I just don't get it II

[James Pallas]

I see a lot about hollow grinding and wonder why. First let me say I feel that I know my way around grinders from hand cranks to 3 hp 12 inch wheel monsters to grind bevels on heavy steel plate and such. The only time that I usually grind is when fixing a chip, making a blade or the like. I usually sharpen on stones by hand. I side sharpen so I can run the blade the full length of the stone and from left to right across the stone in a Z fashion. When the bevel gets a little wonky I use a guide to flatten it. Most of the time I can go across the stone once and get a burr. Sometimes I have to go back to a medium stone if I've been lazy. I seldom go to the grinder just to get a hollow grind. I do have PMV 11 plane irons and they are a little more time consuming. Not enough to make me feel I want to grind. Am I missing something here?
Jim

PS I know, one of those "Sharpening threads"

[John C Cox]

You really truly don't understand why people do it.... Or you have tried it and decided it's not for you?

I will hollow grind a bevel in 1 second when I have to deal with deep chips, pitting, or a wonky edge. I am absolutely not too proud..

But as a normal maintenance routine - no...

But I understand why people do it...

[Doug Hepler]

James,

Who am I to say whether you are missing something? I tend to hone and touch up by hand, without a jig. A hollow grind helps me find the correct angle on the stone, diamond plate, etc. Eventually I can't feel the angle any longer so I give the edge a light pass or two on an electric grinding wheel to restore the angle and the hollow grind.

My electric grinder is "indispensable" for turning tools, especially scrapers.

Doug

[James Pallas]

You really truly don't understand why people do it.... Or you have tried it and decided it's not for you?

I will hollow grind a bevel in 1 second when I have to deal with deep chips, pitting, or a wonky edge. I am absolutely not too proud..

But as a normal maintenance routine - no...

But I understand why people do it...

i understand the repairing an edge part. What I don't understand is making it a part of normal edge maintenance. If you have a good edge why grind it off and go back thru all the stones again. And yes I have tried it because I make repairs that way.
Jim

[James Pallas]

James,

Who am I to say whether you are missing something? I tend to hone and touch up by hand, without a jig. A hollow grind helps me find the correct angle on the stone, diamond plate, etc. Eventually I can't feel the angle any longer so I give the edge a light pass or two on an electric grinding wheel to restore the angle and the hollow grind.

My electric grinder is "indispensable" for turning tools, especially scrapers.

Doug

i fully understand the turning tools. I guess the self jigging thing may be the key to it.
Thanks Jim

[bill tindall]

If you have a good edge why grind it off and go back thru all the stones again.
Jim[/QUOTE]

The # 1 rule is that you never grind a good edge away. As you correctly state, once the edge is straight it needs to not be subjected to the risk of grinding it otherwise. Properly done for routine maintenance the hollow grinding is done not quite to the edge. This step quickly removes metal that otherwise would be more slowly removed by hand power. Edge refinement is then only done on the narrow edge that remained unground, which is quick. An added benefit for some smooth finish stones" is that the hollow sucks down flat on the surface making registration reliable.

A hollow ground edge is easier to refine for less experienced honers.

A properly selected wheel is important. I grind with a 120 grit H grade pink wheel, 3600rpm, followed by fine diamond fixed plate and one more polishing step.


Bottom line....it works well for some and others have other means to end.

[bridger berdel]

i understand the repairing an edge part. What I don't understand is making it a part of normal edge maintenance. If you have a good edge why grind it off and go back thru all the stones again. And yes I have tried it because I make repairs that way.
Jim

I hone freehand. It's not uncommon for an edge to get a bit rounded over, especially if it's a thick blade, i'm in a hurry or working in stuff that wears a blade fast. I suppose i'm a bit lazy. When that does happen rather than spending a lot of time with a coarse stone i'll spend a little time at the grinder, then a little time at the coarse stone. I don't grind to the edge unless there are nicks or the like to remove.

[James Pallas]

If you have a good edge why grind it off and go back thru all the stones again.
Jim

The # 1 rule is that you never grind a good edge away. As you correctly state, once the edge is straight it needs to not be subjected to the risk of grinding it otherwise. Properly done for routine maintenance the hollow grinding is done not quite to the edge. This step quickly removes metal that otherwise would be more slowly removed by hand power. Edge refinement is then only done on the narrow edge that remained unground, which is quick. An added benefit for some smooth finish stones" is that the hollow sucks down flat on the surface making registration reliable.

