Sharpening mower blades

[LD1]

I prefer my angle grinder.

1. as others said, it aint rocket science
2. I already have many

I would hate to buy a $650 tool for the sole purpose of sharpening mower blades....unless I owned a mowing business and had many mowers.

 

[the old grind]

I'm with oosik, too. Clamp blade in vise or similar with the edge up. Hold the AG firmly with your arms and rock your body to go across the cutting edge. This will help you maintain a consistent angle, whatever you choose.

Don't be concerned with 'facets' when grinding. Don't try to remove every nick, either, they'll clean up on a successive re-sharpen.

Balancing the blade is most important to reduce vibration and wear & tear on spindles. Edge quality (sharpness) is secondary, and only on the first cutting after sharpening are blades razor sharp. Keep it simple, and mow 'tall'. :thumbsup:

tog
(journeyman toolmaker/tool grinder, ret'd)

 

[prs]

I have large belt sander intended for wood working. The bed or platen can be set from angled down to fat to straight up. With the bed set horizontal and with metal sanding aggressive belt in place it makes short work of getting blades razor sharp without over heating and keeping original bevel for full depth of cutting edge. I figured the belt would ruin quickly with tool steel blades, but I have used it for years with same belt and I sharpen about every 25 hours of use. It will do normal and left hand blades with same ease. Mine takes common 8" X 48" belts. I balance on a NoMar motorcycle wheel balance stand, the rod fits the Ventrac holes perfectly. And a tip in general, when I sharpen the blades are razor sharp, but if I use them that way the edge peens back and dulls quickly, but if take a medium carborundum axe stone and hand rub the razor edge at 90 degrees in circular motion very lightly to soften that razor edge, they cut just as well much longer.

prs

 

[jcummins]

Burr King x4 Mower Blade Sharpening - YouTube

But no way I buy one of those, unless I was in the business of sharpening blaes.

 

[PhysAssist]

I have always used an angle grinder, because that was easier for me than the small 6" bench grinder that I had used before that, and putting the blade into a vice was part of the why it was easier.

For the past couple of years, I have been using my small [compared to KThompson and PRS's monsters @ 4" x 36"] HF belt sander with a 60 grit Zirconia belt.

The sander has just enough platen for me to sharpen my blades and with the belt laid flat, and oriented that way, maintaining the angle is really easy.

A hint my old man gave me a long long time ago: If you get the edges sharpened to where you want/need them, and then find out that one end is heavier than the other, don't regrind the edge, just grind a little off either the flat [non-edge] corner or the flat edge of the heavy end.

Thomas

 

[pmsmechanic]

Sometimes cleaning under the deck takes much longer than replacing the blades to remove all the mud adhering from splattered crawfish mounds.

I find that mowing the grass when it's damp makes the grass stick to the deck really well. So I mow either on the dew or when the grass is bone dry. The best is just after or during a rain. The water droplets wash everything off.

 

[prs]

I have always used an angle grinder, because that was easier for me than the small 6" bench grinder that I had used before that, and putting the blade into a vice was part of the why it was easier.

For the past couple of years, I have been using my small [compared to KThompson and PRS's monsters @ 4" x 36"] HF belt sander with a 60 grit Zirconia belt.

Thomas

I was trying to think of what kind of abrasive and what grit grade the belts are; same as you say. I would not pay the new price for the machine either and mine is so old (1969) when I was more into wood working. I also do as you explained about having the platen flat and holding the blade by hand at correct angle, its easy peasy.

I check balance before sharpening so if one end is a bit heavy, I go ahead and give it an extra pass or two across the belt. Then check balance again after the fact. My first step is to remove all organic build-up on the blades and then use a mill file to remove any nicks on the flat side by running the file on the flat -- NO bevel there.

prs

 

[PhysAssist]

I was trying to think of what kind of abrasive and what grit grade the belts are; same as you say. I would not pay the new price for the machine either and mine is so old (1969) when I was more into wood working. I also do as you explained about having the platen flat and holding the blade by hand at correct angle, its easy peasy.

I check balance before sharpening so if one end is a bit heavy, I go ahead and give it an extra pass or two across the belt. Then check balance again after the fact. My first step is to remove all organic build-up on the blades and then use a mill file to remove any nicks on the flat side by running the file on the flat -- NO bevel there.

prs

Great clarification and description, I need to go back to the file.

My SWMBO has been mowing more often than I have because of my work hours, and she has a real knack for finding the hidden rocks [usually more like boulders], so there have been a lot more [and a lot bigger] dings in our blades.

While I'm not at all committed to a pristine lawn [our "yard" is more like clearings between the trees, and we have a lot of areas where it's more broadleaf than grass, having a set of spare blades sharpened and ready to pop on seems like a great idea.

Thanks,
Thomas

PS: I might start looking on CL for a big old used belt machine in addition to my other regular local searches.

 

[TNMark1]

I flip the mower up and lightly dress them with an angle grinder that was about $20 at Harbor Freight... Takes a couple minutes every 20 hours or so..

Mark H

 

[Ford850]

I buy a second set of blades, and sharpen them when I have time, so that spare set is always ready to swap out when the set in use gets dull. Then install the sharp set and toss the dull blades on the bench to be sharpened on a rainy day.
I clean the blades with a putty knife and/or wire brush before sharpening. It's worth the couple minutes and makes it easier to sharpen and balance.
I've settled on the flap disk in an angle grinder, with the coarsest grit I can find. They sharpen fast, remain cool, and leave an excellent edge. I lightly hit the full angled edge a couple passes, then add a quick steeper angle to sharpen just the edge. That steeper angle stays sharp longer and allows me to have more blade life by taking less off while sharpening. I don't avoid sticks and limbs, actually I try to mow them to chop up and clean my deck.
This year I bought an extra angle grinder from HF to use as my dedicated blade sharpener. That way I can leave the flap disk on and it's ready to go on those rainy days. I used to hate sharpening blades, but now it's enjoyable and only takes minutes to clean and sharpen 6 blades.