I am cutting dovetails (learning) and I find plenty of info on sharpening a chisel with a primary and secondary bevel. But after you pound on it 25 blows or so, how do you get a nice edge back on it? Edge maintenance?
I have granite blocks, 600, 1100, 3000,5000 & 7000 sandpaper and a MKII honing kit. I purchased a leather strop on Amazon but the leather is so thin I’m not sure it works. Is there any good info on keeping blades sharp. Thanks.
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Replies
More often than not, I just resharpen it. On occasion, I will use a strop to get the edge better. By the way, 25 blows seems like a low number. In terms good info on keeping blades sharp there are two sources I trust. Paul Sellers (info readily available on YouTube) and the book Sharpen This by Lost Art Press - also blogs and a video series you can purchase. Both systems work really well and involve only 3 grits and take just a few minutes per chisel. Pick one and stick to it.
If you want to keep any given chisel sharp, you can strop it as you suggest. I use a Tormek primarily and will kiss an edge on the leather honing wheel (approx 4000 grit) to bring it back to a razor after use. Sometimes it will need to go on the whetstone but as often as not this is not required.
Glue your leather onto some MDF suede side up and charge with a little green or yellow honing compound. I have also had good results with green compound directly applied to MDF.
There is no advantage in being ultra sharp (grits much over 4000) for most work. Edges that are too fine will simply degrade faster anyway. You are cutting wood, not tomatoes.
It is useful to avoid using chisels to remove too much wood, especially cross-grain cutting such as in dovetails, where you are slicing across grain fibres. Some wood should part away with each blow - I will usually take relatively small bites, until close to the line, then halve the distance to the line each cut until the line is the only place to cut. If you need more than gentle taps with the mallet then you are not doing it right.
"Pound it"? This isn't really the way to perfect a dovetailed profile. As others intimate, careful small slicing cuts are needed. To ensure that they are careful and small, avoid the mallet in favour of a very sharp paring chisel used entirely by hand. There shouldn't be much left to pare after sawing dovetail notches.
On the other hand, you can mallet the cuts and this may even be advantageous if you adopt the right malleting technique - no pounding but just gentle taps, as another poster describes. Use of one of those brass-headed mallets, holding it by the head rather than the handle as you tap-tap, is the way.
The advantage of such malleting is that, unlike with hand-paring, it automatically limits the passage of the chisel, per-tap, through the teeny bits of wood to be removed without making an unintended over-thrust and resultant overcut.
I'll disagree with the notion that its pointless ('scuse pun) to bring (some) chisels up to a very fine sharp edge. If the chisel is to be used for very fine and accurate cuts, a low angle of cutting edge made very sharp indeed is beneficial. Moreover, it's easier to strop such an edge back to original keeness without a need to resharpen, for many iterations. The low forces involved with hand paring mean that the chisel edge is far less stressed than that of anything being "pounded".
With some chisels (carving chisels being the prevalent example) low cutting edges frequently stropped back to "very keen" is the norm, even when the chisel is malleted. Although I have, as yet, not that much experience in carving tasks, I can already confirm unequivocally that its possible to use a very keen edge at a low cutting angle to improve the capabilities of the chisel to make intricate and fine cuts, whilst also being able to strop it back to "very keen" numerous times before resharpening becomes necessary.
Just passing along some info about carving chisels that might be hard to find otherwise. I’ve been taking a carving class one night a week for a year. At this point, know the instructor quite well. He has not done anything other than strop his carving chisels for the past 20 years; they have never needed to be reground on a stone.. I was surprised by this. After 10ish minutes of use of a carving, he strops the chisel 10 or so strokes. They have a 15 degree bevel on. Them from the factory. I don’t think this is applicable to traditional woodworking operations but seems to work well for carving; he carves a lot by the way.
That's very interesting to say the least.
I've been stropping cabinet making chisels and plane blades for some years now. It's certainly possible to bring them back to working sharpness a number of times purely by stropping (assuming the edges are good & sharp to start with). But at some point I find I have to reform at least the micro bevel.
