Found this article

[scottish steve]

Don't know if this has been posted before but I thought it was quite interesting. If you want to follow this frther or see the diagrams the URL is p://chestofbooks.com/home-improvement/workshop/Turning-Mechanical/Section-III-Setting-Razors.html

Description
This section is from the book "Turning And Mechanical Manipulation", by Charles Holtzapffel. Also available from Amazon: Turning and Mechanical Manipulation.

Section III. - Setting Razors
Perhaps of all cutting instruments, the razor possesses the most general and personal interest, in respect to the conditions required for its perfect action, and it is therefore proposed to notice at moderate length the principal circumstances on which the perfection of its edge depends.

The razor notwithstanding the peculiarity of its outline, conforms strictly to the ordinary wedge form section of most cutting tools, but as it requires the most delicate edge that can be produced, it is so formed as to facilitate to the utmost the process of sharpening. For instance in the plane iron, chisel, penknife, lancet, and most other instruments, the angles of the one or both the sides of the wedge or cutting edge are determined by the particular inclination at which the tool is held upon the stone, but if the hand wavers, the setting or facet instead of becoming a plain flat surface, becomes rounded and ill defined.

In the razor on the other hand the proportion between the width of the blade, and the thickness of the back, is almost always such that when the blade is laid perfectly flat on the hone, or so that the edge and back both touch, the suitable angle is obtained, and which varies from about 17 to 20 degrees; the exact measure of the angle is very little studied, although in reference to the principle of cutting tools some little variation ought to be made, in choosing the thickest edge for the strongest beard. It does sometimes happen that the razor is not laid quite flat on the hone, but that it is slightly tilted, this occurs when a wide razor that has been ground on a large stone is required to be sharpened for a stiff beard; but it so rarely occurs that the razor is placed otherwise than flat on the hone, that the exception may be overlooked.

The magnified sections of razors in figs. 1031 to 1036, which for distinctness are drawn three times their full size, and for comparison, of the same angle or 18 degrees throughout, exhibit various modes adopted to avoid the necessity for sharpening the entire side of the imaginary wedge, represented by the dotted lines, by hollowing the sides in different ways. It is apparent that it would be much more tedious and difficult to wear down the imaginary flat sides represented by the dotted lines, than the small portion of the same which are supposed to remain; and indeed the entire dotted line if sharpened, would most probably become rounded instead of flat. The concavity therefore facilitates the placing of the razor on the hone, it thins the edge leaving but little for the stone to abrade, and it prevents the finished appearance given to the sides of the razor being detracted from by the sharpening.

Figs. 1031 and 1032, represent the section of that description of razor blade which is by far in the most common use, as before observed the widths of the blade and the thicknesses of their backs are such as to give in each an ultimate edge of 18 degrees when the blade is sharpened on the hone, but fig. 1032, is ground transversely on a wheel of four inches diamater, and fig. 1031, on one of twelve inches, the general extremes of curvature. It is clear that the former possesses an edge that is thinner and more flexible, and that presents a narrower edge or plane to be abraded by the hone; and which latter in consequence will cut with greater precision and delicacy than if it had to abrade the entire surface. The curvature in most general use for best razors is intermediate, or from 5 to 6 inches, but stones of from 12 to 15 inches diameter are from motives of economy resorted to for common razor blades.

Figs. 1031.


1032.


1033.


Figs. 1034.


1035.


1036.


In some few cases the edge of the razor is ground lengthways on the stone, so as to become nicked in, in the manner represented in fig. 1033, and in this way any degree of thinness may be given, and also extended throughout any desired width. This mode of grinding the razor is however more difficult, and the feebleness of the edge may be thereby easily carried to excess; and from the vibration to which they are liable when applied to a strong beard, they are called by the Sheffield cutlers, rattler razors.

Sometimes the two methods of grinding are combined, as shown in fig. 1034, in this case the razor is first ground transversely as for fig. 1032, and it is subsequently ground lengthways so as to be nicked in for about half its width; these razors are known by Sheffield workmen as half rattlers. For the sake of variety the longitudinal grinding is sometimes only extended about one quarter of an inch from the edge.

Other razors as in fig. 1035, are made as very thin acute blades fixed in a detached back somewhat like a dovetail saw, in this case the edges of the blade and of the back are simultaneously whetted on the hone; but no advantage appears to result from the construction, on the contrary the blade cannot be reground without removal from the stock, which implies the risk of its being reduced below the edge of the stock so as to prevent its replacement.

