Mechanick exercises, or, The doctrine of handy-works by Joseph Moxon.

MECHANICK EXERCISES: OR, The Doctrine of Handy-Works.

Applied to the making of Hinges, Locks, Keys, Screws and Nuts Small and Great.

Of Hinges.

IN Fig. 1. A the Tail, B the Cross, CDDDDE the Joint, DDDD the Pin-hole. When the Joint at C on the Tail, is pin'd in the Joint at E in the Cross, the whole Hinge is called a Cross-Garnet.

Hinges, if they be small (as for Cup-board doors; Boxes, &c.) are cut out of cold Plate Iron with the a Cold-Chissel, but you must mark the out-lines of your in∣tended Hinge, as Fig. 1. the Cross-Garnet, either with Chalk, or else rase upon the Plate with the corner of the Cold-Chissel, or any other hardned Steel that will scratch a bright stroke upon the Plate; and then laying the Plate flat upon the Anvil, if the Plate be large, or upon the b Stake, if the Plate be small, take the Cold-Chissel in your left hand, and set the edge of it upon that Mark, or Rase, and with the Hand-hammer in your right hand, strike up∣on the head of the Cold-Chissel, till you cut, or rather punch the edge of the Cold-Chissel almost thro' the Plate in that Place, I say, almost through, because, should you strike it quite through, the edge of the Cold-Chissel would be in danger of battering, or else breaking; for the Face of the Anvil is hardned Steel, and a light blow upon its Face would wrong the edge of the Cold-Chissel; be∣sides,

it sometimes happens, that the Anvil, or Stake, is not all over so hard as it should be, and then the Cold-Chissel would cut the Face of the Anvil, or Stake, and con∣sequently spoil it: Therefore when the edge of the Cold-Chissel comes pretty near the bottom of the Plate, you must lay but light blows upon the cold Chissel; and yet you must strike the edge of the Cold-Chissel so near through the bottom of the Plate, that you may break the re∣maining substance asunder with your Fingers, or with a pair of Plyers, or sometimes by pinching the Plate in the Vice, with the Cut place close to the Superficies of the Chaps of the Vice; and then with your Fingers and Thumb, or your whole hand, wriggle it quite asunder, But having cut one breadth of the Cold-Chissel, remove the edge of it forward in the Rase, and cut another breadth, and so move it successively, till your whole in∣tended shape be cut out of the Plate.

When you cut out an Hinge, you must leave on the length of the Plate AB in this Figure, Plate enough to lap over for the Joints, I mean, to Turn, or Double about a round Pin, so big as you intend the Pin of your Hinge shall be, and also Plate enough to Weld upon the inside of the Hinge below the Pin-hole of the Joint, that the Joint may be strong.

The size, or diameter of the Pin-hole, ought to be a∣bout twice the thickness of the Plate you make the Hinge of, therefore lay a wyre of such a diameter towards

[illustration]

the end B, in this figure on the Tial piece, a-thwart the Plate as CD, and Double the end of the Plate B, over the wyre to lap over it, and reach as far as it can upon the end A; then hammer the Plate that is lap'd over the wyre close to the wyre, to make the Pin-hole round; but if your Plate be thick, it will require the taking of

an Heat, to make it hammer the closer to the wyre, and consequently make the Pin-hole the rounder: Your work may also sometimes require to be Screwed into the Vice, with the doubled end upwards, and the bottom side of the wyre close against the Chaps of the Vice, and then to hammer upon the very top of the Pin-hole, to round it at the end also. When you have made the Pin-hole round in the inside, take the Pin CD out of the Pin-hole, and put the Joint-end of the Hinge into the Fire to make a Welding-heat; which when it hath, snatch it quickly out of the Fire, and hammer, or weld, the end B upon the Tail-piece A till they be incorporate together. But you must have a care that you hammer not upon the Plate of the Pin-hole, lest you stop it up, or batter it; when it is well Welded, you must again put in the Pin CD, and if it will not well go into the Pin-hole (because you may perhaps have ham∣mer'd either upon it, or too near it, and so have somewhat closed it (you must force it in with your hammer; and if it require, take a Blood-heat, or a Flame-heat, of the Joint end) and then force the Pin into the Pin-hole, till you find the Pin-hole is again round within, and that the Pin, or Wyre, turn evenly about within it.

