US2978084A - Safety interlock - Google Patents

Safety interlock Download PDF

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Publication number
US2978084A
US2978084A US768594A US76859458A US2978084A US 2978084 A US2978084 A US 2978084A US 768594 A US768594 A US 768594A US 76859458 A US76859458 A US 76859458A US 2978084 A US2978084 A US 2978084A
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electrodes
operator
safety
operation
machine
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Expired - Lifetime
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US768594A
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Hugo L Vilkaitis
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SAFEGUARD Manufacturing CO
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SAFEGUARD Manufacturing CO
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Priority to US768594A priority Critical patent/US2978084A/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16PSAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
    • F16P3/00Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
    • F16P3/02Screens or other safety members moving in synchronism with members which move to and fro
    • F16P3/04Screens or other safety members moving in synchronism with members which move to and fro for machines with parts which approach one another during operation, e.g. for stamping presses
    • F16P3/06Screens or other safety members moving in synchronism with members which move to and fro for machines with parts which approach one another during operation, e.g. for stamping presses in which body parts of the operator are removed from the danger zone on approach of the machine parts

Description

April 1961 H. L. VILKAITIS 2,978,034

SAFETY INTERLOCK Filed Oct. 21, 1958 FIG. I

" INVENTOR.

3 HUGO L. V/L m4 lT/S I /6 a7 33 ATTORNEYS United States Patent SAFETY INTERLOCK Hugo L. Vilkaitis, Thomaston, Conn., assignor to Safeguard Manufacturing Company, Woodbury, Conn., a corporation of Connecticut Filed Oct. 21, 1958, Ser. No. 768,594

Claims. (Cl. 192-131) This invention relates to safety devices which control the operation of a machine and more particularly to a safety interlock requiring the presence of the operator or a portion of the operators body in a specific place before the machine can be operated.

It is an object of this invention to provide a safety interlock which is responsive to direct contact with the human skin to control the operation of a machine.

It is a further object of this invention to provide a reliable safety interlock that utilizes the operators body as part of an electrical circuit that controls the operation ofa machine and to do so in such a way as to avoid discomfort and possible injury to the operator by its use.

It is a still further object to provide a safety device which is inexpensive to manufacture, extremely reliable and foolproof in operation.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. l is a schematic side view of a press utilizing a preferred embodiment of this invention;

Fig. 2 is a perspective view of a pair of wristlets usable with the preferred embodiment;

Fig. 3 is a perspective view showing an alternate embodiment of a wristlet usable with this invention; and

Fig. 4 is a block diagram of an' electrical circuit usable with this invention.

Referring now to Fig. 1, it is seen that a punch press generally designated as 1 is provided with a poweroperated reciprocating slide 2 which engages a workpiece (not shown) on table 3 when the operator depresses treadle 4 to actuate the drive mechanism. Support pedestal 5 is mounted in front of press 1 and is provided with inwardly extending arm 6 which pivotally supports lever 7 at point 8. Lever 7 is pivotally connected to slide 2 by link 9 at one end and is secured to steel cables 10 and 11 at its other end so that depression of slide 2 pivots member 7 upwardly to draw cables 10 and 11 away from the punch press. Under normal conditions, wristlets 12 and 13 are secured to cables 10 and 11 and are firmly strapped on the wrist of the operator so that depression of treadle 4' operates slide 2 to forcibly withdraw the hands of the operator from the work area in the event that the operator himself fails to do so.

This safety system suffers from the difiiculty that the operator can merely fail" to wear the wristlets, thereby defeating the safety features of the machine while subjecting himself to possible serious injury. To prevent such unsafe operation of the machine and in accordance with the teachings of this invention, applicant provides a safety interlock which prevents operation of punch press ICC 1 unless wristlets 12 and 13 are properly worn by the operator.

Referring now to Figs. 1 and 2, it is seen that wristlet 12 is provided with an electrode 15 on its inner face so that when the wristlet is strapped in place electrode 15 engages the normally moist skin of the operator. Cable 10 is attached to wristlet 12 and carries therewith conductor 16 which leads to an external circuit subsequently described. Wristlet 13 is similar to wristlet 12 and is provided with an electrode 17 which is connected to an external circuit by conductor 18 which can be carried by cable 11. As most clearly seen in Fig. 2, wristlets 12 and 13 are bands of leather which adjustably engage the operators wrist through the action of buckle fasteners 19. As hereafter described more fully, electrodes 15 and 17 are made from dissimilar metals.

