181:, which is a collar that is pressed over the head of the bushing and has a long tail. The tail may be bent at the end so it can lock around the edge of the jig plate or it may be left straight if it can butt up against another object. Another option to keep the renewable bushing from rotating is to pin it, either by putting a pin in the renewable bushing and a hole in the liner or vice versa. A more complicated version uses a hole in the bushing collar and a pin with a head; the head on the pin holds the edge of the collar down, but for removal the bushing can be rotated so that the hole lines up with the pin.
126:
169:
606:
134:
82:
613:
A common problem encountered is when two or more holes are too close for independent standard bushings. In this case one large renewable bushing can be made with two (or more) holes in the proper location (the first example in the image). Another possibility is to make a custom bushing with an
141:
Renewable bushings are installed in liner bushings. This type of bushing is used in large production runs where a bushing will wear out over time or when multiple renewable bushings are used in one liner to provide various sized holes. There are two types of renewable bushings:
176:
Renewable bushings must be secured in their liner bushing, otherwise the tool can cause it to spin, which rapidly wears out the liner, or chips can force the bushing out of the liner. There are many different types of locking systems for renewable bushings. One system is a
618:
hole and then notches on the outside of the head are used to locate the proper position of the bushing for each location (the middle example in the image). Another common need for a custom bushing is when the hole needed is perpendicular jig plate; in this case a
289:
inch (7.94 mm, 9.53 mm, 12.7 mm, 19.05 mm, 25.4 mm, 34.93 mm and 44.45 mm). The letter "U" is used after the OD number to designate that extra stock should be left on the OD for
85:
Types of drilling bushings: A. Headless wearing press-fit bushing B. Head wearing press-fit bushing C. Headless liner bushing with renewable bushing D. Head liner bushing with renewable bushing
137:
Four types of dogs. Key (A) shows how the end of the dog can be bent down to wrap around the edge of the jig plate; key (B) shows how a pin can be used to keep the dog from rotating.
113:, are permanently installed into the jig and accept liners that can easily be replaced. Press-fit wearing bushings are used in short run applications or in applications where the
157:
with a given sized liner so that two different sized slip renewable bushings can be used in one liner bushing. This facilitates the ability to do multiple
153:
Fixed renewable bushings are used in applications where the liner is meant to be used until it wears out. Slip renewable bushings are designed to be
776:
62:
73:
bushings are standardized via ASME B94.33.1. There are over 50,000 standard configurations of customary sized bushings.
795:
291:
161:
operations that require different inner diameter (ID) bushings, such as drilling and reaming. They usually have
97:
bushings. Other classification methods include by head type, by use, and by liner type (or lack thereof).
129:
Four features that can be incorporated into small renewable bushings for easy removal with a screwdriver.
615:
197:
Where the ID is specified as a decimal, drill letter size, drill number size, or fraction; the OD is an
154:
114:
707:
221:
th of an inch. The lengths of press-fit bushings are standardized to typical jig plate thicknesses:
125:
168:
772:
211:
th of an inch (0.40 mm); the length is an integer that relates to a multiple of a
605:
789:
117:
on a hole location is so tight that it cannot facilitate the use of a liner bushing.
70:
81:
39:
32:
133:
766:
755:
639:
In general, a drill bushing's length should be at least 2 times the nominal ID.
51:
47:
35:
628:
158:
43:
189:
Customary bushings are specified using the following specification layout:
198:
162:
58:. They are designed to guide, position, and support the cutting tool.
55:
708:
http://catalog.asme.org/Codes/PrintBook/B94331_1998_Jig_Bushings.cfm
624:
604:
167:
132:
124:
80:
335:
The following two tables give the tolerances for the ID and OD.