Afterwards with a Punch of hardned Steel (as you were taught Numb. I. fol. 11. 12.) Punch the Nail-holes in the Plate; or if your Plate be very thin, you may Punch them with a •• cold Punch. After all, smooth it as well as you can with your Hand-hammer; take a Blood-red Heat, if your Work require it, if not, smooth it cold; so shall the Tail-piece be fit for the Pile. Double, and Weld the Cross-piece, as you did the Tail-piece.

Having forg'd your Hinge fit for the File, you must pro∣ceed to make the Joint, by cutting a notch in the middle of the Pin-hole between DD in Plate 2. on the Cross, as at E, and you must cut down the ends of the Pin-hole on the Tail-piece, as at DD, till the Joint at C fit exactly into the notch in the Cross, and that when the Pin is put into

the Pin-hole DD on the Cross, the Pin-hole in the Tail-piece may also receive the Pin; then by holding the Tail-piece in one hand, and the Cross in the other, double the Tail and Cross towards one another, to try if they move evenly and smoothly without shaking on the Pin; which if they do, the Joint is made; if they do not, you must examine where the Fault is, and taking the Pin out, mend the fault in the Joint.

Then File down all the irregularities the Cold-Chissel made on the edges of your Work, and (if the curiosity of work require it) file also the outer flat of your work. But Smiths that make quantities of Hinges, do brighten them, (as they call it) yet they seldom file them, but Grinde them on a Grind-stone till they become bright, &c.

Having finished the Joint, put the Pin in again; but take care it be a little longer than the depth of the Joint, because you must batter the ends of the Pin over the ou∣ter edges of the Pin-hole, that the Pin may not drop out when either edge of the Cross is turned upwards.

The chiefest curiosity in the making these, and, in∣deed, all other Hinges is, 1. That the Pin-hole be ex∣actly round, and not too wide for the Pin. 2. That the Joints are let exactly into one another, that they have no play between them, lest they shake upwards or downwards, nor yet are forced too hard into one a∣nother, lest when they are nailed on the door, the Joint be in danger of breaking. 3. That the Cross, and the Tail lie on the under-side exactly flat, for should they wrap out of flat when they are nailed on, the Nails would draw the Joint a-wry, and not only make it move hard, and unevenly, but by oft Opening and Shutting break the Joint. 4. If your Work be inten∣ded to be curious, the true Square-filing the upper-side, as you were taught Numb. I. fol. 14, 15, 16. is a great Ornament.

a Smiths call all Chissels they use upon cold Iron, Cold-Chissels.

b The Stake is a small Anvil, which either stands upon a broad Iron foot, or Basis, on the Work-Bench, to remove as occasion offers; or else it hath a strong Iron Spike at the bottom, which Iron Spike is let into some certain place of the Work-Bench not to be removed. Its office is to set small cold Work straight upon, or to Cut or Punch upon with the Cold-Chissel, or Cold-Punch.

c Smiths call all Punches they use upon cold Iron, Cold-Punches.

If the Hinge you are to make be large, and Plate-Iron is not strong enough for it, you must Forge it out of flat Bar-Iron, as you were taught Numb. I. Fol. 8. to 13.

The manner of working Duftails, Fig. 5. and Side-hinges, Fig. 6. &c. is (the shape considered) in all respects the same I have here shewed you in Cross-Garnets; but in these (or others) you may (if your work require cu∣riosity) instead of Doubling for the Joint, Forge the Round for the Joint of full Iron, and afterwards Drill a hole through it, for the Pin-hole; and by curious Fi∣ling, work them so true into one another, that both sides of the Hinge shall seem but one piece; as I shall shew more at large, when I come to the making Com∣passes, and other Joints for Mathematical Instruments.

Of Locks and Keys.

AS there are Locks for several purposes, as Street-door Locks, called Stock Locks, Chamber-door Locks, called Spring-Locks, Cupboard-Locks, Chest-Locks, Trunk-Locks, Pad-Locks, &c. So are there several Inventions in Locks, I mean, in the making and contriving their Wards, or Guards. But the contrivances being almost innumerable, accor∣ding to the various fancies of Men, shall be referred to a∣nother time to discourse; and I shall now shew you the working of a Spring-Lock, which when you know how

to do, your Fancy may play with Inventions, as you best like.

