For those of you who use hollow grinding on your chisels and plane blades, what method/tool do you use for the hollow grind? Wet or dry? Thanks. Tom
“Notice that at no time do my fingers leave my hand”
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Replies
I have the Jet slow speed wet grinder(Tormek clone) and add 2 degrees more bevel than the standard bevel. Can shave with the results after stroping.
Work Safe, Count to 10 when your done for the day !!
Bruce S.
I could be wrong, but isn't hollow grind used only on razors and knife blades? I use it on screwdriver blades to grasp the screw flats better and prevent the tool riding up . Steinmetz
Some woodworkers prefer to put a hollow grind on the bevel of chisels and plane blades. It makes honing easier as there is less steel to remove and hone. It also gives you two points of reference during honing. Tom"Notice that at no time do my fingers leave my hand"
I’m a big fan of hollow grinds on all my chisels and plane blades. I picked this up from Krenov’s book, “The Fine Art of Cabinetmaking” a LONG time ago. I use a cheap 6” Delta high speed, (yes high speed), grinder with a 60 grit white wheel because the hollow is pretty deep. Just go lightly and have a can of water to dip the edge in. Also, I do not use a jig, just grip the blade and let my fingers guide it on the tool rest. I hone on a hard white Arkansas oil stone with WD-40 and that’s it. Keep the edge and the heel of the hollow grind on the stone and you have very little metal to remove. You can hone quite a few times before the hollow is gone and grinding is necessary. Sharpening should not require spending big money. IMO it is sold as a black art that needs all manner of paraphernalia that is designed to take cash that could be better spent on a new L-N 4 ½ or some nice cherry stock.
I, like Bruce, use the slow speed wet grinder. But mine is the real thing - the Tormek. I am a novice so others probably get their blades much sharper than I, but I have sharpened blades for others who said their blades had never been that sharp before.
I have one question and I'll address it to any one with an answer. Tormek calls the other wheel a honing wheel. It is lined with leather. I always thought of honing being done on a stone and stropping done on leather. What say ye?
Edited 4/30/2007 11:10 pm ET by tinkerer2
I've always heard of honing being done on stones or sandpaper on glass/granite. Tom"Notice that at no time do my fingers leave my hand"
Tinkerer,My dictionary says that honing is to sharpen or smooth on a whetstone. My older dictionary (1952) defines a hone as a fine whetstone. Sharpening with leather seems more accurately described as stropping. We may be showing our ages on this one.Cadiddlehopper
Regarding honing, the Tormek is a Swedish machine and I was wondering if it was a translation issue.
Looks like I'm in good company ...
6" high speed grinder with Norton 60 grit white wheel.
Accessory is a Veritas grinder rest.
Regards from Perth
Derek
DerekHow do you keep from overheating the tool edge? Tom"Notice that at no time do my fingers leave my hand"
Simple, a can of water and a light touch. It is not at all hard to do. All I have ever used is a high speed grinder.
Exactly as Napie says - a very light touch .... just caress the wheel.
You need to keep your fingers on the back of the blade and remove the blade as soon as you feel it heating up.
With the right wheel and touch you actually get relatively little heat. Use a coarse and friable wheel, not a hard, smooth wheel. Dress the wheel as soon as it starts to gunge up (I use a single point diamond stick).
I currently use the Veritas grinder rest. It is fine, but it is made of aluminium and a little light weight for my taste. I plan to make my own from hard phosphor bronze. This will have the dual task of acting like a heat sink. (I recall a tip of old computer heat sinks in place of water for cooling the blades).
I wonder how close to the edge other grind the iron? I try and stop about 1mm, but the last couple of mm can take a longish time as it must be done very , very gently with frequent quenching to avoid over heating.
Regards from Perth
Derek
The tool rest on my el-cheepo grinder is a piece of ½” conduit on blocks set even with the centerline of the wheel. Being round it is very easy to pivot the blade into the wheel at what ever angle you are looking for.
Derek, I would like to add some comments here that may be useful to you, those who are thinking about this method and those who maintain that high speed grinders are not a good way to go:-
1)Definitely gentle pressure is essential otherwise there will be over heating.
2)Assuming the correct wheel is used then frequent dressing is absolutely essential, especially with steels like A2 and D2. It is this dressing which enables the wheel to cut cool without undue pressure.
3)The best way to dress these wheels is with a diamond dresser- either a tee bar or single point.Star wheel dressers, stone sticks etc are history- there is nowt to beat diamonds.
4)If you really want an easy ride then you should grind with the aid of a cool mister-kiss goodbye to the risk of heated finger tips and that dust which gets into every thing. It is basically an apparatus which combines an air jet with a coolant which is directed onto the stone or work. It can be adjusted to have any combination of air and coolant and the coolant can be water or water soluable oil.Air consumption and noise is minimal. The effect on grinding is magical, plus there is not the need to stop every so often because you are nervous of over heating-makes it easy to maintain an angle.
