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The Importance of Attention to Jig Details

The Importance of Attention to Jig Details Workshop and Production Section AIRCRAFT ENGINEERIN G April, 1945 By H. Moore INC E th e design of drill jigs permits the adop ­ particula r spindle. Anything, wood or shee t metal, word : try your own hand on them, not for a second, bu t for a full five minutes, an d see where it tion of an almost unlimited range of new ideas mad e to a channel iron shape will do a s well if th e hurt s th e most. it is curiou s t o not e th e lack of originality in th e real thing is no t available. It is possible, also, t o Th e smallest of all jig details is th e pin . Dealing minor components. Most of the common acces­ provide small shelves for th e bushings , attached to sories—clamps, screws, pins , bushings an d th e like — th e spindle heads just above the pinion shafts. only with th e locatin g variet y we find i t place d often hav e remained unaltered for years . And yet , in all This is bette r even than channel iron, bu t i t usually where i t i s mos t difficult to see . It migh t b e argued of them , there is som e room for improvement . It is costs more t o produce . A good typ e of spindl e shelf tha t th e shap e of th e wor k determines th e position tru e that the measur e of possible improvement is can be mad e of shee t metal, bu t in it s improvized of th e pin . But ofte n it is only too plai n tha t th e no t great; often it is merely a pin here, a screw form it is jus t th e lid of a tin held t o th e castin g b y a moving of th e wor k around would re-position th e there, an alteration of a n existing part, or perhaps small screw. After all, it is th e position of th e shelf pins in a bette r way. Not nearl y enough thought is only a rearrangemen t of some of th e parts . But all tha t is important , not it s materia l or shape . given to thi s aspect of jig work . The troubl e ap ­ thes e changes are withi n the scope of th e operator pear s t o lie in th e inabilit y of th e ji g make r t o mul­ Turnin g now for a moment to screws. It is a himself; he shoul d not wait for th e jig produce r t o tiply b y thousands . It might b e eas y t o place on e matte r for surpris e tha t th e slotte d variety continues furnish him with ideas. As a matte r of fact, if an y to b e used on jig wor k when there ar e so man y really piece in a jig i n a good light—and most tool rooms ar e better lighted than th e shops—bu t t o repea t th e little defect is allowed to continue unchecked it is good types of safety screws on th e market . The performance a thousand times in a poorer light is th e fault, no t of th e producer , bu t of th e ji g operator slotted screw is th e sourc e of on e of th e few dangers somethin g entirely different. It is sometimes pos­ who, because h e is using th e jig in actua l practice, of jig operation. The real danger, of course, lies in is in th e bette r position to see wher e it is wrong. sible, however, to obtain a slight alleviation by th e screw driver which so often slips off th e screw At any rate, as far a s th e presen t writer can ascer­ drilling a hole in th e wall of th e ji g t o ligh t u p th e and lacerates th e han d of th e perso n holding th e jig. tain , nothing on thi s subject has ever before been obscure pin . Wheneve r these screws are i n a jig, and canno t for published from th e ji g producin g end. It remains, any reason be changed , they should be rendere d as Althoug h cutting tools ar e no t strictl y speaking jig therefore, for someone at th e other end—the jig harmless as possible. Grinding a portion off th e details they cannot entirely be excluded from th e operatin g end—to point out som e of th e defect s of end until th e head is well below th e surface reduces argument . There are a few ne w thing s to b e said. small accessories an d ho w t o correct them. These th e danger. Deepening the slot to twice or three Counterbores and facing tools, for example , usually notes, althoug h the y chiefly concern th e operator , ar e time s its norma l depth and grinding th e screwdriver carr y a collar or lock-nuts as stops. The overall directed to th e produce r as well, because many of to fit actuall y t o th e botto m is also a good safeguard. dimension t o whic h these mus t be se t is stampe d on th e ideas t o b e mentione d could well b e incorporated An additional precaution is the rounding off a pad in th e ji g nea r th