Tap (tool)

“ Taps for general use by hand are frequently used to tap holes that do not pass entirely through the work; hence, the taper tap must have a short length of taper so that the second tap may be enabled to carry a full thread as near as possible to the bottom of the hole without carrying so heavy a cut as to render it liable to breakage, and the second or plug tap must in turn have so short a length of its end tapered that it will not throw too much duty upon the bottoming tap. ”

“ The depth of the tapping hole should be made if possible equal to one and a half times the diameter of the tap, so that in case the hole bottoms and the tap cannot pass through, the taper, and what is called in England the second, and in the United States the plug tap, will finish the thread deep enough without employing a third tap, for the labor employed in drilling the hole deeper is less than that necessary to the employment of a third tap. ”

“ But, on the other hand, such a tap produces, when used by hand, more accurate work, the threaded hole being more parallel and of a diameter more nearly equal to that of the tap, it being observed that even though a hand tap have no clearance it will usually tap a hole somewhat larger than itself so that it will unwind easily. ”

“ As a sample of duty, it may be mentioned that, at the Harris-Corliss Works, a tap of this class, 27⁄8 inches diameter, with a 4 pitch, and 10 inches long, will tap a hole 5 inches deep, passing the tap continuously through without any backing motion, two men performing the duty with a wrench 4 feet long over all, the work being of cast iron. ”

“ It is necessary to correct the errors before the tap has entered the hole deeply, because the deeper the tap has entered the greater the difficulty in making the correction. If the pressure on the tap wrench be made excessive, it is very liable to cause the tap to break, especially in the case of small taps, that is to say, those of 5⁄8 inch or less in diameter. ”

“ Taps are used for the purpose of letting off or stopping at pleasure the flow of liquids from vessels or through pipes. The forms of stop-cocks are very various, but the form shown at fig. 1 is by far the most general; it consists of a short curved tube, having an upright cylinder in the centre in which a plug with a handle turns; this plug is perforated in the direction of the length of the handle, so that when this is turned crosswise the communication is shut off (figs. 2, 3, and 4) . The “nose” or end of the tap is sometimes prolonged into a spout, for filling bottles, &c., as in fig. ”

“ If a long tap is employed to cut a three-quarter full thread, it may be wound continuously down the hole, without requiring to be turned backwards at every revolution or so of the tap, to free it from the tap cuttings or shavings, as would be necessary in case a full thread were being cut. ”

“ Furthermore, a pin and washer admit of more speedy disconnection than a nut does, and also give a more delicate adjustment for end fit.
In drilling the tapping holes for standing bolts, it is the practice with some to drill the holes in cast iron of such a size that the tap will cut three-quarters only of a full thread, the claim being that it is as strong as a full thread. ”

“ If a short pipe bent at right angles like the letter L is fitted by one arm on to the end of the tap, while the other is turned vertically upwards, and the vat is full as before; when the tap is turned, the water will shoot up into the air, and after rising for a certain distance will stop, and then fall. ”

“ The working of the apparatus, which only requires the manipulation of a single tap, is very simple. When the mercury is raised, the tap is turned in such a manner that the surplus of the liquid can pass into the enlarged appendage, a, placed above the tap, and communication is then cut off by turning the tap to 90 degrees. ”

“ With a tapered tap, or a tapered solid die, the full threads do not come into operation until after the tapered threads have started the cut. A properly made thoroughfare tap, or a tapered die, will cut an average sized screw at one traverse, provided lubrication is ample. Taps are now made with very narrow edges and wider clearances than formerly, very different from the common taps with broad edges and narrow grooves. There is thus little friction, and there is plenty of clearance for the chips, essential conditions for cutting screws rapidly at a single traverse.
Dies are held in stocks. ”