In Fig. 2. AAAA the Main plate, BC the Key-hole, EDE the Top-hook, EE Cross-wards, F the Bolt, G the Bolt-Toe, or Bolt-Nab, H the Draw-back Spring, I the Tumbler, K the Pin of the Tumbler, LL the Staples.

In Fig. 3. AAAA the Cover-Plate, B the Pin, DCD the Main-ward, DD Cross-wards, E the Step∣ward, or Dap-ward.

In Fig. 4. A the Pin-hole, B the Step, or Dap-ward, C the Hook-ward, D the Middle, or Main Cross-ward, EE the Cross-ward, F the Main-ward, GG Cross-ward, H the Shank, I the Pot, or Bead, K the Bow-ward, L the Bow, BCDEEFGG the Bit.

First, Cut out of an Iron Plate with a Cold-Chissel, the size and shape of the Main-Plate, as you were taught to cut the Cross and Tail-piece of the Cross-Garnet; then con∣sider what depth you intend the Bit of the Key shall have, and set that depth off on the Main-Plate, by leaving about half an Inch of Plate between the bottom of the Key-hole, and the lower edge of the Main-Plate, as at C (or more or less, according to the size of the Lock.) Then measure with a pair of Compasses between the bottom of the Bit, and the Centre of your Key (or your intended Key) and set that distance off from C to B, near the middle between the two ends of the Main-Plate, and with the a Prick-punch make there a mark to set one foot of your Compasses in, then opening your Compasses to the middle of the Bit of your intended Key, as to D, describe the Arch EDE for the true place the Top-hoop must stand on.

Then cut out another piece of Plate as AAAA in Fig. 3. for a Cover-plate, with two pieces one on each side, long enough to make Studs of to turn downwards, and then outward again as FF, GG, that the Cover-plate may stand off the Main-Plate, the breadth of the Bit of the Key; and at the two end of these Studs Punch holes, as GG,

to Rivet the Cover-Plate into the Main-Plate. In the middle of this Plate make the Centre, as at B, then open your Compasses to three quarters the length of the Bit, and half the Diameter of the Shank of the Key, and pla∣cing one foot in the Point B, describe with the other foot the Arch DCD for the true place of the Main∣ward, then set your Compasses to a little more than half the Diameter of the Shank, and place one foot (as before) in the Centre B, and with the other foot describe the small Arch E, for the true place the Step-ward, or (as some call it) the Dap-ward must stand: So have you the true places of the Wards, for an ordinary Spring-Lock; you may (if the depth of your Bit will bear it) put more Wards in your Plates. But you must note, that the more Wards you put in, the weaker you make your Key; be∣cause that to every Ward on the Plates, you must make a slit, or Ward in the Bit of the Key; and the more Wards you make, the weaker the Iron of the Bit will be; and then if the Bolt shoot not easily backwards, or forwards, the Bit may be in danger of breaking.

Having marked on your Plates the places of all your Wards, you must take thin Plate, and with Hammering and Filing make them both b Hammer-hard, and of equal thickness all the way. Then file one edge very straight, by laying a straight Ruler just within the edge of it, and draw∣ing, or racing with a point of hardned Steel, a bright line by the side of the Ruler; File away the edge of the Plate to that line, then draw (as before) another straight line parallel to the first straight line, or which is all one, pa∣rallel to the filed Edge, just of the breadth you intend the Wards shall be, and File as before, only, you must leave two, or sometimes three Studs upon this Plate, one near each end, and the other in the middle, to Rivet into the Main-plate, to keep the Ward fixt in its place. There∣fore you must take care when you elect this thin piece of Plate, that it be broad enough for the Ward, and these

Studs too. Then laying the Plate a-thwart the Pike of the Bickern, hold your hand even with the face of the Bic∣kern, and hammer this Plate down somewhat by the side of the Pike, and by degrees you may (with care taken) bring it unto a circular form, just of the size of that Cir∣cle you described on the Main-Plate; which when you have done, you must apply this Ward to the Circle you described on the Main-Plate, setting it in the position you intend it shall be fixed, and marking with a steel Point where the Studs stand upon that Circle, in those marks punch holes to Rivet the Studs to. Work so by all the other Wards.