e hol e in which the y are used. in th e ji g before it is delivere d to th e shop . smoothl y of all th e shar p edges on th e screwdriver This dimension is always given in decimal figures, blade. There will b e muc h less danger of it s cutting which are liabl e to accidental alteration. A slight Th e loose bus h tha t fits into th e liner bush in th e the n and a screwdriver with rounded edges fits into knock in th e righ t place and th e figure one becomes jig body is a n excellent example of a component a screw slot more readily than without. a seven, a nought becomes a nine an d so on . Any­ which never alters bu t which is, nevertheless , cap­ one experiencing trouble from this cause should mill abl e of minor improvements. For instance, it is Ho w th e usefulness of a component may b e in­ difficult to understand why drill and reame r loose th e figures off an d replace the m with letters. When creased b y a simple alteration of a n existin g par t is bushes are alway s made with only th e letterin g on 1.315 becomes "one point three one five" there is bes t illustrated by th e sprin g lifted slotted clamp. th e top t o identify them; when a groove in th e little chance of erro r from accidental cause. This clamp is used th e world over. It is a flat piece middle of th e reame r bushing head would reveal it s Th e setting of tape r reamers is alway s a delicate of steel with a long slot in th e middl e through which description at a glance. An error of really long jo b when the machine stop is used. Fortunately, th e tightening bolt passes an d underneat h which, on standin g concerns the loose bush that projects a ther e is usually some par t of th e ji g wher e it is pos­ th e bolt, is a spiral spring. Now th e function of thi s considerable distance inside th e jig . It is because spring from time immemorial has been solely to sible t o mak e a tes t hole—mostly in th e feet. With this projecting par t is no t left small tha t th e operato r lift the clamp clear of th e work when the, bolt is a taper hole th e correct depth in th e ji g itself there is compelled to exhaus t himself twisting tight bush­ loosened. But th e operator has still t o pull th e is no difficulty in setting the reame r either to th e ings all th e wa y dow n and out . Small bushings ar e clamp back t o th e en d of th e slo t before he ca n re­ machine stop or t o a collar on th e reamer itself. th e cause of muc h needless exertion. It is a mistake move th e work—an d often there are a dozen of thes e Many operators find it har d to se t a countersin k in a t o mak e th e head s of smal l bushings proportionately clamps on one jig. Yet, i t require s only a small hole jig. The simplest and sures t way is t o us e a steel small merely because they look nice. They should in the jig near the bolt and a similar one in th e block with th e requisite countersinks in i t th e same be large—even to th e point of ugliness—and the underside of th e clamp , into which th e end s of th e height from the tabl e as thos e in th e wor k when it knurling made a s roughl y as possible to enable th e spiral spring, after giving it a twist, are inserted; is in th e jig . The block, of course, is kep t always operato r to ge t a good grip. in th e sam e box a s th e jig . The reamin g of blind an d th e sam e spring not only lifts th e work , bu t also holes in cas t iron calls for mentio n here because it is I t is, however, in th e dispositio n and th e handling pulls it back out of th e way . It should be pointe d one of th e job s tha t causes difficulties far ou t of pro ­ of loose bushings tha t most of th e scope for improve ­ ou t here that a spring tha t fits th e bolt too closely canno t be used for thi s dual purpose. portion to their apparent simplicity. The troubl e men t lies. Some jigs have two dozen or mor e an d is tha t the reamin g cannot be done until the drill much of th e cost of productio n will depend on how Nex t to th e slotted clamp, probably the best cutting s have been removed from the hole. This is thes e are handled . The ide a behind all loose bush­ known of all clampin g devices is th e ji g leaf. The effected on small jigs b y turnin g them over t o allow ing arrangements is, of course, to provid e a known screw used for tightenin g this has a flat head equal th e cuttings to fall out. But quit e a jarring effect place for each of the m and so t o ensur e tha t th e on e in width to th e slot in the leaf. By giving it a is