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Thread: Convex bevel a la P. Sellers

  1. #46
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    Quote Originally Posted by ken hatch View Post
    Jim,

    I haven't a dog in this fight, as with most things in life somethings work for some folks, some don't. But I'm curious why there are such strong negative opinions as well as positive about Mr. Sellers. Why would you not take another class? Nine days is a long time to be unhappy, I expect I would have "walked" after a day or two if it was not what I paid for. When you are older than dirt, time is too valuable to waste.

    I need to go with SWMBO to visit in-laws this year and I have been thinking about using that time in the UK to take a class from someone, PS was one of the ones I thought about. It would give me something to do and could make the near 50 hours flying steerage almost bearable or at least worthwhile. Anyway to not hijack this thread, if you would like to vent or at least give me a reason to not waste my time, how about either PMing me or start a PS thread.

    Heck, Ill start a PS thread.

    ken
    One pays their money and takes their chances. If the money would be refunded then maybe walking would be a good way to go. Otherwise, one can always hope there are some worthwhile bits of information being exchanged for the misery of being there.

    If my travels were taking me to the UK my first order of business wouldn't be to taking classes, it would be to identify every tool dealer that may be of interest to visit. My next order of business would be to figure out how to get as much spending money as possible and how to get all my new found treasure home.

    My recollection is there was a recent thread on Paul Sellers. It became so heated it was closed and removed.

    Mr. Sellers isn't my cup of tea, but that doesn't mean he doesn't have lessons of value for me to learn.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  2. #47
    Quote Originally Posted by Pat Barry View Post
    How in the world do you make sense of this statement. If they had no honing guides then they did it freehand and if they did it freehand they certainly were not precise about degrees.
    First, as Jim K. mentioned, a grinding wheel with a tool rest helps a lot.
    Second, even without a grinding wheel, there are all sorts of ways to do this. The method most often mentioned in those old texts--I think it's in Nicholson but I'm too lazy to look--is to make the bevel twice the thickness of the blade. That's a nicely practical way of saying sine 30° = 1/2. If you can measure accurately, you can hit 30° within a degree this way.
    Third--assuming we are talking about 17th-19th c. Europeans and Americans, not Neanderthals in caves--they may not have had honing guides, but they had protractors. So you grind, measure, and grind again. Eventually you develop the muscle memory to hit your angles accurately. By the way, if they had wanted honing guides, they certainly could have made them, but they were making tools for professionals, not accessories for amateurs.

    Its virtually impossible to get anything other than a convex bevel going freehand. No one is that precise such as to avoid some degree of convexness.
    Pat, you have a tendency to assume that difficult for you = virtually impossible. You made some similar comments before about the supposed impossibility of jointing an edge by hand, which is a fundamental, gateway skill in furnituremaking.
    In Japan, the normal method of sharpening is a full flat bevel, done freehand, no jigs. So yes, it is possible--they have been doing it for a very long time indeed.
    The human mind and body are capable of some pretty amazing things. One of the most fulfilling and addicting things about hand tool work is when you exceed what you thought was possible with your own two hands. But to do that, you have to shed your preconceptions, and most importantly, be willing to fail. Try it some time--you might surprise yourself.
    "For me, chairs and chairmaking are a means to an end. My real goal is to spend my days in a quiet, dustless shop doing hand work on an object that is beautiful, useful and fun to make." --Peter Galbert

  3. #48
    I was trained to sharpen freehand at a constant angle in 1962. By the time Sellers was starting a few years later, I had no trouble keeping an angle and had a nice reputation for my edges. I have sharpened chisels and plane irons without a grinder for my entire professional career as a hand tool only woodworker.

    It has been a long time since I paid much attention to an exact angle, but when I measured everything a few years ago for a forum discussion, I found that everything was within a degree of 30. And this evening when I checked 8 chisels, they seemed right at 30. It is kind of surprising because I do not think the exact angle is that important.

    Of you just taking light cuts with a chisel it doesn't matter if the bevel is flat or concave or convex, as long as the very tip is a reasonable angle. However there are chisel techniques where in addition to cutting at the tip, the chisel also acts as a wedge, pushing tissue with the bevel. Here the flat bevel works best because it forms a nice wedge. Mortising is one time a flat bevel works best.

  4. #49
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    Another here in the 'i'm no expert' camp, but getting consistently excellent results with waterstones and a honing guide. Pardon my not working through the whole thread.

    There's no reason why a convex bevel can't cut perfectly well in that the wood probably only 'sees' the angle right at the edge - but speaking from a pure geometry perspective some wariness of the method seems advisable. There's several fairly obvious potential issues - which i'm sure have been mentioned already - by Jim and Warren and probably more:

    1. The humped bevel risks lifting the cutting edge off the stone if the honing angle is reduced even slightly below that at which the blade was previously sharpened - making it likely (unless enough work is done to hone away the part of the 'hump' causing the problem) that the edge will not be sharpened. The obvious temptation is to create this effect by steepening the bevel with every sharpening in an effort to ensure edge contact with the stone. Which can't be done very often. It all points to the need to precisely control the honing angle in the first place.

