OldTools Archive
Recent | Bios | FAQ |
265056 | Thomas Conroy | 2018‑02‑08 | Leather paring and knives, was: Strop |
Brent Beach asked for "A bit further explanation, please." I'm going to break my reply up by his questions. It gets long, I'm afraid. "What kind of a knife are you using here - what shape, length, bevel angles?" I work normally with an English paring knife for beveling the edges of leather for a cover (on the inside), and with a modified spokeshave for overall thinning of the leather. The English paring knife is pretty much like a cabinetmaker's skew chisel, but less than 1/16" thick overall, perhaps 1-1/8" wide (give or take a bit), and often made without a handle. Mostly I use knives made by Barnsley before they closed http://www.hewitonline.com/English_Paring_Knife_p/tl-070-pk.htm but Hewit found another firm that copies the Barnsley knives almost exactly. I normally hone to roughly 18 degrees (1 rise to 3 run), but Jeff Peachey who makes boutique binders' equipment normally hones to, if I remember correctly, 15 degrees, perhaps less. I grind back the primary every once or twice I hone. Barnsley knives are surprisingly soft, perhaps as low as Rc54, but this means that they are also comparatively easy to resharpen, and I like the trade-off. Jeff Peachey goes in the modern direction of exceedingly hard steel, which most amateur binders love because they have never before used a sharp knife and it holds its edge, but the hard steel is correspondingly dreary to sharpen and tempts you into trying to work for too long with a dull blade. My opinion that leather takes off an edge quickly is not based on the soft Barnsley knives alone, by the way, but more on spokeshave blades where I have a direct comparison between use on wood and use on leather. A 151-style spokeshave can be used for leather out of the box, but many (most?) experienced binders lower the bedding angle from 45 degrees to as little as 31 degrees, open the mouth out to allow leather shavings to pass through easily without clogging, and there are various other tuning points, some of which also apply to spokeshaves for wood. For leather the blade should be honed to, again, 15 or 18 degrees at most, and this means that the ground bevel must be wide. I hollow-grind my Stanley/Record blades with a bevel 1/4" wide, on Hock I grind 3/8" wide due to the extra thickness of the blade. I was taught to keep and sharpen blades in batches, so that when a blade goes dull halfway through paring a cover you can go on working with a fresh blade without completely changing gears for resharpening. For years I used Stanley and Record blades (bought early in my career) at work, and my good Hock blades at home; when it finally got through to me that this was backwards I changed and used just the Hock blades at work. With the chrome-vanadium Stanley/Record I generally had half-a-dozen in my working batch, but with Hock I found that three was enough. For Barnsley paring knives I kept four to six going at any one time, with a few older and better knives for special use. I also have a little knowledge of the Scharfix and similar paring "machines" (they are more like big jigs) which offer some less-subjective evidence on how quickly leather dulls an edge. https://www.youtube.com/watch?v=_c8hIzkJlAs These come with special blades, but are normally used with double-edged razor blades, which are normally discarded after taking off two or three strips of leather, say about 40" total length. I know one highly skilled binding teacher who buys her razor blades by the thousand-blade box, because that lets her get the top quality blade of her preference. You can buy special blades for the Scharfix that come sharp, but they cost about 40 cents each. A Scharfix appeals to many binders because it seems to reduce the amount of skill needed for paring leather (it doesn't really, but that is another matter), but the big draw is that you don't have to do any sharpening at all. And a Scharfix comes with a big price tag, for the machine (about $400.00 new) and for blades. There are other tools used by German, French, and other style binders, but the principles are the same. The shoe industry uses genuine (powered) tubular- bladed paring machines, and these have a built-in grinding wheel for resharpening, in some brands running in constant contact with the blade. "How exactly do you strop the knife? How do you hold it? How many strokes on the rouge?" I normally start with the rouge (hardware store stick) charged on flesh- side leather glued to a flat board held flat on the bench; I stroke five times on the flat followed by five on the bevel, being careful not to pull up and round the bevel on the turn; repeat five; then three on each side repeated; then one each two or three times. Then repeat on uncharged grain-side leather. It sounds like a lot, but it actually takes very little time (OK, I shortcut it a lot of the time, strop a third or half that much on many stroppings), and I am normally thinking what to do next while I do it. The big danger is allowing the blade to drift up at the end of the stroke, rounding the edge, and this danger becomes acute when you go from stropping the flat to stropping the bevel. The danger of rounding can be reduced by turning the blade over "over the back," lifting the edge first from the surface, rather