needed in addition . For thi s reason it i s bette r t o needed shall be th e one alway s nearest to hand. quarte r tur n back th e slot i n th e leaf will pas s over it ; If th e bushings ar e few an d on e only used with each drill all th e holes first. This necessitates' turning a quarter turn forward and i t will be locked. The tool a mix-u p can b e avoide d by leaving th e bushing th e jig over to reach the various holes and this screw is moved with a spanner and it is almost on its respective tool in the revolving spindle. movement, together with the vibration caused b y impossible t o sto p th e loosening movement with th e Slightly knurling th e shan k of th e drill or reamer th e drilling, effectually clears th e cutting s from all screw head exactly in line with the slot. Usually th e holes. will enlarge it enough to preven t th e bushing s from it goes past and ha s t o b e turne d back. To force falling off. Sometimes th e shap e of th e jig permit s th e head to stop in th e righ t place it is necessary Ther e is much more to be said but within th e th e drilling of a rough hole, a t each side of th e real only to pu t a pin in th e leaf close t o th e slot . Thus limits of a shor t article i t is possibl e t o mentio n none hole, into which the bushings can b e placed each simply can a n annoyance be ended—yet one ma y bu t the best known and most used components. tim e after use. Naturally, the difficulty of th e look a long time before one sees a stop pin in a ji g And even thes e mus t b e touche d on bu t lightly . The orderly arrangement of bushings increases with th e leaf. Before leaving this jig ther e is a detai l a t th e essential purpose, however, is t o point out tha t a numbe r used with th e jig. It makes n o difference othe r end tha t should receive some mention. It is proper attention to detail s is no t only desirable bu t how carefully these are arranged on th e dril l table ; th e handle designed to resis t th e torqu e of th e drill. imperativ e if th e fullest possible advantage is t o b e the y are alway s liable t o b e swep t off wit h th e cut ­ Sometimes it bear s a slight resemblance t o a handle, gained from their use. The perfect drill jig is th e tings or displaced by th e movemen t of th e jig . A often it is jus t a straight , flat piece of metal . It is a one that can b e operate d with the leas t amount of length of channe l iron—two inch will do—laid across mistak e t o thin k tha t th e shap e of thi s handle is no t effort and th e fewest number of movements. The th e table a t th e bac k will provide a n excellen t place important . Anyone who has held one for an y adoption of any of the ideas which have been for the bushings used on a six spindle drilling lengt h of tim e against th e torqu e of a dragging drill- described here will contribute helpfully towards machine. In this is laid, behind each of th e will agree tha t few thing s can b e mor e tiring. To makin g jig wor k easier and mor e profitable than it spindles, th e bushings used with the tool in that all those engaged in th e manufactur e of ji g handle s a ha s ever been before. "Euco" Giant Blue Print Wall Chart of Free­ Trade Catalogues Wanted Trade Publications Received man's Screw Thread and Engineering Tables. Magneto Testing Equipment Any firms interested and associated in th e pro­ [Euc o Tool s Ltd. , London . 10s. 6d. ] Engine Starter Test Equipment duction of machin e tools, factory plant and equip ­ ment , physical and chemical laboratory equipment, [Cit y Electrical Co., London. ] "Compo" Oil Retaining Bearings electrical equipment, switch gear, motors, trans­ 'Sieray' "Warm White" Fluorescent Lamps, "Bound Brook" Graphited Bronze Bearings . formers, generators, etc., hydraulic pumps, air [Siemens Electric Lamps and Supplies Ltd. , compressors, etc. , wh o ar e willing t o deposi t a copy London.] "Ferrocile" (Powder Metallurgy) Iron Valve of their latest catalogues are asked t o sen d the m t o Scrivener Centreless Grinding Machine No. 2 . Guides th e Librarian, Power Jets (Research and Develop­ [Arthu r Scrivener Ltd., Birmingham.] [Boun d Brook Bearings (G.B.) Ltd., Bir - ment ) Ltd., Whetstone , Leicester, for inclusion in Bakelite Resins mingham. ] th e trade catalogue section of thei r Library. [Bakelite Ltd., London.] 12 2 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

The Importance of Attention to Jig Details

Aircraft Engineering and Aerospace Technology , Volume 17 (4): 1 – Apr 1, 1945