If you have a Pin to the Lock, Punch a hole through the Centre on the Cover-Plate, somewhat smaller than the Wyre you are to make your Pin of, because you may then file one end of the Pin away to a Shank, which must fit the smaller hole on the Plate, and the whole thickness of the Pin will be a Sholder, which will keep the Pin steddy in the Centre-hole of the Plate, when the Pin is Rivetted into the Plate. But because there is some Skill to be used in Rivetting, I shall, before I proceed a∣ny farther, teach you.

The manner of Rivetting.

Rivetting is to batter the Edges of a Shank over a Plate, or other Iron, the Shank is let into, so as the Plate, or other Iron, may be clinched close, and fixed between the battering at the end of the Shank and the Sholder. So that

When you Rivet a Pin into a hole, your Pin must have a Sholder to it thicker than the hole is wide, that the Sholder slip not through the hole, as well as the Shank; but the Shank of the Pin must be exactly of the size of the hole the Shank must be Rivetted into, and somewhat longer than the Plate is thick; file the end of the Shank flat, so

shall the Edges of the end, the easilier batter over the Plate; then put your Shank into the hole wherein it is to be Rivetted, but be sure you force the Shank close up to the Sholder; then turn the top of this Sholder downwards (Plate and all) upon your Stake, but lay it so, as that the Sholder lie solid, and the Shank, at the same time, stand directly upright, and with your left hand, keep your work bearing hard upon the flat, or face of the Stake. Then holding your hammer in your right hand, hold the edge of the face of it dripping a-slope from the right hand outwards, and lay pretty light blows upon the edge of the end of the Shank, turning with your left hand your work round to the face of the Hammer, till you have battered the edges of the Shank quite round a∣bout; but this is seldom done, with once turning your work about; therefore you may thus work it round a∣gain and again, till you find it is pretty well Rivetted; then lay heavier blows upon it, sometimes with the face, sometimes with the Pen of the hammer, till the end of the Shank is battered effectually over the Plate.

One main consideration in Rivetting is, that the Pin you rivet in, stand upright to the Plate, or other Iron you rivet it upon; for if it do not stand upright, you will be forced to set it upright after it is rivetted, either in the Vice, or with your Plyers, or with your Hammer, and that may, if your Plate be thin, bow it, or if it be thick, break the Sank, or else the Sholder of your Rivet, and so you lose your labour, and sometimes spoil your Work.

Another consideration is, that when you rivet a Pin to any Plate, and you fear it may afterwards twist about by some force that may be offered it, you must, to provide against this danger, file the Shank you intend to Rivet, either Square, or Triangular, and make the hole in the Plate you rivet it into, of the same size and form, and then rivet in the Shank, as before. There are two ways to make your Hole, Square or Triangular, one is by filing

it into these forms, when it is first Punched round; the other by making a Punch of Steel, of the size and shape of the Shank you are to rivet, and punching that punch into the Plate, make the same form.

Now to return where I left off. The Pins and Shanks of these Wards must be made of a long square form, because, (the Plates of the Wards being thin) should you make them no broader than the Plate is thick, the Studs, or Shanks would be too weak to hold the Wards, therefore you must make the Rivetting-shank three or four times, or sometimes more, as broad as the Plate is thick, and then rivet them in, as you were taught just now.

Then place the Cover-plate upon the Main-plate, so as the Centre of the Cover-plate, may stand directly over and against the Centre of the Main-plate, and make marks through the hole GG, of the Studs of the Cover-plate up∣on the Main-plate, and on those marks Punch holes, and fit two Pins into them, to fasten the Cover-plate on to the Main-plate, but you must not yet rivet them down, till the Key-hole be made, because this Cover-plate would then stop the progress of the File through the Main-plate, when you file the Key-hole. When you have placed the Cover-plate upon the Main-plate, and fitted it on with Pins, so, as you may take it off, and put it on again, as your Work may require, you must Punch the key-hole, or rather drill two holes close by one another, if the Key-hole falls near the Wards, because Punching may be apt to set the Wards out of form, and with small Files, file the two holes into one another, to make the hole big e∣nough to come at it with bigger Files, and then file your Key-hole to your intended size and shape.