than over the edge in the instinctive manner, and this is what I teach; but I learned about the technique too late to work it into my habits. Stropping on the uncharged grain size does make a perceptible difference in the ease of use of the knife; after rouge alone the knife may be usable, but it will be cranky and intractable, not sweet- cutting. The bevel side of the spokeshave can be stropped without disturbing the setting by pulling it backwards toward you over the strop, and I used to do this with Stanley/Record blades, but I don't bother with Hock blades. The problem with stropping the spokeshave is that taking the blade out disturbs the setting, and once you have it out you might as well do a thorough job of sharpening. So blades must be sharpened frequently when over-all thinning leather, no way around it. Leather of different colors (i.e. different pigments or dyes) differ in how abrasive they are to the blade, but with most black leathers and with alum-tawed skin (whitleather, i.e. white, to the Elizabethans) a spokeshave blade may go dull while thinning a single 12" x 18" piece for one cover. "What is the paring action? What does 10-25 inches of paring mean?" Edging with the knife bevels the leather down from the full thickness as supplied down to nothing, over about 3/4". The edge moves directly into the skin, removing a strip the full length of the edge. The skew bevel is necessary to allow the knife to cut; if you try paring with the knife edge at right angles to the leather edge, it will hang up and refuse to cut, no matter how sharp it is. Here is the video of Jeff Peachey doing a nice job of paring an edge, already linked to above: https://www.youtube.com/watch?v=QB5ZHNdqTPQ Jeff is apparently paring with the tip of the knife along the left edge of the cover as it rests in front of him (one of the legitimate choices, but possibly the filming angle is deceptive and he is paring left-to-right on the far edge). Notice the ease and evenness of the stroke, and that the strips of leather come off intact, and that he gets an even bevel about 3/4" wide with just the knife. Taking the three strips off gives a rounded shape to the pared area; a single sharp arris would leave a visible ridge on the outside after the leather is put on. Further blending of the slope can be done with the spokeshave. I was taught to edgepare with the heel of the knife-edge on the right side of the cover, pushing away from myself; I still teach this way, since there is a conceptual clarity about controlling the angles when paring with the heel (picking up the terms pitch, roll, and yaw from aviation). In practice I usually pare with the tip from left to right along the far edge of the leather, which I think is easier once you have the conceptual understanding of the ways the edge can tilt. I found another video, however, that is rather more instructive than the one of Jeff paring, since the guy who made it is not highly skilled with the knife (the actual demonstration of paring, as opposed to hot air, runs from 2:08 to 4:50): https://www.youtube.com/watch?v=GKQNVC_l0OQ He does OK on the first strip, certainly at first, but notice that he has the forefinger of his left hand on the blade. This means that he is pushing the knife to get it to move at steady speed and angle, and this means that the knife is not quite sharp. Sharp enough to work with at a pinch, but not sweet, not sharp enough to use with ease or pleasure. Things go to pieces on the second stroke, where he is taking off the arris left by the first stroke; from the beginning it is fluffy-edged and narrower than the first strip (notice that each of Jeff's strips was wider than the last, and precise). Within four inches of the start of his stroke, the leather removed is breaking up into dust; and as he goes on, an educated eye can see that his edge wobbles up and down, leaving something akin to a chatter on a large scale. I think he is using an old Barnsley knife, and he didn't strop it between strokes. Things really go to pieces at the end, where he is trying to thin and clean up the corner of the leather; by this time the knife is so dull that it will barely cut, and will only scrape a bit of dust off with each stroke. I said this guy is not highly skilled with the knife; well, in fairness, he is probably more skilled than eighty or ninety per cent of bookbinders. And he does seem to be a professional. He does a nice enough job of demonstrating round bible corners in leather at the end of the video. But he doesn't pare well, and it is because he doesn't know how to strop----in what I called the "hot air" part of the video, and he makes stropping moves with his hand around 1:10-1:12; these show that he habitually rounds the edge while stropping, dulling the knife. You can work around poor skills, but it ain't fun. One more video is useful in showing how not to do things: https://www.youtube.com/watch?v=qK6hb7pcjcU This guy is a general leatherworker, and I'm not going to judge his skill at his own craft and by comparison with others of his kind. But he doesn't know how to sharpen and he doesn't know how to pare ("skive" to saddlers and other heavy- leather craftsmen). Notice that he uses a sawing back-and-forth action. Instead of pushing one section of the edge along the leather, he runs repeatedly from the tip of the