“ In plate p is a groove g to hold the head h at a right angle to the slideway in c, there being a projection beneath h and beneath c to fit into g. The tap t is threaded through h, but not fluted at the part that winds through h when the tapping is being done, so as not to cause the thread in h to wear. h acts as a guide to the tap and causes it to start the thread at the same point in the bore of each piece s, and the stem will be so threaded that the screw starts at the same point in the circumference of each piece. ”

“ The upper part of the cylinder has an opening (of different shapes) leading to the top of the plug, &c., a key being made to fit it (fig. 9) . The American wooden taps (fig. 8) , are just like it, but have the handle united instead of a key. The four-way tap is a clever contrivance for uniting four passages in alternate pairs; figs. 10 and 11 indicate the different positions of the plug. This kind of tap was formerly an important part of the steam-engine, and allowed the steam alternately to enter above and below the piston. ”

“ Tap, tap, n. a hole or short pipe through which liquor is drawn: a place where liquor is drawn: any particular liquor drawn through a tap.—v.t. to pierce, so as to let out fluid: to open a cask and draw off liquor: to broach a vessel.—v.i. to act as a tapster:—pr.p. tap′ping; pa.t. and pa.p. tapped.—ns. Tap′-bolt, a bolt with a head on one end and a thread on the other, to be screwed into some fixed part instead of passing through and receiving a nut; Tap′-cin′der, slag produced during puddling; Tap′-house, a tavern; Tap′lash, poor stale swipes; Tapote′ment, percussion; Tap′per, one who taps ”

“ In practice it is advisable to keep the pump always working, and to regulate the delivery to the boiler by means of a by-pass tap on the feed pipe, through which all or some of the water may be returned direct to the tank. ”

“ A piece of old cycle tyre tubing, tied to the waste pipe and long enough to reach below the edge of the bath, will prevent splashing—which, when chemicals are being poured away, might prove disastrous to light-coloured clothes.
The supply pipe has a siphon-piece of “compo” tubing at the top, to draw off the water when the tube has been filled by suction, and a small tap at the bottom. This tap, when not in use, should be held back out of the way by a wire hook attached to the lowest of the upper shelves. A piece of linoleum should be cut to fit the bath-shelf and protect the drawer below. ”

“ Fig. 1863 represents the socket for driving the tap, so devised that when the tap is strung for its intended length with nuts, the top nut releases the tap of itself, the construction being as follows: s is the socket that fits into the driving spindle of the machine; its bore, which fits the stem of the tap easily, receives two headless screws b, a pin p, which is a sliding fit, and the screw a. r is a ring or sleeve fitting easily to the socket, and is prevented from falling off by screw a. ”

“ Boring Tapers with a Boring Bar or Attachment.—In cases where the degree of taper is very great a live centre may be bolted to a chuck plate, as in Fig. 1143, by which means any degree of taper may be bored. Instead of a star feed, a gear feed may be provided by fastening one gear, as a, on the dead centre, and another, as b, on the feed-screw. The cutting tool must stand on the side of the sliding-head—that is, farthest from the line of lathe centres. ”

“ A pin through the centre connects it with the steam-funnel. The pin represents the steam-pipe. We now require taps, which we make out of pins, by cutting off the heads and bending them at right angles about one-eighth of an inch from the headless end. The point is pushed through the card, leaving outside about one-eighth of an inch in addition to the bent part, as shown in accompanying cut. [370] Above this we gum another piece of bent pin this size and shape, for handle of tap. Two or three of these should be placed on the boiler end, at the left side above the furnace. ”

“ Did you ever try to split trap-rock with a hammer? You may batter all day at one side and you will only knock off chips, spoil your hammer, and hurt your hands: but, when you have found the right spot, a tap knocks it in pieces. ”

“ When, for example, a tap is put into the tapping machine, it is at its normal temperature, and of a diameter due to that temperature, but as its work proceeds its temperature increases, notwithstanding that it may be freely supplied with oil, because the oil cannot, over the limited area of the tap, carry off all the heat generated by the cutting of a tap rotated at the speeds usually employed in practice. ”

