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Zouave Thu 31 May 2012 13:19

Solid State Relay - Router control?
So, as I understand it, the PMDX sends a 5VDC signal to a relay, which turns on the router, so long as it is wired correctly. Am I understanding this properly?
If so, my main question: I am starting out with a Porter Cable 7518 router motor. It is rated as a 15Amp motor, which in theory falls under the SSR linked below...

Does the Porter Cable draw more on start-up, to the point where I would need something other than the SSR I have posted above? There is a 25Amp one available, but I am having a horrible time finding one that will mount on a DIN rail, they're all cabinet mounted, which I would like to avoid if at all possible.

At some point, I will be upgrading to a spindle, it just isn't in the budget right now, and I already have the extra Porter Cable motor lying around.

Thanks for the help.

domino11 Thu 31 May 2012 15:05

Eric, it would be ok except for the fact that the SSR is only rated for 50V DC load. NOT AC. You need a 120V AC load rated SSR.

Zouave Thu 31 May 2012 15:17

Wow, I totally mixed up the two I was looking at. One was a 10A for 24-280V, the other the 15A for 50VDC... And, of course, they don't have a 15A for 120V. -.-
Back to searching.
Thanks for pointing out my error.

domino11 Thu 31 May 2012 22:20

Eric, have you considered a super-pid instead of an ssr? It gives you closed loop speed control and the ability to turn the router on and off from Mach 3.

Super-PID Router Speed Controller

Super-PID Homepage

Richards Fri 01 June 2012 06:24

The Porter-Cable 7518 has solid state speed control, which means that it won't turn on/off well when driven by an SSR.

You might consider using an SSR or the relay on-board on your BOB to control the coil of a standard relay or contactor and then use that relay or contactor to turn the 7518 on/off. Connect the Porter-Cable to the contacts of the auxiliary relay or contactor.

Neither a relay's coil or a contactor's coil pulls much current, so be sure to test things thoroughly. If the SSR needs more current to work reliably, put a load in parallel with the coil. The load could be an indicator lamp or something else that draws 100mA or more.

Solid State Relays, especially those with zero-crossing detection, greatly prolong the life of standard incandescent lamps and other resistive loads, but they have two draw-backs. They need at least minimum load in order to turn on/off and they "leak" when turned off. The minimum load depends on the relay, but the Opto-22 relays that I often use seem to be reliable with as little as 100mA. "Leaking" means that the "load" terminal might always have some voltage, so, unlike a relay or contactor, you can get a shock if you touch a "dead" output.

When I work on a circuit that has an SSR, I always turn off the power before servicing anything driven by that SSR.

Zouave Fri 01 June 2012 12:45

Thanks for the suggestions on both. The Speed Controller looks pretty cool, I may go that direction.

Mike, I am going to be using a PMDX-126, which I'm not very familiar with just yet (printed the manual last night, haven't had a chance to read it through yet). Does the relay on-board work to control something like this:
16A (15A Router), 120VAC

I am having difficulty finding what the voltage requirement is to trigger the contactor, so I'm really not sure if that's what we're looking for. Unfortunately, contractors and relays are a little beyond my level of knowledge (which is just barely above a semi-trained monkey with a battery and a paperclip) :-D so I am working my way through this and trying to understand how they all work, but understanding all of the terminology is tricky sometimes.

MetalHead Fri 01 June 2012 14:05

The 126 can handle 30 Amps straight from the board to start a router. No other circuit needed. That should be covered in the 126 documents or in the "aditional information" on the PMDX website.

If you don't like "direct to the 126 link" you can used the coils on the 126 board to set a latch on a 120v coil of a standard contactor like the one we use on the control box. No need for electronic relays at all (accept the one on the PMDX-126).

Yet another option is to use the PMDX 104 relay board that gives you 4 control circuits at 5 amps each 120 volts. These are plenty to set the latch on the contactor coils.

