Re: [Emc-users] estop switch question
On 6/25/2011 11:29 AM, David wrote: >>> So, it is like the most useless machine, where one flips a toggle and >>> then it immediately shuts itself off? The difference being that the >>> saw is a useful machine. >>> >> Yes, but that would be safe. ;-) >> >> My 7x12 horizontal bandsaw has the same setup as described. A tab of >> metal hangs down and contacts the on-off toggle switch when the saw >> swings down all of the way. >> >> It is very simple. >> >> Another way to do it electrically is to use a contactor to switch the >> motor power on and off and then construct a control circuit around the >> contact so pushing one button energized the contactor and seals it on >> with an auxilary contact, and then >> a stop button and a "saw off" switch break the seal on the contactor. >> The saw off switch would need to be normally closed, push to open etc. >> >> Here is an example of a seal-in circuit. >> http://www.allaboutcircuits.com/vol_4/chpt_6/4.html >> >> Push the Forward button and M1 stays on. Ignore the line below that >> has M2 as the output. >> >> Picture putting a normally closed stop pushbutton where the normally >> closed M2 contact is, and also put in series a normally closed saw stop >> switch. >> >> You lift the saw and push the start button, M1 comes on and stays on and >> the saw runs, you push the stop button or the saw closes (contacts the >> saw stop switch) and the saw goes off. >> >> The OL normally closed contact to the far right is the motor overload >> contact for M1, which is not needed to create the functionality you want. >> >> The wiring shows it being driven by L1 and L2 which normally means line >> voltage, usually 230 volts and up in the US, but the same thing could be >> done with 24 volts DC or AC. >> >> Dave >> > Hi, > > The original power switch arrangement used the toggle switch but had to be > changed when the requirement in certain jurisdictions became that the saw did > not restart after a power outage. > > The people making these saws changed the power switch to a double button > arrangement with a magnetically latching "ON" button and a separate "OFF" > button in a small plastic pod near where the toggle switch was previously > located. > > The action of these was arranged similar to the toggle switch with the saw > starting when the "ON" button was pressed and the tab of metal on the saw > frame pressed the "OFF" switch at the end of cut. > > This is somewhat less satisfactory when you need to switch the saw off from > the > button panel especially close to the end of cut. - better to switch off at the > power switch? > > If you wished to go all stops out the ultimate setup I saw on a site > recommending changes to the circuitry for use in schools saw a "Klockner > Moeller" surface mount emergency stop button (big red and about 150 mm dia) > mounted on the free end of the saw and a "Telemechanique" direct on line > starter (DOL) in surface mount on the frame above the hinge. The DOL starter > had on/ off buttons as part of the package. > > As this starter was a three phase unit, the usual arrangement of converting to > single phase use by looping the active through two poles of the contactor and > the neutral through the third would need to be adopted to defeat the single > phasing protection of the thermal cutout. > > >>If you wished to go all stops out the ultimate setup I saw on a site recommending changes to the circuitry for use in schools saw a "Klockner Moeller" surface mount emergency stop button (big red and about 150 mm dia) << Ahh I could do much better than that;-) How about a horn attached to the circuitry that beeps for 5 seconds warning all around that the saw is about to start up... then once the saw starts running a flashing yellow light comes on to warn people that the saw is actually running. We could even carry it a bit further by putting light curtains around the saw just in case an idiot tries to reach into the moving blade. That would require the addition of a brake on the saw so it could be stopped within a millisecond of the light curtain break.Seeing that it is a light curtain, a redundant safety PLC would be a good match to insure safety system operation. I recently programmed a Siemens Safety PLC that cost about $3000, a light curtain system could cost an easy $3000, box, buttons, pneumatic brake, framework for the light curtains, 24 volt power supply... I'm guessing we are talking about $10,000 including programming. The saw could be supplied by Harbor Freight and retrofit to the application. My saw cost $699.So the entire system, along with the idiot proofing would cost roughly $10699. :-) I know this sounds outrageous, but I work around safety systems like this all of the time. Dave -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record
Re: [Emc-users] estop switch question
