I’ve got a few large mortise chisels (Sorby) that have sides that are ever-so-slightly (and intended to be) not parallel. After a great deal of difficulty getting my mortises to go straight down, I finally realized that I’ve been using these jigs to produce an edge that’s at the wrong angle.
Every sharpening jig (including the Veritas Mark II that I’ve been using) I’ve seen is set up to make the edge of the chisel perpendicular to one of the sides, which in this case is wrong.
I don’t need to hear from the guys who just want me to get rid of the jig. While you may be capable of producing a perfect edge using just an oil-stained driveway, I’ve tried (and tried and tried some more) to sharpen without a jig. I can get a reasonably usable edge without a jig, but not an edge that I WANT to use. Extremely sharp tools are just more fun to play with :-).
Since my Sorbies aren’t the only chisels out there that are widest at the edge and get slightly narrower toward the handle, I’m guessing this is a common problem. How do you guys sharpen such chisels? A shim is the obvious answer, but I haven’t figured out a convenient or reproduceable way to shim the chisel against the jig yet.
The angle is only about 2 degrees, btw.
Thanks, Mike
Replies
drill and tap an adjustable set screw to the side of your jig.
Expert since 10 am.
I have to use a jig, too. My dad could shave after three strokes with an old dished oil stone that he inherited from his dad - not me!
For tools with taper, ...
Eyeball it "straight" in the jig. Lock it. Reshape the bevel at that setting and sharpen it. This is now your reference standard for that chisel. It's square by definition.
When next it needs sharpening - eyeball it in the jig, again (you'll be very close). Then make one or two strokes on your medium or fine grit and observe the shinny spot made on the bevel. Adjust the chisel angle left or right to make the shinny spot appear evenly across your chisel. One or two more strokes will tell you when you are spot on (same width shinny spot across the entire bevel). Lock the chisel in the jig and finish sharpening.
Mike,
The other Mike, Mike D is right on the money. Set, test, adjust, sharpen. One reason I love my Norton stones is that the area on the stone where my tool is contacting turns gray. An light shading of gray the width of the tool lets me know that I have the tool positioned properly.
Another way, if you want a more precise way, is to use a caliper to measure from the front of the Veritas Mk II (where the blade is clamped) to the cutting edge of your tool. Assuming your edge is square to start with, you will end up with a square edge if the measurement taken from both sides of the blade are the same. I hope that makes sense.
Chris @ flairwoodworks
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
"How do you guys sharpen such chisels? "
The humble Eclipse is shaped so as to deal with this minor discrepancy....Observe the shape of the jaws...
I may be wrong, but I think that newer versions and imitations of this guide are not made with this facility. I have had mine for about 40years.
The "squaring" of any blade is easy to do in the Eclipse type jig.
I describe the method, which simply employs varying the force applied with two forefingers on the blade, in my chisel prep DVD.
A fine permanent felt tip line across the back is very helpful, and in your case it will need to be applied with an adjustable bevel.
A certain amount of trial and error is involved but it does not take that long.
Best wishes,
David Charlesworth.
MaxYak,
At the risk of disagreeing with two of my hero's (Charles, Philip), I don't think the eclipse really works that well for non-beveled, thick chisels...it is one of the reasons I also bought the MKII and, as you know, that doesn't work that well either. You've got to give the driveway another chance.
Seriously though, what has helped me is to side sharpen (ie. blade goes form side to side). The jig helps hold the angle and the fingers create a nice even stripe of brightness along the edge...this eliminates the consequences of any unevenness on the stone too.
The angle is only about 2 degrees, btw.
Just a dumb old man here but I would take the time to cut a sheet metal template of the exact angle of each chisel you have with non-parallel sides. Template made with one flat edge to reference the jig edge and a tapered edge to contact the chisel. Slip that 'little wedge in, tighten the clamp, and away you go!
I guess you would need to mark each template for the chisel it mates and then keep them in a safe place so they stay in good shape.
