Grinding bevel on chisel or plane blades with a bench grinder

[Pat Barry]

I would like to use my bench grinder to do the primary bevel on my chisels and plane blades so that I can do this task more quickly. I have two questions:

1) Do you grind into the point of the chisel or away from it? It frankly scares me to touch the tool such that the tip is on the leading edge of the wheel. It seem that I would be asking for the tip of the tool to get caught in the wheel and throw it or break my finger / wrist. How do you this operation safely? Or do you grind from heel to toe? Any other tips to make this operation safe and effective?

2) Also, I know that I mustn't dwell too long so that I don't generate too much heat and muck up the temper. Maybe having small cup of water to quench the blade and keep it cool would be a good idea, I've seen this technique practiced by machinists previously. Do you fellows do this, or do you just rely on touch to let you know its getting to hot and let it cool down in air?

[Daniel Rode]

http://www.finewoodworking.com/how-to/article/grind-perfect-edges-without-burning.aspx

[David Weaver]

Keep your rest close to the wheel, grind with the wheel turning into the bevel, and use a coarse wheel (that you keep dressed regularly if it's hard and tends to glaze over).

I have never kept water at my grinder for maintenance grinding. I've switched to a pink surface grinding wheel in the last year, 46 grit (hard to find if your grinder isn't 7", and mine's not) and I can touch the iron to my hand when I'm done grinding. I grind approximately once every 4 full hones, depending on what the iron tolerates, and I grind when the bevel gets large enough that it takes longer than I want to raise a wire edge.

Experience is what you need grinding. Keep your wheel fresh, start with light pressure until you learn what you can get away with (it's never going to be heavy pressure, but you will progress to moderate) and keep the iron or chisel moving. Expect to have some ugly hollows the first few times you grind, but it's like riding a bike - seems hard to do accurately at first and then is thoughtless pretty quick.

[Jessica Pierce-LaRose]

Joel Moskowitz's article that Daniel linked below is a good one, helpful. Worth tracking down if you can. If you don't have FWW, try your local library.



I would like to use my bench grinder to do the primary bevel on my chisels and plane blades so that I can do this task more quickly. I have two questions:

1) Do you grind into the point of the chisel or away from it? It frankly scares me to touch the tool such that the tip is on the leading edge of the wheel. It seem that I would be asking for the tip of the tool to get caught in the wheel and throw it or break my finger / wrist. How do you this operation safely? Or do you grind from heel to toe? Any other tips to make this operation safe and effective?


I'm not even sure how you'd grind a chisel any other way than how one would normally grind it, unless you've just got a big open wheel with no guards and no tool rest. I guess I'm almost lost by your question here. Just look at any image of grinding a chisel, or look at how aftermarket tool rest like Lee Valley's set up, and you should get the idea. Heck, just look at how the tool rests that come on most bench grinders are positioned, and it answers your question, I guess.

A properly adjusted tool rest will keep the tool from getting caught in the grinder and breaking something. The action of the wheel actually pushes the tool into the rest. If you managed to find a way to sharpen the tool in the other direction (perhaps working on the top of the wheel, or the wheel spinning the wrong way or something?) it be much more apt to try to pull the tool and fling it away.





2) Also, I know that I mustn't dwell too long so that I don't generate too much heat and muck up the temper. Maybe having small cup of water to quench the blade and keep it cool would be a good idea, I've seen this technique practiced by machinists previously. Do you fellows do this, or do you just rely on touch to let you know its getting to hot and let it cool down in air?

I keep a little cup of water by my grinder in case things get too hot. I often let a little bit of water rest on the back of the tool, if it starts to "dance a little bit, I know it's getting hot.

[Dave Cullen]

I'm sure there will be multiple answers, as each woodworker seems to have a different approach.


I would like to use my bench grinder to do the primary bevel on my chisels and plane blades so that I can do this task more quickly. I have two questions:

1) Do you grind into the point of the chisel or away from it? It frankly scares me to touch the tool such that the tip is on the leading edge of the wheel. It seem that I would be asking for the tip of the tool to get caught in the wheel and throw it or break my finger / wrist. How do you this operation safely? Or do you grind from heel to toe? Any other tips to make this operation safe and effective?

Yes, I grind with the edge "up". With a good tool rest platform, the angle is always upward against the wheel and there's no real way to catch the tool and throw it back.



2) Also, I know that I mustn't dwell too long so that I don't generate too much heat and muck up the temper. Maybe having small cup of water to quench the blade and keep it cool would be a good idea, I've seen this technique practiced by machinists previously. Do you fellows do this, or do you just rely on touch to let you know its getting to hot and let it cool down in air?