> > So, it is like the most useless machine, where one flips a toggle and > > then it immediately shuts itself off? The difference being that the > > saw is a useful machine. > > Yes, but that would be safe. ;-) > > My 7x12 horizontal bandsaw has the same setup as described. A tab of > metal hangs down and contacts the on-off toggle switch when the saw > swings down all of the way. > > It is very simple. > > Another way to do it electrically is to use a contactor to switch the > motor power on and off and then construct a control circuit around the > contact so pushing one button energized the contactor and seals it on > with an auxilary contact, and then > a stop button and a "saw off" switch break the seal on the contactor. > The saw off switch would need to be normally closed, push to open etc. > > Here is an example of a seal-in circuit. > http://www.allaboutcircuits.com/vol_4/chpt_6/4.html > > Push the Forward button and M1 stays on. Ignore the line below that > has M2 as the output. > > Picture putting a normally closed stop pushbutton where the normally > closed M2 contact is, and also put in series a normally closed saw stop > switch. > > You lift the saw and push the start button, M1 comes on and stays on and > the saw runs, you push the stop button or the saw closes (contacts the > saw stop switch) and the saw goes off. > > The OL normally closed contact to the far right is the motor overload > contact for M1, which is not needed to create the functionality you want. > > The wiring shows it being driven by L1 and L2 which normally means line > voltage, usually 230 volts and up in the US, but the same thing could be > done with 24 volts DC or AC. > > Dave Hi, The original power switch arrangement used the toggle switch but had to be changed when the requirement in certain jurisdictions became that the saw did not restart after a power outage. The people making these saws changed the power switch to a double button arrangement with a magnetically latching "ON" button and a separate "OFF" button in a small plastic pod near where the toggle switch was previously located. The action of these was arranged similar to the toggle switch with the saw starting when the "ON" button was pressed and the tab of metal on the saw frame pressed the "OFF" switch at the end of cut. This is somewhat less satisfactory when you need to switch the saw off from the button panel especially close to the end of cut. - better to switch off at the power switch? If you wished to go all stops out the ultimate setup I saw on a site recommending changes to the circuitry for use in schools saw a "Klockner Moeller" surface mount emergency stop button (big red and about 150 mm dia) mounted on the free end of the saw and a "Telemechanique" direct on line starter (DOL) in surface mount on the frame above the hinge. The DOL starter had on/ off buttons as part of the package. As this starter was a three phase unit, the usual arrangement of converting to single phase use by looping the active through two poles of the contactor and the neutral through the third would need to be adopted to defeat the single phasing protection of the thermal cutout. -- Regards, David -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense.. http://p.sf.net/sfu/splunk-d2d-c1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] estop switch question
> So, it is like the most useless machine, where one flips a toggle and > then it immediately shuts itself off? The difference being that the > saw is a useful machine. > > Yes, but that would be safe. ;-) My 7x12 horizontal bandsaw has the same setup as described. A tab of metal hangs down and contacts the on-off toggle switch when the saw swings down all of the way. It is very simple. Another way to do it electrically is to use a contactor to switch the motor power on and off and then construct a control circuit around the contact so pushing one button energized the contactor and seals it on with an auxilary contact, and then a stop button and a "saw off" switch break the seal on the contactor. The saw off switch would need to be normally closed, push to open etc. Here is an example of a seal-in circuit. http://www.allaboutcircuits.com/vol_4/chpt_6/4.html Push the Forward button and M1 stays on. Ignore the line below that has M2 as the output. Picture putting a normally closed stop pushbutton where the normally closed M2 contact is, and also put in series a normally closed saw stop switch. You lift the saw and push the start button, M1 comes on and stays on and the saw runs, you push the stop button or the saw closes (contacts the saw stop switch) and the saw goes off. The OL normally closed contact to the far right is the motor overload contact for M1, which is not needed to create the functionality you want. The wiring shows it being driven by L1 and L2 which normally means line voltage, usually 230 volts and up in the US, but the same thing could be done with 24 volts DC or AC. Dave -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense.. http://p.sf.net/sfu/splunk-d2d-c1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] estop switch question