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Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb031243
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Abstract

Workshop and Production Section AIRCRAFT ENGINEERIN G April, 1945 By H. Moore INC E th e design of drill jigs permits the adop ­ particula r spindle. Anything, wood or shee t metal, word : try your own hand on them, not for a second, bu t for a full five minutes, an d see where it tion of an almost unlimited range of new ideas mad e to a channel iron shape will do a s well if th e hurt s th e most. it is curiou s t o not e th e lack of originality in th e real thing is no t available. It is possible, also, t o Th e smallest of all jig details is th e pin . Dealing minor components. Most of the common acces­ provide small shelves for th e bushings , attached to sories—clamps, screws, pins , bushings an d th e like — th e spindle heads just above the pinion shafts. only with th e locatin g variet y we find i t place d often hav e remained unaltered for years . And yet , in all This is bette r even than channel iron, bu t i t usually where i t i s mos t difficult to see . It migh t b e argued of them , there is som e room for improvement . It is costs more t o produce . A good typ e of spindl e shelf tha t th e shap e of th e wor k determines th e position tru e that the measur e of possible improvement is can be mad e of shee t metal, bu t in it s improvized of th e pin . But ofte n it is only too plai n tha t th e no t great; often it is merely a pin here, a screw form it is jus t th e lid of a tin held t o th e castin g b y a moving of th e wor k around would re-position th e there, an alteration of a n existing part, or perhaps small screw. After all, it is th e position of th e shelf pins in a bette r way. Not nearl y enough thought is only a rearrangemen t of some of th e parts . But all tha t is important , not it s materia l or shape . given to thi s aspect of jig work . The troubl e ap ­ thes e changes are withi n the scope of th e operator pear s t o lie in th e inabilit y of th e ji g make r t o mul­ Turnin g now for a moment to screws. It is a himself; he shoul d not wait for th e jig produce r t o tiply b y thousands . It might b e eas y t o place on e matte r for surpris e tha t th e slotte d variety continues furnish him with ideas. As a matte r of fact, if an y to b e used on jig wor k when there ar e so man y really piece in a jig i n a good light—and most tool rooms ar e better lighted than th e shops—bu t t o repea t th e little defect is allowed to continue unchecked it is good types of safety screws on th e market . The performance a thousand times in a poorer light is th e fault, no t of th e producer , bu t of th e ji g operator slotted screw is th e sourc e of on e of th e few dangers somethin g entirely different. It is sometimes pos­ who, because h e is using th e jig in actua l practice, of jig operation. The real danger, of course, lies in is in th e bette r position to see wher e it is wrong. sible, however, to obtain a slight alleviation by th e screw driver which so often slips off th e screw At any rate, as far a s th e presen t writer can ascer­ drilling a hole in th e wall of th e ji g t o ligh t u p th e and lacerates th e han d of th e perso n holding th e jig. tain , nothing on thi s subject has ever before been obscure pin . Wheneve r these screws are i n a jig, and canno t for published from th e ji g producin g end. It remains, any reason be changed , they should be rendere d as Althoug h cutting tools ar e no t strictl y speaking jig therefore, for someone at th e other end—the jig harmless as possible. Grinding a portion off th e details they cannot entirely be excluded from th e operatin g end—to point out som e of th e defect s of end until th e head is well below th e surface reduces argument . There are a few ne w thing s to b e said. small accessories an d ho w t o correct them. These th e danger. Deepening the slot to twice or three Counterbores and facing tools, for example , usually notes, althoug h the y chiefly concern th e operator , ar e time s its norma l depth and grinding th e screwdriver carr y a collar or lock-nuts as stops. The overall directed to th e produce r as well, because many of to fit actuall y t o th e botto m is also a good safeguard. dimension t o whic h these mus t be se t is stampe d on th e ideas t o b e mentione d could well b e incorporated An additional precaution