So you feed power into the primarys of the contactor (I say down stream from your master cut off switch on the control box) then wire the coil of that contactor to the 126 (or 104) board to turn that power path on or off to the router/dust vac/whatever . Remember the contactor can support 220v feed throughs but only need 110v to set the coil (That is if you ordered a contactor with a 110v coil). Also note doing this that all current runs through the contactor and not the PMDX boards

Zouave Fri 01 June 2012 15:02

I would like to keep the router circuit separate from the PMDX, so that when/if I switch over to a spindle, I can deal with whatever amperage/voltage requirements I have on the DIN rail, and not have to worry about whether it matches up with the PMDX. Which, it probably would anyway, but for my sanity, keeping it in a discrete circuit makes things easier. What else might you use the control circuits for? Adding 4 seems a bit excessive, but I simply may not be looking far enough ahead.
I do like being able to run 220 through, so the contactor seems like the most attractive option at the moment. Any suggestions for one other than through FactoryMation's site? The one I would get from there is backordered.

danilom Fri 01 June 2012 17:02

For the spindle you don't have to think about contactor as thats done with a vfd and you can control him by simple relay to short the RUN input or modbus etc...
So if you are now using a router design the system that matches him, nevertheless its good to separate everything from BOB and using relay to switch on the contactor is best way to start it.

MetalHead Fri 01 June 2012 22:45

Look up this number on Factory site or one like it. They do not carry the old ones like we used to use any longer.


To set up to two realys like the one above you can use the PMDX without the 104 boards.

Also to control the spindle in the future you would/could use the PMDX-107 board.

Red_boards Wed 04 July 2012 04:43

I'm using the PMDX, but I think that the 126 is very similar. In the MDX 125 it's specified that there are two one board relays. One is a N/O contact rated at 10A, the other is either N/O or N/C rated at 30A. The second also has a metal oxide varistor that helps absorb inductive voltage spikes.

I'm planning on using the relay directly to replace the off-board system I've been using.

So my question builds on Eric's.
  • Do I just route the live wire from power via the e-stop circuit through the relay to the router (I'm using a Makita 3612).
  • Can I lock the router switch on or should I remove the switch all together?
  • How do I remove the switch and retain the noise suppresion circuit?

bradm Wed 04 July 2012 08:27

Assuming you're clear on keeping the high voltage and low voltage pieces separate, then yes, route the live as you stated.

I prefer to leave the router switch in place in the on position. I can then turn it off as a failsafe when changing bits. That assumes there is nothing that prevents the router from being switched on and off by it's supply, which I think is the case with a base level 3612.

Zouave Wed 04 July 2012 08:46

I am actually going to have two switches on mine. The first one will be on the control box, the second on the Y-car. Other than those, I will have a contractor that is operated by the Pmdx. Doing so isolates the router power from running through the Pmdx, gives me multiple legends of safety, and a lot of convenience to shut off the router, while retaining control of it through Mach 3. Then I can leave the router switch locked on and never have to touch it.
Not sure what you mean by routing the wire for the estop to the router. On my setup, the 120v line that the estop goes off of is my Line 1 through the contractor. Line 2 is for the router. But I have 220 (Well, American 220 at least) coming into my enclosure. So two hot lines of 110v.

KenC Fri 13 July 2012 00:47

Do you also put a fuse in front of another fuse to have extra layer of protection?

Zouave Fri 13 July 2012 01:31

I worked at a woodworking store and saw people with missing digits every single day. When it comes to a tool that removes fingers, i want to make sure it doesn't come on when i don't want it to.

KenC Fri 13 July 2012 02:04

Practicing safe working habit. Human error is human error.

Surfcnc Sat 14 July 2012 05:48

Hi Eric

I agree with Ken on this one and would encourage you to rethink your switching design.
While you are attempting to make a system more safe by using more switches in practice this is not the case.
The reason for this is that the second switch introduces more complexity and it is that additional complexity in the design that leads to an increased probability with user error.
While it might intuitively seem that more "off" states in the switches would impart more safety, in fact it increases the probability of the state of the switching system being unknown over a simple on or off system.

This is not be be confused with a system lock out switch that would disable the whole of a system universally. If you are intent on introducing a good level of safety into the system, i would advocate the use of this strategy rather than locking out sub components of the whole system.


Gerald D Sat 14 July 2012 07:19

Some years ago somebody posted a picture of their collet wrench being used to close part of the router/spindle circuit.....he probably has another old wrench permanently in there by now.......

Surfcnc Sat 14 July 2012 07:27

Ha ha. Sounds very safe to me as long he always stood in a puddle of water to provide additional protection.

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