66:
46:. Other tools that are commonly used in a drill bushing include
28:
105:
Press fit are available in two types with liners or without (
623:
is used. It is a hardened piece of right angle steel that
294:
to size. The type is a letter referring to the following:
754:Colvin, Fred Herbert; Haas, Lucian Levant (1922),
609:Three more common types of custom drill bushings
89:Drill bushings can generally be classified as:
721:
719:
717:
715:
691:
689:
687:
685:
683:
681:
668:
666:
664:
8:
109:bushings). Liner bushings, sometimes called
737:
655:
172:Various methods to lock renewable bushings
725:
695:
672:
760:(2nd ed.), McGraw-Hill, p. 44.
456:
337:
648:
627:to the jig plate and is located with
165:heads so they can be easily removed.
7:
14:
201:that relates to a multiple of a
65:bushings are standardized via
1:
768:Jig and fixture design manual
765:Henriksen, Erik Karl (1973),
812:
771:, Industrial Press Inc.,
458:OD grinding tolerances
738:Colvin & Haas 1922
656:Colvin & Haas 1922
610:
173:
138:
130:
86:
608:
171:
136:
128:
84:
325:- Headless press-fit
459:
413:19.05–38.10 mm
340:
796:Metalworking tools
740:, pp. 45, 47.
611:
457:
390:6.35–19.05 mm
387:0.25–0.75 in
338:
174:
139:
131:
121:Renewable bushings
101:Press-fit bushings
87:
23:, also known as a
778:978-0-8311-1098-7
757:Jigs and fixtures
598:
597:
547:7.94–5.16 mm
505:3.97–6.35 mm
455:
454:
410:0.75–1.5 in
367:0.00–6.35 mm
307:- Fixed renewable
193:ID-Type-OD-Length
16:Metalworking tool
803:
782:
761:
741:
735:
729:
723:
710:
705:
699:
693:
676:
670:
659:
653:
575:
574:
570:
543:
542:
538:
533:
532:
528:
501:
500:
496:
491:
490:
486:
460:
451:0.00762 mm
428:0.00508 mm
405:0.00254 mm
382:0.00254 mm
341:
331:- Head press-fit
313:- Headless liner
301:- Slip renewable
288:
287:
283:
280:
274:
273:
269:
266:
260:
259:
255:
250:
249:
245:
240:
239:
235:
230:
229:
225:
220:
219:
215:
210:
209:
205:
42:, most commonly
811:
810:
806:
805:
804:
802:
801:
800:
786:
785:
779:
764:
753:
750:
745:
744:
736:
732:
724:
713:
706:
702:
694:
679:
671:
662:
654:
650:
645:
637:
621:bracket bushing
603:
601:Custom bushings
572:
568:
567:
540:
536:
535:
530:
526:
525:
498:
494:
493:
488:
484:
483:
448:0.0003 in
445:0.01778 mm
442:0.0007 in
425:0.0002 in
422:0.01524 mm
419:0.0006 in
402:0.0001 in
396:0.0005 in
379:0.0001 in
376:0.01016 mm
373:0.0004 in
364:0–0.25 in
285:
281:
278:
276:
271:
267:
264:
262:
257:
253:
252:
247:
243:
242:
237:
233:
232:
227:
223:
222:
217:
213:
212:
207:
203:
202:
187:
155:interchangeable
123:
111:master bushings
103:
79:
63:Customary sized
17:
12:
11:
5:
809:
807:
799:
798:
788:
787:
784:
783:
777:
762:
749:
746:
743:
742:
730:
728:, p. 156.
726:Henriksen 1973
711:
700:
698:, p. 155.
696:Henriksen 1973
677:
675:, p. 154.
