#31
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Hi Gerald,
you say "Our MechMate has 2 "contact blocks" under each E-Stop head/operator. Both contacts are normally closed (NC) - pushing the E-stop opens both contacts.....and holds them open until the head/operator is released. One contact block opens the main contactor and therefore carries 110/220V mains power. " Is this the main power into the box? So in theory this kills all power to the system, both to the controller card, the amplifier power, controller power for geckos and pmdx and spindle? This would still leave power on the capacitors on the power supply? I'm sorry I'm not very good at reading those wiring diagrams. I wonder if a single contact block connected to several relays would do the same job and you could selectively choose what the E-stop actually kills. Cutting tool and DC power to the motors should be enough in addition to the signal to the controller, no? |
#32
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Havard,
"One contact block opens the main contactor and therefore carries 110/220V mains power. " Notice that the N/C switch opens the circuit to the coil of the contactor. It does not have to carry very much current. As to your question about using multiple relays, you could easily adapt the same principle to control several self-latching contactors to selectively disable various circuits such as: - One contactor controlling the router/spindle - One contactor controlling the vacuum hold-down Anyway, you get the idea. Cutting the power between the capacitor and the Gecko stepper controllers was something that I suggested a little while ago; however, it is NOT a good idea. Although it would immediately stop the stepper motors, it would also cause extremely high currents to flow through the Gecko (several hundred amps). Doing that repeatedly would destroy the Gecko stepper controllers. Mariss personally answered the telephone when I called Gecko support to ask for their opinion. He led me through several mathematical equations so that I could see how much current would have to be dumped through the stepper controllers. He suggested cutting the power to the break-out board or opening the circuit that provides step pulses to the Gecko. Opening the circuit that provides step pulses would require having a contactor or other circuitry with at least four circuits. So, doing things the way that Gerald does would work very well without adding a lot of complexity to the system. |
#33
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Quote:
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#34
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Quote:
Checking factorymation's web site, their WEG pushbuttons, double contact block is NO on one side and NC on the other side. Haven't found a double contact block with 2 NC switches. I know this is pretty easy stuff, but what the heck am I missing? I do understand why you would want to separate the two voltages and the purpose of shielded cable. Is there a block diagram or schematic of the E-stop circuit. The BOB circuit is easy to understand, but I want to make sure I understand the main power E-stop. Greg |
#35
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OK, I found a circuit that shows the main E-stop (couldn't post schematic, but that's just me). I'm not getting how the two contacts on the one pushbutton operator fit together or how you physically mount them as far apart as possible.
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#36
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Greg, I think you missed the bit in brackets "(if your style of E-stop allows it)"
The Lovato range of actuators and contacts allow 3 contacts side-by-side. For the E-stop, I leave the middle position blank. |
#37
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Its amazing what a good nights sleep will do for you.
I get it. My E-stop push button operator will "accomadate up to two actuators" (from the spec sheet). I'll get two NC actuators. I new this should've been easy. I even get where this all fits in Mike N. and Gerald's electrical schematic. Thanks Gerald, Greg |
#38
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Greg, there is confusion in the terminology. Operator and actuator are normally one and the same thing. The stuff underneath are called the contact blocks. The spec sheet should be saying accommodate up to two contact blocks, and you should be getting 2 NC contact blocks.
If you put your whole shopping list here, we can tear it to pieces... Factorymation catalogue: http://factorymation.info/catalog/fmcat_pb.pdf (940kB) Factorymation's WEG range (supposedly ex-Brazil) looks remarkably similar to our Lovato range (supposedly ex-Italy)? |
#39
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Thanks Gerald,
I'll do the list this weekend. I just need to slow down a little and make sure my terminology is correct. Sorry. I did place orders for the PMDX-122 BOB, the 4 Gecko G203V drives, and 4 PK296A1A-SG7.2 stepper motors, last night. I'll order the Antek power supply today (if I don't get to busy with my day job) My wife is also helping, she came home with a new computer for the shop! What a gal . Greg |
#40
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Maybe J.R. has updated his spreadsheet of his shopping list and we can compare?!?!.
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#41
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Gerald / Anyone
On the E-Stop operator, there are two contact blocks. One for the low voltage PMDX BOB. The other is for the 115 VAC circuit. On the 115 VAC circuit, does the contact block attached to the E-Stop need to be rated for higher current? I didn't see any voltage/current rating in the contact block spec sheet. I don't think there is a difference, since the contact block is wired to the contactor for the mains. The contactor switching the mains takes the full load and not the contact block attached to the E-Stop. Just need verification. On the contact blocks for the E-Stop, do I what delayed break or not. Not sure what the difference is. |
#42
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The current ratings are not an issue - your thinking is correct.
If you are stacking various contact blocks under one pushbutton, and you want to be sure that a block is the last one to break as you push the button downwards, then you need a delayed break. We don't need this for E-stops. |
#43
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Thanks Gerald,
I'm putting together my "small parts" material's list for the "kitchen" project. I'm upping the current rating for the mains contactor (TECO IEC Contactor) from 16 A to 22 A. I'm going to want to (I think thats proper english ) test the limits of this beast. If all 4 steppers draw 5.5 amps (total) and the router is making a deep cut at 15 amps, then I think 16 amps is low. |
#44
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Small Parts List
Greg,
Did you ever come up with a small parts list? I'm virtually finished with the mechanical stuff and now I'm ready to start ordering the electrical pieces. Lots of decisions to make. I'd feel much better if Gerald had blessed off on the stuff I need for a 203V system if he will agree to do so. If you don't have a completed list, I'll try to put one together over the next few days. |
#45
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Doug,
Yea, I have an excel spreadsheet. Let me make the corrections (and clean it up) to what I actually ordered. Should only take me 1/h hour and I'll try to upload tonight. Have to go into town (post office) to pickup the bearings for J.R.'s skate, and look for a drill press vise. Been so busy with other things, that I havn't had time to work on this project. Greg |
#46
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Doug,
It didn't take as long as I thought. What's your email address (send it by PM) and I'll email the excel file. Greg |
#47
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Hi Greg
How is your design for your "skate" coming along, I am also in the process of designing my own and would appreciate a look at your ideas. Regards Al |
#48
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Hey Alan,
The design is getting near completion. Drawings and all. I just haven't had the time to work on it. It's a 3 day holiday weekend on my side, so I'll finally get to have some fun and start working on it. I quickly put together a parts list for McMaster Carr and ordered Monday so I would have something for this weekend. I don't want to put out drawings till I've made the "skate", but I certainly don't mind sending you what I've got. If your interested, I'll send something this weekend. Greg |
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