyway.

I believe our Walmart has cone balancers on their shelf and since they're so cheap, might get one just to see if the one I have is bad. Can always have need for one anyway, for portable use.
 

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To have any real comparisons we would have to have a number of the same style balancers and balance blades repeatedly and then have some sort of high tech super digital/laser/scale balancer to see the real results.
Feeling a difference on one machine is hardly definitive. I rarely get blades that are that out of balance.
I run a shop so I see hundreds a year and I have had 3 bad one this year.
Only three were so bad that if you hung them on a nail one end would head straight to the floor and stay there.
Only one of these made the handle of the mower vibrate to where you knew it was more than normal.

I don't see it being that big of a deal to be close to perfect. Simply not really bad will 98% of the time result in same life of components.
The most unbalanced ones I typically get in will hang about 2-3 inches lower on a nail or as they go back and forth you can see them favor one side.

It is also very worth noting that VERY often you will see a large noticeable difference in felt vibration by just rotating blade 180 on the blade adapter.
This rules out balance for the most part.
Of course an out of balance one should be amplified one way and reduced the other but the fact that even with only a slightly out of balance blade that there is such a difference tells me there is more to it with mounting and center hole fit etc.

The first time I show someone this in person they are always amazed.
I start it and tell them to hold the handle and feel it. Then I turn it off, loosen the bolt and rotate the blade 180 and tighten it back and have them feel the handle then.
Most are no difference but some are really distinct.
 

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I bought a used Magna Matic and it's ridiculously sensitive. Unless the blade center hole is a precision or interference fit onto the spindle boss there is I see no reason to keep grinding off weight until the blade sits perfectly horizontal when it's on the balancer. A few degrees off horizontal is fine.

I used to use a motorcycle tire balancer for balancing my mower blades and it too was incredibly sensitive. The only reason I got rid of it was that it took up too much space.

That being said, the worst 'vibrating' deck I had was due to a primary belt that had a worn section. The deck would move forward and backward about 1/4" or so. Really caused a lot of noise and harmonics.
 
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