There are three chisels in my kit that are for a specialized use. They are ground at 90º. They work kind of like a one toothed float.Originally Posted by Edward Weber
jtk
Contributor
There are three chisels in my kit that are for a specialized use. They are ground at 90º. They work kind of like a one toothed float.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Contributor
I wouldn't take the chisels to the grinder, try to determine what angle it came from the factory. If it's close to 25 degrees, just use whatever that angle is.
If you are using sandpaper, try 80 or 120 grit to aggressively reset the bevel angle with a guide. Try not to burn your fingers.
Two or three degrees plus or minus off of 25° is not a big deal. Focus on getting the back flat (1/4", 1/2" something like that) and can raise a burr when working the other side.
Contributor
If you are going to use the sled regularly, and if you feel confident that you can repeatedly set it up the same way, accurately, then I would set it at 25-degrees on your sled and grind away until you regrind the entire bevel. Your angle will wind up somewhat less than 25-degrees, but no matter. There's no magic to 25-degrees, it's just a reasonable compromise between a very shallow and sharp 20-degree bevel and a more obtuse and sturdy 30-degree bevel.
DC
Contributor
It's kind of silly for the manufacturer to state a specific sharpening angle. It depends on the use, the users technique, and the properties of the steel. Could be anywhere from 15 to 40 degrees, but most often between 30 and 35 for me.
Anyways you need to figure out what the current angle is. Use a protractor or slowly increase the angle of your jig until you start to get contact at the cutting edge. You might find the factory grind is too obtuse to be usable- sadly its not uncommon. I wouldn't want the primary bevel to be over 30 degrees in any case. If it is, you'll need to remove quite a bit of material off of the bevel.
If you don't have a grinder, the way I suggest to do this is to get a decent length of coarse sandpaper (60 to 100 grit) and stick it on a hard flat surface - could be a table saw top or jointer table, cutting board, etc. It doesn't need to be perfectly flat for working the bevel side. Use a honing guide set for something a bit less than you want your final sharpening angle to be- I recommend 20 to 25 degrees - and grind away using long strokes. This will go much quicker than using diamond plates, and will keep your plates from wearing out too quickly.
Keep grinding and checking the new flat surface you're creating at the top of the bevel. Check that you are not grinding it at a skew - if you find that you are, compensate by applying pressure to the side with more metal remaining. Use the whole bit of sandpaper and change it every 5 minutes or so of grinding - it dulls quickly and will cut much slower than fresh paper. Once the flat reaches the edge you are done with grinding. Now you can reset your guide for your actual sharpening angle (I recommend 30 degrees to start) and take it to the stones. You should be able to raise a wire edge almost immediately.
You might also find that the back needs work as well. If its more than can be quickly honed out using your stones, then I suggest again using the coarse sandpaper. But take more care to find a flat surface- I like to use a granite surface plate. Small imported ones from Grizzly, Woodcraft, etc. are not too expensive and are nice to have around.
Contributor
These make it easy to not only get the angle you want, but it's exactly repeatable every time. Back when I had helpers, I would hire illiterate people that no one else would hire. The last two, working together, could almost read a tape measure. They had no trouble sharpening chisels good enough to suit me, which is Really sharp.
Member
"Factory" "specs" are arbitrary. If a "factory" would have know a thing or two about chisels - they would make better chisels. You're getting one spot of contact precisely because it's arbitrary and because the "factory" didn't really grind it at 25˚ (assuming your jig is accurate). In general this is normal: scales don't match on different jigs, so what's marked as 25˚ on a grinder support might correspond to 28˚on a sharpening guide. So don't paint by numbers, but rather inspect the contact surface and adjust the jig until the bevel has 2 points of contact or when a point of contact is at the edge (depending on your preferences)
The brand you're mentioning is just an entry level tool with a lot of price engineering on it, sloppy grinding is a part of it. This is good and bad at the same time. Bad is because every chisel from the batch has it's own hardness and the range is wild. So you have to figure the grinding and honing angles at which a given chisel retains its edge for the most reasonable time. From the experience (I have several sets of these btw) the angle will be closer to 30˚ rather than to 25˚ and that every chisel will have another angle, but the good part is that you can experiment not worrying about destroying a good tool. E.g. you can try different bevel geometry, vary angles, etc. to better understand what do you want from a chisel.
Btw, "sharpening for a _long_ time" is better avoided, this is why there are grinders. A grinder removes the bulk of steel and establishes a primary angle which you then refine. Refining is really polishing, so if you don't want to spend a couple of weeks re-establishing a primary bevel on ANSI400, you have to grind it to an angle you think might work and only then hone. These chisels are also good for learning to grind - something you will have to master, because what you're doing is an operation that happens at least a couple a times on a given day. Therefore if you don't want to be just a walking tool grinder and if you're determined to make things out of the wood at some point - you have to figure how to get this process in under 3-5 mins per tool.
[OP]
Member
Wow. What an incredible set of answers. I learned a lot and also got some really good, practical, advice. I'm eager to grind the chisel to 25 degrees, so I can make a nice 30 deg bevel in the back. Thanks.
Contributor
I may be misinterpreting your “30 deg bevel in the back,” but you do not want a back bevel. You want a secondary bevel of 30 degrees.
Contributor
Yes, Gary is right.
Back flat, bevel only on the topside whether you want a flat (single) bevel or sharpen using a secondary bevel.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Member
Just making sure it was clear: the angle at the edge is what defines edge life and that the final edge is honed on the same side where the bevel is ground. A grind bevel has anything to do with edge longevity only if a honing angle matches the grinding angle.
