Using a balancer on a mower blade

[Geza]

Hi Everybody!

I know, that this bone has been chewed on by so many and so many times that there is no way, that anyone can say anything new about this subject, but I'm reviving this thread because I decided that I'm gonna get an Oregon cone balancer IF it has the right sized diameter rim on it, right for my lawn mover.

So, I was wondering if someone who happen to have an Oregon cone balancer, would you please, measure the diameter of the rims in the approximate range of 19.6 mm (0.77") to see if one of them might be close enough for this diameter? Because if none of the rims of the cone is close enough to 19.6mm, then I wouldn't be able to use it successfully since for e.g. 1mm difference in diameters could throw off the balance.

Geza

 

[stevestd]

Bought a Tecomec blade balancer on ebay (similar to a Magna-matic Mag 1000) after wearing out a spindle bearing and have not regretted it. Have previously tried most methods of blade sharpening; have ended up using a bench belt sander (Ryobi) with a 40 grit paper. At first it was difficult to get a sharp edge with a constant angle, but with a bit of practice it is easy. I have a mulching mower so the blades wear the most about 1 inch from the end of the blade, leaving a curve at this point. As the curve is where the most work is done by the blade, it is this section of the blade that needs the most attention. If I sharpened the blades with a strait cut, the blade would be mainly ground away. I now replace the blades when the wing tips are worn.

 

[Geza]

Hi Steve,
the balancer you mentioned costs a lot of money from where I stand and since I'm no pro, wouldn't worth it for me. $100 in Hungary means a lot more money than in the US. The Oregon cone balancer is not available in Hungary so I'd order it using E-bay but I don't want to buy it if I couldn't use it and I would have to throw it in the trash. That's why I posted my question of whether if you have one would you measure it for me?

But you said something about not sharpening the blade in a straight line but in a curve of some sort. Could you post a picture of it and also could you post a picture of a blade, that you already trashed (if you still have it somewhere) so we could see what you're talking about?

Géza

 

[stevestd]

Hi Géza,
In my view, people who only maintain their residential yard with a small mower probably do not need to worry too much about blade balancing. If you do buy a balancer, choose the type which best suites you. The cone balancer looks like a cheap and easy method for smaller machines, although I have not tried one. They have steps on the cone so most blades with a central circular hole should fit, and must be a much better option than a nail. Because the blades on my mower are heavy and rotate quickly, balance is far more important than on a smaller machine with a thinner/lighter blade which doesn’t spin as fast. I only bought the Tecomec after much deliberation as it cost me US$130 with postage ($90 + $40); whilst a spindle bearing in Australia cost nearly US$400. Yes, our mower parts and other goods in Australia are much more expensive than in the USA. I will post some photos tomorrow.

 

[Geza]

Hi Steve,
I totally agree with you on your points. Our Al-Ko classic 38e is 2007 year German made electric (corded) lawn mower with a 38cm (15") long blade and a 1300W (220V), 2800RPM asynchronous motor (no brushes to wear out) used in direct drive (no belt).

Here you can see a few pictures of it: http://pumi.org/geza/temp/browseable/al-ko_classic_3.8e/

We use it around our apartment building on a 1600m2 (1900 yd2) lawn once a month from March through November. I just recently changed the bearings of the motor and the blade holding fan-disk, so so far it looks like it is the right size lawn mower for the task if I had to replace the bearings first time on this 9 year old mower just now.

If you want to buy a new one of the same model today it'd cost you about 150 Euros, I'm not sure about the quality of it though, a lawn mover tech told me recently that the older models are a lot better than the new ones because of the asynchronous motor and direct drive, while the new ones have belt driven blades, cheapo bearing housing, etc.

So, I think you'd consider this lawn mover a smaller unit, it is true, but if or when the blade is out of balance the handle bar can vibrate so badly that it can really bother you plus it can really shorten the life of the motor bearings too. So, this is why I started to care about balancing. The blades are cheap here, around 10 Euros, but I hate to waste and throw them out when it would be time to sharpen them, and since my original trade is auto mechanic, it's no problem for me to mess with this even though it is not mine but belongs to 27 apartment owners. And the owners would kill me if I'd purchase a US$100 worth of balancer for a 150 Euros worth lawn mower.

 

[stevestd]

Photo 1 - Belt sander used for sharpening.
Photo 2 - Worn blade on left showing curve on cutting edge; near new blade on right. If you look closely you can see the differences in the thickness of the wing tips on both blades.

I was surprised when using the Tecomec just how out of balance my old blades were, being previously told by other contractors to use a nail. My local mower shop doesn't even have a blade balancer.

 

[Geza]

" If you look closely you can see the differences in the thickness of the wing tips on both blades."

I'm not sure what you mean. Maybe you could add some arrow to the photo and post it again?

I just watched a Youtube video on this very same model of sander, it's a nice piece of machinery especially if you consider the price of it too.

 

[stevestd]

Enlargement as requested.

 

[Geza]

Here I'm quoting your sentence from your very first reply:
" I now replace the blades when the wing tips are worn."

Why do you care about that tip since it is not on the cutting side of the blade but the rear side? If I'm assuming correctly that the cutting side is the right one, it seems to me that way. I don't even see, why that part of the blade gets worn out at all since that is not the cutting side. I must be missing some info here to see this matter clearly.

 

[bertsmobile1]

Because the wins control the air flow under the deck.
The wing ( flute to some ) errodes at the bend then cracks then breaks off and goes flying out at 14,000 ft/ sec.
Good enough reason ?