These are just running comments, but are applicable to the common bench grinder as much as specialised machines such as the surface grinder pictured- that is what I use to surface grind my planes (and any other thing like blades and machine parts).Philip Marcou
Hi Philip
Totally agree with everything you wrote.
Half the battle is over when the wheel does not overheat the edge, and it is more likely to do so if hard, smooth, or one that is glazed over. A clean, rough, and friable wheel is choice. I use a 6" white Norton 60 grit but I have heard good things about Norton Blu-Max Grinding Wheels (but no evidence as such - anyone know these and how they differ from the white?). I also dress mine with diamonds, either a T-bar or a single point.
I'd like to try out a cooling system such as you describe. I know some who have rigged up a water spray. I just use the "finger sensor" method - fingers on the edge of the blade about 5mm from the spinning wheel - and then dunk in water as it warms.
Regards from Perth
Derek
Philip,
Can you recommend a source for a cool mister? Plus, does it's use make a sufficient mess that you need your grinding station to be away from your other machinery? Or is there a simple way to control spray?I ask because in the shop where I last worked, all of our grinding machines used coolant and had to be totally enclosed as the grinding wheel "flung" grinding-laden coolant over a wide area if not enclosed.Mike D
Mike, the one I have is made by Nogos- same company that makes magnetic bases and stands for dial test indicators-Israeli company.
There is very little mess or spray. Unlike conventional grinding coolant methods which rely on liquid volume the coolmist combines an air stream with the coolant -much like a spray gun.Philip Marcou
Mike,
"Can you recommend a source for a cool mister? "
There hasn't been a really cool mister available since Steve McQueen died. Well, Paul Newman comes pretty close I guess. Clive Owen? Maybe.
Cheers,
Ray
Hi Ray , How about Clint E ?
dusty
dusty,
I'll see your Dirty Harry, and raise you a Sean Connery.
Ray
Hey dusty,
How about " Play Mister for Me" ?
Paul
( I know, it's kind of a stretch )
All you guys are doing is rounding up the usual suspects.
Sorry Mike- I got the name wrong. You can see the the thing here http://www.noga.com/nogaProducts.php?catID=moco. Click on "mini cool".
Apologies to Clint Eastwood, Ray Mahogany et al.Philip Marcou
Edited 5/15/2007 4:08 am by philip
Hi Philip,
It looks like the berries, but the only source that I could find for it on line wants $211 and some change for one (not counting shipping).
Do you know of a more reasonable source, or is that considered reasonable?
Me old Scots ancestors would nip my last dime in half before allowing me to append something so dear to my $60 slow speed grinder before investigating further.
Mike
HI Philip,
I actually have another question. Am I right in inferring that the mister requires being plumbed into house water as source of pressured water? Also into house pressured air as a source of pressurized air?On later reflection, if the device makes it easier to not ruin the edges of my chisels and plane irons, it might justify it's $200 plus cost in no time. Mike D
No Mike, it works like a spray gun-it draws water from a container, and it must be connected to a source of compressed air. The container can be anything suitable and does not need to be at the same level-can be lower. I just use a 2 litre plastic bottle. Consumption volumes of both liquid and air are very very small.
The best way to avoid over heating of steel when using a bench grinder is to use the correct wheel for the material and to dress it frequently....
Philip Marcou
Thanks, Philip,
I do use good "friable" wheels and dress them frequently, but my ham fisted approach to grinding often causes me grief, anyway. I can't seem to stop and dip soon enough and sufficiently reliably enough to not see that wretched blue mark appearing at my edge just as I'm finishing up.
Perhaps my good wheels are loading up/glazing faster than I realize.
Mike D
"Perhaps my good wheels are loading up/glazing faster than I realize."
That is possible. Also there is a big difference between diamond dressers and alternatives like star wheels and dressing sticks. I think diamond dressers give much better results, without blunting the abrasive grit tips- results in less pressure applied in grinding, so heat generation rate is decreased.Philip Marcou
Hi Mike ,
I have no experience with the misting systems but do use grinders and have learned that a simple grinder outfitted with the correct wheel or stone can produce excellent results .
In this case as is true in many scenarios it's not so much what you have that's as important as what you've learned and know .
Sounds like your on the learning curve of grinding and still are getting a handle on the finesse it takes to grind , shape and sharpen without burning . I also use water and cool as I go , it takes little time to dip and cool , so try not to rush the process .
A few years ago I bought a used scissors sharpener for my seamstress wife and her many pairs of scissors that need re sharpening like every few months or so , at like $4 - $6 bucks a piece the machine paid for itself in a year or so .
The first 5 or 6 times I used it I pretty much tried to hog off material and quickly began to ruin the expensive scissors , the finesse was missing and a feather light touch was what was needed and ultimately learned . I am not an expert scissors sharpener but I do a better job each time . The feel and touch and knowing how not to burn and what feed rate and how much pressure is needed is an acquired skill . One can not become proficient until the hands on experience has sunk in .
In this case as in many other subjects , you can read an article or book on a given subject for general information and guidelines , but until you have experience all you have is information .
regards dusty
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