The Key-hole being finished, forge your Key, as you were taught, Numb. I. fol. 8. and if your Key is to have a Pin-hole, drill the hole in the middle of the end of the shank, then file the Wards, or Slits in the Bit with thin Files; yet sometimes Smiths Punch, or Cut them with a Cold-Chis∣sel,

at the same distances from the middle of the Pin-hole in the end of the Shank (which is the same Centre which was made before, in the Main-plate on the Cover-plate) which you placed the Wards at, from the Cen∣tre of the Main and Cover-plate. But before you file these Wards too deep into the Bit of the Key, make trials, by putting the Bit into the Key-hole, whether the Wards in the Bit, will agree with the Wards on the Plates, which if they do, you may boldly cut them to the depth of the Wards on the Plate; if not, you must al∣ter your course till they do; but you must take great care in cutting the Wards down straight, and square to the sides of the Bit; for if they be not Cut down straight, the Wards on the Plates, will not fall in with the Wards in the Bit of the Key; and if they be not square to the sides of the Bit, the Bit will not only be weaker than it need be, but it will shew unhan∣somely, and like a Botch to the Eye.

The Cross and Hookwards is made, or, at least, entred at the Forge, when the Iron hath a Blood, or almost a Flame Heat, yet sometimes Smiths do it on cold Iron, with a thin Chissel, as you was taught Numb. I. fol. 11, 12. But you must take care that your Chissel be neither too thick, or too broad, for this Punching of Wards is on∣ly to give the thin Files entrance to the work; which entrance when you have, you may easily file your Cross, or Hook-wards, wider or deeper, as your Work may re∣quire; but if your Chissel be too broad, or too thick, it will make the Wards in the Bit too long, or too wide, and then (as I said before,) the Bit of your Key will prove weaker than it needs to be.

Having made the Wards on the Plate, and in the Bit of the Key, you must Forge the Bolt of a considerable sub∣stance, thick and square at the end that shoots into the Staple in the frame of the Door, that it may be strong enough to guard the whole Door; but the rest of the

Bolt that lies between the two Staples on the Main-plate, may be made very thin inwards, that is, the side that lies towards the Main-plate, which because it cannot be seen when the Bolt is fixed upon the Plate, I have made a Figure of it, and turned the inside to view, as in Fig. 4. where you may see, that the end A, hath a considerable substance of Iron to guard the whole Door, as afore∣said, and B is a square Stud, which doth as well keep the outside flat of the Bolt on the Range, as serve for a Stud for the Spring H in Fig. 2. to press hard against, and shoot the Bolt forwards: This Bolt must be wrought straight on all its sides, except the Topside, which must be wrought straight only as far as the Sholder G, called the Toe, or Nab of the Bolt, which rises, as you see in the Figure, considerably high, above the straight on the Top of the Bolt: The office of this Nab, is to receive the bottom of the Bit of the Key, when in turning it a∣bout, it shoots the Bolt backwards, or forwards.

Having forged and filed the Bolt, you must fit the hollow side of it towards the Main-plate, at that distance from the Key-hole, that when the Key is put into the Key-hole, and turned towards the Bolt, the bottom of the Bit may fall al∣most to the bottom of the Nab, and shoot the Bolt back so much, as it needs enter the Staple in the Door-frame. And having found this true place for the Bolt, you must with square Staples, just fit to contain the Bolt with an easie play, fasten these Staples, by Rivetting them with the Bolt within them, one near the Bolt end, the other near the Nab end, as at LL to the Main-plate.

The Punch a pretty wide hole in the Main-plate, as at K, to receive a strong Pin, and file a sholder to the Shank of the Pin that goes into the Plate. This Pin is called the Pin of the Tumbler; the Tumbler is marked I, which is a long piece of Iron, with a round hole at the top to fit the Pin of the Tumbler into, that it may move upon it, as on a Joint, and it hath an Hook returning at the low∣er

end of it, to fall into the breech of the Bolt, and by the Spring H forces the Bolt forwards, when it is shot back with the Key. This Spring is made of Steel, and af∣terwards temper'd (as I shall shew you in proper place.) It is fixed at the bottom of the Main-plate, by two small Shanks proceeding from that edge of the Spring that lies against the Main-plate, as at OO: These Shanks are to be Rivetted (as you were taught even now) on the other side of the Main-plate.