Referring now to Fig. 3, it is seen that an alternative embodiment of applicants invention utilizes a single wristlet in which two electrodes 20 and 21 are carried by the adjustable leather band or wristlet 22. Connection to the external circuit is established by conductors 23 and 24 and attachment to a safety cable 25 can be established by eyelet 26 fastened to the wristlet.

Referring now to the drawings in general and particularly Figs. 1 and 4, it is seen that electrodes 15 and 17 are connected to amplifier 30 through wires 16 and 18. It has been found that it is not necessary, however, to utilize separate conductors since the steel pull on cables can be used to transmit the signal. Amplifier 30 is of any common type, the only requirement being that it be capable of sensing the potential between elec trodes 15 and 17 and producing an output responsive to this potential which is of a sufiicient amplitude to operate a safety device. Amplifier 30 is energized from a suitable power source 31 through amplifier power sup ply connections 32 and 33. The output of amplifier 30 is connected to safety device 35 through connections'36 and 37. As most clearly seen in Fig. 1, the safety device generally designated as 35 in Fig. 4 is a solenoid 38. Solenoid 38, when energized, withdraws locking pin 40 from notch 41 in operating bar 42 thereby releasing treadle 4 for movement to operate punch press 1.

In operation, electrodes 15 and 17, when strapped on the wrists of the operator, establish a low potential between them because of the electrolytic action experienced when dissimilar metal electrodes are placed in contact with an electrolyte. The saline nature of moisture normally present on the surface of human skin acts as the necessary electrolyte in this invention. This potential difference will produce a minute current in the input of amplifier 30 which is amplified to actuate the safety device 35 (relay 38 in Fig. 1). The selection of metal for electrodes 15 and 17 can be made from the Table of Electrode Potential Series as set forth in International Critical Tables, volume 6, McGraw Hill Book Company, 1929. Any two metals from this series will exhibit a potential difference between them when in contact with an electrolyte. It has been found, however, that zinc and silver provide the best operating electrodes since they are reasonably inexpensive, not subject to excessive body action corrosion and produce a substantial potential difference by comparison between them. It has also been found that additional metals such as aluminum, gold and rhodium can be utilized with reasonable success.

Fig. 3 illustrates a wristlet containing two electrodes thereby permitting one-hand closure of the interlock circuit to control the operation of a machine. Fig. 3 also most clearly illustrates the use of mesh as the electrode. It has been found that the use of a mesh electrode not only permits intimate contact with the skin, but also can be used to greatly improve the mechanical strength of the 3 wristlet as, for example, by fastening the pull out cable 25 to the mesh.

It is therefore seen that this invention provides a reliable safety interlock that is sensitive to contact with human skin and that is ideally suited for use in a great many safety applications where reliability, comfort to the user, and size are of great importance.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above describedwill become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

l lai 1. A safety device for power operated machines comprising a plurality of dissimilar metal electrodes, means for positioning said electrodes in contact with the normally moist skin of the machine operator thereby to establish an electrolytic potential between the electrodes, means electrically connected to said electrodes for amplifying the electrolytic potential established therebetween,

and means for controlling the operation of the machine, said last named means being operable by the output of said amplifier thereby to permit machine operation only when said dissimilar metal electrodes are in engagement with the skin of the operator.

2. A safety device for power operated machines comprising a plurality of dissimilar metal electrodes, a wristlet for positioning said electrodes in contact with the normally moist skin of the machine operator thereby to establish an electrolytic potential between the electrodes, means electrically connected to said electrodes for amplifying the electrolytic potential established therebetween,

and means for controlling the operation of the machine, said last named means being operable by the output of said amplifier thereby to permit machine operation only when said dissimilar metal electrodes are in engagement with the skin of the operator.