knife to the heel. This is a classic way of getting a dull knife to cut in some degree; the problem with it is that you have little control, and it takes far longer than it should. In fairness again, he is working on salvaged leather that is probably thicker and harder than binding leather, andd he may be fighting glue residues and old thread in the visible sewing holes. As with the previous guy's failure to strop, you can get a knife to work this way, sort of. Since paring isn't the only thing you do in binding, you can be a very good binder and not have good paring skills. Laura Young, one of the most successful book restorers and binding teachers of the generation before mine, never learned to sharpen or pare, as shown by her frequently republished manual on binding (and I have had her deficiency confirmed by a number of my friends, many of whom were her students). Young described the sawing -action type of paring for occasions when a knife couldn't be avoided, but her basic advice was to get a Fortuna skiver, a heavy-duty industrial machine that costs (now) $1500.00 new and sprays grinding swarf over the freshly-pared area (this doesn't matter in a shoe that will be trash in a year, but does matter as the life of a book stretches from the decades to the centuries). So you can be a very good bookbinder indeed without being able to pare skillfully When I entered the field, many San Francisco fine binders would send their leather to France to be pared professionally, much as San Francisco miners of the Gold Rush would send their laundry to China. I still think you ought to be able to do your own work, and do it well. OK, I'm exhausted, and if you aren't as well, I'm surprised. My vile antiquated PC with vile Microsoft hardware and vile Yahoo that I chose for my email many years ago are between them crashing about every forty minutes, which means that I've spent a good many hours on this. Lord, return me safely to Apple, with up- to-date software. Brent, many thanks for asking such clear and well-organized questions, which have made it much easier for me to answer with (I hope) a degree of clarity and organization. Tom ConroyBerkeley |
|||
265059 | Claudio DeLorenzi <claudio@d...> | 2018‑02‑08 | Re: Leather paring and knives, was: Strop |
Hi Tom: Re the knife used in these videos reminds me of the ones my dad used in upholstery. He copied an old Osborne one, making his own from discarded Swedish steel metal cutting saw blades from a metal shop (I’m pretty sure these were high carbon steel, not high speed steel). These metal cutting blades were about 1.5” by 24” and maybe 1/16” thick and he would cut off a length, grind off the teeth and then make similar single bevel knives like those shown in the video. Watching these videos brought back memories of him showing me how to work leather, button tuft diamond patterns, turn corners... My dad taught me another important lesson: That you can learn something useful from just about anybody if you are open to it and treat them with respect, even a janitor (nothing against janitors, my mom was a cleaning lady). Speaking of which, I just remembered the first time I chatted with the janitor at the metal factory when I was a young dumb teen in a summer job. I innocently asked the old Polish man about the greenish colored numbers tattooed on his forearm. I didn’t really know anything about concentration camps at the time. Claudio |
|||
265070 | Chuck Taylor | 2018‑02‑08 | Re: Leather paring and knives, was: Strop |
==snip== Brent Beach asked for "A bit further explanation, please." I'm going to break my reply up by his questions. It gets long, I'm afraid. ==unsnip== Tom, Thank you for taking the time to describe so clearly your experience with sharpening and using knives for paring leather. From your description of working with leather, wood seems to be a much more forgiving material than leather. With wood we can sometimes compensate for a not-quite-sharp edge with a bit of brute force. Apparently that doesn't work so well with leather. I'm reminded of the words of that great philosopher Yogi Berra (American baseball player of yore, Jeff): "In theory, there is no difference between theory and practice. In practice, there is." Chuck Taylor north of Seattle |
|||
265071 | "John M Johnston (jmjhnstn)" <jmjhnstn@m...> | 2018‑02‑08 | Re: Leather paring and knives, was: Strop |
See also the immortal Sir Boyle Roach, who like Yogi Berra was also known for enlightening quotes. https://en.m.wikiquote.org/wiki/Boyle_Roche https://h2g2.com/edited_entry/A673607 Cheers John “P.S. If you do not receive this, of course it must have been miscarried; therefore I beg you to write and let me know.” - Sir Boyle Roche, M.P. I'm reminded of the words of that great philosopher Yogi Berra (American baseball player of yore, Jeff): "In theory, there is no difference between theory and practice. In practice, there is." Chuck Taylor |
|||
265072 | Kirk Eppler <eppler.kirk@g...> | 2018‑02‑08 | Re: Leather paring and knives, was: Strop |
On Thu, Feb 8, 2018 at 5:27 AM, Thomas Conroy via OldTools < oldtools@s...> wrote: > Here is the video of Jeff Peachey doing a nice job of paring an edge, > already linked to above: > https://www.youtube.com/watch?v=QB5ZHNdqTPQ > > And just for everyone's information, this is why all of the BAGS stand back in fear whenever Tom brings out one of his leather blades. There's Scary Sharp, and then there is Bookbinder Sharp, which is somewhere beyond Terrifying Sharp. My best sharpening work pales in comparison. -- Kirk Eppler in Half Moon Bay, CA, working with a new foster dog last night. |
