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tutorial blade sharpening ,freehand grind

#1

M

motoman

If enough demand I might do a pic tutorial on how I sharpen. It's sure to stir everyone up. Well...?


#2

L

Lawnranger

Go for it! You got my vote. Watcha got?


#3

Blade Runner

Blade Runner

Lets see it. I need to sharpen my blades soon. I found out that when new blades hit bits of brick left from tornado damage, there are no winners.:biggrin:


#4

C

cjdave

I would love to see it.


#5

Parkmower

Parkmower

Don't be bashful if you've re-invented the wheel!


#6

Berniebac

Berniebac

It would sure help me out. I need some instruction on how to sharpen.


#7

B

benski

Sure! I'm feeling a little, uh, edgy!:wink: No matter what the technique, I'm a big advocate of balancing things up during a sharpening.


#8

M

motoman

OK peeps, give me some time to get the pics ready, etc. I plan to say something about "walking pedestal grinders," and show "two way tool" easily made from lowly pieces you have on hand or can easily get.:smile:


#9

M

motoman

Craftsman DYT 4000 , Intek 24 , 48" deck, 400 hrs , Bought new 2004 , Original blades still in use

This will proceed the tedious way due to limitations in these text blocs, by contnuation.

GRINDING: The grinder a good lifetime friend, but... (1) Wear a full face shield,no exceptions. (2) Don't drink and grind (3)Dropped grinding wheels crack-check 'em and pitch 'em if any doubt. Good wheels should ring when lightly tapped. (4) Leave paper washers on as received. (5) Grind on outer circumference. (6) Clean wheel periodically (below)

MACHINES: A bench top should work if the outer wheel radius is accessible. Motor sizes vary. A smaler (1/4 HP) may be better for beginners . The metal comes off slower, wheel speed is lower from 6" wheels , burning is less likely, and stallout may also help in developing the right touch. Used here is the H-Frt 1/2 HP with 8"" wheel. It doesn't stall and removes metal quickly. Pedestal is not secured to floor.


#10

M

motoman

WHEELS Shown later is the H-Frt grey wheel, 60 grit ($8-$9) 8" dia Like many chinese products quality is spotty. Sometimes the arbor hole is slightly undersize requiring drilling and/or not centered. Such wheels must be heavily "trued." (later). You can spend a lot on better wheels. I am not making furniture here. You will not hear about honing . (wheel balancing tip later).

REMOVE BLADES The owner's manual gives severe safety warning about accidental starting. As you know a tuned engine starts quickly. I only remove /install blades on cold tractor. You could be turning a propeller. :thumbdown:

Jack, Secure blade, Loosen/remove,outside first. A jackstand if you want.

CLEAN BLADE Try a duller wood chisel to loosen the "dried spinach," both sides. Wire brush.

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#11

M

motoman

BLADES Writer's experience is on 48" deck blades shown. Thickness varies by tractor. Blades shown .200" thick! Perfect for grinding. Rust resistant, alloy steel. Too nice to keep replacing and they ain't cheap....Notice below the straight edge aligned against one blade depicting the material removed in 8-9 years of sharpening (about 1/4 to 3/8") . The heft of this blade is useful as a "heatsink" during grind, lessening worry about metal burn/softening. It is also relatively easy to hold against the grind stone with your (sensitive) bare hands . As new. the blades had "hollow ground" edges (think straight razor). These pretty edges are easy to sharpen and nice and narrow. They will disappear in several sharpening episodes, at which time you will be into the "thick" of it , .200" in this case . Hollow grinding is probably not for the home shop . If you sharpen wood planes or chisels you can sharpen these blades. :smile:

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#12

M

motoman

SHARPENING We all know some fancy names for the various sharpening angles and probably know a lot of recommended angles. Not used here. If you grind a wide slope toward the edge of the blade and then grind a a decent edge the blade will CUT. No angles are therefore specified. Lets just say that too narrow an edge will not hold up as well , and too thick an edge will not cut as well. The cutting edge should be a narrow band ( say 1/16 to 1/8"). Back of it going uphill to the blade body thickness is a slope. I would like 1/2", but usually don"t make it (lazy?) The 3 blades shown have about 3/8". You will do heavy grinding to keep moving the slope slightly back to accomodate the new edge you create. Sometimes just a touch up on the edge is enough. Large nicks are not a problem here, only mole hills , weeds and grass. I think I would sharpen over deep nicks If I had them, to preserve blade material. They will eventually disappear.:thumbsup:

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#13

C

cjdave

What is the blue and red tool? Looks some thing like a blade holder. Is it home made or store bought? Thanks for the info David


#14

M

motoman

motoman said:
Craftsman DYT 4000 , Intek 24 , 48" deck, 400 hrs , Bought new 2004 , Original blades still in use

This will proceed the tedious way due to limitations in these text blocs, by contnuation.

GRINDING: The grinder a good lifetime friend, but... (1) Wear a full face shield,no exceptions. (2) Don't drink and grind (3)Dropped grinding wheels crack-check 'em and pitch 'em if any doubt. Good wheels should ring when lightly tapped. (4) Leave paper washers on as received. (5) Grind on outer circumference. (6) Clean wheel periodically (below)

MACHINES: A bench top should work if the outer wheel radius is accessible. Motor sizes vary. A smaler (1/4 HP) may be better for beginners . The metal comes off slower, wheel speed is lower from 6" wheels , burning is less likely, and stallout may also help in developing the right touch. Used here is the H-Frt 1/2 HP with 8"" wheel. It doesn't stall and removes metal quickly. Pedestal is not secured to floor.
Click to expand...

The H-Frt motor used is 3/4 hp, not 1/2. Author correction Motoman


#15

M

motoman

cjdave said:
What is the blue and red tool? Looks some thing like a blade holder. Is it home made or store bought? Thanks for the info David
Click to expand...

It's the 2 way tool I mentioned above. The sketch and dims are provided below. I originally made it to break the 100 ft lb flywheel nut loose and somehow pressed into service pulling blades. Country people may recognize the red metal as a fence post "arrow," and car people may recognize the blue as an extra hydraulic jack handle. A real simple, low cost tool that WORKS. :cool:


#16

M

motoman

motoman said:
BLADES Writer's experience is on 48" deck blades shown. Thickness varies by tractor. Blades shown .200" thick! Perfect for grinding. Rust resistant, alloy steel. Too nice to keep replacing and they ain't cheap....Notice below the straight edge aligned against one blade depicting the material removed in 8-9 years of sharpening (about 1/4 to 3/8") . The heft of this blade is useful as a "heatsink" during grind, lessening worry about metal burn/softening. It is also relatively easy to hold against the grind stone with your (sensitive) bare hands . As new, the blades had "hollow ground" edges (think straight razor). These pretty edges are easy to sharpen and nice and narrow. They will disappear in several sharpening episodes, at which time you will be into the "thick" of it , .200" in this case . Hollow grinding is probably not for the home shop . If you sharpen wood planes or chisels you can sharpen these blades. :smile:
Click to expand...

punctuation error


#17

M

motoman

FREEHAND GRINDING This means no jigs, or guides, just your feel and judgement. You all have it or can develop it. Practice on an old blade or even mild steel sheet if you want. Be as careful as you can with the blades, but I have found them forgiving .

TAPER Either final edge or the larger taper can be done first. It seems easier to start with taper. Hold the grinding side of the blade to the wheel at an angle (pic) You may find another way, but horizontal seems to encourage a notch at the end of the grinding passes near the center ( see "R" with semicircle in bluing on previous blade pics). Notches provide a weak area for cracks. Rotate the cutting edge toward you (top edge) so the wheel meets the taper area . An air gap shoulld be seen between the cutting edge and the wheel which must be maintained while grinding the taper. (...do not grind the final edge now). Start grinding at the end and moving up the blade toward the center . At the radius reduce pressure. If confident , rotate the blade slightly , (maintain the air gap), and start toward the end. If unsure , lift blade and inspect grinding path. Start over. After confidence is reached you will be able to make numerous heavy passes and reduce the .200" to a slope of your choosing. A taper pass with my beast takes 4-5 seconds, no burning. Keep wheel clean ( below). Swap blade ends and apply same number of passes and pressure . Keep blade moving.