4 3. A safety interlock for presses and the like having a pair of wristlets that are, cable actuated by the press to withdraw the hands of the operator from the press operating area, said interlock comprising a first electrode positioned in one of the wristlets and engageable with the skin of the operatona second electrode positioned in the other of the wristlets and engageable with the skin of the operator, said first and second electrodes being made of dissimilar metals, an amplifier having input terminals connected to saidelectrodes thereby to amplify the electrolytic potential produced by contact of the electrodes with the normally moist skin of the operator, :1 safety device operable to permit press operation and means connecting the output of said amplifier to said safety device thereby to prevent operation of the press unless the electrodes carried by the wristlets are in engagement with the skin of the operator.

4. A safety device as set forth in claim 1 wherein each of said electrodes is made from a flexible metal mesh.

5. The safety device as set forth in claim 1 wherein said plurality of dissimilar metal electrodes includes at least one electrode made of zinc and a second electrode made of silver.

References Cited in the file of this patent UNITED STATES PATENTS 371,553 France Jan. 26,

US768594A 1958-10-21 1958-10-21 Safety interlock Expired - Lifetime US2978084A (en)

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Cited By (46)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047116A (en) * 1958-08-27 1962-07-31 Rockwell Standard Co Safety device for power presses
US3289671A (en) * 1963-09-11 1966-12-06 Troutman Edwin Glenn Iontophoresis method
US3522868A (en) * 1969-01-31 1970-08-04 Bretford Mfg Inc Supplemental safety device for press
US4566457A (en) * 1982-08-04 1986-01-28 Gunter Stemple Defibrillator circuit and electrodes therefor
EP0362937A2 (en) * 1988-10-04 1990-04-11 Giorgio Grasselli Safety control system for power operated equipment
US4965909A (en) * 1988-10-04 1990-10-30 Mccullough Timothy J Safety control for power operated equipment
FR2658586A1 (en) * 1990-02-20 1991-08-23 Barbagli Andre System of security and industrial protection.
US5198702A (en) * 1990-03-07 1993-03-30 Mccullough Timothy J Control and safety system for electrically operated devices
US5272946A (en) * 1992-03-20 1993-12-28 Food Industry Equipment International, Inc. Safety control system for power operated equipment
US5510685A (en) * 1993-07-29 1996-04-23 Grasselli; Giorgio Electric motor control based on conductive contact of machine component with operator for injury prevention
US20020017176A1 (en) * 2000-08-14 2002-02-14 Gass Stephen F. Detection system for power equipment
US20020017336A1 (en) * 2000-08-14 2002-02-14 Gass Stephen F. Apparatus and method for detecting dangerous conditions in power equipment
US20020020265A1 (en) * 2000-08-14 2002-02-21 Gass Stephen F. Translation stop for use in power equipment
US20020059854A1 (en) * 2000-09-29 2002-05-23 Gass Stephen F. Miter saw with improved safety system
US20020069734A1 (en) * 2000-09-29 2002-06-13 Gass Stephen F. Contact detection system for power equipment
US20020190581A1 (en) * 2001-06-13 2002-12-19 Gass Stephen F. Apparatus and method for detecting dangerous conditions in power equipment
