# rotozip for grinding?



## Rald (Jan 29, 2010)

I already have a rotozip rz20 that I purchased for previous projects and would like to use it with a flap disk to sharpen my lawn mower blades. I started researching to make sure I purchase the right disk and couldn't find anyone using their rotozip this way. Any unique safety concerns using the rotozip like an angle grinder? If not unsafe, any suggestions on which disks to use/avoid?


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## joecaption (Nov 30, 2011)

Wrong tool for the job.
A 4-1/2" right angle grinder with a metal grinding blade would be safer and faster.


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## VIPlumber (Aug 2, 2010)

I was at Lee Valley the other day and had seen this bit for use in a drill, http://www.leevalley.com/en/garden/page.aspx?p=10185&cat=2,2160,40710


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## user1007 (Sep 23, 2009)

My sharpening folks used to charge me $2-5 or something to sharpen and balance mower blades. 

You are going to spend that on a disc or two and melt that Roto tool in your hand trying to use it to grind decent metal mower blades. It is the wrong tool for the job. You will never be able to hold a cutting angle.

If you must sharpen your own blades a bench grinder with decent wheels will set you back a bit but will come with a plate to hold the blade at a fixed angle against the wheel. If all you need it for is sharpening your lawnmower blade I would guess you could pick one up, with grinding wheels for $40 or so. I nice one with a diligent motor will, of course, be more. 

I used to take a hand held cross cut file to mower blades after each use also. Would never dream of taking a roto tool or even an angle grinder to sharpening a lawnmower blade though.


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## Rald (Jan 29, 2010)

The local shop has gone up to $8 per blade in my area. With 3 blades and several acres, it's worth a little equipment investment. Many use the 4 1/2 angle grinder on mower blades. It seems like one could keep an adequate angle with the blade in a vice. The angle grinder will cost me less than a bench grinder with tool plate. Is it difficult for the 'average' DIY person to do a good job with an angle grinder?


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## joecaption (Nov 30, 2011)

Simple to do, do not try and grind at a steep angle like a knife blade. About 15 deg. is all that's needed. To steep an agle and the blade will be to thin and dull up to fast.


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## user1007 (Sep 23, 2009)

joecaption said:


> Simple to do, do not try and grind at a steep angle like a knife blade. About 15 deg. is all that's needed. To steep an agle and the blade will be to thin and dull up to fast.


Hugh?Sublime to absurd the comment, the OP is not going to hold any consistent angle holding but a hand file to a degree edge cut by a machine sitting on a bench. Clamping his rototool in a vice will not help even with a little 5" quarter inch thick disc spinning. He needs to respect and hold the blade in hand, not the cutting/sharpening wheel.

As has been posted, the OP is trying to justify the wrong tool for the job. I don't mean to hurt his feelings but... Buy the bench grinder set up that will take on hardened steel lawn mower blades. 

Guys/gals who think they can hand hold and take angle grinders to the task of sharpening anything live in the land of fools.


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## toolaholic (Jul 31, 2011)

I use my dremel with the lawn mower blade attachment that keeps the sharpening stone at the right angle! Works fine!


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## PaliBob (Jun 11, 2008)

toolaholic said:


> I use my dremel with the lawn mower blade attachment that keeps the sharpening stone at the right angle! Works fine!


 Cool tool, Dremel sells it as a *Lawn Mower and Garden Tool Sharpener Attachment* 
The guide keeps the included grinding stone at the correct angle.
http://www.amazon.com/Dremel-675-Garden-Sharpener-Attachment/dp/B00008Z9ZR
.


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## Maintenance 6 (Feb 26, 2008)

Welcome to the land of fools. I've used a handheld 4-1/2" angle grinder to sharpen mower blades for years without any ill effects. As long as you hold a reasonable angle and balance the blade, it will cut. The grass only cares that the blade is sharp, not how it got that way. Sharpen too thin and the edge won't last. Too blunt and it will take more power to cut and not do a very nice shearing job. It's a mower blade, not a surgical instrument.

p.s. I don't use the angle grinder to sharpen my jointer knives........ but then I don't cut grass with the jointer either.


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