All things being thus fitted, punch an hole on each cor∣ner of the Main-plate for Nails to enter, that must nail the Lock to the Door. Or if you intend to Screw your Lock on the Door, you must make wide holes, big enough to re∣ceive the Shank of the Screw. Last of all, river down your Cover-plate to the Main-plate, and file your Key, and polish it too, if you will; so shall the Lock and Key be finished.

a A Prick-punch, is a piece of temper'd Steel, with a round point at one end, to prick a round mark in cold Iron.

b Hammer-hard, is when you harden Iron, or Steel, with much hammering on it.

The making of Screws and Nuts.

THE Shank of the Screw for Doors, and many other purposes, must be Forged square near the Head, because it must be let into a square hole, that it may not twist about when the Nut is turned about hard upon the Screw-pin. Therefore take a square Bar, or Rod of Iron, as near the size of the Head of the Screw-pin as you can, and taking a Flame-heat of it, lay so much of this Bar as you intend for the length of the Shank, with one square side flat, upon the hither side of the Anvil, and hammer it down to your intended thickness: But have a care you do not strike your Iron on this side the edge of the An∣vil, lest you cut the Iron, as I told you Numb. I. fol. 11. Thus, at once, you will have two sides of your Shank forged; the under-side made by the Anvil, and the up∣per-side

beaten flat with the Hammer: The Head will be in the main Rod of Iron; then if your Iron grows cold, give it another Heat, and lay one of the unwrought sides upon the hither-side of the Anvil, just to the Head, and hammer that down, as before, so shall the two other square sides be made; then hammer down the Corners of so much of this Shank, as you intend for the Screw-pin, and round it, as near as you can, with the Hammer; set then the Chissel to the thickness you intend the Head shall have, and strike it about half through, then turn the sides successively, and cut each side also half through, till it be quite cut off. If the Sholder be not square enough, hold it in your square-nos'd Tongs, and take another Heat, and with speed (lest your Work cool) screw the Shank into the Vice, so as the Sholder may fall flat upon the Chaps of the Vice; then hammer upon the Head, and square the Sholder on two sides, do the like for squaring the o∣ther two sides. This was, in part, taught you before, in Numb. I. fol. 11. but because the cutting this Iron Rod, or Bar, just above the Sholder makes the Head, and for that I did not mention it there, I thought fit (since the purpose required it) to do it here: The Forging of the Nuts are taught before, Numb I. Fol. 11, 12.

Having forged and filed your Shank square, and the Head either square or round, as you intend it shall be, file also the Screw-pin, from the risings and dents left at the Forge; and file it a little tapering towards the end, that it may enter the Screw-plate; the Rule how much it must be Tapering is this, consider how deep the Inner Grooves of the Screw-plate lie in the outer Threds, and file the end of the Screw-pin so much smaller than the rest of the Screw-pin, for the outer Threds of the Screw-plate must make the Grooves on the Screw-pin, and the Grooves in the Screw-plate, will make the Threds on the Screw-pin. Having fit∣ted your self with a hole in your Screw-plate (that is, such a hole whose Diameter of the hollow Grooves, shall be e∣qual

to the Diameter of the Screw-pin, but not such an hole, whose Diameter of the outer Threds, shall be equal to the Diameter of the Screw-pin, for then the Screw-plate will indeed turn about the Screw-pin, but not cut any Grooves, or Threds, in it) screw the Shank with the Head down-wards in the Vice, so as that the Screw-pin may stand di∣rectly upright, and take the handle of the Screw-plate in your Right-hand, and lay that hole flat upon the Screw-pin, and press it pretty hard down over it, and turn the Screw-plate evenly about with its handle towards you, from the Right towards the Left-hand, so shall the outer Threds of the Srew-plate cut Grooves into the Screw-pin, and the substance of the Iron on the Screw-pin, will fill up the Grooves of the Screw-plate, and be a Thred upon the Screw-pin. But take this for Caution, that, as I told you, you must not make your Screw-pin too small, because the Screw-plate will not then cut it, so if you make it too big (if it do enter the Screw-plate where it is Taper) it will endanger the breaking it, or, if it do not break it, yet the Screw-plate will, after it gets a little below the Tapering, go no farther, but work and wear off the Thred again it made about the tapering.

