# Sharpen a blade?



## CenlaLowell (Apr 21, 2017)

What is the best way to sharpen your mower blades? I now use a handheld grinder and even though it looks sharp when I finish I'm still getting dull blades. Let's hear it what tools do you use to sharpen your mower blades?


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## DTCC_Turf (May 26, 2018)

I use a bench grinder most of the time. I know I don't keep the original angle, but it seems to be just fine.


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## pennstater2005 (Jul 17, 2017)

DTCC_Turf said:


> I use a bench grinder most of the time. I know I don't keep the original angle, but it seems to be just fine.


Same. Bench grinder. I just don't do it enough.


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## FlaDave (Jul 10, 2018)

I use an angle grinder with 180 grit and finish with a knife sharpener. Seems to work well


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## chrismar (May 25, 2017)

angle grinder here too, with an 80 grit flap roloc.


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## jbaav (Jul 13, 2018)

I mount mine in a vise and use a 10" mill bastard file. Doesn't take long at all to get a nice edge. I try to count my strokes and match on each edge so I can balance easily. I get better results this way than when I used my bench grinder.


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## g-man (Jun 15, 2017)

^+1


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## ForsheeMS (May 21, 2018)

I use one of these on a 4.5" angle grinder. Nowhere near as aggressive as a stone but much quicker than a file. I sharpen my blades often so it only takes a few passes to get the edge back.


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## CenlaLowell (Apr 21, 2017)

ForsheeMS said:


> I use one of these on a 4.5" angle grinder. Nowhere near as aggressive as a stone but much quicker than a file. I sharpen my blades often so it only takes a few passes to get the edge back.


I'm really considering going buy one of these. This is what I'm using.


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## CenlaLowell (Apr 21, 2017)

The reason I'm asking these questions is because I'm still getting torn grass blades not all over the yard just in certain spots I don't want any more fungus Lord knows


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## Powhatan (Dec 15, 2017)

I use a hand file on my 22" push mower blade every time I mow with it, not perfect but it get's the job done fairly well. For my JD riding mower, I let the local JD dealer sharpen the mulch blades, I presume they use a bench grinder because the blades come back nice evenly sharp.


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## g-man (Jun 15, 2017)

@CenlaLowell check your rpm too.


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## Shindoman (Apr 22, 2018)

I use a 3 x 21 belt sander


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## CenlaLowell (Apr 21, 2017)

g-man said:


> @CenlaLowell check your rpm too.


How do you do that? It's a Craftsman push mower.


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## g-man (Jun 15, 2017)

On Amazon they sell rpm meters. They use the spark plugs to determine the machine rpm. You then adjust to the manual specifications. @GrassDaddy has a video of it. Search his videos.


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## Rene (May 18, 2018)

You can download differently free stroboscoop in the app store. Works reasonable well.

Don't measure the blade but the fan on the engine.


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## CenlaLowell (Apr 21, 2017)

I think I found the problem with rpm. Filter was dirty and engine was missing just a little. I couldn't tell at first because I wear headphones when I cut grass. Thanks


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## marshtj (Apr 9, 2018)

I'll add my two cents. I was struggling with this, then bought an angle grinder with the disks. This method works great, but for me was a little time-consuming. So, I bought:

https://www.amazon.com/Micro-Mark-Wet-Dry-Utility-Sharpener/dp/B06XH7FW1Q/ref=pd_sbs_469_2?_encoding=UTF8&pd_rd_i=B06XH7FW1Q&pd_rd_r=dfaea81f-91df-11e8-bdf3-a194229cc61a&pd_rd_w=x4Idx&pd_rd_wg=zXKRp&pf_rd_i=desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=8702255303818932494&pf_rd_r=1VP7Z5ND589ECTFE2ZE1&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=1VP7Z5ND589ECTFE2ZE1

This thing is perfect for lawn mower blades.


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## FlaDave (Jul 10, 2018)

marshtj said:


> I'll add my two cents. I was struggling with this, then bought an angle grinder with the disks. This method works great, but for me was a little time-consuming. So, I bought:
> 
> https://www.amazon.com/Micro-Mark-Wet-Dry-Utility-Sharpener/dp/B06XH7FW1Q/ref=pd_sbs_469_2?_encoding=UTF8&pd_rd_i=B06XH7FW1Q&pd_rd_r=dfaea81f-91df-11e8-bdf3-a194229cc61a&pd_rd_w=x4Idx&pd_rd_wg=zXKRp&pf_rd_i=desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=8702255303818932494&pf_rd_r=1VP7Z5ND589ECTFE2ZE1&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=1VP7Z5ND589ECTFE2ZE1
> 
> This thing is perfect for lawn mower blades.


That's interesting. Have you used it for knives at all?


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## marshtj (Apr 9, 2018)

No, I sharpen my knives by hand. I have used it to sharpen some various garden tools.


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## Superbigstevie (Aug 12, 2018)

I use a rolok disk and a die grinder. Cut pretty cool and therefore will not remove the temper of the steel like a bench grinder will.


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## marshtj (Apr 9, 2018)

Superbigstevie said:


> I use a rolok disk and a die grinder. Cut pretty cool and therefore will not remove the temper of the steel like a bench grinder will.


You would have to get the temperature of the blade way above the limit of what someone could hold onto to even affect the temper.


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## gene_stl (Oct 29, 2017)

> You would have to get the temperature of the blade way above the limit of what someone could hold onto to even affect the temper.


The small area just by the cutting edge often glows white hot and even dull red destroys temper. The only place the temper matters very much is at the edge. This is why for example when you (used) to sharpen drill bits. there was a water can sitting next to the grinder so that you could cool it off and not anneal or draw the temper of the steel. Even high speed steel can be annealed and mower blades are not made of high speed steel. Sparks are for fireworks not tool sharpening.

There are pros and cons to all the different methods. I like belt grinders and wet wheels though wet wheels are a royal pia.
They give accurate angles and don't draw the temper. Mower blades work harden during their use and as they get older probably hold the edge longer. If you jam them into a grinding wheel (as many commercial sharpening machines do)
you anneal them down to a very soft state.


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## Chaseweeks1 (Jul 27, 2018)

If the blade is really beat up then I start with a bench grinder, then refine it with an angle grinder then I finish everything with a long file, if you don't finish with a hand file then it won't be as sharp.


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