On Wed, Jun 22, 2011 at 10:47 PM, Jake Anderson wrote: > Simple answer is to make the on/off switch down there a toggle switch. > Thats how ours is done, when the saw gets down there it flips the toggle > switch off, > when you want to turn it back on you flip the same switch to on So, it is like the most useless machine, where one flips a toggle and then it immediately shuts itself off? The difference being that the saw is a useful machine. -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] estop switch question
On 06/23/2011 02:31 AM, Sebastian Kuzminsky wrote: > I'm reviving an old band saw that someone donated to our hackspace. It > looks a bit like this one, but way older and junkier, and without the girl: > > http://www.oceanmachinery.com/images/kmt-band-saw.jpg > > It has an automatic shut-off switch that triggers when the saw has cut > all the way through the workpiece, like a bottom limit switch -- it just > opens the circuit that powers the motor. > > It used to have a toggle switch on the front that would let you turn the > motor on (if the saw was up off the bottom limit switch), but that > on/off switch was dead when we got it. > > We removed the broken on/off switch and jumpered the power cable there > instead, so now whenever you plug it in to the wall outlet (and lift the > saw off the bottom limit switch), the motor turns on. > > We got the machine running and cleaned it up, and now it's time for a > new on/off switch. > > I think I want a button that latches on, can be easily unlatched by > punching it (like an e-stop button), and that unlatches automatically > when the bottom limit switch (or the fuse) opens the circuit. > > Any suggestions? > > Simple answer is to make the on/off switch down there a toggle switch. Thats how ours is done, when the saw gets down there it flips the toggle switch off, when you want to turn it back on you flip the same switch to on -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] estop switch question
Hi Seb, If you have room for a relay or small contactor big enough to operate the motor, then I'd vote for the classic latching circuit. This has some examples, but it's in the form of a quiz: http://www.ibiblio.org/kuphaldt/socratic/output/acmcc.pdf That way lots of things can stop the motor, but if you want it to start again, you have to go back to the start button. Very safe. How much is the saw *with* the girl? Kim On 06/22/2011 11:31 AM, Sebastian Kuzminsky wrote: > I'm reviving an old band saw that someone donated to our hackspace. It > looks a bit like this one, but way older and junkier, and without the girl: > > http://www.oceanmachinery.com/images/kmt-band-saw.jpg > > It has an automatic shut-off switch that triggers when the saw has cut > all the way through the workpiece, like a bottom limit switch -- it just > opens the circuit that powers the motor. > > It used to have a toggle switch on the front that would let you turn the > motor on (if the saw was up off the bottom limit switch), but that > on/off switch was dead when we got it. > > We removed the broken on/off switch and jumpered the power cable there > instead, so now whenever you plug it in to the wall outlet (and lift the > saw off the bottom limit switch), the motor turns on. > > We got the machine running and cleaned it up, and now it's time for a > new on/off switch. > > I think I want a button that latches on, can be easily unlatched by > punching it (like an e-stop button), and that unlatches automatically > when the bottom limit switch (or the fuse) opens the circuit. > > Any suggestions? > > -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] estop switch question
On 22 June 2011 17:31, Sebastian Kuzminsky wrote: > I think I want a button that latches on, can be easily unlatched by > punching it (like an e-stop button), and that unlatches automatically > when the bottom limit switch (or the fuse) opens the circuit. How about a standard NVR switch downstream of the cutoff switch? http://cpc.farnell.com/jsp/level5/module.jsp?moduleId=cpc/266810.xml -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] estop switch question
I'm reviving an old band saw that someone donated to our hackspace. It looks a bit like this one, but way older and junkier, and without the girl: http://www.oceanmachinery.com/images/kmt-band-saw.jpg It has an automatic shut-off switch that triggers when the saw has cut all the way through the workpiece, like a bottom limit switch -- it just opens the circuit that powers the motor. It used to have a toggle switch on the front that would let you turn the motor on (if the saw was up off the bottom limit switch), but that on/off switch was dead when we got it. We removed the broken on/off switch and jumpered the power cable there instead, so now whenever you plug it in to the wall outlet (and lift the saw off the bottom limit switch), the motor turns on. We got the machine running and cleaned it up, and now it's time for a new on/off switch. I think I want a button that latches on, can be easily unlatched by punching it (like an e-stop button), and that unlatches automatically when the bottom limit switch (or the fuse) opens the circuit. Any suggestions? -- Sebastian Kuzminsky -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