To fit the Pin therefore to a true size, I, in my Practise, use to try into what hole of the Screw-plate, the Tap or place of the Tap, (if it be a tapering Tap,) I make the Nut with, will just slide through; (Threds and all;) (which generally in most Screw-plates is the hole next above that to be used) for then turning my Pin about in that hole, if the Pin be irregularly filed, or but a little too big on any part of it, the Threds of that Hole will cut small marks upon the Pin, on the irregular places, or where it is too big; so that afterwards filing those marks just off, I do, at once, file my Pin truly round, and small e∣nough to fit the Hole I make my Screw-pin with.

As the Hole of the Screw-plate must be fitted to the Screw-pin, so must the Screw-tap that makes the Screw

in the Nut, be fitted to the round hole of the Nut; but that Tap must be of the same size of your Screw-pin too, which you may try by the same hole of the Screw-plate you made the Screw-pin with. Screw the Nut in the Vice directly flat, that the hole may stand upright, and put the Screw-tap upright into the hole; then if your Screw-tap have an handle, turn it by the handle hard round in the Hole, so will the Screw-tap work it self into the Hole, and make Grooves in it to fit the Threds of the Screw-pin. But if the Screw-tap have no handle, then it hath its upper end filed to a long square, to fit into an hollow square, made near the handle of the Screw-plate; put that long square hole, over the long square on the top of the Tap, and then by turn-ing about the Screw-plate, you will also turn about the Tap in the hole, and make Grooves and Threds in the Nut.

But though small Screws are made with Screw-plates, yet great Screws, such as are for Vices, Hot-Presses, Printing-Presses, &c. are not made with Screw-Plates, but must be cut out of the main Iron, with heavy blows upon a Cold-Chissel. The manner of making them, is as follows.

The Rules and manner of Cutting Worms upon great Screws.

THE Threds of Screws, when they are bigger than can be made in Screw-plates, are called Worms. They consist in length, breadth and depth; the length of a Worm begins at the one end of the Spindle, and ends at the other; the breadth of the Worm, is contained be∣tween any two Grooves on the Spindle, viz. The upper and under Groove of the Worm, in every part of the Spin∣dle; the depth of the Worm, is cut into the Diameter of the Spindle, viz. The depth, between the outside of the Worm, and the bottom of the Groove.

The depth ought to be about the one Seventh Part of the Diameter, on each side the Spindle.

You ought to make the Groove wider than the Worm is broad, because the Worm being cut out of the same in∣tire piece with the Spindle, will be as strong as the Worm in the Nut, tho' the Worm on the Spindle be smaller; for you cannot come at the Worm in the Nut, to cut it with Files, as you may the Spindle, and therefore you must either Turn up a Rod of Iron, to twist round about the Grooves on the Spindle, and then take it off, and Braze it into the Nut, or else you must Cast a Nut of Brass upon the Spindle, which will neither way be so strong as the Worm cut out of the whole Iron, by so much as Brass is a weaker Mettal than Iron, and therefore it is that you ought to allow the Worm in the Nut, a greater breadth than the Worm on the Spindle, that the strength of both may, as near as you can, be equallized; for both being put to equal force, ought to have equal strength. The Worm may very well be the One Seventh Part smaller than the Groove is wide, as aforesaid.

Having considered what breadth the Worm on the Spindle shall have, take a small thin Plate of Brass, or Iron, and file a square notch at the end of it, just so wide, and so deep, as your Worm is to be broad and deep, and file the sides of the Plate that this notch stands between, just to the width of the Groove. This Plate, must be a Gage to file your Worm and Groove to equal breadth by; then draw a straight and upright line the whole length of the Spindle; divide from this line the Circumference of the whole Spindle into eight equal parts, and through those Divisions, draw seven Lines more parallel to the first Line; then open your Compas∣ses just to the breadth of one Worm, and one Groove, and set off that distance so oft as you can, from the one end of the Spindle to the other, (but I should first have told you, that the end of your Spindle must be truly square

to the outside) and with a Prick-Punch, make a mark to every setting off on that line: Do the like to all the other straight upright Lines. Note, that you may chuse one of these eight upright lines for the first, and make the next towards your left hand, the second (but then the first must stand towards you) and the next that, the third, and so on. And the top mark of every one of these upright straight Lines, shall be called the first Mark, the next under that the second Mark, the third, the third Mark, and so downwards in Order and Number.