|||
265073 | Claudio DeLorenzi <claudio@d...> | 2018‑02‑08 | Re: Leather paring and knives, was: Strop |
My fav YB: “I looked like this when I was young, and I still do.” C On Thu, Feb 8, 2018 at 12:54 PM Chuck Taylor via OldTools < oldtools@s...> wrote: |
|||
265084 | rock harris <nombre7@g...> | 2018‑02‑10 | Re: Leather paring and knives, was: Strop |
*From your description of working with leather, wood seems to be a much more forgiving material than leather.* As a burgeoning leatherworker/leathercrafter, I can attest to this. My skills at sharpening are helping me greatly with sharpening leather knives. The only thing giving me fits because I haven't come upon a good process is sharpening my head knife. (a half moon knife that is emblematic of the leatherworking profession). I thought woodworking meant a lot of sharpening, then I started making leather objects. Woof. I can see why razor blades used by the hundreds is standard among hobbyists like me. rock harris lesser programming deity, budding dilettante furnituremaker, analog photographer, and aficionado of obsolete machinery st. louis, mo 314.221.5941 Yeah, well, you know, that's just, like, your opinion, man. On Thu, Feb 8, 2018 at 11:52 AM, Chuck Taylor via OldTools < oldtools@s...> wrote: |
|||
265085 | Thomas Conroy | 2018‑02‑10 | Re: Leather paring and knives, was: Strop |
Rock Harris wrote: "The only thing giving me fits because I haven't come upon a good process is sharpening my head knife. (a half moon knife that is emblematic of the leatherworking profession). I thought woodworking meant a lot of sharpening, then I started making leather objects. Woof. I can see why razor blades used by the hundreds is standard among hobbyists like me." Get a copy of "Leathercraft Tools: *How to Use Them *How to Sharpen Them." by Al Stohlman. This gets across far more of the basics of leather tools than any other source I know. It is a kind of book that normally drives me to agonies of contempt, lots and lots of pictures and comparatively little text. But Stohlman had the touch, he is concise in his pictures and concise in his text and everything needed is there (I think, a memory of the first times I used the book) and it is all correct (ditto). In the same category, as an absolute essential, is his "The Art of Hand Sewing Leather." I think I had learned most of what he has in the book before I discovered Stohlman, a fact or two at a time from a dozen different books, none of which had more to offer than that one isolated fact. But Stohlman gives a whole. Most of Stohlman's other books are "project" books, and I could care less. Project books have always bored me and struck me as unnecessary. And Stohlman's biggest focus was on Western-style leather carving and, well, lets just say he wasn't Frederick Remington. But on basic leatherworking technique he is unmatched. No one else can even be compared. Leatherworking has suffered from a two-angle learning slope. It is very easy to learn how to do some simple basic things, and have a bit of fun for a while. But to go from those simple things to work that is really rewarding for a long period, the level of technique to be learned is staggering. Leather is one of the most versatile and profound materials, but it demands high skill to get the best out of it, or even to advance beyond laced-edge keyholders. The difficulty in learning to sharpen a head knife is sort of emblematic of the difficulties, in a way, just as the knife itself is (as you say) emblematic of the whole craft. In America in the last century the craft went through cycles of popularity, and with each cycle there was a generation of "teachers" who had never tackled the second, steeper, slope, and each generation knew less and less technique. By now, it is hard to recover the lost skills. Compare the horribly crude work of a storefront sandlemaker of the 1970s with some of the sixty-to- the-inch stitching on English riding boots of the nineteenth century, shown in John Waterer's Leather Craftsmanship (New York: Praeger, 1968), the best introduction I know to the deep possibilities of leather. Waterer writing in the 1960s said that saddlers had preserved more of the heavy- leather skills than anyone else, and bookbinders more of the light-leather skills. That still looks pretty much true to me (though skilled bookbinding is under assault from weekend-workshop "book artists"). I suspect that skilled saddlery will survive as long as there are saddles at all. After all, if a saddler isn't skilled, a horse gets a sore back. No arguing with that, no real way to say "I like it better that way," and a great big financial hit if you have to throw a saddle away and try to make a better one. Tom Conroy(not a real leatherworker, not for heavy leather, but at least a little way up that second, steeper, slope). |
|||
265096 | rock harris <nombre7@g...> | 2018‑02‑11 | Re: Leather paring and knives, was: Strop |