Fig. 1036 represents another of the modes in which razors are occasionally constructed, in this a loose frame or guard of brass is added to the blade. The idea in this case is to prevent the liability to accident incurred by nervous or infirm persons from the tremor of their hands. The frame is intended to act as a muzzle or guard to prevent the edge penetrating to any serious depth, and the instrument is known as a guard razor.

The keenness of the edge of the razor is commonly tried by-making a faint incision in the thick skin covering the inner edge of the palm of the left hand, but the cutler also tries the razor upon the thumb or finger nail. The razor is either placed in a line with the finger and obliquely across the end of the nail, or a still more sensitive test is to place the blade at right angles to the finger, and allow it to rest upon the back of the nail, that of the third finger being by some considered the most sensitive. In this manner a very minute notch in the edge is quite perceptible, and the keenness may also be appreciated by the degree in which the razor hangs to the nail, as the keen blade will make the deeper incision, and appear to offer a more dragging yet smooth resistance, whereas the blunt razor will slide over with less penetration and drag.



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turning, mechanical manipulation, crafts, woodwork, alloys, lathes, tools, casting, wood, timbre, metal turning, engraving, materials, metals, cutting, soldering, steel

 

[Seraphim]

Very nice. Thanks!

 

[SavantStrike]

I concur, that was a fun read .

 

[scottish steve]

Just noticed the link doesnt really work
Setting Razors. Part 2
A more scientific method was proposed by Mr. Kingsbury in his pamphlet on the razor, namely the examination of the entire edge with a magnifier, and which process when applied in a sufficiently powerful degree will doubtless exhibit the causes why the razor fails in its purpose, and which are sometimes threefold, namely first the razor may be notched, secondly it may have a loose pliant film or wiry edge, or thirdly, instead of a keen acute edge it may be blunt and obtuse, which is generally due to the excessive use of the razor strop; upon each of these considerations some few observations will be offered.

First, notches are liable to occur in a razor from the blade having been overheated, either in the forging or hardening, a fault which is irretrievable, as it renders the steel permanently brittle, and altogether incapable of receiving a fine acute edge, as the particles of the metal break away at the extreme edge on the hone. The brittleness may occur in a somewhat less degree, when the razor without having been overheated is simply left too hard, so as to require to be let down or. tempered a little lower than at first. Secondly, the wire edge generally occurs from the hone being too much used, as when the two faces of the wedge are rubbed away beyond that point at which they first meet, the slender film of steel commences to form, because the extreme edge is then so thin that it bends away from the hone instead of being rubbed off. The wire edge is more liable to occur when the one side of the blade is more whetted than the other, and if it be obstinate in its resistance to removal, it frequently indicates further that the blade is too soft, as if the razor blade be made too hard, the metal will be brittle instead of flexible, and the thin extremity break off instead off forming the filmy edge.

The temper of the blade ought to be such as to be indisposed to become either permanently notched or wiry from the action of the hone. But in the application of the various grinding and polishing wheels, especially the latter, there is always some risk, as the temptation to expedite the work causes too much vigour to be occasionally used, thereby giving to the blade so much heat as to reduce its temper; an error the unscrupulous may easily gloss over, by touching the work more lightly, and thereby removing the colour, or that index whereby the temper of the instrument is commonly estimated. But the experienced cutler is generally able to distinguish by the feel of the cut, or of the action of his own particular hone, between such blades as either exceed or fall short of the appropriate temper.

Thirdly, in a new or a recently ground razor, the thick obtuse edge shows that the blade has not been sufficiently rubbed on the hone, and in a used razor, it more commonly indicates that partly by the using of the razor, and partly by its being intermediately stropped to renovate the edge, it has been too much rounded; so that instead of the two narrow facets constituting the edge being plane surfaces and meeting at from 17 to 20 degrees as left from the hone, they are seen to have become considerably rounded, so as probably to meet at more than double the original angle, a condition explained by the diagrams figs. 1037 and 1038, in which for perspicuity the extreme edges are shown about twenty times their true size. This fault or the rounded edge is also readily detected with the magnifier, and is almost sure to occur from the use of a soft strop, as the leather immediately against the edge from being indented, rises as an abrupt angle and mutilates the keenness of the blade. If however the razor at any of its stages of manufacture or setting have been treated without uniformity, it may possess at different parts of its edge all these errors, but which is less to be expected than that the one error should prevail.

Figs. 1037.


