# Automatic switch-on for Dust Collector



## DonJohnson (28 Oct 2014)

I recently purchased the DK6683 Chip & Dust Extractor from Rutlands, and it has reduced the sawdust mess in my garage workshop considerably.

The only negative aspect - for me - is that it is fitted with a NVR (No Volt Relay) switch, with the familiar red and green buttons and panic 'off' cover. This means I have to move from my table saw to the dust extractor just as I have got the saw set up for a cut, to switch it on - and leave the saw again after the cut to switch it off.

I prefer to switch the extractor remotely. 

So, WITH THE MAINS DISCONNECTED, I removed the two screws securing the NVR unit, which could then be pulled out slightly so as to see the connections. There are a pair of blue wires, and a pair of red/brown wires, which were pushed onto connections in the NVR using 1/4 inch Lucas spade-type connectors. I pulled these four spades connectors off the NVR.

I obtained some of the male versions of these spade connectors - the insulated type - and crimped them onto the ends of two lengths of about 2 inches of of wire, one blue and one brown, taken from 5A flexible mains cable. The brown one was used to connect together the two red/brown wires on the dust extractor, and the blue one the two blue wires. I ensured that the male connectors were pushed right into the spades so that they were covered by the insulated boots on each spade. There was room in the housing to push the linked wires inside, and then to fit the NVR back with its two screws. The body of the NVR and the recess in which it lives is all made of plastic, so there is little chance of any shorts occurring if the connections are made carefully. As expected, the extractor then started up immediately its plug was inserted into a mains socket.

To provide remote control, I used a remote 13A switchable socket I purchased from Lidl some years ago. The switchable socket plugs into a mains socket, and the extractor plug goes into it in turn. I can now leave the switchable socket control on the saw (or in my pocket), and operate it from the saw (or other machine) without having to go to the extractor. Similar products to my Lidl version can be found on EBay (Remote Control Socket Wireless Switch Home Mains UK Plug AC Power Energy Outlet) for about £6.50. 

I hope that this may be helpful to others, but the above explanation of the procedures I undertook are best carried out by someone qualified to deal with electrics, and I take no responsibility for any accidents occurring to persons who follow them but are not competent to know what they are doing.


----------



## Eric The Viking (31 Oct 2014)

I have mixed feelings about this.

I have just the same problem, probably worse because my workshop is full of clutter and it's a PITA to reach the buttons of the DX unit. I have a push stick labelled "DX". 

But I am remoting it and I've taken a slightly different route to you:





There's just room inside this to fit the circuit board of a remotely-switched mains socket. That's what I'm doing, then I'll remove the NVR altogether from the dust extractor, and fit the new switch onto the front of the box, over the hole made by removing the NVR.

It needs to be a plastic case, otherwise the signal won't reach the receiver. I'm replacing the channel selector switches with solder links (my controller has five pairs of on/off switches, so I can dedicate one channel).

This way, I get to keep a local switch on the machine. There will be a warning added to the front about only clearing blockages with the power removed though, as it has heavy metal vanes on the fan (would take no prisoners). Ideally, I'd prefer the remote switch to be downstream of the NVR switch, but it's not possible mechanically. The biggest weakness is that this is only a single-pole switch, but I can't find an inexpensive double-pole one.

I'm not comfy without there being a switch local to the machine, so I can check for "off-ness" before poking around. I'd be_ very_ uncomfortable if the 'on' switch could be hidden and remotely operated, for example by a curious child, or even someone else's controller nearby (there are a very limited number of channels). Yes, you can pull the plug (and you should), but even so...

Like yours, it's also a reversible mod, should I ever sell the DX machine.


----------



## shipbadger (31 Oct 2014)

Hi all,

I still have my extractor and cyclone cluttering up my workshop until I have built a lean to outside for it. One of the things that I knew I had to do was to provide for switching on and off remotely and had envisaged mounting the NVR in a box on the wall and then running the cables back to the machine. Following something I read on another thread last week I bought the wireless switches from Tool Station (pack of three) mentioned on another thread. Originally I wanted it for the Trend T30 but trials with the Jet chip extractor shows that they are perfectly capable of running that as well. Now I have no need to disturb the factory wiring 

Tony Comber


----------



## Eric The Viking (31 Oct 2014)

shipbadger":3mugikjg said:


> Hi all,
> 
> I still have my extractor and cyclone cluttering up my workshop until I have built a lean to outside for it. One of the things that I knew I had to do was to provide for switching on and off remotely and had envisaged mounting the NVR in a box on the wall and then running the cables back to the machine. Following something I read on another thread last week I bought the wireless switches from Tool Station (pack of three) mentioned on another thread. Originally I wanted it for the Trend T30 but trials with the Jet chip extractor shows that they are perfectly capable of running that as well. Now I have no need to disturb the factory wiring



Fair enough. But that can only work if the DX doesn't have an NVR switch. If it does, your remote can only be an 'off' switch, unless you modify the DX. That's the problem I had. 

With my 'shop vacuum, the remote switch is fine for both functions without alterations. As such it's good for the mitre saw, routers (and router table), bandsaw, biscuit joiner, morticer and sanders. The planer needs the big DX, and it's easier to use it for the tablesaw, too, although that really doen't need that much extraction.

E.