This geometry was brought to my attention by David W. It's the only geometry that could work reliably in dreaded KD Douglas Fir and allow for some serviceable results. It's different from the "microbevel" because I haven't heard "microbevel" people advocating for a really low grinding angle, also their "micro" bevels aren't that "micro-", I keep seeing honed edges taking like half of a bevel. Or in other words two arbitrary angles don't make this geometry: the honed edge has to be as small as you can get it and a difference between angles must be considerable.
The "22˚grind and 30+˚ honing angle" actually was described in one of the Paul Hasluck's books. Hasluck was an editor, so individual chapters were written by various people. What's interesting that it seems to be the only book where Hasluck published anything on sharpening, other books just mention sharpening equipment, but doesn't utter a word on how to shape an edge. Except this one book, "The woodworking". The chapter is short and well worth the read, if only for flames and brimstone hurled at convex bevel people. It was written by somebody with initials J.D. (promise I have nothing to do with it, I was busy with something else at that time), who goes back to the "Work" magazine times, where Hasluck was an editor and J.D. wrote most articles on toolmaking, steels, etc. The chapter can be found in "Work" btw, it explains it in great details and even has a forces vector diagram, which is why exactly nobody read it ("there's no vectors in my timber!").
There's another advice of constantly maintaining a low grinding angle. I don't really want to drown you in details, because at this point it's more important to be able execute this accurately and neatly rather than figuring theory behind it. But if you're interested I could dig out this book.
Member
How do you make sure a chisel in a red jig stays square? I have a similar Veritas guide (not manufactured anymore) and I like it because it holds a chisel better than a side clamping jig, but setting and keeping it square to the edge is pretty much impossible.
Contributor
The red jig doesn't hold anything square. I would never sharpen the narrow chisel in it with that jig, but just grabbed what was close at hand to show that any chisel can be set in any jig with them. That red jig is an old Record, and just has a ball for a roller. It works good for irons with short radiuses like Scrub plane irons, or 8 to 10 inch radius Jack plane irons. I have no idea when they stopped making it.
I don't think I own any jig, including the old ones that I rely on to keep the edge square. Even that Veritas jig, which is rarely used, keeps the cambered roller on it. I don't think it's been used since I made those setting jigs, and that was in 2015 or 16. I had a helper that could use it as it came when sharpening with oil stones if we were using a microbevel, but no microbevels since back then either. The picture is the day I stuck those jigs together back then. There is another now with 18 and 27 degree angles.
As far as grinding angle, for us it's just to get the bevel out of the way. I don't worry about, and have no idea what they are exactly-mostly just done by eye. My helpers could never sharpen anything by hand alone so we don't depend on a hollow grind to register on a stone. We hollow grind because the grinder has round wheels.
The edge bevel is what we use those setting jigs to get. There is nothing to fumble with or repeat exact setting on, so they are foolproof. We just sharpen flat bevels with no microbevels, so the edge bevel can take over as much of the ground bevel that it likes until there is edge damage. Only with edge damage will the cutter revisit a grinder.
My plane irons have not visited a grinder in years.
Contributor
I've had the old clamp on top veritas sharpening jig since they were first introduced, mine has the old block with different angles, before they switched to the hex (or is it Octagonal) wheel design.
I struggled for years with the jig trying to keep chisels, particularly narrower ones square. I had a tendency to favor one side, which would cause the blade to drift and pivot toward the right (in the jig). Once I realized this, the cure was to sort of pretend the jig wasn't there and use a light touch.
I keep my eyes and my focus on the edge being ground, keeping it square with my body and hand positioning and letting the jig set only the angle of the bevel. It isn't a mindless activity it requires a fair bit of attention. Eventually I got the hang of it, and retrained my body to apply even pressure.
I bought the new(er) Mark II jig, but it had way too much gizmosity (in my opinion) and used it once, then sold it.
I rarely use the old jig nowadays. The only time I use it regularly is with my LN No. 9 which I use for shooting. That iron wants to be dead square and with a very shallow grind and microbevel.
Jack Dover: I now use a very shallow angle (less than 20-degrees) and a convex bevel on a lot of my bench and paring chisels. I've been experimenting with this for years now, and so far I am convinced that there is some value there, when freehand sharpening. If you do dig out the Hasluck book (which one?) to find the article by J.D. I'd be interested to read his criticism of the technique.
DC
Member
Can't find where the book can be found in its proper form, but this is one of versions that has most images removed for copyright purposes: https://www.google.com/books/edition...s/HyyCDwAAQBAJ
The chapter you're looking for is titled "How Chisel Edges Should be Shaped". It's supposed to have several pictures, but only one has particular interest, where a diagram of forces is shown. The premise of the chapter is that there's a geometry providing the least resistance to the wedging action and there's a geometry that has the longes edge life, so these two can be combined for an operator's benefits.
I used to use this book as a reference, but this chapter was always skipped ('cos I assumed I can sharpen already). Then David W. pointed to it in an unrelated post, I tried it and I'm pleasantly surprised. Especially about a recommendation to grind often to maintain a low main bevel angle - apparently it's just one light touch of a grinder wheel in the bevel's heel area.
Member
There are plenty of good sharpening videos online. If you don't have much equipment, sandpaper can be a good place to start. A quality coarse/medium combination carborundum stone and a fine india stone works well too.
In general, the process is:
Grind to establish the bevel and remove damage. This can be done via power units, very coarse stones, or sandpaper.
Hone to refine the bevel.
Lots of people love stones. I ended up power sharpening with a Worksharp unit and buffing the final edge.
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