1038.


If neither of the above three faulty conditions are discernible by the careful use of a lens of one half to one third of an inch focus, (or of a linear power of twenty or thirty,) such razor will in general be found to act with satisfaction, but the keenest razor when delicately examined with a lens of one fifth to one tenth of an inch focus, (or a linear power of fifty to one hundred,) or still better with a microscope of not less than equivalent power, will present a faintly undulating and irregular edge, which resembles rather a ripple mark, than the angular teeth of the edge of the saw, to which it is usually compared. Indeed the edge of a razor of ordinary quality, bears the microscopic examination much better than might be expected; but as no surface polished by art is free from scratches, it must happen that every such scratch when continued to the edge formed by two planes meeting at so small an angle, deprives the otherwise continuous edge of a small portion of its material, and thence constitutes a notch, but the notches are the smaller, the finer the abrading surface used in producing the edge.

When however the errors are so minute as to require to be thus magnified some fifty or one hundred times, to render them visible, they are too minute to be detected by the skin, the nail, or the employment of the instrument on the beard. Having explained the good and bad condition of the razor, the practice of setting the instrument will be now the more easily understood, and it is proposed first to describe the sharpening of a new razor, and then that of one which has been rendered dull by use.

Various kinds of whetstones are more or less used in sharpening razors, commonly in pieces measuring from eight to ten inches long, by one and a half to two inches broad, and great importance is deservedly attached to their being perfectly flat on the face, with which view they are occasionally rubbed on a large gritstone with water, but in use they are always supplied with oil and kept remarkably clean.


The Charnley Forest stone is generally preferred for the first stage or for striking off the wiry edge of the blade. The Turkey oilstone is sometimes used for the same purpose. The Green hone or Welsh hone, which is harder than the Charnley Forest, and generally in smaller pieces, is occasionally used for razors, and is by some preferred to Charnley Forest for finishing pen and pocket knives, and especially for setting surgeons' instruments.

The yellow German hone, particularly the slabs from the lower strata known as old rock, is greatly preferred to all the above for the principal office in setting razors, as it cuts more slowly, smoothly, and softly, than any of them. The Iron stone or slabs of the hematite iron ore, are occasionally used for giving the final edge, it consists principally of oxide of iron, and chemically resembles crocus, but that it is in a compact, instead of a disentegrated form. The iron stone is however so very hard that it appears to act more as a burnisher than a hone, and renders the edge almost too smooth, so that when at all used, the razor is in general only passed once or at most twice on each side along the iron stone.

Taking the razor from the last stage of its manufacture described at page 1051, it is to be observed that as the glazers and polishers revolve away from, and not towards the edge, they always leave a thin filmy edge, which as the first step towards setting, is struck off on a Charnley Forest stone. The blade is grasped in the right hand by its tang, and near to the cutting part, and is placed square across the one end of the stone but tilted about ten or twenty degrees, and is then swept forward along the stone, edge foremost in a circular arc, so as to act on the entire edge; each side in general receives only one stroke, and this produces a comparatively obtuse edge measuring from forty to sixty degrees. Should this fail to remove the wiry edge, the blade is placed perpendicularly upon, and drawn with a little pressure across, a strip of horn, (generally a spoiled razor handle,) which is fixed down to the bench, the friction of the horn against the edge generally suffices entirely to remove the wiry film, otherwise the blade is struck once more on each side along the stone. Should the film of steel be left on the stone, it is removed before another blade is applied.

One object in the striking off, is to avoid the necessity for so far wearing down the back of the razor, as to give it the appearance of an old one that has been repeatedly set, and it is also especially required in wide blades ground on large stones, as the wiry film is then very difficult to remove otherwise.

The next and principal part of the setting is accomplished almost invariably on the German hone. The razor is held as before, but it is now placed quite flat down, or so as to touch on the back and edge. Some prefer a long sweeping stroke backwards and forwards, others prefer small circular or elliptical strokes, and others a short zig zag movement, but all gradually work from heel to point, or draw the razor forward so as to act on all parts alike, and most persons lift the razor endways towards the conclusion, allowing its point still to rest on the hone, with the view of sharpening the circular end of the blade. The choice of these methods seems to be principally a question of individual habit, and to be nearly immaterial, provided the entire edge is acted on alike, and that at very short intervals the razor is turned over so as to whet it upon its opposite sides alternately, but it is general to conclude the process by sweeping the razor edge foremost, once on each side steadily along the hone, as if in shaving off a thin slice of the hone, this lessens the disposition to the wire edge.

