157:
149:
190:
the tumbler is nearly centered, it slips into the receiving hole in the hammer mass, and releases the hammer. The hammer mass is then allowed to move forward, propelled by the rear spring. Because the hole in the hammer mass does not go through the mass and is less deep than the end section of the tumbler, the tip of the tumbler bottoms out in the hole in the hammer, and the impulse of the hammer mass is transmitted through the tumbler, through the punch, and to the workpiece.
204:
182:. (The spring's preload compression can usually be adjusted by loosening or tightening the end cap at the back-most portion of the punch, to decrease or increase the force of the punch.) A stopped hole drilled in the front center portion of the hammer mass facing the tumbler acts as a receiver for the rod, and as an anvil for the punch action.
17:
65:
provide the striking impulse. A number of patents have been issued for these designs, and they continue to be referenced in patents into the 21st century. There are also a number of examples of hammer and punch combinations intended for one-handed use, but being modeled upon a conventional hammer striking a separate punch tool.
189:
As the punch is further pressed against the workpiece, the tumbler travels back until the point where its tapered midsection begins contacting the surface of the guide hole in the body of the punch. As it continues back, it is pushed into alignment with the center axis of the tool. When the tip of
80:
The Sweet patent of 1942 is the first description of the most manufactured trigger type in the later 20th century, using a tilted intermediate pin to hold back the hammer until the main spring is compressed. This design is referenced by a large number of other patents, and was the basis for the Frey
76:
Some of the modifications introduced in the Seiler patent of 1923 saw substantial manufacture in the United States, and this patent has been referenced by other patents into the 21st century. This design uses a sliding block similar in concept to the Adell and
Starrett patent, but with a coil spring
215:
This mechanism is used in heavy duty punches as it is less likely to bind on reset than the Sweet mechanism, it doesn't tend to wear the inside of the body as much as the Sweet mechanism and, because the end of the hammer can be used to provide impact on a larger area of the punch tip, reduces the
185:
The tumbler provides the automation. When reset, a provision is made such that the tumbler rod is cocked slightly, so that its resting position is skewed and the tip contacts the hammer mass on the face of the hammer slightly offset to the hole. This is commonly done by using a special bent end on
68:
The earliest US patents for the modern automatic center punch were filed during 1904 by
Hartley and Stryhal for designs using a leaf spring catch to release the hammer, both assigned to Brown and Sharpe. In 1905, Seitz patented a manually triggered punch that has many of the internal structural
64:
A number of designs for automatic center punches have been developed since the late 19th century as improvements over punches requiring the use of a striking tool. The earliest types were not fully automatic, using a captive weight lifted by the user or a spring and weight drawn by the user to
211:
The Adell and
Starrett mechanism uses a sliding block crosswise through the hammer rather than an intermediate pin. The hammer has a hole through its center that the top of the punch sits in, and holds the top of the punch centered. The sliding block has a hole through it that, when reset, is
72:
Adell and
Baltzer, of L. S Starrett Co., patented a design with concentric shells and pins in cam slots as the triggering mechanism, and Adell and Starrett received a 1907 patent for a design using a sliding block actuated by a tapered bore in the body to hold back the hammer.
69:
elements of some later fully automatic models, and
Spalding was granted a patent in 1908 on an application filed in 1904 for a different design of leaf spring controlled fully automatic punch that included easy adjustment of blow as well as interchangeable, threaded on points.
224:
The Frey mechanism uses a steel ball and an out-of-flat end for the intermediate pin to force the intermediate pin to cock at reset. This means the intermediate spring doesn't need a special end, but the high stresses at the contact with the steel ball can lead to
60:
The patent history of automatic punches indicates two principal goals for the development of the tool: repeatability of impact, and convenience of operation. Other desirable properties include low recoil when triggered, ease of adjustment, and reliability.
212:
misaligned with the hole through the hammer. When the body is pressed to the trip point, a taper in the body forces the block sideways until the hole in the block is aligned with the hole through the hammer, and the hammer is released to strike the punch.
186:
the tumbler spring or using an out-of-flat face on the bottom end of the pin or top of the punch. It bears on the hammer mass and pushes it back against its spring as the punch is pressed, storing energy in the hammer spring.
216:
stress on the material. The primary disadvantages are that there are more parts than in the Sweet design, and that both the hammer and the block require manufacturing other than on a lathe.
90:
A variety of other mechanisms also exist and have been used, including cam based, ball bearings trapped in a sliding collar, and bidirectional mechanisms that take pulling attachments.
