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View Full Version : Blade Sharpening (Rounded/Square Edges)


pgiambat
09-19-2005, 11:02 AM
I've been getting 'stringers' of grass left in a straight line down the middle between my blades. Is this because I have slightly rounded the corners of my blades over the last few years when I sharpen them? I sharpen and balance my own blades. I get the blades nice and sharp and balanced but did not pay attention to rounding the corners, they are not too bad, but thay are not "new and squared".

Drew Gemma
09-19-2005, 11:10 AM
most likely that is what happened. It only takes a little bit of a rounded edge and you start missing stringers.

DLCS
09-19-2005, 12:40 PM
Rounded corners affect some mowers differently. The more blade overlap you have the less you need to worry about rounded corners. When you sharpen always try to even out the blade by keeping the edge straight and cleanup the corners. This could sometimes mean taking alot more materail off to get a square corner. I use a 4.5" angle grinder with a flap sanding disc, makes short work of sharpening blades.

pgiambat
09-19-2005, 12:53 PM
Drew & DLCS,
Thanks for the comments. I get my blades very sharp, no problem there, I try to stay away from the tip but using a 4.5" angle grinder I go over now and then and it takes material off rather well.
I've actually been looking at different attachments when I go to Hadware stores and have been eyeing the flap wheels, I might give it a try, staying away from the corners better and finish them up with a file since I always touch up a rough sharpen with a file anyway, habit from High School Metal Shop.

Precision
09-19-2005, 01:39 PM
blades should be sharpened to an angle not square.

from the center pin to the outside edge (the part you are rounding) should gradually become more triangular.

this increases blade surface area as well as getting rid of your rounded corners. It also keeps the blade stronger at the center incase you hit something they areless likely to grenade.

topsites
09-19-2005, 01:45 PM
Unless you've sharpened them to where you've ground them down to a couple of slivers that look like some kind of ninja knives and measure about a foot across, that is... Don't know exactly how to describe it but it would take 2-3 years of full-time use on the same set, maybe 1-2 years if you like to grind off more steel than I do... I mean, do they still MEASURE the same as a new blade, from side to side?

Don't laugh, I've seen it more than once.
Not saying you're one of them, and it would be odd, but it crossed my mind, heh...

pgiambat
09-19-2005, 02:42 PM
Below is what I'm talking about as a "Rounded Corner". I'm thinking that I might have rounded them off too much and unless I want to spend a lot of time grinding and balancing, I was going to pick up a new pair and be a lot more careful with the corners.

The blades are still the same length from side to side: 18".

I don't take off much material at all, just enuff to get an edge back if I've hit something and have a 'bite' or 'ding'.

My blades look like Fig 2. The Original SCAG blades. I still have a lot of 'Non Sharpened Edge' left. The other set are 'No-name' from a Lesco dealer (1/2 the price as SCAG blades and a little thicker, not much), they look the same os Fig 2. and leave stringers as well.

My spindles are TIGHT, no play, and I keep the deck clean underneath. I keep getting stringers. Maybe it's just the grass length and when the grass is longer thats when the rounded corners come into play. I do notice it more when I'm cutting thick, healthy, fetilized and watered grass. When I double cut all turns out SWEET. Is this just the nature of the cut?

Click on image to get a bigger shot of it.
http://img165.imageshack.us/img165/993/blade5gl.th.jpg (http://img165.imageshack.us/my.php?image=blade5gl.jpg)

Drew Gemma
09-19-2005, 03:56 PM
switch blades and when you measure blades go corner to opposite corner to get the true length. try diff set or new set see if you have a difference.

pgiambat
09-19-2005, 06:55 PM
Are you talking about point A to point B or C to D?

I imagine the shorter the distance (A to B, through sharpening) the 'shorter' the blade, yes, no?!?!

The shorter the blade, the chance of stringers increases?!?!

http://img27.imageshack.us/img27/3263/blade22zt.th.jpg (http://img27.imageshack.us/my.php?image=blade22zt.jpg)

imdawrlus
09-19-2005, 08:12 PM
distance c to d dosent change....he must be talking about a to b.....

Nosmo
09-19-2005, 10:31 PM
From A to B is the length of the cutting blade. C to D could be slightly longer when sharpened several times as a post above mentions -- at an angle like a triangle at the end.

Nosmo

pgiambat
09-20-2005, 09:57 AM
I know that, I just wanted to draft up another picture. Sometimes the draftsman in me needs out.

I just got my 52" out of the shop so this is a minor problem.

I appreciate all the replies.