I judge by feel. I never let the tool get hot enough so I can't put my fingers on it. I will keep a cup of water near the grinder but rarely use it. Compressed air works well too. But basically my grinder is used to touchup a nicked bevel or regrind the hollow grind on a plane iron, and that's very light passes.

[Daniel Rode]

I use a 8" white Norton Aluminum Oxide 60 grit wheel. My grinder is variable speed but I only run it on the slowest speed and use a light touch. After a little practice, I can get an even grind and the iron stays cool enough to handle.

FWIW, the Lee Valley grinder tool rest is a big help.

[Jeff Ranck]

I use a white wheel with a slow speed grinder. I grind the point away (90" into the wheel) and then grind at the bevel angle (hey what do you have two wheels and rests for anyway?). I find that I'm more accurate to 1) making sure the chisel is square and 2) making sure the grind is even across when I have the flat face to work from.

[ian maybury]

Most will know this, but more than what might seems enough care is probably advisable to prevent overheating an edge when grinding. It's reckoned by some to be very deceptive. The 'V' extremity of the edge which because of its thin section has a limited ability to conduct heat away into the body of the blade may get quite hot without much sign of heating in the main body of the blade - because even though the temperature may get quite high the total amount of heat energy is quite low. So it may be almost unnoticeable once heat sinked into the body of the blade.

Not sure how it plays out in practice given how transient the effects likely are (it'd be interesting to test it with a suitable fast response remote reading infra red camera - but it'd need to be very fast, and able to pick out a very small area) , but this effect could also serve to cool the extremity of the edge fast enough so that it hardens again. Wonder might it even perhaps over harden a very localised area right out at the tip to cause the sometimes reported chipping after intitial sharpenings? (after heavy grinding to establish the primary bevel)? This might hone away after a few re-sharpenings on e.g. waterstones.

[george wilson]

I have never EVER had a tool get caught on the grinding wheel. Ever. It just doesn't happen. It can certainly happen,and WILL happen if you stick a chisel pointing upwards into a buffing wheel. But,a grinding wheel is solid,totally different.

I use my old flat face 1963 Craftsman bench grinder to establish a hollow grind. My old grinder has 2 piece tool rests. There is a short piece of slotted heavy gauge steel going from the grinder's wheel housing,to the L shaped tool rest. I can loosen the wing nuts and stick the tool rest out fairly far from the wheel. I get the distance I want established,to make the degree of bevel I desire. I catch the bolster of the chisel against the outer edge of the extended tool rest. This is repeated every time I want to dip the chisel and put it back against the wheel. I get perfect results putting the chisel back every time,and grind smooth,even bevels,with no "facets" on them at all. Just smooth,continuous bevels.

For gouges,I do the same thing,catching the bolster against the out stretched tool rest,and rolling the bevel against the wheel.

I dip the chisel about every 2 seconds,and leave water on the end,close to the bevel. As soon as the water sizzles,I instantly dip the chisel again. Being especially careful as the edge is ground thinner and thinner. It gets hotquicker.


If you have only single piece tool rests,as most of the more modern grinders seem to have,clamp a little "C" clamp part way down the blade of the chisel. Catch the underside of the C clamp against the outer edge of the tool rest. This will give the same results.

Actually,these days,I use the Wilton Square Wheel grinder similarly,but I used the bench grinder with coarse WHITE wheels for many years as described. Use Norton wheels. The Camel wheels always seemed too soft,and easily worn out. But,I haven't used them in years,so maybe they have gotten better?


Don't rely on the heat from the grinder "re hardening" the edge. Even if it did,the edge would not be properly tempered,and would be too brittle. It isn't happening any way. Just be alert to the water sizzling,and dip fast. If you burn the chisel blue,the only cure is to grind it away,losing chisel length,and start again. If you just burn it light brown,it is o.k.,because that was the original tempering color anyway. Best to not burn it at all.

[David Weaver]

The Camel wheels always seemed too soft,and easily worn out. But,I haven't used them in years,so maybe they have gotten better?


They are definitely soft - if you can find them cheap, they're OK, but you wouldn't want to do heavy grinding with them (like iron blanks, etc), because of the softness. For refreshing a hollow, they're pretty good, though. They don't release particles too fast doing that, and even if you never dress them, they don't get loaded. I found two of them for $13 each...or Griggs found two for $13 each, I guess, and I bought them right away (they were on clearance).

