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07-18-2011 08:55 PM
I understand that the "standard" for grinding wood chisel bevels is about 25%. I have been grinding mine at much more than that. I have an 8 in. white grinding wheel. If I set the tool rest at 25%, will I get a 25% bevel on the chisels, or does the arc of the grinding wheel have to be taken into account?
07-18-2011 10:41 PM
No you do not make any adjustments for the diameter of the grinding wheel. What you will be achieving is called a hollow grind. You can achieve a razor sharp edge on a hollow ground chisel faster than on a flat ground chisel. A hollow ground chisel also dulls faster.
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07-19-2011 12:33 AM - edited 07-19-2011 12:36 AM
The normal way grinder chisel is not on the round part of the wheel but on the side of the wheel. Hold the chisel to approximately 25°After that you can put a second bevel on the tip of the chisel that is approximately 30° usually ID the 30° portion on my MPower PS S diamond: hone. This tool cost around $80 and does a marvelous job of honing your chisels to a razor-sharp edge that you can literally shave with there are several retailers that sell this product but my favorite is the Japan woodworker. I found that Hollow grinding chisels as you have been doing makes the tip very weak and thus are prone to breaking.Granted there are 1 million ways to sharpen your chisels the way I am recommending will provide you with a razor-sharp edge and is very safe the PS S by MPower is a foolproof way to put a great edge on your chisels even if you are a novice sharpeningI hope this helps sincerely Lance granumthe dude 50 formerly the dude
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07-19-2011 02:58 AM - edited 07-19-2011 03:05 AM
With standard grinding wheels and 8" or 6" grinders - do NOT use the side of the wheels. This is NOT a safe practice. Yes, you can get away with it for a while but it is not recommended.
From Nortons safety poster. Side pressure on thin straight wheels is dangerous. Most wheels will stand quite a lot of straight radial pressure, but there is a limit to what they can take. Heavy pressure with vitrified wheels is apt to cause the wheel to get hot. If it gets too hot too quickly, it is apt to break.
Sudden bumping or pounding is more dangerous than steady, even pressure. All bench and pedestal wheels must be dressed to prevent loading. Loading can cause excessive heat, damage to the workpiece, and wheel breakage. Dressing exposes new cutting edges and provides chip clearance.
The answer to your question as others have said - it depends on what you are doing and what the wood happens to be. My softwood chisels are set at a lower angle (25 degrees or so) than my hardwood chisels (30 degrees or so). You are putting a hollow grind on your chisels.
Typicaly, I put a hollow grind on my chisels. I then switch over to my waterstones to hone the chisels. When they get dull, I just give them a few strokes. The top and the bottom of the bevel are the only thing that gets honed or sharpened then. After the chisels lose the hollow, they go back to the grinding wheel. If you do it that way, you can use waterstones, oil stones, sandpaper or whatever to hone the chisels.
07-19-2011 01:02 PM
I agree with JL. using the side of the wheel is dangerous. I know we have all gotten away with it but it's one of those things that only takes once to ruin your day.
My hand chisels are ground to 25 degrees. any chisel that will be used with a mallet is ground to 35. I personally don't believe a hollow grind makes a chisel dull faster. You still have the same angle for 1/16" or so if you hone the edge with a diamond hone. Now if you use a mallet a hollow grind might be weaker but I generally use an 8" wheel so the hollow grind is just thousandsths of an inch less metal than a flat grind.
07-19-2011 01:05 PM
JL North GA I have been using this practice for over 30 years it is safe because it requires very little pressure as you can see in this video http://www.ehow.com/video_4418697_sharpening-marpl
proud member since 1995