Export thread

I purchased a bench grinder several years ago an heve never used it. When sharpening my Kubota mower blades should I use the angle guide on the grinder? Aside from wearing safety glasses and gloves, are the any other cautions? The wheel turns toward me and I assume I should place the sharp edge up. Is that correct?

Check your mower owner's manual for correct blade sharpening angle. I've seen a range of 20-30 degrees depending on cutting conditions. Look at the current angle and you should grind to an angle similar to the existing angle. Yes to your question-sharp edge will be at top of grinding wheel.

Read the grinder owner's manual for all the safety precautions they recommend. You may want to wear a wrap-around face shield to protect your face & neck, too.

Be sure that the blade is balanced after you sharpen it, can cause problems.

You should practice on a scrap piece of metal to get the hang of using your bench grinder.

Wear gloves and eye protection. Keep flamable items away.

Practice makes perfect.
Good Luck,
MNBen

Be sure not to overheat the metal when grinding - overheating will destroy the hardening of the metal!
I use a angle grinder - it's more easy to mount the knifes in a bench clamp and then grind carefully with the angle grinder...

On push mower types I put mine in the vise and use a belt sander. Easy to follow the angle and it looks like a new one when finished. If it needs much I just buy a new one.

wosadczuk said:

I purchased a bench grinder several years ago an heve never used it. When sharpening my Kubota mower blades should I use the angle guide on the grinder? Aside from wearing safety glasses and gloves, are the any other cautions? The wheel turns toward me and I assume I should place the sharp edge up. Is that correct?

Click to expand...

(2 part answer from motoman)
I have sharpened for years like you are planning. Still use the original blades since 2004. Some tips.
I use a roughing wheel (60 grit ), 8" H-Frt bigger pedestal grinder. My blades came with "hollow ground" edges. These will disappear in several grindings so you need to get aggressive with the blade thickness behind the cutting edge .. Specifically to put a "secondary bevel" behind the "primary bevel." This sounds like BS? Then forget the words and know that the blade thickness must be reduced up to 1/2 " back of the cutting edge, and sloped toward your final cutting edge.

Yes, the wheel comes toward you and you may find you must hold the blade at an angle for your grinding passes. Practice to make continuous passes so you do not notch or burn the blade. I typically make 3 heavy passes for the "secondary" and then two lighter passes for the final (primary).

wosadczuk said:

I purchased a bench grinder several years ago an heve never used it. When sharpening my Kubota mower blades should I use the angle guide on the grinder? Aside from wearing safety glasses and gloves, are the any other cautions? The wheel turns toward me and I assume I should place the sharp edge up. Is that correct?

Click to expand...

( part 2 answer motoman) The primary bevel (cutting edge) can be finished on a finer wheel if you have one until the classic "wire" is felt on the reverse side. Stroke the back side flat with a mill file to eliminate the wre.

Mfgrs make a big deal out of sharpening and often prohibit it. This is probably sales oriented, but be careful about notches which are often culprits in metal failure. At the end of the grinding pass inboard you will encounter the termination area which blends into the rectangular cross section of the blade at the center section. Try to go easy there and end in a gentle radius. This "blind" grinding is not so easy at first, but you will develop a feel for it. Keep cleaning the wheel to minimize burning.
I have never tried the free hand disc or belt:thumbsup: grinding but they seem to have their advantages. I have not had to balance yet . Good luck

Thanks for all the helpful suggestions. Will give it a try soon and report back.

Two things to remember when and if you should grind a blade. One, when the thickness of the blade on the back corner is less than 1/32" the blade should be replaced. Two, on mulching and high lift blades, if you see undercutting on the wing, the blade should be replaced. This is just a safety precaution, most people don't realize that blades wear on the back edges also.