673:Henriksen 1973
660:
647:
646:
644:
641:
636:
633:
602:
599:
596:
595:
594:0.508 mm
592:
591:0.020 in
589:
586:
585:0.015 in
583:
580:
577:
564:
563:
562:0.381 mm
560:
559:0.015 in
557:
554:
553:0.010 in
551:
548:
545:
522:
521:
520:0.254 mm
518:
517:0.010 in
515:
512:
511:0.005 in
509:
506:
503:
480:
479:
477:
474:
472:
469:
466:
464:
453:
452:
449:
446:
443:
440:
437:
434:
430:
429:
426:
423:
420:
417:
414:
411:
407:
406:
403:
400:
399:0.0127 mm
397:
394:
391:
388:
384:
383:
380:
377:
374:
371:
368:
365:
361:
360:
358:
355:
353:
350:
347:
345:
339:ID tolerances
333:
332:
326:
320:
314:
308:
302:
195:
194:
186:
183:
122:
119:
102:
99:
78:
75:
15:
13:
10:
9:
6:
4:
3:
2:
808:
797:
794:
793:
791:
780:
774:
770:
769:
763:
759:
758:
752:
751:
747:
739:
734:
731:
727:
722:
720:
718:
716:
712:
709:
704:
701:
697:
692:
690:
688:
686:
684:
682:
678:
674:
669:
667:
665:
661:
658:, p. 44.
657:
652:
649:
642:
640:
634:
632:
630:
626:
622:
617:
607:
600:
593:
590:
588:0.381 mm
587:
584:
581:
578:
566:
565:
561:
558:
556:0.254 mm
555:
552:
549:
546:
524:
523:
519:
516:
514:0.127 mm
513:
510:
507:
504:
482:
481:
478:
475:
473:
470:
467:
465:
462:
461:
450:
447:
444:
441:
438:
435:
432:
431:
427:
424:
421:
418:
415:
412:
409:
408:
404:
401:
398:
395:
392:
389:
386:
385:
381:
378:
375:
372:
369:
366:
363:
362:
359:
356:
354:
351:
348:
346:
343:
342:
336:
330:
327:
324:
321:
318:
315:
312:
309:
306:
303:
300:
297:
296:
295:
293:
200:
192:
191:
190:
185:Specification
184:
182:
180:
170:
166:
164:
160:
156:
151:
149:
145:
135:
127:
120:
118:
116:
112:
108:
100:
98:
96:
92:
83:
76:
74:
72:
68:
64:
59:
57:
53:
49:
45:
41:
40:cutting tools
37:
34:
30:
26:
22:
21:drill bushing
767:
756:
748:Bibliography
733:
703:
651:
638:
620:
612:
582:Greater than
579:12.7 mm
439:Greater than
436:38.1 mm
433:1.5 in
334:
328:
322:
319:- Head liner
316:
310:
304:
298:
196:
188:
178:
175:
152:
147:
143:
140:
110:
106:
104:
94:
93:bushings or
90:
88:
61:In the USA,
60:
52:countersinks
48:counterbores
33:metalworking
24:
20:
18:
463:Nominal OD
344:Nominal ID
69:B94.33 and
25:jig bushing
643:References
629:dowel pins
44:drill bits
616:eccentric
576: in
544: in
502: in
370:including
159:machining
115:tolerance
95:renewable
91:press fit
38:to guide
790:Category
476:Minimum
471:Maximum
357:Minimum
352:Maximum
292:grinding
31:used in
571:⁄
539:⁄
529:⁄
497:⁄
487:⁄
284:⁄
275:, and
270:⁄
256:⁄
246:⁄
236:⁄
226:⁄
216:⁄
206:⁄
199:integer
163:knurled
107:wearing
56:reamers
27:, is a
775:
635:Design
625:screws
261:, 1 ,
71:metric
54:, and
416:incl.
393:incl.
144:fixed
77:Types
773:ISBN
148:slip
146:and
67:ASME
36:jigs
29:tool
179:dog
792::
714:^
680:^
663:^
631:.
541:64
537:13
531:16
489:32
317:HL
251:,
241:,
231:,
228:16
218:16
208:64
150:.
50:,
19:A
781:.
573:2
569:1
550:_
534:–
527:5
508:_
499:4
495:1
492:–
485:5
468:_
349:_
329:H
323:P
311:L
305:F
299:S
286:4
282:3
279:+
277:1
272:8
268:3
265:+
263:1
258:4
254:3
248:2
244:1
238:8
234:3
224:5
214:1
204:1
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