Yeah, I have many of Stohlmann's books, but not the tool book. I'll look into it. I've been working on my stitching, and I'm making a stitching horse to help (two actually, and keeping on list topic, I'm using a lot of hand tools to make it). Leatherworking is a lot like woodworking in the tool department. Unique and really really cool. I get what you say about the basics versus the true art. But I got time. And it's fun.... rock harris lesser programming deity, budding dilettante furnituremaker, analog photographer, and aficionado of obsolete machinery st. louis, mo 314.221.5941 Yeah, well, you know, that's just, like, your opinion, man. On Sat, Feb 10, 2018 at 1:05 PM, Thomas Conroy |
|||
265121 | Thomas Conroy | 2018‑02‑13 | Re: Leather paring and knives, was: Strop |
Claudio wrote: "Re the knife used in these videos reminds me of the ones my dad used in upholstery. He copied an old Osborne one, making his own from discarded Swedish steel metal cutting saw blades from a metal shop (I’m pretty sure these were high carbon steel, not high speed steel). These metal cutting blades were about 1.5” by 24” and maybe 1/16” thick and he would cut off a length, grind off the teeth and then make similar single bevel knives like those shown in the video. Watching these videos brought back memories of him showing me how to work leather, button tuft diamond patterns, turn corners..." Machine hacksaw blades were particularly favored paring knives and lifting* knives by the generation of English binders who taught many of my generation of Americans. They were mostly born around 1935 and trained in seven-year apprenticeships or in comparably rigorous art school courses. The preference was not just for machine hacksaw blades, but "pre-war" blades, which were said to take a sharper edge and hold it longer than any other form of knife. I suspect that they were finding high-carbon-steel blades, though these would have been obsolescent in America by the 1930s. Until quite recently lifting knives couldn't be bought; you had to grind your own. I've made them, for myself and for half-a-dozen or a dozen students, from old trashed hacksaw blades (25 cents with luck, but more often a dollar now); from new Vaughan English "all-hard" or "high speed steel" hacksaw blades (the markings differ, but they seem to be otherwise just the same); and from new Starrett "Red Stripe" HSS blades. The first step is to snap the (12" or 14" long) blade in half, and with an old hacksaw this will tell you if you have a good single-steel blade or an unusable bimetallic blade. The good blade will snap cleanly with a fine-grained crystal surface on the break; a bimetallic blade will snap cleanly in the eight inch near the teeth, but the rest of the width will twist and deform before breaking. My favorites are the old blades, but this may be partly sentiment. The Vaughan blades are good, a bit hard; the Starrett far, far too hard for this use, since it is extremely tedious to resharpen them. Lifting the leather on the side of the book, you are cutting through highly-abrasive binders' board, full of trash and impurities, and you may lose the sharpness of the edge in lifting four inches; so you go through three blades lifting on one board. Not to speak of 19th-century board, when it was sold by weight and some manufacturers would throw sand into the pulp to increase the weight. Fortunately, a highly refined edge isn't necessary for lifting; a slightly saw-edged knife works as well or better than the most highly polished, so I do touch-ups while lifting on the coarse side of a "punjab" razor hone, equivalent to maybe a soft arkansas or an 800-grit (or coarser) water stone. _________________________________________________ *Lifting: in conventional reattachment of boards, the covering cloth or leather is raised from the board along the spine edge, then the new leather is slipped in under the flap that has been created. The same is done on the inside, for the endpapers. There are several techniques for partly detaching the covering, depending on the leather or paper, the board, and on how good the attachment is. On most books at least one side of the board will have to be lifted with the knife, which is similar to a paring knife but skewed opposite and with a smaller skew angle. This is used to cut between the leather and board, or better, through the board itself leaving a paper-thin layer of board still on the leather. Any lumpiness in the cut will be seen when the work is done. And everything you are trying to cut is crumbly. Want some idea of how hard this is on a knife's edge, and how hard period? Take a short 1-1/4" chisel and try to bevel the edge of a piece of eight-inch thick cardboard with it, making the bevel an inch wide and running down to a feather edge. Do it without going over any spot twice. And consider that to lift the leather on an ordinary-sized book, you will need to make an even surface three inches (not one inch) wide and nine inches long. I couldn't find any videos of doing it; my guess is that it is too hard for the sort of binder who makes videos, and they don't want to show the botch-up they make of it. But maybe I'm just a cynic. And don't even get me started on lifting an old spine that is adhered directly to the book. I did find at least one video of this, but it was being botched, so I averted my eyes. Tom Conroy. (Just let me ramble on a few more hours, eventually I will go to sleep and you can escape) |
|||
Recent | Bios | FAQ |