US20030002942A1 (en) * 2001-07-02 2003-01-02 Gass Stephen F. Discrete proximity detection system
US20030005588A1 (en) * 2001-07-03 2003-01-09 Gass Stephen F. Actuators for use in fast-acting safety systems
US20030020336A1 (en) * 2001-07-25 2003-01-30 Gass Stephen F. Actuators for use in fast-acting safety systems
US20030115804A1 (en) * 2000-03-15 2003-06-26 Goran Sundolm Fire door and a fire protection system
US6813983B2 (en) 2000-09-29 2004-11-09 Sd3, Llc Power saw with improved safety system
US6880440B2 (en) 2000-09-29 2005-04-19 Sd3, Llc Miter saw with improved safety system
US6945148B2 (en) 2000-09-29 2005-09-20 Sd3, Llc Miter saw with improved safety system
US6994004B2 (en) 2000-09-29 2006-02-07 Sd3, Llc Table saw with improved safety system
US7000514B2 (en) 2001-07-27 2006-02-21 Sd3, Llc Safety systems for band saws
US7077039B2 (en) 2001-11-13 2006-07-18 Sd3, Llc Detection system for power equipment
US7197969B2 (en) 2001-09-24 2007-04-03 Sd3, Llc Logic control with test mode for fast-acting safety system
US20070240786A1 (en) * 2000-08-14 2007-10-18 Gass Stephen F Motion detecting system for use in a safety system for power equipment
US7481140B2 (en) 2005-04-15 2009-01-27 Sd3, Llc Detection systems for power equipment
US7610836B2 (en) 2000-08-14 2009-11-03 Sd3, Llc Replaceable brake mechanism for power equipment
US7707920B2 (en) 2003-12-31 2010-05-04 Sd3, Llc Table saws with safety systems
US7784507B2 (en) 2000-09-29 2010-08-31 Sd3, Llc Router with improved safety system
US7788999B2 (en) 1999-10-01 2010-09-07 Sd3, Llc Brake mechanism for power equipment
US7827890B2 (en) 2004-01-29 2010-11-09 Sd3, Llc Table saws with safety systems and systems to mount and index attachments
US7832314B2 (en) 2000-08-14 2010-11-16 Sd3, Llc Brake positioning system
US7836804B2 (en) 2003-08-20 2010-11-23 Sd3, Llc Woodworking machines with overmolded arbors
US7921754B2 (en) 2000-08-14 2011-04-12 Sd3, Llc Logic control for fast-acting safety system
US7991503B2 (en) 2003-12-31 2011-08-02 Sd3, Llc Detection systems for power equipment
US8061245B2 (en) 2000-09-29 2011-11-22 Sd3, Llc Safety methods for use in power equipment
US8065943B2 (en) 2000-09-18 2011-11-29 Sd3, Llc Translation stop for use in power equipment
US8100039B2 (en) 2000-08-14 2012-01-24 Sd3, Llc Miter saw with safety system
US20120152072A1 (en) * 2010-12-17 2012-06-21 Jeff Buchanan Wearable safety device for cutting machine
US8459157B2 (en) 2003-12-31 2013-06-11 Sd3, Llc Brake cartridges and mounting systems for brake cartridges
WO2015025069A1 (en) * 2013-08-20 2015-02-26 Jose Maria Martinez Sanchez Device for preventing work accidents
US9724840B2 (en) 1999-10-01 2017-08-08 Sd3, Llc Safety systems for power equipment
US9927796B2 (en) 2001-05-17 2018-03-27 Sawstop Holding Llc Band saw with improved safety system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US505561A (en) * 1893-09-26 Electrical connection
FR371553A (en) * 1906-11-16 1907-03-11 Charles Chardin electrode for medical applications currents
US1889271A (en) * 1931-04-22 1932-11-29 Gustav A Zerne Electrical contact pad
US2013441A (en) * 1934-10-12 1935-09-03 Clarence M Goff Safety device for power presses
US2815749A (en) * 1953-11-30 1957-12-10 Nathan H Friedman Electrocardiographic contact attachment