I wish they were that cheap all the time. Otherwise, before that I used a mid-grade al-ox wheel that needed to be dressed (not as hard as the gray wheels, but still a hard wheel), but still didn't have any particular issues with burning - it did make for a hotter grind than the pink camel wheels, though.

[Steve Voigt]

Pat,

In 22 years, I have never had a grinder catch or kick back. As George said, it just doesn't happen. You'd have to do something really unwise to make it happen.

Couple other thoughts:

- I like to have my index finger on top of the tool, an inch or less from the edge, and my thumb a couple inches behind the index finger. Especially on a narrow tool rest, this can keep you from rocking the tool, which can mess up your angle.

- when it gets too hot to keep my index finger there, I dunk the tool. This almost always keeps me out of trouble. Once in a while, I burn the acute corner of a skewed tool a tiny bit, but I have not burned a straight chisel or plane iron in years.

- the important thing to remember is that the thinner your edge gets, the easier it is to burn. If you have a 1/16 flat on the end of a chisel, you can apply quite a bit of force. But as the edge gets thinner, you need to lighten your touch and stop or dunk more frequently.

- per an earlier comment, you can't "reharden" an edge on the grinder. You'd have to get it bright red, which is a thousand degrees hotter than you're likely to get it.

- you might want to practice on beater tools first. Also, if you sharpen vintage (late 19th - early 20th c.) tools, as George says you can get the edge hot enough that it turns brown without doing any damage. Not that you want to, buts it's nice to have that comfort zone if you're new to grinding. However, if you take O1 past light straw color, you are probably affecting the temper. A2 and PMS-whatever, I don't know anything about.

[steven c newman]

I made a small jig for the old grinder I have294250used the grinder's wheel to make a slot. Used a "slider" to grind the edges straight across294251just gives me a wider table to work at. Yes, I do have a cup of water handy. Seems to work ok, for the irons i go with294252

[george wilson]

A2 would be the same. I don't know about powdered metal,though. Trouble is,it's just a split second to go from brown to blue. Keep the edge wet and look for the water to sizzle. I think that is better than trying to get your finger exceedingly close to the thinnest part of the cutting edge that you're grinding.

[Pat Barry]

Thanks all for your information. Mine is an off brand bench grinder (Astro power) with 6 inch wheels and one piece tool rests. It is stated as 3450 RPM, is that too fast? The wheels are the dark gray (cheap) type. One is coarse, one is finer. Its a fine grinder for sharpening lawn mower blades but I never tried to do a real tool. Both wheels are pretty bad shape and could use a good dressing or replacement. I will look into the white wheels - I think Rockler has them but I don't recall seeing them at Home Depot or hardware stores - maybe I just missed them.
294255
I think steven and George are telling me the same thing - I will give the C clamp idea a try and see what happens with these wheels

Oh, and Joshua, counter to the way I see it done on the pictures on the internet such as FWW site, I was thinking to pull out the tool rest, get the tip of the chisel pointing downward in-between the tool rest and the wheel and then push downward on the handle to rotate the bevel up, into the wheel. That's the direction I have been going to do my lawnmower blade, just can't use the tool rest to do it.

Like this:
294256

[David Weaver]

Pat, the gray wheels and high speed setup w/6 inch wheels is fine. You'll need some kind of dressing tool for the wheels, though.

[Tom M King]

I've used my CBN wheel on the Metabo grinder a number of times lately while spending days with a chisel. It has the nice LV rests, and set it with the Batty gauge. Not just fast, but dayam fast. I do dip still in water if a big chunk needs to be ground out-have found a few flooring nails. It's a bigger jump to this setup, with no fiddling/truing required, than it was going to power windows in a car from crank up windows. I'm sure going back to friable wheels would be more aggravating than going back to window cranks.

[Winton Applegate]

I don't know . . .
Setting the angle of a tool rest . . .
clamping a C clamp on the blade . . .
that all smacks too much of " Sharpening Jig".
That's unnnnnnnn cool.
Keep that up and you will be sitting on the B squad bench with me.

I will show you my prize wheel dresser I got from an old time hardware store.
I have other ones, diamond and carbide or some such.

