Thread: Chisel - Sharpness

Originally Posted by Clinton1

I have a “good enough” rule for sharpness.
I stop sharpening when I can run a fingernail down the edge and feel nothing in the nail bed.
That’s all I’m looking for.
Works for me.
I got tangled around the axels 20 years ago when I got serious about wood work, but at the end of the day, sharpening is the maintenance work for production.
Being productive was more important for me.
So I decided to draw a line of “good enough”, and got doing what I wanted, which was making things.

I’d also suggest that if you need a special sharp chisel to pare off material to make a joint, there are other things to work on, such as layout, cutting and glue result.

I think it depends on how you work and what you do. If you work a lot by hand, you can't avoid high sharpness - it's part of productivity. The tedious methods taught to get high sharpness for beginners aren't really part of productivity, but beginners aren't skilled workers and people who teach them need to see beginners have success or beginners won't come back and pay for a second month of subscription or class or whatever else.

However, really high sharpness isn't special sharp. It's regular sharp. It takes the same time to get it as it does for you to do less sharp and then test the edge for damage.

I think the sharpness in the picture isn't anything other than routine sharpness, and the older texts that wring the time out of the sharpening without wringing out the results wouldn't have any trouble. A lot of amateur woodworkers and a lot of professions would have difficulty producing that edge quickly, though. And some wouldn't.

Hand tools is a strange subject - it's one that a lot of people like to talk about on forums, but often with sort of an undertow of "well, but we don't want to get in too deep or go too far with the hand tools thing".

I see you said you were away. Welcome back.

Completely agree with you, David.

Regards from Perth

Derek

Originally Posted by derekcohen

Completely agree with you, David.

Regards from Perth

Derek

You know (or maybe not), George hates sharpening discussions. But he doesn't like them because they end up being arguments about dippy things (which stones, which method, etc.) instead of results. I don't think he'd want to talk long about results, either, because fine work has good results sharpening as a given and he probably thought people would like to delve further into chasing finer work.

But, when I've talked to him offline and something comes up with the topic, there is a constant end, and that is in his apprentices, the lack of desire to keep tools truly sharp is the biggest impediment he saw in the shop. And it's funny that he would mention that (their need for sharpness would've been high making violins and such), because Richard Jones at one point mentioned an interest in collecting faster sharpening methods due to the fact that in shops where he is teaching, the students will continue to use dull tools until they can't be used at all and then leave them dull. Notable because Richard is of the fame of "my master spit on a red stone and stropped the tool on his hand and said get back to work" or something along those lines.

There's no requirement for people to use hand tools to do fine work, but at some point, lack of fast and fine sharpening becomes limiting and at a point above, it's completely disabling. Things like carving and fine smoothing work (which can be done without hand tools, of course - carving can't be done at a fine level without them, though), and cutting mouldings by hand where the planed surface is generally the finished surface require it. too much of the older work is considered more difficult than it is not for the complex things, but lack of doing the basic things well enough. since I don't delve much out into power tool woodwork (too much planning and organizing for me - somehow hand making things seems to avoid the need for as much by a factor of 10), that's probably also the case for power tool work.

This video was posted on the blog of the late Chris Hall. Funahiro chisel ...





Regards from Perth

Derek

Thanks, Derek. I liked the "sparkling" surface, and noted that he waxed his chisel.

Coincidentally, I spent a couple of hours yesterday being shown how to cut a variation on a dovetail. Like in the video, my tutor also waxed his chisels after sharpening - common parafin wax - and it did seem to make a useful improvement.

I routinely wax hand plane soles and hand saw blades, it substantially improves performance, but I had never considered waxing chisels or even plane irons.

Perhaps I should consider waxing all blades?

• hand plane blades,
• chisels,
• knives,
• drill bits,
• router bits?

Originally Posted by GraemeCook

Thanks, Derek. I liked the "sparkling" surface, and noted that he waxed his chisel.

Coincidentally, I spent a couple of hours yesterday being shown how to cut a variation on a dovetail. Like in the video, my tutor also waxed his chisels after sharpening - common parafin wax - and it did seem to make a useful improvement.

I routinely wax hand plane soles and hand saw blades, it substantially improves performance, but I had never considered waxing chisels or even plane irons.

Perhaps I should consider waxing all blades?

• hand plane blades,
• chisels,
• knives,
• drill bits,
• router bits?