----------



## shipbadger (31 Oct 2014)

Eric,

From what you say does that mean that the Jet extractor's switch is not actually a NVR device. It has two big buttons for on-off but not the big round kill button typically found on NVR switches. All I did was turn it on and from then on use the remote to turn it off and on. So from what I understand from your comment if the original was not an NVR switch then it works. The only slight doubt I have is that there is a high current draw on start up (I think, as occasionally it trips the mcb) and this may effect the wireless switch in time.

Tony Comber


----------



## Eric The Viking (31 Oct 2014)

NVR = "No-Volt Release"
In other words, there's a spring inside. You turn it on against the spring (there's an electromagnet that comes on too, to grab it and hold it on), and whenever the power is taken off the machine, the spring pushes the switch to 'off' as well. The only purpose of a NVR switch is to stop power coming on unexpectedly.

There are other types of safety switch (e.g. stop 'mushrooms'), that may or may not also be NVR switches.

The acid test:


Turn the machine on. 
Pull out the mains plug, but don't manually operate any switches, anywhere.
Put the plug back in (again don't touch any switches).

If the machine comes on again by itself, whatever is fitted to it is NOT an NVR switch.

There's an increasing trend towards NVR switches on everything workshop-ish, if it's a static (bench or free standing) tool. You can argue that's quite unnecessary, for example on a small grinder, AND the quality of cheap NVR switches can be dreadful (see threads on here about failures!), but that's what manufacturers are doing.

Older stuff tends to have a more sensible approach - if it would be dangerous coming on unexpectedly, it has an NVR switch, otherwise just a switch. Also every NVR switch I've seen, SO FAR, is double pole, meaning it isolates the tool from the mains by disconnecting both live and neutral. As long as that works, it's a good thing. You might see single pole ones as a cost reduction.

There's no substitute, safety-wise, for pulling the plug when working on a machine - cleaning or setting it up.

Regarding current surges, that shouldn't be a problem. The wear on switches is arcing across the contacts. That happens when they switch off, rather than on. 

Ideally, there should be a spark suppressor in the remote control circuitry to reduce this and/or one across the motor. It's the direct equivalent of the condensor/suppressor for the points on older petrol-engined cars (no, you can't use one of those for the mains!).
. . .
I'd expect a remote to fail fairly soon because of switch-OFF arcing in the relay. They're built for domestic TVs and stereo systems - at most a few hudred watts. The switch off spike for a workshop motor can be high voltage, and potentially high current too. That kills relays quickly.

Most, though, use standard relays that can be changed if you can use a soldering iron. It's what I'll do if I need to, as they aren't expensive.

But switch-off arcing can still be a problem. A few years ago I tried to make a brake for my mitre saw using the back-EMF (when you release the trigger) as an electromagnetic brake. The principle works just fine, but a big saw blade has a lot of kinetic energy stored in it, that gets translated into a big power spike when it switches off.

I made a test rig, dumping said energy into an ordinary mains lightbulb when you released the saw's trigger. I blew several bulbs with a big flash of light (25W then 40W)*. The circuit was fine theoretically, but the relay I used would have only lasted a few weeks at most, so I've shelved the idea, as it needs 'clever' switching to work properly.

E.

*the bulbs were momentarily connected across ONLY the saw's spinning, unpowered motor, NOT to the mains at all.
Physics is fun


----------



## shipbadger (31 Oct 2014)

Eric,

Thanks for explaining. The only point I'd add is that in this case each remote switch claims to be rated at 13A, rather more than those intended for hi-fi use I expect. I think I'll leave it in place and see if it does fail, (if it does I'll report back). After all I only needed one for the T30 vac, the other two came as a bonus as there are three in the box so I've nothing to lose, but possibly something to gain if it doesn't fail.

Tony Comber


----------



## DonJohnson (31 Oct 2014)

An unexpected application of the remote switching is that I can leave my garage door open this evening, with the DC near the front of the dark interior. When the local kids come Trick or Treating, I can turn the DC on - producing an appropriate howling noise as it starts up. I've put a small light to come on inside the filter bag, and will pin a pumpkin face design printed on transparent film to the bag, so that a horrible face will rise up as the howl starts. Should give some of the kids a scare !


----------



## Eric The Viking (31 Oct 2014)

Shipbadger, I thinlk they have to claim that rating because they are switching 13A plugs and sockets and there is no fuse.

But two things:

1. That'll be resistive load - inductive loads such as motors cause arcing far more than resistive loads do.

2. I expect if you look at the relay inside you'll probably see a lower rating. The one I'm using for my DX has an interesting muddle written on the relay: 


```
16A @ 250 VAC, 
20A @ 125VAC (this is stupid!), but 
1hp @ 250VAC.
```

Ignore the 120V rating - it's stupid, as I said. Being generous, 1hp is about 800W, which is only 3.3A at 240V. So why the obvious discrepancy? Because the horsepower thing is there to take inductive loads into account (in a crude way). The thing has the potential to wear out rapidly if you put a 3hp motor onto it (which I'm about to do!).

And the third thing is they are _designed_ for hi-fi, table lights, etc. Given that's how they're sold, the makers don't expect many failures because of overload or big motors. It's a game of statistics for them - failures are acceptable if the product cost is low enough.


----------