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US505561A (en) * 1893-09-26 Electrical connection
FR371553A (en) * 1906-11-16 1907-03-11 Charles Chardin electrode for medical applications currents
US1889271A (en) * 1931-04-22 1932-11-29 Gustav A Zerne Electrical contact pad
US2013441A (en) * 1934-10-12 1935-09-03 Clarence M Goff Safety device for power presses
US2815749A (en) * 1953-11-30 1957-12-10 Nathan H Friedman Electrocardiographic contact attachment

Cited By (76)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047116A (en) * 1958-08-27 1962-07-31 Rockwell Standard Co Safety device for power presses
US3289671A (en) * 1963-09-11 1966-12-06 Troutman Edwin Glenn Iontophoresis method
US3522868A (en) * 1969-01-31 1970-08-04 Bretford Mfg Inc Supplemental safety device for press
US4566457A (en) * 1982-08-04 1986-01-28 Gunter Stemple Defibrillator circuit and electrodes therefor
EP0362937A2 (en) * 1988-10-04 1990-04-11 Giorgio Grasselli Safety control system for power operated equipment
US4965909A (en) * 1988-10-04 1990-10-30 Mccullough Timothy J Safety control for power operated equipment
EP0362937A3 (en) * 1988-10-04 1992-03-11 Giorgio Grasselli Safety control system for power operated equipment
FR2658586A1 (en) * 1990-02-20 1991-08-23 Barbagli Andre System of security and industrial protection.
WO1991013285A1 (en) * 1990-02-20 1991-09-05 Barbagli Andre Industrial protection and safety system
US5198702A (en) * 1990-03-07 1993-03-30 Mccullough Timothy J Control and safety system for electrically operated devices
US5272946A (en) * 1992-03-20 1993-12-28 Food Industry Equipment International, Inc. Safety control system for power operated equipment
US5510685A (en) * 1993-07-29 1996-04-23 Grasselli; Giorgio Electric motor control based on conductive contact of machine component with operator for injury prevention
US9969014B2 (en) 1999-10-01 2018-05-15 Sawstop Holding Llc Power equipment with detection and reaction systems
US9925683B2 (en) 1999-10-01 2018-03-27 Sawstop Holding Llc Table saws
US9724840B2 (en) 1999-10-01 2017-08-08 Sd3, Llc Safety systems for power equipment
US9522476B2 (en) 1999-10-01 2016-12-20 Sd3, Llc Power equipment with detection and reaction systems
US10335972B2 (en) 1999-10-01 2019-07-02 Sawstop Holding Llc Table Saws
US8408106B2 (en) 1999-10-01 2013-04-02 Sd3, Llc Method of operating power equipment with detection and reaction systems
US7895927B2 (en) 1999-10-01 2011-03-01 Sd3, Llc Power equipment with detection and reaction systems
US7788999B2 (en) 1999-10-01 2010-09-07 Sd3, Llc Brake mechanism for power equipment
US8196499B2 (en) 1999-10-01 2012-06-12 Sd3, Llc Power equipment with detection and reaction systems
US20030115804A1 (en) * 2000-03-15 2003-06-26 Goran Sundolm Fire door and a fire protection system
US20020017336A1 (en) * 2000-08-14 2002-02-14 Gass Stephen F. Apparatus and method for detecting dangerous conditions in power equipment
US8151675B2 (en) 2000-08-14 2012-04-10 Sd3, Llc Logic control for fast-acting safety system
US8100039B2 (en) 2000-08-14 2012-01-24 Sd3, Llc Miter saw with safety system
US9038515B2 (en) 2000-08-14 2015-05-26 Sd3, Llc Logic control for fast-acting safety system
US6957601B2 (en) * 2000-08-14 2005-10-25 Sd3, Llc Translation stop for use in power equipment
US7832314B2 (en) 2000-08-14 2010-11-16 Sd3, Llc Brake positioning system
US8522655B2 (en) 2000-08-14 2013-09-03 Sd3, Llc Logic control for fast-acting safety system
US7921754B2 (en) 2000-08-14 2011-04-12 Sd3, Llc Logic control for fast-acting safety system
US20020020265A1 (en) * 2000-08-14 2002-02-21 Gass Stephen F. Translation stop for use in power equipment
US8191450B2 (en) 2000-08-14 2012-06-05 Sd3, Llc Power equipment with detection and reaction systems
US20070240786A1 (en) * 2000-08-14 2007-10-18 Gass Stephen F Motion detecting system for use in a safety system for power equipment
US7610836B2 (en) 2000-08-14 2009-11-03 Sd3, Llc Replaceable brake mechanism for power equipment
US20020017176A1 (en) * 2000-08-14 2002-02-14 Gass Stephen F. Detection system for power equipment