84:
There are a variety of other mechanisms used, of varying complexity and reliability, some of which have been patented or had patent applied for into the 21st century.
207:
Operation of Adell & Starrett patent US843655 simplified in cross section with springs not shown. Green is punch, red is hammer, and blue is trigger slide block.
52:
that drives the punch, producing the dimple. The impulse provided to the point of the punch is quite repeatable, allowing for uniform impressions to be made.
118:
In many applications, such as hardness testing, the mechanism does not have an adjustment for impulse strength, and may require periodic calibration checks.
587:
426:
483:
465:
447:
164:
The most common mechanism is based upon the Sweet patent. Within the body of the punch, there are three principal moving parts arranged in line:
549:
81:
patent of 1965, which was intended to improve the reliability of the device resetting. This design has also seen substantial manufacture.
957:
87:
Better quality modern designs tend to follow on Sweet's patent or Frey's patent, though some are based on the Adell and
Starrett design.
980:
1615:
1625:
580:
77:
to return the sliding block rather than a leaf spring, but a more involved scheme to slide the block to release the hammer.
1228:
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647:
36:
used to produce a dimple in a workpiece (for example, a piece of metal). It performs the same function as an ordinary
573:
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1667:
498:
705:
535:
98:
The automatic center punch mechanism has been used for a wide variety of other applications. These include
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A release mechanism that releases the stored energy at a consistent point in the travel of the body
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Marking and starting a hole for drilling without the bit "walking" out of alignment
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Glass-breaking tools used in rescue work and a common tool for a car thief.
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The hammer mass is spring-loaded from the back of the punch by a large
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of the intermediate pin end or the top of the punch by the ball.
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424:
General 70079 Center Punch manual retrieved 2013aug8
143:
481:General 78 Center Punch manual retrieved 2013aug8
463:General 77 Center Punch manual retrieved 2013aug8
445:General 87 Center Punch manual retrieved 2013aug8
1654:
419:
417:
160:Operation of Sweet patent automatic center punch
44:. When pressed against the workpiece, it stores
238:
139:A provision to reset the device after actuation
1222:
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152:Animation of automatic center punch operation
126:All designs have several elements in common:
260:
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48:in a spring, eventually releasing it as an
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499:PTC316 hardness tester retrieved 2013aug8
392:
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133:A mass to provide the impulse (a hammer)
15:
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1210:
569:
531:
114:Pin presses for electronic assembly
13:
121:
14:
1679:
557:
111:Impact tool for hardness testing
144:Typical Mechanism and Operation
93:
1236:
219:
171:The intermediate rod (tumbler)
1:
232:
24:of an automatic center punch
7:
366:Adell and Starrett US843655
40:but without the need for a
10:
1684:
933:Magnetic switchable device
355:Adell and Baltzer US789520
55:
1575:
1267:
1244:
1151:
1094:
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883:
785:
734:
646:
603:
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1616:Machine and metalworking
1547:Tongue-and-groove pliers
174:The hammer (hammer mass)
130:A spring to store energy
1668:Metalworking hand tools
1626:Measuring and alignment
991:Engineer's spirit level
194:Other common mechanisms
706:Oxy-fuel cutting torch
486:April 6, 2013, at the
468:April 6, 2013, at the
450:April 6, 2013, at the
429:April 6, 2013, at the
208:
161:
153:
30:automatic center punch
25:
1191:Tools and terminology
958:Measuring instruments
206:
159:
151:
19:
1591:Cutting and abrasive
245:Geisenhoner US833712
199:Adell & Starrett
278:Berninger US2602360
1272:Adjustable spanner
1081:Thread pitch gauge
1046:Optical comparator
800:Combination square
597:Metalworking tools
410:Utz US2004/0154171
267:Williams US1458961
256:Ainsworth US913677
209:
162:
154:
26:
1650:
1649:
1562:Upholstery hammer
1204:
1203:
1147:
1146:
344:Spalding US889409
300:Komatar US1341373
105:Letter stamp sets
1675:
1437:Pencil sharpener
1231:
1224:
1217:
1208:
1207:
1021:Machinist square
830:Needlegun scaler
825:Machinist square
638:Water jet cutter
605:Cutting machines
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521:Morgan US4577400
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377:Seiler US1572046
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1487:Punch down tool
1467:Plumber's snake
1263:
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1090:
986:Engineer's blue
952:
885:Machine tooling
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757:Hydraulic press