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#18

M

motoman

Sorry "slope first pass" is out of sequence. For those who love action here's some anemic sparks. I had to "one hand" these pictures so I could take pictures. Your spark trail should be much heavier,

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#19

M

motoman

CUTTING EDGE Rotate the blade edge (top) away from you toward the wheel, eliminating the air gap. With lighter pressure than on the taper , grind toward center. Again try to finish the pass with a gentle radius rather than a notch. Feel the backside of the blade for a burr or "wire." If detected, and if you are satisfied with the cutting edge width, stop. If no burr you probably have not completed the cutting edge. Rotate the cutting edge a little further onto the wheel and repeat. You should not burn with this gentle pass ( and you keep moving , right?). Putting on the final cutting edge can be done on a finer grit wheel if you have one ( say 80 grit). You will get a smoother edge which may hold up a little better. Under magnification however , all edges look sawthooth . Finer grit wheels are more prone to burn. Just kiss the edge. Remove the wire backside with flat strokes from a mill file (flat, no angle). The first pic below shows cutting edge blued. The 4th pic below has slope blued to show the ground cutting edge. Total one way grind pass duration is about 3 seconds ( you are not presssuring the blade nearly as much as on slope )

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#20

M

Molerj

I use a 36 grit stone & a fine stone just to take off the lip on the back side. Follow the angle on the blade. If the angle is gone, time to chuck the blade. The 36 grit removes the metal faster and doesn't heat the blade so much. If I have some real heavy blades to sharpen, I will dip the blade in water every so often to avoid overheating. I also use a magna matic blade balancer. It also has a rod attached to the balancer to check if the blade is bent. If the blade isn't too bad, I use a 4 1/2 grinder with the blade in a vise. That works well on some of those odd shaped curved mulching blades.


#21

M

motoman

BALANCE The use of a 5/8" shanked bolt as a pivot point to check blade balance is specified in the Craftsman owners manual. The writer has used this method and never balanced in 9 years of grinding. Elsewhere in this forum another owner has had similar experience after 11 years grinding. This technique can not detect imbalance of just under 1/2 oz because in the course of this thread the author has assembeld a ball bearing based balance that shows one blade apparently balanced with the bolt method that is off 1/8 oz. The author's second blade that is apparently balanced is off 1/4 oz. The third blade is n/a as a show- and -tell for this thread, and only ground one side. Just below the 1/2 oz. imbalance the bolt method starts to work by allowing the heavy side of the blade to deflect. This raises the question: Is Crafstman telling us that blade imbalance below 1/2 oz is ok? Not balancing the author's tractor in 9 years has apparently not hurt, but last week 2 sump bolts loosened. This tractor is a rough ride over heavily rutted 1 -1/2acres. Let's not forget the "Harley" engine with its "potato" "potato" motion and solid motor mounts. I'll use my new balancer.


#22

M

motoman

Molerj said:
I use a 36 grit stone & a fine stone just to take off the lip on the back side. Follow the angle on the blade. If the angle is gone, time to chuck the blade. The 36 grit removes the metal faster and doesn't heat the blade so much. If I have some real heavy blades to sharpen, I will dip the blade in water every so often to avoid overheating. I also use a magna matic blade balancer. It also has a rod attached to the balancer to check if the blade is bent. If the blade isn't too bad, I use a 4 1/2 grinder with the blade in a vise. That works well on some of those odd shaped curved mulching blades.
Click to expand...