Having marked one of these eight Lines at the top of the Spindle, to begin the winding of the Worm at, with a Black-lead Pencil, draw a line from that Mark to the second Mark, on the next upright line towards the left hand, from thence continue drawing on with your Pencil to the third Mark, on the third upright line, draw on still to the fourth Mark, on the fourth upright line, and so onwards, till you have drawn o∣ver the eight straight lines, which when you have done, you must still continue on, drawing downwards to each lower Mark on each successive upright line, till you have drawn your Worm from end to end: Then exa∣mine, as well as you can, by your Eye, whether the Worm you have carried on from Mark to Mark with the Black-lead Pencil, do not break into Angles, which if it do any where, you must mend it in that place: Then with the edge of an half-round File, file a small line in that Black-lead line, and be sure that the line you are filing, run exactly through all the Marks that the Black-lead Pencil should have run through (if it did not, for want of good guidance of the hand.) This small line is only for a guide to cut the Groove down by; for the ma∣king of a Screw is, indeed nothing else, but the cutting the Groove down, for then the Worm remains: But you must not file in this small line, but leave it as a guide

to lie on the middle of the Worm (as I said before): Therefore to cut down the Groove, take a Cold-Chissel, somewhat thinner than you intend the Groove shall be wide, viz. about the thickness of the breadth of the Worm, and, with heavy blows, cut out the Groove pretty near. The reason why you should not offer to cut the Grooves to their full width at the first, is, because your Hand may carry the Cold-Chissel somewhat awry, and should your Cold-Chissel be as thick as the Groove is wide, you could not smooth the Irregularities out, without making the Worm narrower than you intended it: Then with a Flat-file open and smooth the Groves, filing in the middle between the two next fine lines cut by the Half-round File, till you have wrought the Spindle from end to end, so shall the Worm remain. But you must not ex∣pect, that though the Groove be cut, it is therefore fini∣shed, for now you must begin to use the thin Plate-Gage, and try First, whether the Worm have equal breadth all the way. Secondly, whether rhe Groove have equal breadth all the way. And Thirdly, whether the Groove have equal depth all the way; and whereever you find the Worm too broad, you must file it thinner, and where the Groove is not deep enough, file it deeper; there∣fore in cutting down the Groove you may observe, that if, at first, you file the Worm ne'er so little too narrow, or the Groove ne'er so little too deep, you shall have all the rest of the Worm, or Groove, to file over again; be∣cause the whole Worm must be wrought to the breadth of the smallest part of it, and the whole Groove to the depth of the deepest place all the way, especially if the Nut be to be Cast in Brass upon the Spindle; because the Mettal running close to the Spindle will bind on that place, and not come off it; but if the Nut be not to be Cast in Brass, but only hath a Worm brazed into it, this niceness is not so absolutely necessary, because that Worm is first Turned up, and bowed into the Grooves of

the Spindle, and you may try that before it is Braz'd into the Nut, and if it go not well about, you may mend, or botch it, either by Hammering, or Filing, or both.

The manner of Casting the Nut upon the Spindle, I shall shew when I come to the Casting of Mettals; and the manner of Brazing hath been Taught already. Numb. I. fol. 12, 13.

If your Spindle is to have three or four Worms win∣ding about it, as Coining-Presses, and Printing-Presses have, that they may not wear out too fast, you must divide the Circumference into three or four equal parts; and each of these equal parts, into two equal parts, and having straight upright lines, drawn as before, begin a Worm at each of those three, or four Divisions, on the Circumference, and considering the breadth of your Worm, and width of your Groove, measure that width so oft as you can on all the upright lines, and making Marks on those, at each Setting off, draw, as before, a line from the end of the Spindle, on the first upright line to the Mark below it, which is the second Mark on the second upright line, from thence to the third Mark, on the third upright line, and so on to the other end of the Spindle. Having drawn the first Worm, work the other Worms as this.

Thus much may, at present, suffice for great Screws; when I come to exercise upon Printing, I shall be more copious on Rules for Printing-Press Spindles.

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