    2. The hump will reduce the (potentially already fairly marginal) clearance available on a bevel down plane if the above steepening of the bevel takes place. Possibly so much that that the blade won't cut at all because its skidding on the hump.

    3. Some use chisels from time to time off the bevel side, it can be useful to have a flat bevel to use like the sole of a plane to prevent the blade 'diving' in a hard to control manner as it pares. (micro bevels may compromise this too)

    The pretty aggressive/high pressure stropping technique seen in some videos (where a significant amount of metal is removed/needs to be removed to create a sharp edge because the prior sharpening step used a fairly coarse stone/plate) seems likely also to tend towards creating a convex bevel steepening right up to the cutting edge, with similar consequences to the above. Think i prefer the idea of finishing an edge most of the way on a fine waterstone, then (and it's hardly necessary) lightly stropping on a flat and hard surface, controlling the angle carefully and not using too much pressure.

    A chisel sharpened with a flat primary bevel, and a few degrees steeper of a micro bevel seems in comparison to be likely to be significantly more tolerant of minor inaccuracies (in either direction) in the honing angle used when re-sharpening. It's unlikely that much metal will require to removed to hone away the wear bevels.

    The bottom line seems to be that the bevel angle needs to be pretty precisely controlled no matter what sharpening method is used - which suggests that it comes down to either using a honing guide, or else developing the skill needed to accurately repeat the honing angle when sharpening by hand… As Warren the precise bevel angle chosen may not be that critical, but re-sharpening does seem to require getting back close to it….
    Last edited by ian maybury; 02-09-2015 at 1:12 PM.

  5. #50
    Quote Originally Posted by Jim Koepke View Post
    One pays their money and takes their chances. If the money would be refunded then maybe walking would be a good way to go. Otherwise, one can always hope there are some worthwhile bits of information being exchanged for the misery of being there.

    If my travels were taking me to the UK my first order of business wouldn't be to taking classes, it would be to identify every tool dealer that may be of interest to visit. My next order of business would be to figure out how to get as much spending money as possible and how to get all my new found treasure home.

    My recollection is there was a recent thread on Paul Sellers. It became so heated it was closed and removed.

    Mr. Sellers isn't my cup of tea, but that doesn't mean he doesn't have lessons of value for me to learn.

    jtk
    Jim,

    That, "...so heated it was closed and removed" is what amazes me. I don't see a reason one way or the other but....SWMBO tells me I live in a different world most of the time. Maybe she is correct.

    You gave me a good smile with the tools.....My problem is I have too many now and something would have to go to make room for more. Now sitting in a pub and having a pint with every tool dealer of interest would be something to look forward to.

    ken

  6. #51
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    Quote Originally Posted by Jim Koepke View Post
    If my travels were taking me to the UK my first order of business wouldn't be to taking classes, it would be to identify every tool dealer that may be of interest to visit.
    Now this is interesting. Of all the tools I've bought (and had to import), apart from a Record 405 and some nice Wealden router bits, they all came from the USA (sold not necessarily made).

    What tools do you think are available in the UK that you can't get back home?
    "If you have all your fingers, you can convert to Metric"

  7. #52
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    Quote Originally Posted by Hilton Ralphs View Post
    What tools do you think are available in the UK that you can't get back home?
    Maybe not on other people's list, but I can think of 2 off the top of my head:

    PAX 20" handsaw 8tpi

    Ashley Iles Cabinetmakers Fishtail Skew 7/16 inch

  8. #53
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    What tools do you think are available in the UK that you can't get back home?
    Hilton,

    Back home is all relative. Currently I live in an area that isn't as populated with old tools as other parts of North America. If my travels were taking me to the east coast I would also want to hunt tools. It is always fun to go rust hunting in unfamiliar waters.

    Currently a class on Windsor chair making might persuade me to do otherwise. Then again, getting anything made in the class home might be a challenge.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  9. #54
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    Quote Originally Posted by John Schtrumpf View Post
    Ashley Iles Cabinetmakers Fishtail Skew 7/16 inch
    Brands aside, you could buy one of the Bruce Lie equivalents, perhaps not that exact size though. The AI's I've bought from TFWW have disappointed me somewhat but that's neither here nor there.
    "If you have all your fingers, you can convert to Metric"

  10. #55
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    I ended up getting the 1/2" skews from Lee Valley. But it would be fun to go to the Ashley Iles factory and buy something.
    Last edited by John Schtrumpf; 02-09-2015 at 1:41 AM.

