Super Cheap Lawn Mower Blade Sharpening Jig

[The Suburban Farmer]

Well, after trying to mow yesterday and getting less than an ideal cut, I remembered to check my blades and they were dull, dull, dull. Chipped, too. I THOUGHT that I'd sharpened them at the end of the fall season, but I guess I didn't.

I had a lot of nicks to take out and wanted to make sure I kept a consistent angle, so I rigged up a jig using some scrap lumber and an old unused Harbor Freight angle grinder. I measured my blade angle and it was somewhere around 30 degrees (but hard to tell since they were beat to heck) so I fabbed this with a 30 degree angle. The nice thing is that I can easily make-up another holder using 40 or 45 or anything else I need when the time comes.

Not a high-dollar piece of art, but it was functional and put a great edge on all 3 of my blades in less than 10 minutes. Back-honed the blades with a stone to remove a few burrs and now they look good as new. Sure beats paying $200 for a specialized lawn mower sharpening tool.

I'm not sure if this will work for mulching blades, though. This relies on having a flat and relatively straight back edge on the blade to work.

 

[Sodo]

That ought to do it. Do you balance the blade when you're done? I've been balancing mine on a hacksaw blade and that's been good enough (I think).

I dress them a few times without removing the blade from the mower - by using the top of the grinding disc. But you have to pay attention to the fabric ontop of the disc, if you lose more than just a little you should understand that fabric ontop could be holding your stone together. So keep it down to a minor dressup if using the top of the disc. You don't want a rounded edge ontop of the disc.

 

[Sysop]

Awesome jig. I'd also balance the blades after taking out chips and notches. Being off even a bit is enough to cause premature wear and failure on the spindle bearings. Replacing one spindle is generally $100+ for all the decks I've ever messed with, and I've never seen a deck all the blades couldn't be replaced for MUCH cheaper. Seeing as I'm always working with limited time, I don't buy a mower without buying a set of extra blades. I've found it best to have a spare set of blades sharpened and ready to go. When I have time in the schedule to mow, I don't have additional time to spend sharpening blades (rather do that during bad weather when I can't cut grass). Anytime I don't get a satisfactory cut, I take the ten minutes to swap blades and go back to work laying the old set aside for a rainy day. I think my next rainy day will be spent making a jig similar to yours. My bench grinder has an adjustable plate to help control the angle of your stock to the wheel, but it is very imperfect of a solution. I think your setup would create a flatter more precise edge.

 

[The Suburban Farmer]

Yes, I balance them as well using one of these little things that I got on Amazon for like $3 a while back:



When I took out the big nicks, they were a bit out of balance, so I ran them through the sharpening jig until they floated perfectly level on the balancer. Now, hopefully, if I do the same number of passes on each side, they should stay in balance for touch up.

 

[deerseeker001]

thats what I use.

Yes, I balance them as well using one of these little things that I got on Amazon for like $3 a while back:

View attachment 421682

When I took out the big nicks, they were a bit out of balance, so I ran them through the sharpening jig until they floated perfectly level on the balancer. Now, hopefully, if I do the same number of passes on each side, they should stay in balance for touch up.

 

[Bird]

Yes, I balance them as well using one of these little things that I got on Amazon for like $3 a while back:

View attachment 421682

When I took out the big nicks, they were a bit out of balance, so I ran them through the sharpening jig until they floated perfectly level on the balancer. Now, hopefully, if I do the same number of passes on each side, they should stay in balance for touch up.

I, too, have that same balancing gadget.

 

[franklin2]

What is the significance of the angle on the blade and what can one expect when going one way or the other(-30 or +30 degrees)?