The line of policy is just to continue this secondary process, until the new facets constituting the wedge of seventeen to twenty degrees, exactly meet at the extremity of the more obtuse angle given by the striking off, and which if mathematically done, would prevent the formation of the wiry film, which is one of the most troublesome obstacles in the process.

Should the film nevertheless arise, it is to be removed by passing the blade occasionally across the slip of horn, and continuing the whetting for shorter periods on each side, some persons indeed suffer the film if very minute to be abraded on the razor strop, but which latter unless very cautiously used is a very mischievous instrument. It is of course to be understood that the hone is not given up, until at any rate the notches are no longer perceptible, when the blade is drawn across the thumb or finger nail, which detects them more faithfully than the slip of horn, and that when viewed edgeways, the edge is merely discovered as the meeting of the two sides of the blade, and not from possessing itself any visible thickness or width.

As before observed, the blade is by some persons passed once on each side along the iron stone, but this practice is by no means common, and may, according to the questionable doctrine advanced by some cutlers, spoil the blade by rendering it too smooth, or too free from the saw-like teeth, but which it would appear can hardly be the case, unless it also increase the angle of the edge, or render it less acute and keen.

When the edge of the razor admits of being drawn smoothly across the horn, and the edge is not distinguishable by the eye, the hone may be considered to have fulfilled its purpose, and the razor is slightly stropped, but in this case, as the edge of the blade becomes somewhat embedded in the leather, it would cut if moved forwards as in setting, and therefore the razor is always stropped backwards, and usually from heel to point.

Disregarding the high sounding names and praises bestowed on various razor strops, it may be added that within moderate limits, they are the better the harder their surfaces, and the less they are supplied with abrasive matter. As when they possess the opposite qualities of softness and superabundance of dressing, or that they are used in excess, they rapidly round the edge of the razor, and change its edge from the well-defined angle of seventeen or twenty degrees produced by the stone, to twice that angle or more, and entirely unfit it for use.

Perhaps for the razor strop a fine smooth surface of calf skin, with the grained or hair side outwards, is best, it should be pasted or glued down flat on a slip of wood, and for the dressing almost any extremely fine powder may be used, such as impal-pably fine emery, crocus, natural and artificial specular iron ore, black lead, or the charcoal of wheat straw; each of these two latter act as abrasives in consequence of containing a minute portion of silex. Combinations of these and other fine powders, mixed with a little grease and wax, have been with more or less of mystery applied to the razor strop. The choice appears nearly immaterial, provided the powders are exceedingly fine, and they are but sparingly used.

One side of the strop is generally charged with composition; on the other side the leather is left in its natural state, and the finishing stroke is in general given on the plain side.

It is of great importance that all razor strops be kept scrupulously clean, and with which view they are provided with sheaths, which should be marked so as to prevent the composition being accidentally carried over to the clean side of the instrument. The strop should be always employed in the most sparing manner, so as rather to wipe than rub the razor; many, indeed, never strop the razor after use, but simply wipe it dry on clean wash leather, a silk handkerchief, or a soft towel, and only employ the strop before using the razor. A good mode was suggested to preserve the edges of surgical instruments from rusting when laid by, namely, the drawing them lightly through a tallow candle; this leaves a minute quantity of grease on the edge, which defends them from the air, and becomes deposited on the strop before the blade is used.

When a razor, from continued use and stropping, has become dull, it mostly arises from the edge having been rounded and thickened as explained by the diagram, figs. 1037 and 1038; in this case the setting, if attempted by the amateur, may with advantage be only so far pursued as barely to remove the rounded part. On close inspection it will be seen the part of the facet towards the back is first touched by the hone, the effect of which is seen by the less polished surface it leaves; and if the setting be only continued until the bright rounded part is all but removed when examined with a magnifier, no wire will be formed, and the blade will be again brought within the province of the razor strop. The razor, after having been repeatedly set, becomes so wide in the bevil or facet, as to require to be re-ground, to thin it away to the first state, as the blade should always be so thin as to be sensibly pliant at the extreme edge, when pressed flat on the thumb nail and slightly tilted; but the re-grinding should be done with a proper regard to the relative width of the back of the blade, and the preservation of its proper temper.



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[Seraphim]

Awesome stuff!

here's the link:
http://chestofbooks.com/home-improvement/workshop/Turning-Mechanical/Section-III-Setting-Razors.html