730:
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388:Sweet US2384707
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122:Common elements
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1581:Types of tools
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1537:Tactical light
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1514:
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1489:
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1479:
1477:Podger spanner
1474:
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1462:Plumber wrench
1459:
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1392:Locking pliers
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1011:Go/no go gauge
1008:
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777:Stamping press
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391:
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1553:
1552:Torque wrench
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1527:Stitching awl
1525:
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1512:Socket wrench
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1442:Persian drill
1440:
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1428:
1425:
1423:
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1413:
1412:Monkey wrench
1410:
1408:
1405:
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1398:
1395:
1393:
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1383:
1382:Impact driver
1380:
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1375:
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1370:
1368:
1365:
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1360:
1358:
1357:Hammer tacker
1355:
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1342:Glass breaker
1340:
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1277:Antique tools
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1086:Vernier scale
1084:
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1071:Surface plate
1069:
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1034:
1032:
1031:Marking gauge
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913:Indexing head
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762:Machine press
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752:English wheel
750:
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743:
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735:Forming tools
733:
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648:Cutting tools
645:
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564:
560:
553:
548:
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541:
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489:
485:
482:
477:
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70:
66:
62:
53:
51:
47:
43:
39:
35:
31:
23:
22:exploded view
18:
1532:Strap wrench
1507:Slide hammer
1502:Sledgehammer
1427:Paint roller
1312:Caulking gun
1282:Basin wrench
1129:Steam hammer
1076:Tape measure
1066:Straightedge
1051:Radius gauge
1026:Marking blue
1016:Height gauge
996:Feeler gauge
976:Center gauge
943:Rotary table
923:Lathe center
835:Piercing saw
820:Hand scraper
691:Hand scraper
559:Metalworking
516:
505:
494:
476:
458:
405:
394:
383:
372:
361:
350:
339:
328:
317:
306:
295:
284:
273:
262:
251:
240:
223:
214:
210:
188:
184:
177:
163:
125:
117:
97:
94:Applications
89:
86:
83:
79:
75:
71:
67:
63:
59:
38:center punch
29:
27:
1641:Woodworking
1497:Screwdriver
1492:Scratch awl
1452:Pipe wrench
1302:Breaker bar
1287:Block plane
1161:Fabrication
1139:Trip hammer
1134:Swage block
1119:Hardy tools
1036:Marking out
1006:Gauge block
893:Angle plate
855:Tap and die
772:Screw press
767:Punch press
721:Tipped tool
676:Countersink
671:Counterbore
220:Frey (1963)
1663:Hand tools
1657:Categories
1522:Staple gun
1517:Spike maul
1432:Paintbrush
1422:Nut driver
1417:Multi-tool
1397:Lug wrench
1377:Hole punch
1347:Grease gun
1238:Hand tools
1181:Metallurgy
1041:Micrometer
966:Bore gauge
787:Hand tools
233:References
227:brinelling
1542:Tire iron
1407:Mitre box
1332:Fish tape
1307:Cat's paw
1259:Workbench
1176:Machining
1171:Jewellery
870:Workbench
805:Drift pin
628:Miter saw
168:The punch
34:hand tool
1596:Forestry
1586:Cleaning
1557:Tweezers
1367:Headlamp
1249:Sawhorse
1186:Smithing
1124:Pritchel
1061:Sine bar
726:Tool bit
681:End mill
618:Cold saw
484:Archived
466:Archived
448:Archived
427:Archived
1621:Masonry
1611:Kitchen
1472:Plunger
1447:Pincers
1372:Hex key
1327:Crowbar
1322:Crimper
1297:Bradawl
1254:Toolbox
1196:Welding
1166:Forming
1156:Casting
971:Caliper
948:Wiggler
938:Mandrel
908:Fixture
850:Scriber
810:Hacksaw
701:Nibbler
613:Bandsaw
56:History
50:impulse
1631:Mining
1601:Garden
1567:Wrench
1457:Pliers
1402:Mallet
1352:Hammer
1337:Gimlet
1114:Fuller
903:Collet
875:Wrench
840:Pliers
815:Hammer
716:Shears
711:Reamer
666:Chisel
656:Broach
633:Plasma
180:spring
46:energy
42:hammer
1636:Power
1482:Punch
1317:Clamp
1292:Brace
1109:Forge
1104:Anvil
1056:Ruler
1001:Gauge
898:Chuck
860:Tongs
845:Punch
795:Clamp
742:Brake
623:Laser
32:is a
1606:Hand
1387:Jack
1362:Hawk
865:Vise
686:File
661:Burr
918:Jig
747:Die
28:An
20:An
1659::
437:^
416:^
1230:e
1223:t
1216:v
589:e
582:t
575:v
551:e
544:t
537:v
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