  11. #56
    Britain is especially great to find old tools. Here are some tool dealers: http://www.cornishworkshop.co.uk/tooldealers.html

    Apart from that, Britain has amazing history. You won't have to feel bored when you look around to visit nice old towns, castles, musea etc.

  12. #57
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    Quote Originally Posted by Steve Voigt View Post
    First, as Jim K. mentioned, a grinding wheel with a tool rest helps a lot.
    Second, even without a grinding wheel, there are all sorts of ways to do this. The method most often mentioned in those old texts--I think it's in Nicholson but I'm too lazy to look--is to make the bevel twice the thickness of the blade. That's a nicely practical way of saying sine 30° = 1/2. If you can measure accurately, you can hit 30° within a degree this way.
    Third--assuming we are talking about 17th-19th c. Europeans and Americans, not Neanderthals in caves--they may not have had honing guides, but they had protractors. So you grind, measure, and grind again. Eventually you develop the muscle memory to hit your angles accurately. By the way, if they had wanted honing guides, they certainly could have made them, but they were making tools for professionals, not accessories for amateurs.



    Pat, you have a tendency to assume that difficult for you = virtually impossible. You made some similar comments before about the supposed impossibility of jointing an edge by hand, which is a fundamental, gateway skill in furnituremaking.
    In Japan, the normal method of sharpening is a full flat bevel, done freehand, no jigs. So yes, it is possible--they have been doing it for a very long time indeed.
    The human mind and body are capable of some pretty amazing things. One of the most fulfilling and addicting things about hand tool work is when you exceed what you thought was possible with your own two hands. But to do that, you have to shed your preconceptions, and most importantly, be willing to fail. Try it some time--you might surprise yourself.
    I never meant to imply that someone doesn't develop a degree of muscle memory through repetition. I think that is entirely within the realm of experience for nearly everyone. My only argument had to do with the 'precision' of this process. I interpreted your initial use of the term 'precise' as meaning accuracy. Precision refers to repeatability. I think we can all agree that the actual primary bevel angle itself doesn't really matter all that much within a range of angles that are close to the, lets say Nicholson target of 35 degrees. If everyone wants to be like Nicholson, then they will need to use the formula bevel length = 1.75 times blade thickness. That will give you 35 degrees with a great deal of accuracy. The fact is that Warren apparently likes a 30 degree bevel and feels he is very consistent about 30 degrees but doesn't therefore agree with Nicholson about what is the proper angle merely demonstrates the point that the actual primary bevel angle isn't really all that important. My only point is that accuracy and freehand are mutually exclusive. In the end it doesn't matter. I can see personally that creating a slightly curved bevel transition to the cutting edge is much easier than trying to create a precise secondary bevel. So, if you do your primary bevel freehand, then continue to freehand it and round over that bevel near the cutting edge ever so slightly to get a sharp tool the more important thing to recognize is when that edge angle might be a bit too steep. The wood doesn't care if there is a a curved surface or not.

  13. #58
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    I found the instruction invaluable.

    You might have a different instructor, depending on the time of year.
    Were I in your shoes, I would seek out Adrian McCurdy - he's doing something novel.

    http://www.adrianmccurdy.co.uk/

  14. #59
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    I have never ever measured the degree of a bevel in my life. I think too much is being made of it,really. For hardwoods you use a more blunt angle than for soft woods. My tools work just fine. Never used a sharpening jig. They are a bit convex. So are the cutting edges of Japanese swords,famous for their cutting ability,only convex on BOTH sides!

    I have all kinds of tools for measuring accuracy to very close tolerances. Perhaps I should get out a Starrett vernier angle gauge and check them.
    Last edited by george wilson; 02-09-2015 at 8:59 AM.

  15. #60
    Quote Originally Posted by Jim Koepke View Post
    This is another one of those sharpening questions that ends up with a lot of disagreement and sometimes heated exchanges.

    The convex bevel seems to work for some, but others tend to get it too convex and then with a bevel down plane there isn't enough clearance angel behind the edge of action (for lack of a better name) and a shaving can not be produced.

    My theory on sharpening is to consistently make a sharp edge before trying any of the variations. Very few of my blades have an intentional second bevel. Since most of the time my blades are honed free hand there may actually be a slight secondary bevel or even some convexity.

    In my experience once the back of the blade is good to go there isn't a need for the ruler trick.

    For me it is simple, if a blade isn't cutting, it is because it needs sharpening. It isn't because it is too convex or the back bevel from the ruler trick got rounded or the secondary bevel isn't right.

    Keep it simple, Keep it sharp.

    jtk

    This would be my thought on the matter-

    If I am going to sharpen freehand I find a hollow concave grind on the bevel works great...I use diamonds with no back bevel and I have no problems getting things sharp.

    Chris

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