US7681479B2 (en) 2000-08-14 2010-03-23 Sd3, Llc Motion detecting system for use in a safety system for power equipment
US8065943B2 (en) 2000-09-18 2011-11-29 Sd3, Llc Translation stop for use in power equipment
US7377199B2 (en) 2000-09-29 2008-05-27 Sd3, Llc Contact detection system for power equipment
US6945148B2 (en) 2000-09-29 2005-09-20 Sd3, Llc Miter saw with improved safety system
US7784507B2 (en) 2000-09-29 2010-08-31 Sd3, Llc Router with improved safety system
US8186255B2 (en) 2000-09-29 2012-05-29 Sd3, Llc Contact detection system for power equipment
US6880440B2 (en) 2000-09-29 2005-04-19 Sd3, Llc Miter saw with improved safety system
US6826988B2 (en) 2000-09-29 2004-12-07 Sd3, Llc Miter saw with improved safety system
US6813983B2 (en) 2000-09-29 2004-11-09 Sd3, Llc Power saw with improved safety system
US8061245B2 (en) 2000-09-29 2011-11-22 Sd3, Llc Safety methods for use in power equipment
US6994004B2 (en) 2000-09-29 2006-02-07 Sd3, Llc Table saw with improved safety system
US20020059854A1 (en) * 2000-09-29 2002-05-23 Gass Stephen F. Miter saw with improved safety system
US20020069734A1 (en) * 2000-09-29 2002-06-13 Gass Stephen F. Contact detection system for power equipment
US9927796B2 (en) 2001-05-17 2018-03-27 Sawstop Holding Llc Band saw with improved safety system
US7231856B2 (en) 2001-06-13 2007-06-19 Sd3, Llc Apparatus and method for detecting dangerous conditions in power equipment
US20020190581A1 (en) * 2001-06-13 2002-12-19 Gass Stephen F. Apparatus and method for detecting dangerous conditions in power equipment
US20030002942A1 (en) * 2001-07-02 2003-01-02 Gass Stephen F. Discrete proximity detection system
US7712403B2 (en) 2001-07-03 2010-05-11 Sd3, Llc Actuators for use in fast-acting safety systems
US20030005588A1 (en) * 2001-07-03 2003-01-09 Gass Stephen F. Actuators for use in fast-acting safety systems
US20030020336A1 (en) * 2001-07-25 2003-01-30 Gass Stephen F. Actuators for use in fast-acting safety systems
US7000514B2 (en) 2001-07-27 2006-02-21 Sd3, Llc Safety systems for band saws
US7197969B2 (en) 2001-09-24 2007-04-03 Sd3, Llc Logic control with test mode for fast-acting safety system
US7077039B2 (en) 2001-11-13 2006-07-18 Sd3, Llc Detection system for power equipment
US7836804B2 (en) 2003-08-20 2010-11-23 Sd3, Llc Woodworking machines with overmolded arbors
US7991503B2 (en) 2003-12-31 2011-08-02 Sd3, Llc Detection systems for power equipment
US8489223B2 (en) 2003-12-31 2013-07-16 Sd3, Llc Detection systems for power equipment
US7866239B2 (en) 2003-12-31 2011-01-11 Sd3, Llc Elevation mechanism for table saws
US8498732B2 (en) 2003-12-31 2013-07-30 Sd3, Llc Detection systems for power equipment
US8122807B2 (en) 2003-12-31 2012-02-28 Sd3, Llc Table saws with safety systems
US7707920B2 (en) 2003-12-31 2010-05-04 Sd3, Llc Table saws with safety systems
US8087438B2 (en) 2003-12-31 2012-01-03 Sd3, Llc Detection systems for power equipment
US8459157B2 (en) 2003-12-31 2013-06-11 Sd3, Llc Brake cartridges and mounting systems for brake cartridges
US7827893B2 (en) 2003-12-31 2010-11-09 Sd3, Llc Elevation mechanism for table saws
US9623498B2 (en) 2003-12-31 2017-04-18 Sd3, Llc Table saws
US8505424B2 (en) 2004-01-29 2013-08-13 Sd3, Llc Table saws with safety systems and systems to mount and index attachments
US7827890B2 (en) 2004-01-29 2010-11-09 Sd3, Llc Table saws with safety systems and systems to mount and index attachments
US10052786B2 (en) 2004-01-29 2018-08-21 Sawstop Holding Llc Table saws with safety systems and systems to mount and index attachments
US7481140B2 (en) 2005-04-15 2009-01-27 Sd3, Llc Detection systems for power equipment
US9044760B2 (en) * 2010-12-17 2015-06-02 Jeff Buchanan Wearable safety device for cutting machine
US20120152072A1 (en) * 2010-12-17 2012-06-21 Jeff Buchanan Wearable safety device for cutting machine
WO2015025069A1 (en) * 2013-08-20 2015-02-26 Jose Maria Martinez Sanchez Device for preventing work accidents

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