There are references to fatting chisels apparently all the way back in roubo. With high polish stones now, there is quite a bit of friction/tension that isn't really there with oilstones. I don't know why that is, but if you sharpen something with an oilstone and then sharpen to a very bright polish with synthetic stuff, the chisels have more grip.

When people were providing the power, chisels and drill bits definitely were fatted or waxed, and saws.

hand plane blades won't work well - the part that contacts the wood (the blade tip) is worn off substantially, but waxing the sole does the trick.

router bits I think would lead to waxy smoke, especially with something as easily smoked as paraffin wax. Anything that doesn't stand at room temperature will obviously leave a wet oily splotch on the wood.

David could that just be that the more polished the surface, the more contact there is at a microscopic level, adding to the friction? Or perhaps that when there is polish the grit will commonly all have gone in one direction meaning the scratch patterns will all be in one direction and this functioning to create a grip?

I recall being informed the reason why the Lee Valley plane irons have a dull back, despite being super smooth, is that the way the machining works the final grits are not in coherent directions, leaving them cloudy like from a muddy wetstone. As opposed to when you (say) lap a chisel in one direction on sandpaper, and you fairly quickly get a mirrored edge because of all the scratch patterns going in one direction and creating coherent light reflection.

Originally Posted by D.W.

There are references to fatting chisels apparently all the way back in roubo. With high polish stones now, there is quite a bit of friction/tension that isn't really there with oilstones. I don't know why that is, but if you sharpen something with an oilstone and then sharpen to a very bright polish with synthetic stuff, the chisels have more grip.

When people were providing the power, chisels and drill bits definitely were fatted or waxed, and saws.

hand plane blades won't work well - the part that contacts the wood (the blade tip) is worn off substantially, but waxing the sole does the trick.

router bits I think would lead to waxy smoke, especially with something as easily smoked as paraffin wax. Anything that doesn't stand at room temperature will obviously leave a wet oily splotch on the wood.

Originally Posted by Cgcc

David could that just be that the more polished the surface, the more contact there is at a microscopic level, adding to the friction? Or perhaps that when there is polish the grit will commonly all have gone in one direction meaning the scratch patterns will all be in one direction and this functioning to create a grip?

I recall being informed the reason why the Lee Valley plane irons have a dull back, despite being super smooth, is that the way the machining works the final grits are not in coherent directions, leaving them cloudy like from a muddy wetstone. As opposed to when you (say) lap a chisel in one direction on sandpaper, and you fairly quickly get a mirrored edge because of all the scratch patterns going in one direction and creating coherent light reflection.

I think it's hard to get a bright polish with silicon carbide, even if you polish something with straight strokes. I don't know why that is actually. I'd bet with a fine enough grit and a long enough time, though, you'd get a polish. silicon carbide is a weird thing, though. you have to find a point where it starts such that it will end where you want it to since it's fragile and fractures so easily, but you can buy the very fine stuff, too - it's one of the few abrasives I don't recall buying in really fine grit, though.

As for the stickiness of the synthetic stones, i never really figured it out. you can get an oil stone to row softer chisels and such the same way a synthetic will do harder steels, but I don't remember the stickiness. Maybe it has something to do with how crisp and sharp the tiny abrasive lines are.

Whatever it is, you can notice it when you pare wood. I don't think someone using a firmer and a parer 200 years ago would've tolerated it.

Actually, I'm sure I have a microscope picture of the back of an LV iron somewhere. I no longer have any LV irons on hand, but the dull pattern on the steel isn't fine like we'd think of a fine abrasive. it's very fine for manufacturing, but not 10 seconds away from bright polish with a sigma power 13k.

I wish I knew where I'd kept a picture of a newer iron that still had the tumbled grit artifacts not too far from the edge.

I've also noticed that 100% of vintage used chisels are either black or brown, where many were polished bright prior to their original shipment....

The vast majority of work spaces back in the day were not climate controlled beyond heating in the winter. Some places hung wet cheese cloth on the windows to get some "Swamp cooling." That only works when the ambient humidity is pretty low, and it's not really the best for woodworking.

Condensing humidity indoors was a real thing, even inside houses, as was humidity levels up in the 80% ranges.

That rusts tools in a heart beat. So yeah, waxing them was important.

Personally, I like the way waxed tools work, but I don't like the difficulties the residual wax creates when finishing. As such, I gave up on it. Now, if you were doing a traditional linseed oil/beeswax finish, then it wouldn't matter, but I couldn't abide by the fish eyes it created in varnish/lacquer finishes.