A hollow ground edge is easier to refine for less experienced honers.

A properly selected wheel is important. I grind with a 120 grit H grade pink wheel, 3600rpm, followed by fine diamond fixed plate and one more polishing step.


Bottom line....it works well for some and others have other means to end.[/QUOTE]

Thanks Bill very much my thinking on it. I am interested in your choice of wheels. I still have grey wheels a 36 and an 80. Never have had a problem with overheating or the grinding process but the wheels are getting close to replacement time. So I'm interested in your choice.
Jim

[James Pallas]

I hone freehand. It's not uncommon for an edge to get a bit rounded over, especially if it's a thick blade, i'm in a hurry or working in stuff that wears a blade fast. I suppose i'm a bit lazy. When that does happen rather than spending a lot of time with a coarse stone i'll spend a little time at the grinder, then a little time at the coarse stone. I don't grind to the edge unless there are nicks or the like to remove.

Thanks Bridger. Because I consider myself a wannabe carver I may tend to go to the stones a little quicker. I seldom go back to a course stone during normal routine. Stones are close so I find it easy to go to the stones or a strop for a touch up.
Jim

[Chris Parks]

The hollow grind is done initially and unless the edge gets damaged or the bevel begins to get too wide it is not done after that. It is not a routine method done at every honing or even every 10 honings in fact it is not routinely used after the initial grind.

[Warren Mickley]

One thing you might be missing is that people bring a tool to sharpen in a large range of conditions. Some people's chisels are invariably fractured or chipped or bent when they decide to sharpen, others are just slightly worn. Some people consider that a plane iron needs sharpening when it is still sharper than others have in a freshly sharpened condition. Large range.

All this affects how much material must be removed to get beyond the damaged portion.

[Philipp Jaindl]

The "problem" starts with the can of worms that is "how sharp is sharp", if you ask 5 people how they sharpen you get 10 answers. Whats sharp for one, another considers dull.

In terms of Proffessional shops Chisels are often abused for all sorts of things, scraping glue etc. so the edges often need major work, thats where the Grinder comes in its the quickest way to get dings, chips and so on out.

[James Pallas]

The hollow grind is done initially and unless the edge gets damaged or the bevel begins to get too wide it is not done after that. It is not a routine method done at every honing or even every 10 honings in fact it is not routinely used after the initial grind.

Chris In reading your post I have a question. Do you go back to restore a hollow grind or if the edge remains in good condition do you just maintain as a flat bevel?
Jim

[James Pallas]

One thing you might be missing is that people bring a tool to sharpen in a large range of conditions. Some people's chisels are invariably fractured or chipped or bent when they decide to sharpen, others are just slightly worn. Some people consider that a plane iron needs sharpening when it is still sharper than others have in a freshly sharpened condition. Large range.

All this affects how much material must be removed to get beyond the damaged portion.

I am glad you chimed in Warren. I think that there is surely a big difference in how long a tool is used before it stops working for each person. I'm asking whether you try to maintain a hollow grind or if when the two sides meet you just maintain the edge as a flat bevel. I understand that you don't need to hollow grind for any reason. I think I'm in the the camp of just using grinding with a grinder only when the edge can't be restored easily with just stones. If I recall correctly you are a proponent of flat bevels. Please correct me if I have miss stated this.
Jim

[James Pallas]

The "problem" starts with the can of worms that is "how sharp is sharp", if you ask 5 people how they sharpen you get 10 answers. Whats sharp for one, another considers dull.

In terms of Proffessional shops Chisels are often abused for all sorts of things, scraping glue etc. so the edges often need major work, thats where the Grinder comes in its the quickest way to get dings, chips and so on out.

i agree that sharp is how each person perceives it. I'm asking about hollow grinding here and when or if to use it. I think that using a chisel as a glue scraper or a paint can opener is a whole different subject. I have glue scrapers and paint can openers and don't use them as chisels
Jim

PS I did recently read that Paul Sellers advocates the use of paint can openers to clean out the bottom of mortises