Mike, a guide is only that, a guide. By getting a chisel into a guide (whether the venerable Eclipse or the MK.II or ...) and checking after the first few strokes, one can put greater pressure on the side of the chisel that is not hitting the stone as it ought.
As regards mortise chisels (I have both vintage English oval bolstered and Sorby sash mortise chisels that I use) I think you'll find a non-straight bevel is more efficient--flat/straight is the bevel produced using a jig.
The picture below shows the tips of three of my OVB mortise chisels. Some are shaped well, others with use and sharpening will get there. The one at the top is close but still with a slightly too great a radius. The one in the middle is close. Both it and the lower one someone in the past hollow ground them--which isn't a good shape. I haven't used the bottom one much and so it'll take longer to get into shape because I'll do it while using it.
View Image
My ideal shape for a mortise chisel includes a steeper area at the cutting edge, a nearly flat portion and a rounded heel to the bevel. A slighlty curved bevel with a rounded top to the bevel aids in pushing the waste forward as chopping down and levering (respectively). The middle one is close.
Regardless of the shape of the bevel, though, mortise chisels simply do not need to be "perfectly" ground and honed. I use my stationary belt sander to grind and mearly hone the tip with a drag across the stone (medium Arkansas or 2k Shapton, whichever is sitting there) with a bit of a rocking motion. That is, the chisel is placed on the stone so that the bevel is touching about in mid-point and as the chisel is dragged back across the stone, the handle is raised so that the edge gets hit. A few strokes and I'm ready to continue.
fwiw, I cannot get mortise chisels to work in any jig reliably. The whole honing thing to me is just something to renew an edge between grindings while working. A jig for that is too fussy even when they work.
But I do use jigs--I have several. Just yesterday I honed 7 bevel edge chisels to send to someone. Used the MK.II. Worked great on the bench chisels and was quick. None of the bench chisels had square sides and so the angle portion of the MK.II was merely used for projection and getting the chisels "close" to square. Finger pressure was used from the 1/4" chisel to the 1 1/2" chisel to ensure an even bevel.
Take care, Mike
a guide is only that.. DANG.. And you have pictures!
OK so I give up!
Ha--sorry for being bloody obvious. Didn't mean it to be pedantic and so if that's how I came across I apologize.
I obviously susbcribe to the "I don't overly care" group of sharpeners. I get my edges sharp enough for me. Square? Square enough by eye. Only reason I used the honing guide on the chisels I gave away was to make them as the recipient may expect and to provide a best scenario for their leap into hand tools.
But aside from any dross in my earlier message, the pressure thing can correct a slightly out-of-square position of an edge tool in a guide, regardless of the guide.
Take care, Mike
Wow! Ask a silly little question that's been nagging me for a bit, go to bed, get up the next morning, put the porridge on the stove, check the internet real quick and see 11 useful and thought-provoking responses. I almost let the porridge burn :-).
Thanks to all!
MikeTo the man with a hammer, all the world is a nail.
Mike,
I beg to differ with the majority here. Differential finger pressure on the two sides of the blade will always get you to square eventually.
If the edge is square to start with even finger pressure on each edge will keep you square.
The whole joy of the Eclipse type guide is that the wheel is narrow, (sloppy if old) and does not dictate lateral twist to the tool.
I lay mortice chisels on the cross bars. The fact that it may be twisted slightly in the jaws is irrelevant if you learn to use finger pressure near the front of the blade. There should be virtually no weight on the guide itself, it is purely a device to assist with maintaining a consistent angle. Firm finger pressure near the tip of the blade is what gets the work done.
I can assure you that this technique works, I have been using and teaching it for about 30 years.
Many guides attempt to de-skill honing completely, but they are often not as clever as they seem. Some skill with variable force on two forefingers is worth acquiring!
Happy new year everyone,
David Charlesworth
I also use the MKII. In similar situations I have used a felt-tip marker to extend the line setting the angle across the guide. Then I set the chisel to the line rather than to the side of the guide.
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