[bridger berdel]

Thanks all for your information. Mine is an off brand bench grinder (Astro power) with 6 inch wheels and one piece tool rests. It is stated as 3450 RPM, is that too fast? The wheels are the dark gray (cheap) type. One is coarse, one is finer. Its a fine grinder for sharpening lawn mower blades but I never tried to do a real tool. Both wheels are pretty bad shape and could use a good dressing or replacement. I will look into the white wheels - I think Rockler has them but I don't recall seeing them at Home Depot or hardware stores - maybe I just missed them.
294255
I think steven and George are telling me the same thing - I will give the C clamp idea a try and see what happens with these wheels

Oh, and Joshua, counter to the way I see it done on the pictures on the internet such as FWW site, I was thinking to pull out the tool rest, get the tip of the chisel pointing downward in-between the tool rest and the wheel and then push downward on the handle to rotate the bevel up, into the wheel. That's the direction I have been going to do my lawnmower blade, just can't use the tool rest to do it.

Like this:
294256


That is about the only way there is to have a chisel "catch" while grinding.

[Bernadette Semilla]

From what I know, you want to always be pointing the tool against the rotation of the wheel. I start using a light touch where there is more bulk in the metal, so the very back of the bevel you are creating, to get a good feel and to get comfortable. I do quench with water and use touch as the others have said.

I recently did a whole batch of very old pre-HSS Sheffield chisels freehand on a 3600 rpm 6" Ryobi bench grinder (one of your big box 'chaiwanese' things) using the stock coarse wheel. It was very nerve wracking and I had to finish on 100 grit sandpaper to even out all the little grooves but it certainly can be done if care is taken, even by a first timer like me! Yes, this was my first time grinding any of handtool blades. I did use some unladylike language as a result of burning the corners, so my advice for the very edge would be to either dunk in water every one or two passes or leave it be to do on sandpaper or stone, which won't take much time at all. In the future, I'll just do the bulk of the bevel on my grinder and the very edge that way. Definitely get a dresser, my wheels glazed after a while and this began to cause overheating much more quickly than at first. I have only had experience with a diamond T-bar so I can't advise on different types.

Since I didn't have a rest or angle setting jig, I had a square and angle gauge at hand to check the squareness and angle of my bevel against, and did so often.

[Pat Barry]

That is about the only way there is to have a chisel "catch" while grinding.
bridger, please clarify if you would. Are you saying that grinding with the tip down as a I showed in the picture is to only way to have a chisel catch? I just don't see this as possible. Now that David and other have clarified (in another thread) that you don't actually want to grind right up to the tip the whole method of grinding tip up seems a whole lot safer. I was afraid of the tip digging in and that won't happen if you grind short of the tip.

[Pat Barry]

From what I know, you want to always be pointing the tool against the rotation of the wheel. I start using a light touch where there is more bulk in the metal, so the very back of the bevel you are creating, to get a good feel and to get comfortable. I do quench with water and use touch as the others have said.

I recently did a whole batch of very old pre-HSS Sheffield chisels freehand on a 3600 rpm 6" Ryobi bench grinder (one of your big box 'chaiwanese' things) using the stock coarse wheel. It was very nerve wracking and I had to finish on 100 grit sandpaper to even out all the little grooves but it certainly can be done if care is taken, even by a first timer like me! Yes, this was my first time grinding any of handtool blades. I did use some unladylike language as a result of burning the corners, so my advice for the very edge would be to either dunk in water every one or two passes or leave it be to do on sandpaper or stone, which won't take much time at all. In the future, I'll just do the bulk of the bevel on my grinder and the very edge that way. Definitely get a dresser, my wheels glazed after a while and this began to cause overheating much more quickly than at first. I have only had experience with a diamond T-bar so I can't advise on different types.

Since I didn't have a rest or angle setting jig, I had a square and angle gauge at hand to check the squareness and angle of my bevel against, and did so often.
Thanks for the reply - you noted that it was very nerve wracking. Did something happen or were you just having trouble controlling the heat and squareness? I think grinding from the tip toward the fat part of the tool will drive heat in that direction preferentially, whereas grinding tip down almost certainly causes excessive heat to be pushed to the tip itself and therefore higher likelihood of overheating.

[Jessica Pierce-LaRose]

Burning an edge sucks, but it's not the end of the world. The steel is still harder than wood, and you'll get through that steel sooner or later.

Pat, I just skimmed this thread again, and I realize my initial post probably came off as a little rude, I apologize, I didn't mean it that way. . .

[Pat Barry]

Burning an edge sucks, but it's not the end of the world. The steel is still harder than wood, and you'll get through that steel sooner or later.

Pat, I just skimmed this thread again, and I realize my initial post probably came off as a little rude, I apologize, I didn't mean it that way. . .
Burning? I most likely wouldn't know the difference in terms of cutting for what I do any way. Rude? I didn't see it that way at all. Thanks