“ Tools Required.—The tools required for this job are the saw, rasp, tap borer, bending irons, file, ladle, wiping cloths, shave hook, knife and rule, soldering iron.
Preparation.—To prepare the lead pipe after cutting from the coil and squaring the ends with the rasp is very similar to the 5⁄8-inch branch joint. The center of the pipe is marked and a hole is made in it with the tap borer large enough to admit the bending irons. The hole is enlarged with the irons. A good substantial collar is made around the hole to hold the bib in place. ”

“ The result is that while plenty of adjustable dies are made, there are few expanding taps. Many have been designed, but they are used to a much less extent than the dies. A sizing tap is kept true as long as possible by careful use. and when it falls below the limit dimensions it is replaced by a new one.
Screw milling, the latest development in screw-cutting, involves the use of a special machine, something like the lathe in outline, the piece of work to be threaded being rotated in the axis of the machine. ”

“ I had struck a portion of the pipe that had a thread to it, like that which encircles a bolt of iron and makes a screw of it, and the thought came to me that if I could only succeed in giving a revolving motion to my body, I would with every turn twist myself farther down toward the end of the pipe. ”

“ Pulteney. “The young like it; they are in a position to hack one another’s shins when the teacher’s back is turned.”
When they reached the bedroom, Bredon found himself falling into the attitude of a lecturer. “The guide,” murmured Angela, “taking a party round the ruins of the old dungeon. Scene of the ’orrible crime. Please pay attention, gentlemen!”
“You see how the gas works in here,” began Bredon. “There’s the main tap, we’ll call it A, which controls the whole supply. Tap B is for the bracket; tap C leads through the tube to the standard lamp. ”

“ Though the action of taps resembles in some respects that of common dies, the results achieved are better, partly because the backing off is generally superior, partly because taper taps are commonly used to start a screw hole. Tapered solid dies are also used in some kinds of turret work with the same object, namely, to facilitate the work of an inherently badly formed tool. ”

“ Water-pipes are made by lead being cast in moulds with a steel rod passing through their middles, according to the size required. The lead is poured into the space between the rod and the mould. After it is cool the rod is drawn out by machinery, and the mould which is made in halves is opened and the pipe taken out. The pipe is then much thicker and shorter than is required for use, but it is afterwards drawn between powerful iron rollers with grooves cut in their surfaces, an iron rod being again placed inside it. ”

“ Sometimes, however, a second tempering will bring a long pitch nearer correct.”
“Do you soften your taps after roughing them out in the lathe?”
Answer.—“Never, if we can possibly avoid it. Sometimes it is necessary because of improper annealing at first. The more times steel is annealed the worse the results obtained in making the tool, and the less durable the tool.”
The following are answers to similar questions addressed to the Morse Twist Drill and Machine Co.:—
“The expansion of taps during hardening varies with the diameter. ”

“ If a hand tap is given clearance not only will it cut a hole widest at the mouth, but it will cut a thread larger than itself in an increased degree, and, furthermore, when the tap requires to be wound back to extract it the fine cuttings will become locked in the threads and the points of the tap teeth are liable to become broken off. To ease the friction of long teeth, therefore, it is preferable to do so either as in Fig. ”

“ Hoisting the small bottle to a convenient height, the tap of the larger bottle is carefully opened, the air passes through the flexible tube to the smaller bottle, exerts its pressure upon the surface of the liquid therein contained, drives it up the other tube, and causes it to impinge with any required degree of force against the disk of the spray-producer. ”

“ If, however, one part of the length of a taper turning attachment is much more used than another, it is apt to wear more, which impairs the use of the bar for longer work, as it affects its straightness and causes the slide to be loose in the part most used, and on account of the wear of the sliding block it is proper to wind the tool out from its cut on the back traverse, or otherwise the tool may cut deeper on the back than on the forward traverse, and thus leave a mark on the work surface. ”