Why do you chuck the blade, and why don't you just keep regrinding it?:smile:


#23

M

motoman

Well folks, motoman has raved on enough in this thread. I will start 3 others for your continued reading enjoyment : (1)Two-way tractor tool a simple DIY (2) No stinking walking grinders (aka Put your knows to the grindstone (3) Your trick blade balancer cost WHAT? $250?...$25.?...$2.50? yep. Tell me stop anytime.:laughing:


#24

M

motoman

cjdave said:
What is the blue and red tool? Looks some thing like a blade holder. Is it home made or store bought? Thanks for the info David
Click to expand...

It's not below . Look for a new thread.


#25

M

motoman

motoman said:
FREEHAND GRINDING This means no jigs, or guides, just your feel and judgement. You all have it or can develop it. Practice on an old blade or even mild steel sheet if you want. Be as careful as you can with the blades, but I have found them forgiving .

TAPER Either final edge or the larger taper can be done first. It seems easier to start with taper. Hold the grinding side of the blade to the wheel at an angle (pic) You may find another way, but horizontal seems to encourage a notch at the end of the grinding passes near the center ( see "R" with semicircle in bluing on previous blade pics). Notches provide a weak area for cracks. Rotate the cutting edge toward you (top edge) so the wheel meets the taper area . An air gap shoulld be seen between the cutting edge and the wheel which must be maintained while grinding the taper. (...do not grind the final edge now). Start grinding at the end and moving up the blade toward the center . At the radius reduce pressure. If confident , rotate the blade slightly , (maintain the air gap), and start toward the end. If unsure , lift blade and inspect grinding path. Start over. After confidence is reached you will be able to make numerous heavy passes and reduce the .200" to a slope of your choosing. A taper pass with my beast takes 4-5 seconds, no burning. Keep wheel clean ( below). Swap blade ends and apply same number of passes and pressure . Keep blade moving.
Click to expand...
I noticed that after carefully choosing "slope" I used "taper" here. Same thing, sorry.


#26

M

motoman

motoman said:
CUTTING EDGE Rotate the blade edge (top) away from you toward the wheel, eliminating the air gap. With lighter pressure than on the taper , grind toward center. Again try to finish the pass with a gentle radius rather than a notch. Feel the backside of the blade for a burr or "wire." If detected, and if you are satisfied with the cutting edge width, stop. If no burr you probably have not completed the cutting edge. Rotate the cutting edge a little further onto the wheel and repeat. You should not burn with this gentle pass ( and you keep moving , right?). Putting on the final cutting edge can be done on a finer grit wheel if you have one ( say 80 grit). You will get a smoother edge which may hold up a little better. Under magnification however , all edges look sawthooth . Finer grit wheels are more prone to burn. Just kiss the edge. Remove the wire backside with flat strokes from a mill file (flat, no angle). The first pic below shows cutting edge blued. The 4th pic below has slope blued to show the ground cutting edge. Total one way grind pass duration is about 3 seconds ( you are not presssuring the blade nearly as much as on slope )
Click to expand...
Somehow these two pics did not make it before

Attachments







#27

M

motoman

motoman said:
BALANCE The use of a 5/8" shanked bolt as a pivot point to check blade balance is specified in the Craftsman owners manual. The writer has used this method and never balanced in 9 years of grinding. Elsewhere in this forum another owner has had similar experience after 11 years grinding. This technique can not detect imbalance of just under 1/2 oz because in the course of this thread the author has assembeld a ball bearing based balance that shows one blade apparently balanced with the bolt method that is off 1/8 oz. The author's second blade that is apparently balanced is off 1/4 oz. The third blade is n/a as a show- and -tell for this thread, and only ground one side. Just below the 1/2 oz. imbalance the bolt method starts to work by allowing the heavy side of the blade to deflect. This raises the question: Is Crafstman telling us that blade imbalance below 1/2 oz is ok? Not balancing the author's tractor in 9 years has apparently not hurt, but last week 2 sump bolts loosened. This tractor is a rough ride over heavily rutted 1 -1/2acres. Let's not forget the "Harley" engine with its "potato" "potato" motion and solid motor mounts. I'll use my new balancer.
Click to expand...

After all this time I realize "...Just below the 1/2 oz ..." should read "Just above the 1/2 oz ..." Sorry :ashamed:


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