TURNING. 



hard woods, as box, lignum vitas, iebony, &c. After having 

 poliftied the piece well by fuch means, it fhould be rubbed 

 gently either with wax or olive-oil, then wiped clean, and 

 rubbed with its own turnings or (havings, or with a cloth 

 a little warm. Ivory or horn is polifhed with pumice-ftone or 

 chalk, finely pounded and put upon leather, or a linen cloth a 

 little moiftened with this : the piece is rubbed as it turns round 

 in the lathe ; and to prevent any dirt from adhering to any 

 part of it, every now and then it is rubbed gently with a 

 fmall brufli dipt in water. To polirti metals very finely, the 

 workmen make ufe of a particular kind of earth called tri- 

 poli, and afterwards of putty, or calx of tin. Iron and 

 fleel are polilhed with very fine powder of emery ; this is 

 mixed with oil, and put between two pieces of tin or 

 pewter, and then the iron is rubbed with it. Tin and filver 

 are polifhed with a burnifher, and that kind of red ilone 

 called blood-ftone. Iron and fteel may alfo be polifhed 

 with putty, putting it dry into fhamoy-flcin. 



All kinds of articles in wood are turned in the above 

 manner ; but many contrivances are neceffary to mount dif- 

 ferent things in the lathe. 



The fmall figures in the plate reprefent various chucks, 

 which are occafionally employed, and which are adapted for 

 turning different kinds of work. 



Flgi. 2. and 3. exhibit a fmall wood chuck, which is adapted 

 to be fcrewed to the mandrel at a, a hole being perforated in 

 the centre of it, at b, into which a fmall piece of wood or 

 ivory is to be inferted, in order to turn it. To hold the work 

 fall in this chuck, it is divided at the end b by two faw-kerfs, 

 at right angles to each other, as fhewn in^^. 3. fo as to fepa- 

 rate the end into four fegments, which admit of expanding 

 or clofing : a hoop or ferril is fitted on the outfide of the 

 chuck, which part is made tapering, fo that forcing the ferril 

 farther on, will clofe the four fegments together, and bind 

 faft upon the work, which is introduced into the cavity b. 

 This is a very convenient chuck for holding fmall pieces of 

 ivory, and particularly for the purpofe of polifliing. 



Figs. 12. and 13. exhibit a fimilar chuck, made in brafs, 

 for more delicate work ; it is only divided into two fegments. 



Fig. 4. is a brafs box, to fcrew to the mandrel, and hold a 

 wood chuck, fuch as we have before explained. Wood 

 chucks are ufually made to fcrew on the mandrel by means 

 of a hole in the chuck, which is cut with a female fcrew 

 within. The objeftion to this mode is, that the threads of the 

 fcrew on the wood wear away by conftant ufe. In^^. 4. a 

 brafs female fcrew, a, is cut to fit the fcrew of the mandrel, 

 and at the other end, b, is a box, alfo cut with a fcrew within- 

 fide, into which the wood block or chuck is fcrewed, as fhewn 

 by the dotted lines, fo as not to come out without great 

 force : by this means, the fitting of the chucks to the man- 

 drel is not with a wooden fcrew, as in general, but with a brafs 

 one, which will not be liable to get out of the truth, but 

 will always fcrew up to the fame Ihoulder. The lathe fliould 

 have at leaft two dozen of thefe v/ood chucks, with cavi- 

 ties of different fizes, and fome of them hooped with iron at 

 the outer end, to prevent them fplitting. The brafs box is 

 a great fecurity agair.ft fplitting. 



Fig. 5. is a very ufeful arbor for turning wheels, collets, 

 or any other flat piece of work that will admit of having a 

 fmall hole in the centre of it. A brafs fcrew-chuck, a, is 

 fitted to the mandrel, and a fteel pin, b, is fixed into it, and 

 projefts an inch or more : tlie pin is turned true, and the work 

 is fitted fad upon it, either by turning the pin to the fize, or 

 by broaching the hole in the work : and to prevent the work 

 from flipping round upon the pin, it is pinched faft up 

 againft the flat furface of the chuck, as fliewn by the dotted 

 lines, by a nut d, which is fcrewed on the end of the fteel 



pin b : fey this means, the work will be held faft, and will be 

 carried round by the chuck, fo as to be turned by the ap- 

 plication of proper tools upon the reft. Thefe kinds of 

 arbors ftiould be of all fizes, to fit the holes in different 

 wheels, &c. 



