Sharpening Mulching Blades

[botalvr]

Anyone else have trouble sharping these darned things? I am OK with regualr blades, but these things have a hump surface that gives me fits? Hand grinder? I know I am tired of paying my local sharpening shop $24 each time I get them done, what with a new set at $55. Of course buying a new set each time is silly.
Any advice besides a hand file would be appreciated, my bench grinder chews them up, it must be me.

Thanks

 

[btolle]

4 1/2" grinder. Harbor Freight 4-1/2'' Industrial angle grinder with paddle switch

Bill Tolle

 

[botalvr]

Thanks!

 

[Tom_H]

I also have the Harbor Freight angle grinder and use it on mulch blades. I put the blades in a bench vise and sharpen freehand.

Make sure not to stay in one spot too long; this will overheat and distemper the metal.

Be sure the blade is balanced when you're done. There are fancy tools to get very precise balance, but a finish nail in a garage wall stud is what I use. If one side drops lower than the other, take a little more off that side. Unbalanced blades lead to excessive vibration and the problems which follow from that.

Try to keep the same angle the blade originally had, or as close as you can. It can be a challenge.

Placing the grinding stone perpendicular to the blade will result in a "hollow ground" bevel. Turning the grinding stone parallel to the blade will allow for a bevel which is more "planar" (as in a flat planed surface). Most folks well versed on this will say to avoid hollow ground edges.

Good luck.

 

[escavader]

Yes ,use a hand grinder.Dont forget to balance them after,a nail on the wall,aint too bad for checking this.If it has a tendency to tip one way do some more grinding on the heavy side.No one likes a mower with vibrations
ESCAVADER

 

[Bird]

The last time I sharpened a lawnmower blade, I used my Dremel because I sold my bench grinder and 4.5" grinder when I moved back to town. /forums/images/graemlins/laugh.gif Now a Dremel and grinding stone is slow, but if you aren't busy with something else, and can sit in the shade and sip your favorite beverage while doing it, the Dremel works quite well. /forums/images/graemlins/laugh.gif

 

[Barnboy]

I use the 4 1/2 inch grinder too. They make a sanding wheel for those that does a better job than a grinding wheel. Its not as agressive as the grinding wheel so it dont get the metal to hot. Does a great job! well worth the $8.00 It looks like sand paper laid flat stacked on top of each other in a circle.

 

[Egon]

Anyone try a file or whetstone?

The whetstone is a real good excuse to sit in the shade relaxing and sharpening at the same time. Doesn't overheat the blade and will probably give a better edge. /forums/images/graemlins/grin.gif

Egon

 

[Bird]

Egon, I've used a manual file before and that's even a slower than the Dremel; never tried a whetstone but would think that would really be too slow.

 

[Junkman]

If I used a file or whetstone, I might be dead before I got all 3 blades sharpened. That is why I don't buy green bananas!! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[Egon]

Sounds like you need to relax more! /forums/images/graemlins/grin.gif

Egon

 

[Egon]

Bird:

The object is relaxation. Comfortable chair, shade, nice view , cool refreshment and something to keep " She Whom Will Find Jobs " thinking you are engaged in very usefull work. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Egon /forums/images/graemlins/grin.gif

 

[surfran]

I have used the angle grinder on my old blades several times, but this year on my Kubota I decided to use the hand file and it worked great and didn't take very long.

I made a wooden wedge to get the correct angle and held that with the file to do the filing. Stored the wedge in with the file for future as well.

Now my blades weren't beaten up very bad and that makes a diference, but still wasn't too bad.

Getting the correct angle was the problem I always had with the hand grinder as each pass I seemed to so slightly different.

 

[gsxr1100]

I have to agree. I end up doing my sets of blades and the "old-mans" So it takes me a about 1 hour to do about 12 blades with bench grinder (wire wheel blades clean first), and small 1" belt sander for dress-up work.

Just keep angle the best you can, do not break through heat treat (a few thousandths deep) and then balance when finished. Check with piece of paper when finished (or use finger nail ; with blade perpendicular)

 

[SDT]

Realizing you specifically asked for advise other than the use of a hand file, I recommend the file anyway. I use a 4 1/2 inch angle grinder on both of my bush hogs but a good hand file on both my Kubota 60" MMM with high vacuum blades and my walk-behind trim mower with mulching blade. I can get much better results with the hand file, and remove less metal in the process. Takes me about 5 minutes for the mulching blade, after I have removed it, of course. I do need to buy a good file about every other year however.

Dean

 

[TheKid]

I clamp my cheap old B+D belt sander with a 60 grit belt in my vise. It sharpens pretty quickly without burning the edge.