Hollow grind on chisel

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Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Hollow grind on chisel

Post by Talladam »

I just got a new 6" bench grinder for Christmas with an adjustable speed (down to 1800rpm) and a blue Norton friable wheel. I didn't add a fancy tool rest yet, but that may be coming some day. I just ground a big chip out of the edge of a vintage Charles Buck firmer chisel that I bought online for cheap, and in doing so put a hollow grind on the bevel. The idea is that the hollow grind will make it easier to sharpen freehand. It was a bit of a learning curve to get the bevel straight, but the blade stayed super cool. I kept dunking it in water, but it stayed cold enough that I kind of felt like I was wasting my time. Part of that is because I put a crown on the wheel with the dresser that came with the grinder. I got that bit from Fine Woodworking. I then took the chisel to my waterstones, first 3000 then 8000. I did find that the flat spots put on the bevel by the waterstones didn't end up even. I'm not sure why that was, because I'm pretty convinced that I ground a straight bevel. In any case, the chisel did end up wicked sharp in less time than usual. I still have to work on polishing the back a bit more, or I'm convinced it would have ended up as sharp as I've ever managed. It still shaved my arm and did a nice job on endgrain. I can definitely happily use the sharpness I get out of my system now, I'm just always looking to tweak it a bit. I figured I might as well share a pic here. Hope you enjoy.
ground chisel.jpg
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Mal-2
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Joined: Wed Jan 03, 2018 12:56 am

Re: Hollow grind on chisel

Post by Mal-2 »

The only thing better than a new tool is a new tool you can use to make more new tools.
johnnparchem
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Re: Hollow grind on chisel

Post by johnnparchem »

It will be interesting to see how a hollow grind using a 6" wheel turns out for you. Hollow grind edges drive me up a wall, but I know some swear by them. I use the chisels both bevel up and bevel down. I used a small tormac sharpening system. Now I use a work smart system or waterstones and a guide.

Also careful with your heat assessment. The edge is pretty narrow and it can overheat.
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: Hollow grind on chisel

Post by Talladam »

The only thing I'm thinking is a hollow ground chisel might not be best for brace carving, so I may leave one with a straight bevel. I may even round the top corner like Cumpiano suggests.
johnnparchem
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Re: Hollow grind on chisel

Post by johnnparchem »

Talladam wrote:The only thing I'm thinking is a hollow ground chisel might not be best for brace carving, so I may leave one with a straight bevel. I may even round the top corner like Cumpiano suggests.
Sounds right, I rounded the top corner on a couple of my chisels.
tippie53
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Re: Hollow grind on chisel

Post by tippie53 »

I hollow grind all my chisels

they will do fine
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
ruby@magpage.com
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Re: Hollow grind on chisel

Post by ruby@magpage.com »

There is no difference in use between honing a hollow grind and honing a full flat bevel, not on brace ends or anywhere else. The actual angle that you are using is the angle of the hone right at the last 1/32" at the tip, and if you do it right, it is the same angle a full flat bevel would be. The wood doesn't see a difference. If you were doing heavy morticing, then the bevel would be shaped differently, but for paring, it doesn't matter.

I have used a 6" grinder for the last 40 years with no problems. A hollow grind is easier to hone because there is less surface area in contact with your sharpening medium - until you do it enough that you are essentially honing almost the full flat. At that time, regrind as little as needed and start over for easier honing - if you are careful, you can grind in a hollow without passing your hone.

I like the 6" grinder because when I hone by hand I can tip the chisel or plane blade up and down on my sandpaper on glass and feel the click as it passes the hollow part - this lets me register my angle without looking.

By the way, Talledam, your grind and your hone looks just fine. The important thing is that the edge be straight or slightly curved depending on your desire.

Ed
Ed M
tippie53
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Re: Hollow grind on chisel

Post by tippie53 »

for a carving chisel I use a 2nd angle so I cam come out of the cut with control
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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