chisel grinding angle

What is the best angle to grind chisels? I use them to clean up work, pare of slight amounts, clean mortises, etc....And after I grind, what angle to I hone? Thanks. Robert

Reply to
RWS
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Reply to
Dan Parrell
25deg to 30deg then a micro-bevel of ~2deg

Bob S. (the other RWS...;-)

Reply to
Bob S.

It is common to "grind" chisels. When honing no longer produces an acceptable edge grinding is called for. I use a Baldor slow speed grinder with a 120 grit wheel...usually at a 25 degree angle. After putting a hollow grind on the tip, I then hone at the angle produced by the tip and the heel. The advantage of grinding in this manner is that you don't need to hone the entire bevel....just the tip and heel. Therefore, honing goes much faster. Over time, the hollow grind will be removed by honing. When you no longer have that hollow grind...regrind the chisel.

Bill

Reply to
WORSS

Reply to
Dan Parrell

Many folks around these parts subscribe to this method:

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Reply to
Doug Winterburn

Reply to
Dan Parrell

That's the link I gave you - the original Scary Sharp (TM) referred to in Nick's article.

-DOug

Reply to
Doug Winterburn

Hi Robert,

For general woodworking, you'd grind to nominally 25 deg, then hone a secondary bevel at 30 deg. For a fine bevelled paring chisel, you'd drop these angles by 5 deg. For a heavy duty sash or mortice chisel, you'd up them by 5 deg.

However, at the end of the day, these figures are nominal. Most experienced woodworkers don't use a honing guide - they lay the chisel on the stone on its grinding bevel, then lift it by a few degrees to commence honing. I couldn't honestly tell you what my ultimate honing angle is - it's all done by feel, so it may be a couple of degrees either way from the recommended norms. Whatever you find that works for you.

It's worth while, when you start breaking in a new chisel, to hone the back it completely flat -simply lay it flat on your stone, then work away until the first inch or so at the business end is a uniform shade. For ultimate sharpness, you'd really want a mirror finish (on a very fine stone) on the back, but for general use, a uniform grey colour is fine.

Then when you hone the edge, you work away until when you run your thumb across the back of the edge (not along it!). you feel a raised burr. This means that you've honed the edge so fine that it's started to turn over under the your honing pressure.. Stop honing the bevel at this stage, then turn the chisel over flat on its back and give it a few more strokes flat on the stone to turn this burr (sometimes called the "roafe" or the "wire edge") back again. Then you can either strop it a few times on your palm or a leather strop, or gently draw it edgewise through a piece of wood to break off the burr and leave a clean sharp edge.

Beware when you're grinding on a high speed grinder - you need to keep the edge as cool as possible at all times, which means dunking it frequently. Don't let it get so hot that it starts to blue. A stone which runs at low speed in a water bath is much better, if you have access to one.

Cheers,

Frank.

Reply to
Frank McVey

Reply to
Dan Parrell

I understand and I have the article. I was pointing out that the link I gave is the same one as is referrenced in Nick's article. Nick's honing jig is a value add to scary sharp as well as his mention of the alternatives to glass.

-Doug

Reply to
Doug Winterburn

I second that. 25 degrees then hone 1-2 degrees 26 - 27 degrees. Hollow grinding will make your chisels weak though. NO HAMMERS on them. Just wooden mallets to TAP them home. DON'T hollow grind Japanese Chisels, EVER ! Too brittle for that, they chip bad. Try 20 degrees for paring chisels. I would use a 5x11/2 or or 2 inch SLOW wet wheel and jig. Or use a lot of water to grind VERY slow, then hone up to

Reply to
FOW

It doesn't matter what tool you use, when you are shaping the bevel, you are grinding. Grinding is merely the action of removing material through friction. Me, I use a Tormek water wheel and leather wheel. I flatten the backs on waterstones, but I find the Tormek much faster and more accurate than the waterstones for doing the bevels.

OBTW, honing and polishing are also grinding. Just much finer forms.

Cheers, Eric

Reply to
Eric Lund

My Tormek hollow grinds everything, chisels, plane blades, whatever. My edges last a long time. I used to scary sharp. I have a full set of waterstones, and know how to use them. Heck, my mortice chisels are all done on waterstones. But the Tormek, with it's jigs and simple setup, gives great results in very little time, and I usually resharpen because I feel guilty, not because the edges are actually dull. They seem to last just about forever.

OBTW, I don't have any laminated blades, and I agree that I would not hollow grind a laminated blade.

Cheers, Eric

Reply to
Eric Lund

Hell, I see them at flea markets all the time. I have had good luck grinding on a belt sander with about 150 grit. Good luck with initial flattening on the B/S too. Tony

Reply to
Anthony Diodati

I use 30 degrees with good results. Exact angle unimportant, just make sure the two angles meet "sharply"

I found some old stanley 45 "irons" and measured the angle... all were exactly 35 degrees.

Reply to
Brent Wegher

"Honed out too fast." Honestly, I don't even know what that means. At

90rpm, even graded to 220 grit, it won't remove material fast, and with the water bath, the irons don't even get warm. The key to the Tormek's speed is once the irons have already been done. Subsequent sharpenings need to remove nearly no material, so it goes very fast.

You talk about the weakness of a hollow grind. Well on a 5" wheel, you will get a much weaker edge than a 10" wheel gives. The larger the wheel, the flatter the bevel.

Cheers, Eric

Reply to
Eric Lund

Cheers, Eric

*******I see your point there, as there will be more contour, with less meat behind the cutting edge,**********
Reply to
Anthony Diodati
[...]

Not at all. Grinding is removing material in (small) chips with "geometrically undefined tools", since the edges of the grinding particles have an arbitrary orientation.

Reply to
Juergen Hannappel

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