is the rounding off a pad in th e ji g nea r th e hol e in which the y are used. in th e ji g before it is delivere d to th e shop . smoothl y of all th e shar p edges on th e screwdriver This dimension is always given in decimal figures, blade. There will b e muc h less danger of it s cutting which are liabl e to accidental alteration. A slight Th e loose bus h tha t fits into th e liner bush in th e the n and a screwdriver with rounded edges fits into knock in th e righ t place and th e figure one becomes jig body is a n excellent example of a component a screw slot more readily than without. a seven, a nought becomes a nine an d so on . Any­ which never alters bu t which is, nevertheless , cap­ one experiencing trouble from this cause should mill abl e of minor improvements. For instance, it is Ho w th e usefulness of a component may b e in­ difficult to understand why drill and reame r loose th e figures off an d replace the m with letters. When creased b y a simple alteration of a n existin g par t is bushes are alway s made with only th e letterin g on 1.315 becomes "one point three one five" there is bes t illustrated by th e sprin g lifted slotted clamp. th e top t o identify them; when a groove in th e little chance of erro r from accidental cause. This clamp is used th e world over. It is a flat piece middle of th e reame r bushing head would reveal it s Th e setting of tape r reamers is alway s a delicate of steel with a long slot in th e middl e through which description at a glance. An error of really long jo b when the machine stop is used. Fortunately, th e tightening bolt passes an d underneat h which, on standin g concerns the loose bush that projects a ther e is usually some par t of th e ji g wher e it is pos­ th e bolt, is a spiral spring. Now th e function of thi s considerable distance inside th e jig . It is because spring from time immemorial has been solely to sible t o mak e a tes t hole—mostly in th e feet. With this projecting par t is no t left small tha t th e operato r lift the clamp clear of th e work when the, bolt is a taper hole th e correct depth in th e ji g itself there is compelled to exhaus t himself twisting tight bush­ loosened. But th e operator has still t o pull th e is no difficulty in setting the reame r either to th e ings all th e wa y dow n and out . Small bushings ar e clamp back t o th e en d of th e slo t before he ca n re­ machine stop or t o a collar on th e reamer itself. th e cause of muc h needless exertion. It is a mistake move th e work—an d often there are a dozen of thes e Many operators find it har d to se t a countersin k in a t o mak e th e head s of smal l bushings proportionately clamps on one jig. Yet, i t require s only a small hole jig. The simplest and sures t way is t o us e a steel small merely because they look nice. They should in the jig near the bolt and a similar one in th e block with th e requisite countersinks in i t th e same be large—even to th e point of ugliness—and the underside of th e clamp , into which th e end s of th e height from the tabl e as thos e in th e wor k when it knurling made a s roughl y as possible to enable th e spiral spring, after giving it a twist, are inserted; is in th e jig . The block, of course, is kep t always operato r to ge t a good grip. in th e sam e box a s th e jig . The reamin g of blind an d th e sam e spring not only lifts th e work , bu t also holes in cas t iron calls for mentio n here because it is I t is, however, in th e dispositio n and th e handling pulls it back out of th e way . It should be pointe d one of th e job s tha t causes difficulties far ou t of pro ­ of loose bushings tha t most of th e scope for improve ­ ou t here that a spring tha t fits th e bolt too closely canno t be used for thi s dual purpose. portion to their apparent simplicity. The troubl e men t lies. Some jigs have two dozen or mor e an d is tha t the reamin g cannot be done until the drill much of th e cost of productio n will depend on how Nex t to th e slotted clamp, probably the best cutting s have been removed from the hole. This is thes e are handled . The ide a behind all loose bush­ known of all clampin g devices is th e ji g leaf. The effected on small jigs b y turnin g them over t o allow ing arrangements is, of course, to provid e a known screw used for tightenin g this has a flat head equal th e cuttings to fall out. But quit e a jarring effect place for each of the m and so t o ensur e tha t th e on e in width