Fig. 10. is a brafs chuck, which is very ufeful for holding 

 fmall pieces of brafs work ; it fcrews to the mandrel at the 

 end a : the hollow part, b h, has fix fcrews tapped through 

 it, and pointing to the centre, as ftiewn m Jig. 11. By 

 fcrewing in thefe fcrews, their points will pinch upon any 

 piece of work which is put into the chuck, as ftiewn at d, 

 and wrill hold it firm. The fcrews being regulated, admit 

 of adjufting the work </ to a true centre with the line of 

 the mandrel. 



Figs. 16. and 17. are views of chucks having fimilar proper- 

 ties to the preceding : a {Jig. 16. ) is the end which is fcrew^ed 

 to the mandrel ; ^ ^ is a circle of brafs, having a mortife or 

 opening acrofs the centre of it, as injg. 1 7 ; into this open- 

 ing two fteel dies are fitted, and fcrews d, d, are placed be- 

 hind them, to approach them together : the fcrews come 

 through the outfide of the chuck, and have fquare heads, 

 which are to be tursed by means of a key. The adjaceat 

 furfaces of the two dies are hollowed, fo that they will em- 

 brace a piece of wire or other fimilar fubftance wiiich is put 

 between them, and the dies may be cut like a file, to hold it 

 faft. By means of the two oppofite fcrews (/, d, the work 

 may be adjufted to the centre line of the mandrel. 



Figs. 20. and 21. are a table-chuck, proper for holding 

 wheels or flat plates by the circumference, whilft the centre 

 parts are turned : a is the fcrew to fix it to the mandrel : b b, ; 

 a large circular plate, turned perfeftly flat on the front 1 

 furface. In this plate are grooves, pointing from the centre 

 to the circumference, as fhewn in_^_f. 21 : the grooves are 

 adapted to receive clamp-pieces, d, d, d, by means of 

 which the wheel or other work is bound faft againft the flat 

 furface of the chuck. The grooves admit the clamps d, d, d, 

 to be placed at any diftance from the centre, according to 

 the fize of the work, and to place tliem at thofe parts where 

 it will be moft convenient to apply them. 



The form of thefe clamps is (hewn more particularly in 

 Jg. 22 : J are Aiders of metal, which are fitted to the 

 grooves in the chuck ; and the grooves are dove-tailed, fo 

 that thefe Aiders can be put into the grooves at the back of 

 the chuck, but will not draw through the grooves into the 

 front. Screws are tapped into the Aiders, and draw the^ 

 clamps, h, againft the face of the chuck, and hold faft the 

 work, which is placed beneath their claws. The clamps, h, 

 have fhanks projefting from them at right angles, which 

 pafs through the grooves, and keep the clamp from turning 

 round to one fide. 



Figs. 35. and 36. reprefent the callipers ufed by turners 

 to take the meafure of their work : they are made of two 

 curved pieces of fteel-plate, iniited together by a joint. 

 When they are opened, as in Jig. 36, the dimenfions of a 

 round piece of work may be conveniently taken between 

 their points, as fhewn by the dotted circle ; but if the 

 points are clofed together, as m Jg. 35, fo that they pafs 

 each other, then the callipers are adapted for meafuring the 

 diameter of internal cavities, by the diftances of their points 

 from each other. 



Several other kinds of callipers are ufed by turners, but 

 thefe are the moft convenient, as they ferve equally well for 

 infide and outfide dimenfions. Some callipers are made 

 double, like a pair of fciffars ; and the points at one end are 

 for infide meafures, whilft the others are for outfide mea- 

 fures ; and the diftances of all tlie points from the joint 

 being exaflly the fame, the infide meafure of any hollow 

 1 1 being 



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