sharpen lawn mower blade with file

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Old 08-12-19, 03:37 PM
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sharpen lawn mower blade with file

I was planning on trying to sharpen my lawn mower blade with a metal file. It's an average lawn mower blade for an average gas-powered lawn mower. I have this particular assortment of files, some of which a little on the rusty side from improper storage/maintenance. Any comments on which of these might be most appropriate (or about good enough anyway ) to use, and how would I determine the what course-ness or fine-ness of file to use? Any comments/advice appreciated! (Utility knife in photo there to help show relative size(s) of the files.)

 
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Old 08-12-19, 03:39 PM
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If the blade is real bad start with a course then move to medium. If the edge is totally nicked and blunted, I've my grind stone to bring back to a cutting edge. Just be sure it's balanced.
 
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Old 08-12-19, 04:03 PM
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Thanks Norm 201. I'll go for it.
 
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Old 08-12-19, 04:39 PM
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I use my bench grinder with fine stone, can sharpen any blade in 2-4 minutes, can't imagine trying to work a big nick out of the blade edge by hand!
 
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Old 08-12-19, 07:14 PM
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For what's they're worth I've taken photos of each end of the mower blade so it might be seen/determined the condition of the edge(s) and so as to obtain any further comments thereof. I do have a grinding wheel (bench type) a but the grit on the wheel is not particularly fine; don't really want to spend bucks for a new finer-grit wheel for one mower blade, but could I suppose. Also I have an angle grinder I suppose I could use, with varying grits of wheels for it too. Looks pretty easy/straightforward when the guys on youtube demonstrate filing mower blades with metal file, although I'm not sure whether my blade would be necessarily be considered "totally nicked and blunted" but perhaps it is.



 
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Old 08-13-19, 01:52 AM
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That blade looks to be in very good condition, file away!
 
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Old 08-13-19, 03:08 AM
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Although that doesn't look bad as Marq said I usually us a power tool, belt sander, angle grinder, bench grinder. Don't get carried away with making it ready to carve the Thanksgiving turkey and big nicks can stay as opposed to removing a lot of metal. Do balance.

Bud
 
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Old 08-13-19, 03:40 AM
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Impossible to sharpen an inside radius with a flat file. Suggest you get a semi-round or rattail file (medium cut) to do the inside radius.
 
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Old 08-13-19, 03:49 AM
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Back when I was young and didn't have many tools I sharped lawn mower blades with a file but it's so much easier/quicker to do it with power tools. As Bud said, you can use a bench grinder, angle grinder, belt sander or even a stone chucked up in a drill. I'd use this as an excuse to expand my tool arsenal
 
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Old 08-13-19, 04:52 AM
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I agree with a grinder, but, if my blades looked like that when it came time to sharpen them, I would use a file too. In fact that's how I often did them for a few of the older ladies I used to do things like that for in town. Sure, it might take a little bit longer, although I generally final dress mine with a file anyway so maybe no longer to use the file for the entire job, and no sense removing any more metal than necessary. They had nice flat lawns, few enough branches on the ground to pick them all up each time, paved streets and sidewalks, etc. In my case though for example, country lawn so a little sparse in some areas meaning more soil dust getting picked up, especially with a recycling deck that has plenty of lift, a gravel driveway and gravel road, and lots of trees dropping branches, my blades take too much of a beating and would take way too long to do by hand. But with a thicker and more even lawn, no obstructions, yeah, your blades look in great shape so I would touch them up by hand and call it good.
 
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Old 08-13-19, 05:29 AM
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I have done a ton of blades and drill bits on the bench grinder. As others have mentioned, softer stone and follow the existing angle.
Another thing you will want is a screw or nail in a wall near where you are working, 90' to the wall. When you think you are good, place the blade with the nail through the center hole, blade parallel to the ground. Let go and watch for a side to drop. If one side drops, need to take another pass on that side or hit the back of the blade with the grinder. Test and repeat until you can let the blade go and it stays level.
An unbalanced blade can destroy a motor.
 
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Old 08-13-19, 08:11 AM
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your blades look in great shape so I would touch them up by hand and call it good.
I'd been planning to go this method, following these instructions, to sharpen the blade, as shown on the video, but was just wondering which of my files which vary in size and course-ness might be most appropriate.

https://www.youtube.com/watch?v=qFusHPPmOFo
 
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Old 08-13-19, 08:53 AM
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Oh yeah, sorry, but forgot you had asked about which file to use. The first part is easy, making sure you have the blade firmly secured in the vise, but after that, in my opinion, it becomes a bit more ambiguous, arbitrary, or whatever you want to call it because I'm not sure there is a right or wrong answer in regard to file selection, at least for general use. So first off I would want a file as wide as possible in order to maintain the plane along the cutting edge, definitely not, for example, the three sided one. Then you want to start coarse obviously and work your way to a finer one. As you run your file across your blade it will talk to you. If it doesn't float across the blade you're probably too coarse. If it sort of sings to you you're probably too fine, at the wrong angle, or not clamped good. So basically, clamp the blade good, grab a file, and you'll know if it's the right one. And you're cutting grass, not your beard, so you want it sharp, but don't get too carried away with it because too sharp is going to get knicked up sooner.
 
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Old 08-13-19, 09:15 AM
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Got it.
Thanks everyone for all the helpful replies/comments.
 
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Old 08-13-19, 11:30 AM
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Just don't forget to check the balance of the blade when done. Probably more important than the blade being sharp
 
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Old 08-13-19, 11:54 AM
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Right. won't forget to check balance. thanx
 
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