to th e slot in the leaf. By giving it a is needed in addition . For thi s reason it i s bette r t o needed shall be th e one alway s nearest to hand. quarte r tur n back th e slot i n th e leaf will pas s over it ; If th e bushings ar e few an d on e only used with each drill all th e holes first. This necessitates' turning a quarter turn forward and i t will be locked. The tool a mix-u p can b e avoide d by leaving th e bushing th e jig over to reach the various holes and this screw is moved with a spanner and it is almost on its respective tool in the revolving spindle. movement, together with the vibration caused b y impossible t o sto p th e loosening movement with th e Slightly knurling th e shan k of th e drill or reamer th e drilling, effectually clears th e cutting s from all screw head exactly in line with the slot. Usually th e holes. will enlarge it enough to preven t th e bushing s from it goes past and ha s t o b e turne d back. To force falling off. Sometimes th e shap e of th e jig permit s th e head to stop in th e righ t place it is necessary Ther e is much more to be said but within th e th e drilling of a rough hole, a t each side of th e real only to pu t a pin in th e leaf close t o th e slot . Thus limits of a shor t article i t is possibl e t o mentio n none hole, into which the bushings can b e placed each simply can a n annoyance be ended—yet one ma y bu t the best known and most used components. tim e after use. Naturally, the difficulty of th e look a long time before one sees a stop pin in a ji g And even thes e mus t b e touche d on bu t lightly . The orderly arrangement of bushings increases with th e leaf. Before leaving this jig ther e is a detai l a t th e essential purpose, however, is t o point out tha t a numbe r used with th e jig. It makes n o difference othe r end tha t should receive some mention. It is proper attention to detail s is no t only desirable bu t how carefully these are arranged on th e dril l table ; th e handle designed to resis t th e torqu e of th e drill. imperativ e if th e fullest possible advantage is t o b e the y are alway s liable t o b e swep t off wit h th e cut ­ Sometimes it bear s a slight resemblance t o a handle, gained from their use. The perfect drill jig is th e tings or displaced by th e movemen t of th e jig . A often it is jus t a straight , flat piece of metal . It is a one that can b e operate d with the leas t amount of length of channe l iron—two inch will do—laid across mistak e t o thin k tha t th e shap e of thi s handle is no t effort and th e fewest number of movements. The th e table a t th e bac k will provide a n excellen t place important . Anyone who has held one for an y adoption of any of the ideas which have been for the bushings used on a six spindle drilling lengt h of tim e against th e torqu e of a dragging drill- described here will contribute helpfully towards machine. In this is laid, behind each of th e will agree tha t few thing s can b e mor e tiring. To makin g jig wor k easier and mor e profitable than it spindles, th e bushings used with the tool in that all those engaged in th e manufactur e of ji g handle s a ha s ever been before. "Euco" Giant Blue Print Wall Chart of Free­ Trade Catalogues Wanted Trade Publications Received man's Screw Thread and Engineering Tables. Magneto Testing Equipment Any firms interested and associated in th e pro­ [Euc o Tool s Ltd. , London . 10s. 6d. ] Engine Starter Test Equipment duction of machin e tools, factory plant and equip ­ ment , physical and chemical laboratory equipment, [Cit y Electrical Co., London. ] "Compo" Oil Retaining Bearings electrical equipment, switch gear, motors, trans­ 'Sieray' "Warm White" Fluorescent Lamps, "Bound Brook" Graphited Bronze Bearings . formers, generators, etc., hydraulic pumps, air [Siemens Electric Lamps and Supplies Ltd. , compressors, etc. , wh o ar e willing t o deposi t a copy London.] "Ferrocile" (Powder Metallurgy) Iron Valve of their latest catalogues are asked t o sen d the m t o Scrivener Centreless Grinding Machine No. 2 . Guides th e Librarian, Power Jets (Research and Develop­ [Arthu r Scrivener Ltd., Birmingham.] [Boun d Brook Bearings (G.B.) Ltd., Bir - ment ) Ltd., Whetstone , Leicester, for inclusion in Bakelite Resins mingham. ] th e trade catalogue section of thei r Library. [Bakelite Ltd., London.] 12 2

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Apr 1, 1945

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