Just recently I've been chewin' through many Chris Pye vids, so far all those about tools and their maintenance. In one he explains the nature of stropping, making this contention (words to this effect):
As one strops the cutting edge may be slowly given a tiny rounding, as even thin leather and a light pressure will depress enough to rub the edge at slightly more than the angle the chisel is held. Some folk will also lift the chisel handle at the end of the strop-stroke, which rounds the edge very quickly.
Eventually the angle at which the chisel must be held to make it bite increases from the initial, say, fifteen degrees set by the commissioning & sharpening until one has to hold the chisel at an unacceptably high angle (for carving) to get it to bite.
Mr Pye suggests that he tends to resharpen rather than hone once the it-bites-now angle gets up towards 30 rather than 15 degrees. The resharpen starts on a fine stone (translucent Arkansas) and is done enough to make the bevel dead flat once more from the heel to the cutting edge - enough to remove the tiny round over from honing.
https://youtu.be/fwyFk0J_YRo
See from around 2 minutes in, onwards.
However, he also suggests that if the carver can strop carefully enough (never raising the chisel above the cutting angle and never pressing it at all into the leather or other honing surface) then the whole bevel will be polished and a slightly degraded cutting edge brought back to full-sharp without any gradual rounding of that edge occurring.
My problem is that I seem unable to hone without the leather containing the honing stuff depressing to some very small degree. It's always tempting to press the bevel on to the strop; and even if one doesn't, just the weight of the chisel will depress most honing leathers to a tiny degree.
I've had to resharpen (only a little, with a fine grit) my carving knives because when I strop them I can't seem to help but eventually introduce some rounding to the edge.
Mr Pye says he's tried stropping on hard surfaces such as MDF or a dead flat piece of hardwood but found it wasn't for him (no details why not). I'm wondering now what your instructor strops on to avoid the need for ever resharpening?
I see him on Wed and will ask about his stroping routine.
"...the leather is so thin I’m not sure it works".
The leather doesn't really do the work. It's more of a substrate to hold the honing compound. I sharpen with water stones but previously used the sandpaper method as you do. It works fine. I keep a leather strop on my bench when doing chisel work. It's nothing more than a piece of smooth leather about 3" x 8" glued to a wooden block. I charge it with green honing compound (available at Lee Valley and other sources in stick form). I give the edge a few swipes on the strop periodically and it keeps things nice and sharp.
Also, you want a thinner, harder leather (mounted to a firm piece of wood) to avoid rounding over the edge of the chisel when stropping. A thick, or too soft, piece of leather gives more than a thin piece. As stated, the leather is only there to carry the abrasive compound. The only down side to being too thin is that it might wear out faster.
Below are my stropping leathers. The flat ones are old leather belts that I kept around for making leather washers on chisel handles. I lay them flat on the bench when needed. I use white rouge as a stropping compound because it what I have.
As a younger man I used bare leather to strop my hunting and pocket knives. That worked as well, but slower.
I think the angle one uses to strop is more important than thickness of leather to prevent round over of the edge.
As to the leather wearing out, Mary May claims a to have been using the same piece of thin leather for her carving gouges for +/- 20 years.
As with so much of wood working, it comes down to what works for you.
Experience is at some point going to lead you to setting the edge up in a way that it doesn't roll or dent. it just happens unless you willfully prevent it.
At this point, though, I think you are best off figuring out what angle with the very final bevel prevents damage, and then back off from there and run the edge over a very fine abrasive rolling the tip up just a little freehand as you do it. we are talking about tiny amounts.
So for example, if you find 35 degrees results in no edge damage, then hone the edge to 30, and with honing compound on wood or autosol or something pull the chisel back and rotate the handle up just a little. This will give as good of edge life, but get through the wood more easily.
I was taught to touch up my chisels on an oilstone. I give it maybe 3-5 strokes on the chisel, wipe the oil off, and then strop it. Takes maybe 30 secs and is easy to do before you get to needing to regrind. I always try to spend less time sharpening than cutting:-)